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• Published: 06 March 2024

Plastic pollution amplified by a warming climate

• Xin-Feng Wei   ORCID: orcid.org/0000-0001-7165-793X 1 ,
• Wei Yang   ORCID: orcid.org/0000-0003-0198-1632 2 &
• Mikael S. Hedenqvist   ORCID: orcid.org/0000-0002-6071-6241 1  

Nature Communications volume  15 , Article number:  2052 ( 2024 ) Cite this article

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• Climate-change impacts
• Environmental chemistry
• Environmental impact

A Publisher Correction to this article was published on 21 March 2024

This article has been updated

Climate change and plastic pollution are interconnected global challenges. Rising temperatures and moisture alter plastic characteristics, contributing to waste, microplastic generation, and release of hazardous substances. Urgent attention is essential to comprehend and address these climate-driven effects and their consequences.

Earth’s global average temperature has increased by approximately 1 °C above pre-industrial levels with a current rate of ca. 0.2 °C per decade, primarily due to huge greenhouse gas emissions 1 . The Paris Agreement’s target of limiting global warming to 1.5 °C is projected to be breached in the near term 2 . Extreme regional heatwaves are also showing immediate and marked temperature spikes, sometimes exceeding 10 °C above normal levels 3 . In 2022, extreme heatwaves led to temperature records in many regions (e.g., 40.3 °C in the United Kingdom and 49.1 °C at Smara (Morocco)) 4 . In 2023, the trend continued with July being the hottest month ever recorded 3 . The frequency, intensity, and duration of heatwaves have all increased 5 . In Phoenix, Arizona, during July 2023, all days except one, exhibited a maximum temperature exceeding 110 °F (43 °C) 3 . The high temperatures have caused severe impacts on ecosystems and societies, including excess mortality, wildfires, and harvest failures 4 . This will get even worse in the future as heatwaves are projected to be more intense, frequent, and prolonged due to the enhanced global warming 5 , and developing El Niño conditions 6 , 7 . In addition, a warmer atmosphere increases the evaporation of moisture and, with each 1 °C rise in temperature, saturated air can hold 7% more water vapor 8 . The average moisture content of the atmosphere has increased by approximately 4% since the 1970s 8 .

Deteriorated properties and increased waste

Polymer materials, mainly plastics and rubbers, are notably sensitive to temperature and moisture fluctuations. As temperatures rise, polymers undergo thermal expansion, leading to inferior properties 9 . Commonly used plastics like polyethylene, polypropylene, and polyvinyl chloride can experience an over 20% decrease in stiffness with a service temperature rise from 23/24 to 40 °C 10 , 11 . Time-dependent changes in mechanical properties, such as creep (slow deformation process of materials under constant or varying load), and stress relaxation (the decrease in stress response under sustained deformation), will also accelerate. Furthermore, rising temperatures negatively affect other important properties, such as gas and water vapor barrier properties in food packaging, essential for food preservation. For example, ethylene vinyl alcohol, a common gas barrier polymer, can experience a reduction of over 75 % in oxygen barrier efficiency as the temperature increases from 23 to 40 °C 12 , potentially leading to food spoilage.

In addition to these immediate effects, a warming climate speeds up long-term property loss due to accelerated ageing 9 . Polymers degrade/age over time from factors like heat, light, moisture, chemicals, and mechanical stress, involving oxidation, UV degradation, hydrolysis, biodegradation, and additive migration 9 , 13 . Temperature is a key factor in all these processes. According to the Arrhenius law, the degradation rate increases exponentially with increasing temperature – with a typical activation energy of 50 kJ/mol for plastic degradation, every 10-degree temperature rise doubles the degradation rate 13 .

For hygroscopic polymers, such as thermoplastic starch and other biopolymers, polyamides, and polyesters, moist conditions can add to the negative effects of rising temperature. Water is a powerful “plasticizer” in systems where the uptake is sizeable, leading to a softer and weaker material. Water uptake may also increase the creep rate and the risk of degradation through hydrolysis.

A warmer climate therefore exposes polymers to more challenging conditions, resulting in the deterioration of plastic properties in both the short and long terms. This leads to more frequent failures of plastic components and products, resulting in reduced durability and shorter service life. Consequently, failed products often need to be replaced, increasing the generation of plastic waste and exacerbating the problem of plastic pollution. Extensively degraded plastic waste is generally unsuitable for traditional recycling due to property loss, increasing the likelihood of such waste being excluded from current plastic waste management systems and ending up in both terrestrial and aquatic environments.

Escalated leaching risk of plastic-associated chemicals

Over 13,000 chemicals are associated with plastics and their production, and among them over 3,200 have been identified as potential concerns due to their hazardous properties 14 . These chemicals consist of residual monomers/oligomers from the polymerization process, compounds formed during polymer degradation, and a wide range of additives like lubricants, flame retardants, plasticizers, antioxidants, colorants, and UV/heat stabilizers 14 . These hazardous chemicals can be emitted and released throughout the plastic lifecycle, posing risks to ecosystems and humans. As temperatures rise, both the diffusion and evaporation rates of the species accelerate, intensifying the leaching of these substances into the air, soil, and water 15 . In addition, the accelerated ageing processes in a warmer climate result in faster production of hazardous degradation products 16 . This amplifies the risk of plastic-associated chemicals entering our ecosystems. As a common example, temperature significantly influences the emission of volatile organic compounds (VOCs) from automobile interior plastic and elastomer components, potentially causing ‘sick car syndrome’ 14 . In the case of hygroscopic polymers, the combination of high temperatures and high relative humidity may exacerbate the release of chemicals further.

Increased microplastic risk

Another concern regarding plastic pollution is the formation of microplastics (tiny particles under 5 mm), due to their persistence, wide distribution, and adverse effects. They originate from the manufacturing of plastics (primary sources) and the gradual degradation of plastic items (secondary sources) 17 . A warmer climate accelerates polymer degradation 9 and thus the breakdown of plastic items into smaller species, substantially expediting the generation of secondary microplastics. Accelerated ageing yields microplastics with a greater degree of degradation, which can increase their toxicity due to the accumulation of degradation products in the microplastic particles. The ageing process profoundly alters the physicochemical properties of these microplastics, subsequently affecting their environmental behaviors 16 . These changes encompass surface charge, biofilm formation, transportation, adsorption behaviors, and interactions with their surroundings 16 . For instance, as microplastics age, their surface roughness tends to increase and their hydrophobicity decreases. These changes make them more conducive to bacterial colonization and the subsequent formation of biofilms 16 . Therefore, the acceleration of plastic degradation, induced by a warmer climate, not only increases the rate at which microplastics are generated but also enhances the ecotoxicity of the formed microplastic particles. This further exacerbates the issue of microplastic pollution and poses long-lasting risks to living organisms in both terrestrial and aquatic environments. In aquatic environments, the rising water temperatures, often due to marine heatwaves and global warming, also hasten the degradation of plastic litter and the subsequent release of microplastics. Note that microplastics also experience accelerated ageing in a warming climate, which leads to quicker fragmentation into nanoplastics and their eventual disintegration. This implies that plastics have a reduced persistence in environments under conditions of climate warming.

Increased demands for plastics

Climate change may also significantly increase the demand for materials with the properties of plastics in various applications. With rising temperatures, the need for electrical appliances, such as air conditioners, fans, and refrigerators, all of which heavily rely on plastic components, escalates, as observed in Europe during hot summers 18 . Additionally, initiatives such as renewable energy projects, electrification of transportation, and climate-resilient infrastructure require a significant number of plastic components. Intensified climate-related disasters like wildfires, floods, hurricanes, cyclones, and typhoons also contribute to plastic demand as they require plastics for reconstruction, emergency shelters, personal protective equipment (PPE), and humanitarian aid supplies. These disasters, unfortunately, lead to the widespread destruction of plastics in use, converting them into waste within the affected area on a massive scale. This heightened demand for plastics leads to increased production, consumption, and subsequent waste generation, exacerbating the issue of plastic pollution. Thus, carefully managing plastic use in climate projects is crucial, ensuring our efforts are both environmentally effective and sustainable in material use.

A vicious circle

To conclude, a warming climate has consequences for the use, ageing, and disposal of plastics, fueling plastic pollution with more waste generation, increased release of chemicals from plastics, and generation of more microplastics. On the other hand, the plastic industry is widely known as a significant contributor to emissions of greenhouse gases and, consequently, climate change 19 . This creates a paradoxical situation where the changing climate drives the demand for plastic, further contributing to plastic pollution, while at the same time, the increasing production of plastics and elastomers exacerbates climate change. Thus, a self-reinforcing cycle is formed, creating a vicious circle between climate change and plastic pollution (Fig. 1 ).

The map in the upper left corner represents the air temperatures in the Eastern Hemisphere 13th of July, 2022 (Source: NASA Earth Observatory, https://earthobservatory.nasa.gov/images/150083/heatwaves-and-firesscorch-europe-africa-and-asia ).

Despite the significant role of climate change in intensifying plastic pollution 20 , this particular impact remains underemphasized. As global warming and heatwaves intensify, and with plastic production, usage, and waste reaching unprecedented levels, it is imperative that we urgently draw attention and mobilize efforts across all sectors involved in the plastic lifecycle. This encompasses the plastics manufacturing industry, sectors utilizing these materials such as electronics, construction, and food packaging, retailers, consumers, regulatory authorities, governments, environmental organizations, waste management services, and the academic and research community in both the plastics and environmental fields. Such collaboration is essential to enhance our understanding of how climate change affects plastic properties and pollution, both immediately and in the long term.

To effectively tackle the intertwined challenges of plastic pollution and climate change, we need a multi-dimensional strategy that encompasses global policy and regulation, technological advances, improved waste management, public engagement, and international collaboration. This approach should emphasize sustainable practices, economic incentives, community participation, and continual research to reduce environmental impacts effectively. For example, implementing a ban on single-use plastics, advocating for a circular economy through enhanced reuse and recycling of plastic items, and transitioning to alternative materials with lower carbon footprints and diminished environmental impacts, such as certain bio-based or biodegradable options, are crucial measures. These steps are critical in disrupting the vicious cycle of plastic pollution and climate change, addressing both issues collaboratively, and reducing their economic and environmental toll, ultimately leading to a more sustainable and resilient future.

Change history

21 march 2024.

A Correction to this paper has been published: https://doi.org/10.1038/s41467-024-46860-1

An IPCC Special Report on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. (2018) Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 49–92. https://doi.org/10.1017/9781009157940.003 .

IPCC, 2023: Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, H. Lee and J. Romero (eds.)].IPCC, Geneva, Switzerland, pp. 1–34, 10.59327/IPCC/AR6-9789291691647.001. https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6_SYR_SPM.pdf .

Copernicus Climate Change Service, Surface air temperature for July 2023 . https://climate.copernicus.eu/surface-air-temperature-july-2023 .

World Meteorological Association, State of the Global Climate 2022 . https://wmo.int/publication-series/state-of-global-climate-2022 .

Perkins-Kirkpatrick, S. E. & Lewis, S. C. Increasing trends in regional heatwaves. Nat. Commun. 11 , 3357 (2020).

Article   ADS   CAS   PubMed   PubMed Central   Google Scholar  

World Meteorological Organization. World Meteorological Organization Declares Onset of El Niño Cconditions. (2023). https://wmo.int/news/media-centre/world-meteorological-organization-declares-onset-of-el-nino-conditions#:~:text=World%20Meteorological%20Organization%20declares%20onset%20of%20El%20Ni%C3%B1o%20conditions,-Press%20Release&text=El%20Ni%C3%B1o%20conditions%20have%20developed,disruptive%20weather%20and%20climate%20patterns .

Hobday, A. J. et al. With the arrival of El Niño, prepare for stronger marine heatwaves. Nature 621 , 38–41 (2023).

Article   ADS   CAS   PubMed   Google Scholar  

Coumou, D. & Rahmstorf, S. A decade of weather extremes. Nat. Clim. Change 2 , 491–496 (2012).

Article   ADS   Google Scholar  

Wei, X.-F. & Hedenqvist, M. S. Heatwaves hasten polymer degradation and failure. Science 381 , 1058–1058 (2023).

Amorim, F. C., Souza, J. F. B., da Costa Mattos, H. S. & Reis, J. M. L. Temperature effect on the tensile properties of unplasticized polyvinyl chloride. SPE Polym. 3 , 99–104 (2022).

Article   CAS   Google Scholar  

Momanyi, J., Herzog, M. & Muchiri, P. Analysis of thermomechanical properties of selected class of recycled thermoplastic materials based on their applications. Recycling 4 , 33 (2019).

Article   Google Scholar  

Massey, L. K. Permeability Properties of Plastics and Elastomers: A Guide to Packaging and Barrier Materials. (Cambridge University Press, 2003).

Singh, B. & Sharma, N. Mechanistic implications of plastic degradation. Polym. Degrad. Stab. 93 , 561–584 (2008).

United Nations Environment Programme and Secretariat of the Basel, Rotterdam and Stockholm Conventions (2023). Chemicals in Plastics: A Technical Report . Geneva. https://www.unep.org/resources/report/chemicals-plastics-technical-report .

Wei, X.-F., Linde, E. & Hedenqvist, M. S. Plasticiser loss from plastic or rubber products through diffusion and evaporation. npj Mater. Degrad. 3 , 18 (2019).

Luo, H. et al. Environmental behaviors of microplastics in aquatic systems: A systematic review on degradation, adsorption, toxicity and biofilm under aging conditions. J. Hazard. Mater. 423 , 126915 (2022).

Article   CAS   PubMed   Google Scholar  

Wei, X.-F., Bohlén, M., Lindblad, C., Hedenqvist, M. & Hakonen, A. Microplastics generated from a biodegradable plastic in freshwater and seawater. Water Res. 198 , 117123 (2021).

Europeans Reluctantly Turn to Air Conditioning as Heatwaves Bite. Euronews Green (2023). https://www.euronews.com/green/2023/08/02/europe-reluctantly-turns-to-air-conditioning-as-heatwaves-bite-data-shows .

Shen, M. C. et al. (Micro)plastic crisis: Un-ignorable contribution to global greenhouse gas emissions and climate change. J. Cleaner Prod. 254 (2020).

Ford, H. V. et al. The fundamental links between climate change and marine plastic pollution. Sci. Total Environ. 806 , 150392 (2022).

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Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, SE–100 44, Stockholm, Sweden

Xin-Feng Wei & Mikael S. Hedenqvist

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X.W. conceptualized the paper. X.W. wrote the first draft of the manuscript with help of M.H. M.H. and W.Y. thoroughly revised the manuscripts with vital feedback, key additions, and precise editing.

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Wei, XF., Yang, W. & Hedenqvist, M.S. Plastic pollution amplified by a warming climate. Nat Commun 15 , 2052 (2024). https://doi.org/10.1038/s41467-024-46127-9

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DOI : https://doi.org/10.1038/s41467-024-46127-9

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Plastic pollution: how can the global health community fight the growing problem?

Dieudonne bidashimwa.

1 Health Service Research, FHI 360, Durham, North Carolina, USA

Theresa Hoke

Thu ba huynh.

2 Asia Pacific Regional Office, FHI 360, Bangkok, Thailand

Nujpanit Narkpitaks

Kharisma priyonugroho, trinh thai ha.

3 Asia Pacific Regional Office, FHI 360, Hanoi, Vietnam

Allison Burns

4 Knowledge Exchange, FHI 360, Durham, North Carolina, USA

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Summary box

• Plastic pollution—unmanaged disposal of plastic waste in water and on land—is a growing global crisis affecting the environment and animals, and an expanding body of evidence suggests negative impacts on human health.
• Plastic products and plastic waste threaten human health because of their toxicity, role in disease propagation, possible interference with food supply through their environmental effects and socioeconomic impacts.
• Despite the burden caused by plastic pollution, the topic does not appear to be a priority on the agenda of the global public health community. International health organisations have not been vocal about plastic pollution as a health threat, and the issue is not frequently discussed in the global health scientific literature.
• The global health community should urgently: (1) fill the evidence gap around plastic exposure and impact for human health to strengthen the current indirect and disjointed evidence; (2) join forces with environmentalists and animal health specialists to advocate for policies to influence plastic production, consumption and waste management; (3) advocate for the adoption of a circular economy model in healthcare to reduce plastic medical waste and (4) contribute to combatting plastic pollution through the use of their technical skills, the ‘public health toolbox’.

Plastic pollution is a global crisis of increasing scale and severity. From the extraction of raw materials for production to the ultimate disposal of massive waste, plastics impact negatively several environmental domains, animal health and potentially human health, with possible global health and social implications. 1–3 These effects of plastics are poised to increase with the rate of pollution. The annual rate of mismanaged end-of-life plastic entering terrestrial and aquatic ecosystems will respectively reach 11 million tons and 18 million tons per year in 2040, more than double those of 2016. 4 These threats are being recognised and challenged through global agreements spearheaded by the United Nations (UN) and other international bodies to prevent, reduce and control plastic pollution. 5 Individual nations are also taking action, with bans in over 120 countries on selected single-use plastics. 6 Despite concrete and coordinated preventive and mitigation measures, growing plastic production, over-reliance on single-use plastics, ineffective waste management, and slow decomposition are leading to a significant worsening of pollution and associated impacts. 2 7

Pollution—‘ unwanted waste released to air, water and land by human activity ’ 8 —is increasingly recognised as a threat to human health, 9 yet the growing burden of plastic pollution specifically does not appear to be a priority on the agenda of the global public health community [Global health is defined as ‘ an area for study, research, and practice that places a priority on improving health and achieving equity in health for all people worldwide. Global health emphasises transnational health issues, determinants and solutions; involves many disciplines within and beyond the health sciences and promotes interdisciplinary collaboration; and is a synthesis of population-based prevention with individual-level clinical care ’.] 10 . Guided by a mission to promote health and reduce health inequities within human populations, 11 the global health community is encouraged to take a multisectoral view and join the movement combatting the plastic pollution crisis. 12 13 The aim of this paper is to raise global health professionals’ awareness of the problem posed by plastic pollution and to propose what can be done in response. We begin by making the case that plastic pollution is a One Health problem because of inter-connected impacts on environmental, animal and human health. We present recent trends suggesting inadequate attention by the global health community toward the problems of plastic pollution. We conclude with potential contributions by global health professionals in efforts to combat plastic pollution.

Impacts of plastic pollution: a one health perspective

The UN High-Level Expert Panel defines One Health as ‘ an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals and ecosystems. It recognizes the health of humans, domestic and wild animals, plants, and the wider environment (including ecosystems) are closely linked and inter-dependent ’. 14 An example of a One Health threat, plastic pollution comprises disposed plastic of different chemical compositions and sizes that pose harm to the health of the environment, animals and humans, with inter-connections between them. Although we acknowledge plastic pollution as a One Health issue, we will focus on its consequences on human health to galvanise health professionals to act on it.

Effects of plastics on the environment

Throughout the entire life cycle of products, from the extraction of raw materials to waste management, plastics pose threats to environmental health. The extraction and transportation of fossil fuels needed for plastic production releases considerable quantities of chemical pollutants imposing risks to the ecosystem and air quality. 1 Workers in the petrochemical industry and people living in the vicinity of oil plants are particularly vulnerable to being exposed to these environmental pollutants. 15 The production of plastics contributes significantly to climate change. Throughout their lifecycle, plastics produce 3.4% of global greenhouse gas emissions, of which 90% are emitted during the production phase. 1 Once products are used, poorly disposed plastics accumulate in the environment leading to contaminations of the marine and terrestrial environments. In marine environments, for example, plastic wastes interfere with the absorption of carbon dioxide by marine micro-organisms, with possible implications on climate warming. 16 Small plastic particles also interfere with the production of algae in oceans and could create an imbalance in the marine food chain. 17 In terrestrial environments, plastic pollution affects water infiltration, the microbiome and the structure of soils, with possible implications for agricultural productivity. 17 18 Burning plastics, a common means of managing waste around the world, emits toxic smokes and ashes. These emissions also impact the environment through contamination of soil, water and accumulation on the food chain (plants and animals). 19–21

Effects of plastics on animals

Marine wildlife is highly exposed to plastics of varying sizes and chemical compositions. Contact with large plastic particles by marine animals leads to their entanglement and entrapment increasing risks of injuries and premature death. 22–25 Moreover, marine animals ingest plastics, which causes suffocation and starvation as plastics block their digestive system and interfere with proper food intake. 22 24 Plastics further interfere with marine animals’ nutrition by acting as physical barriers to food supply. 22 Beyond these physical effects, toxic chemicals in small plastics expose marine animals to acute and chronic reactions interfering with their metabolism and physiology. These toxic effects are influenced by the concentration of the chemicals and their association or not with other environmental toxicants. 22 24 25 Limited evidence shows that land animals are also susceptible to plastics’ chemical toxicity with possible systemic effects. 25 26 Moreover, plastic ingestion by animals could lead to their transfer to other animals through reproduction and the food chain, although the implications of these mechanisms are still unclear. 26

Plastic pollution is a One Health issue of global scale

Plastics harm the environment, animals and humans. These effects are connected in that the impact on one system has consequences for another (eg, the environmental effects of plastics affect animals and humans). As such, the interconnections of plastic pollution affect human health through multiple pathways. Some examples of the global impacts of plastics include:

Environmental effects

• Climate change.
• Biodiversity loss.
• Disruption of the absorption of carbon dioxide by marine organisms.
• Impacts on soil with possible implications for agriculture.

Effects on animals

• Premature death of wildlife.
• Limited food availability for wildlife.

Effects on humans

• Chemical toxicity.
• Propagation of infectious diseases.
• Reduced food supplies and threats to food safety through impacts on marine and land ecosystems.
• Socioeconomic impacts.

Effects of plastics on humans

The evidence base suggesting that exposure to plastics could lead to adverse health effects in humans is growing but still disjointed. 13 27 28 Due to ethical and methodological challenges of conducting studies on plastics in humans, this evidence is overwhelmingly dominated by results from in-vitro experiments and animal models using parameters that may or not represent real-life conditions for humans. 27 29 This gap indicates the need for more studies to elucidate the human health impact of plastics. 30 As described in the section that follows, the current evidence on exposure routes and the scientific plausibility of potential pathogenic effects from plastics raise concerns and warrant a precautionary approach for dealing with this crisis while more robust evidence is generated. 28

Humans are exposed to plastics from several sources, including food, water and consumer products through three main routes: ingestion, inhalation and dermal contact. 27 31 32 Recent evidence indicates that humans consume on average 0.1–5 g (or 0.004–0.18 ounces) of micro- and nano-plastics (smaller than 100 nm) weekly 32 33 34 but the exposure–outcome relationship is yet to be characterised and fully understood.

There is some evidence suggesting that plastics are toxic through their chemical properties. Plastics are composed of chemicals added in their manufacturing process such as bisphenol A, phthalates, brominated flame retardants or plasticizers, most of which are recognised as priority pollutants by the US Environmental Protection Agency. 25 In addition to these well-known chemicals, the plastic industry uses several new chemicals, most of which are protected as confidential business information. 13 This practice has raised concerns from experts since the individual and combined toxicity of these new agents is poorly understood. 13 35 Besides the toxicity from the chemicals primarily used in plastic manufacturing, plastic waste can also bind to other chemicals in the environment resulting in more complex toxic compounds. 13 Recycled non-consumer plastics have been found to contain a wide variety of non-intentionally added substances (NIAS) originating from material degradation, cross-contamination with organic waste or contaminants migrating from the external environment. The undesired NIAS in recycled plastics, especially recycled food packaging, causes human health safety and lowers plastic’s recyclability, perpetuating barriers for implementation of a circular economy. 36 37 Plastics pose further health threats through the misuse of non-food grade packages for food products, a practice increasing exposure to chemical pollutants and prevalent in some settings. 38 Overall, exposure to these chemicals contained in plastics could lead to a wide range of diseases and health conditions of public health relevance. These effects include chronic diseases such as cancers, diabetes, obesity, fertility problems (sterility), gastrointestinal problems (liver and microbiome), neurotoxicity and chronic inflammation. 27 31 32 39 In addition, micro-plastics and nano-plastics could have additional toxic properties because of their ability to cross biological membranes such as the brain or the placenta given their small size. 32 39

Some of the clearest evidence of the harmful effects of plastic pollution on human health is its role in the transmission of vector-borne infectious diseases. A growing body of evidence shows that macro and microplastics debris are favourable breeding environments for vectors and pathogens, especially in populated areas with poor sanitation. 39 40 Pathogenic organisms carried by plastic on land and in water include human pathogenic bacteria, mosquitoes transmitting Zika and dengue and schistosome-carrying snails. 39 Another tangible threat to human concerns the impact of plastics on the safety and availability of seafood. Marine organisms at all the levels of the food chain are impacted by plastics, leading to a ‘g rowing concentration of substances in organisms’ tissues at successively higher levels in the food chain ’. 24 41 Thus, the consumption of seafood could increase exposure to plastic particles and chemicals in humans. Although the impact of marine plastic waste on fish availability is yet to be fully elucidated, studies have reported that 210 species of marine fish of commercial importance have ingested plastic debris. 42 This statistic suggests a high prevalence of sub-lethal and lethal effects of plastics on fishes with possible implications for global seafood stocks. 41

Plastic pollution also is a social justice issue with inequalities between high-income countries who are the main plastic producers and low-income and middle-income countries which suffer the most impacts of plastic pollution. 6 Moreover, the plastic industry’s colossal economic and political power allows large multinational plastic producers to transfer the cost and burden of pollution to the public, despite their role as the primary polluters. 43 44 In this dynamic, the burden of pollution is the highest among the least powerful and most vulnerable groups, such as children, workers in the informal waste sector, communities living near burning sites and marginalised communities who are at the receiving end of most unmanaged plastic wastes and their polluting effects. 8 45 46

Gaps in the engagement of global health professionals in the plastic pollution crisis

Addressing the One Health impacts from plastic pollution requires multi-sectoral collaboration among public health experts, environmentalists, animal health professionals and other experts for a concerted strategy. Yet, two main indicators presented below suggest the global health sector is insufficiently engaged in responding to the plastic pollution crisis.

Low recognition by international health and environmental authorities of plastics as a major health threat

Despite the growing indirect evidence from animal models and toxicological studies on the chemical compounds present in plastics, there is apparent reluctance among global health leaders to acknowledge fully the health impacts of plastic pollution. 28 47 For example, a recently published report presenting updated findings related to the 2017 Lancet Commission on pollution and health highlighted the toxicity of chemical pollution but made only two passing references to ‘plastic’. Reporting on progress related to the recommendations made from the 2017 Commission, there was no mention of addressing the escalating production of single-use plastics nor the uncontrolled waste. 9 A WHO 2019 report presenting the state of the evidence documented the ubiquity of microplastics in marine water, fresh water and even food and drinking water, but concluded, ‘… there is no evidence to indicate a human health concern’. 48 Moreover, a compendium of recommendations to strengthen concrete actions on health and environment by the WHO and other UN agencies includes guidance on only three plastic-related matters with direct human health implications. 49 Such a limited approach overlooks the various linkages between plastics and human health. Further, although challenging to quantify globally, single-use plastics for medical and non-medical purposes comprise a meaningful portion of healthcare waste (estimated from 20% to 25%). 50–52 Despite this, the health system’s role in plastic pollution (and the recognition of the harmful effects of plastics on human health) is absent from key guidance documents, such as the US Agency for International Development’s Vision for Health System Strengthening 2030. 53

Similarly, global multilateral environmental leaders engaged in plastic pollution initiatives do not prioritise human health. On 2 March 2022, in Nairobi, UN Member States endorsed a historic resolution to develop an internationally legally binding instrument to end plastic pollution at the Fifth session of the UN Environment Assembly (UNEA-5). Negotiations, aiming to be completed by the end of 2024, have shown governments’ strong commitment to addressing the full life cycle of plastics through international cooperation. 54 However, only a few countries suggested human health protection as the primary objective of the instrument, while more than half of the countries did not acknowledge human health in their official statements at the first session of the intergovernmental negotiating committee. 54 55 To address the full scale of health impacts throughout plastics’ lifecycle, such a monumental global agreement will require greater involvement of global health professionals to bring a health lens to the negotiation process and subsequent implementation of the agreement. 47

Low exposure of public health professionals to the plastic pollution literature

As global health specialists and researchers, we had the impression that plastic pollution is a topic infrequently found in the global health scientific literature normally consulted in our work. To examine the accuracy of this preconception, in April 2023, we conducted a rapid, targeted search of global health journals to explore how much our community is exposed to the issue of plastic pollution in the literature of their field. We targeted the top 50 public health journals based on the Clarivate Journal Citation Reports and Scimago Journal and Country Rank ranking. 56 We searched PubMed for articles on plastics, microplastics or nanoplastics published in the previous 5 years. The search results were screened to retain only the publications on plastic pollution.

From April 2018 to April 2023, 15 journals on our list published 65 articles on plastic pollution; the other 35 journals contained none. Most of the articles (n=51) were published by 2 journals while the other 13 journals published between one and four relevant articles in the past 5 years ( table 1 ). Results from this illustrative, non-exhaustive search suggest a low exposure of health professionals to the topic of plastic pollution and possibly low prioritisation by editors of global health journals, despite the potential links between plastics and health.

Number of articles on plastic pollution published in global health journals from April 2018 to April 2023

Call to action!

It is time for the global health community to join forces with environmental specialists to confront the plastic pollution crisis, consistent with a One Health approach. Global health leaders must acknowledge the inter-connectedness of human health, animal health and environmental health in the case of plastic pollution, and elevate the quest for solutions among the global health sector’s priorities. Commitment to collaboration must be rooted in recognition of the shared goals and interests of these different sectors, along with their complementary capacities and intervention means. As the evidence about the direct public health harm caused by plastic pollution is incomplete, human health specialists can rely on existing clear evidence of the threats to environmental and animal health. The downstream consequences of those threats to human health—for example, through disruptions to marine food supplies—must be considered immediately. The global health sector can make a more complete contribution to a holistic One Health solution through improved information sharing, collaboration and capacity building. The following are practical strategies the global health sector can employ to both mitigate and respond to plastic pollution.

Fill evidence gaps around plastic exposure and impact for human health

A coordinated, multi-disciplinary research agenda is needed to produce convincing epidemiological evidence about plastic exposure and human health impacts. 29 Both scientific reviews 22 29 and global health authorities 48 conclude that there is insufficient evidence of the harmful effect to human health of plastic exposure under real-world conditions. This is a case where the absence of evidence of an effect does not serve as proof of no risk. 28 Rather, it is an indication that far more work needs to be done. The research agenda must be coordinated and prioritised given the diversity of chemical exposures, the range of potential harmful health effects, and multitude of biological research disciplines that are implicated. The global health community can join the calls for research on environmentally relevant exposures to move swiftly toward evidence that will be more convincing to policy makers and the public. The aforementioned inconsistency in recognition of human health as core element of the UN’s legally binding global agreement urges international health researchers and professionals to fill evidence gaps and to participate in cross-disciplinary information exchange. 55 In a coordinated manner, funders should urgently commit to investing in health research to complement the robust body of knowledge of plastic pollution as an environmental threat 3 and the preliminary understanding of its potential health impacts. Given the low accountability of the plastic industry, there is also an urgent need to close the time gap between the adoption of chemical innovations by the plastic industry and evidence generation on the safety of the new compounds. As the evidence base grows, it should be used to influence the public health agenda by knowledge-building among the health community via publication of papers, conference presentations, webinars and on-the-ground trainings.

Support advocacy for change in global, national and local policies to influence production, consumption and waste management

Experts have called for global policy and programmatic strategies to mitigate plastic pollution. Such a strategy should foster close intersectoral and multidisciplinary collaboration between scientists, community leaders, regulators and policymakers. 13 Collaborations should be particularly inclusive of environmental scientists and global health professionals given the extensive consequences of plastic pollution on both areas. While environmental scientists, regulators and policymakers have been able to establish these collaborations and move the needle on plastic pollution from an environmental standpoint, 57 the effort needs increased participation by global health professionals. The global health community must join conversations or initiate new ones focused on policy changes backed by multi-sectoral, mutually reinforcing priorities. Global health leaders are experienced in engaging in discussions with professional peers from multiple sectors in setting priorities, shaping policy and formulating interventions for societal good. These advocacy initiatives should learn from past successes in impacting change despite significant barriers, especially barriers from business lobbying. One such example is the fight against the aggressive and inappropriate marketing of breast milk substitutes (BMS) in the 80s that led to the adoption by the global health community of the International Code of Marketing of Breast-milk Substitutes, aiming to protect and promote breast feeding. 58

As experienced with the BMS industry, however, policies and voluntary agreements may not be enough. There is evidence of persistent violations of the code by the BMS industry which continues inappropriate marketing using misleading and manipulative information on product labels and in promotional campaigns. 59–62 Similarly, while an increasing number of corporations, especially household consumer brands, pledge to reduce their plastic footprint by 2025, 63 corporate responsibility and accountability is not enforced. Many companies not only fail to report their individual data but also miss their committed targets by increasing their total and virgin plastic use to the point of outpacing the progress on recycled content. 44 54 Therefore, policy and advocacy initiatives by global health professionals and collaborators need to emphasise the enforcement of extended producer responsibility and accountability throughout the plastic lifecycle, including advocating for more effective mechanisms for enforcing policies and commitments, monitoring their implementation and evaluating their impacts.

Collaboration should also be established at national and local levels for more meaningful policymaking, and programme design and testing. Examples of a national level initiative on plastic pollution include the Plastic Health Action Partnership (PHA) initiative in Vietnam. As one of its policy advocacy efforts, PHA, with the technical leadership of health and environment organisations, convenes the multistakeholder forum to forge a plastic circular economy framework with considerations of plastic-associated health impacts. 64 These actions will be reinforced by actively engaging local communities to assess needs and implement strategies most adapted to their contexts.

Focus advocacy and technical support for adoption of a circular economy model in healthcare operations to reduce plastic medical waste

The healthcare industry is a major contributor to the pollution problem given its heavy reliance on single-use plastics. These products often are not recycled; instead, they are typically incinerated or disposed in landfills. Plastic pollution generated through medical waste was dramatically compounded by the COVID-19 pandemic, particularly due to widespread use of disposable personal protective equipment (PPE). 65 66 The public health sector has a role to play given its close association with the medical sector, with overlapping priorities, technical language and professional communities. It is well positioned—or at least better positioned than environmental specialists—to advocate for reduced use of single-use plastics in medical care. Further, it can contribute knowledge and skill to advance the design, implementation and scale-up of solutions. Global health specialists with expertise in healthcare management can support medical services in building capacities for its employees, implement plastic elimination and reduction policies across their operations, improve procurement and supply chain procedures, and enhance their waste management practices. They can also facilitate collaboration by private sector plastic producers and importers with health sector stakeholders, including government, academia, health system administrators and healthcare professionals in devising solutions. Priorities for innovation include replacing single-use plastic items and PPE with more ecofriendly materials; products re-designed for reuse and recycling; and products created from recycled plastics for application in healthcare facilities. Technical support can also be offered for use of technology and data to monitor plastic use, identify persistently high consumption and waste and test the effect of solutions through pilot projects and results dissemination. Within healthcare facilities, global health specialists can help to organise plastic reduction/environmental campaigns and training programmes for healthcare professionals so they are aware of the issue and can join efforts to solve problems. They can also help to set up communities of practice among health facilities and other stakeholders to exchange ideas on how to reduce plastic use 24 and make health facilities more climate smart.

Contribute the assets of the public health toolbox in combatting plastic pollution

Global, national and local health leaders operate by means of vast access to and influence over populations. They are often trusted as authoritative sources of information and guidance on individual-level and community-level action. Additionally, the sector offers deep experience in identifying vulnerable populations and projecting differential consequences likely to be experienced by different groups, depending on exposure to risk, access to mitigating measures and inherent resilience. The global health discipline also offers expertise in social and behavioural change (SBC), supported by frameworks, strategies and tools to encourage behavioural change at the individual and group level and evolution in social norms. 67 The power of SBC approaches must be increasingly leveraged to promote change in consumption and waste management practices. Global health epidemiology provides methodological tools and principles to characterise population-level exposures and investigate associations or causations between exposures and outcomes, accounting for population attributes and confounding factors. This global health area will contribute to generating more robust and convincing evidence on the health impacts of plastic pollution. Finally, global health policy uses the available knowledge to advocate, design, promote and evaluate relevant laws, regulations, and guidelines anchored in epidemiological evidence and evidence on the effectiveness and feasibility of interventions addressing issues at various socioecological levels. Experts in this field will strengthen policymaking around plastic pollution, allowing to tackle more holistically its impacts.

Combatting the plastic pollution crisis and related health risks require multidisciplinary and cross-sectoral collaboration. Global health professionals should be involved in multistakeholder dialogues and collaborate with actors from government, civil society, academe and private sector to promote plastics topics in the high-level health agenda and to drive action. The global health community must contribute the diverse powers of its discipline to discover, promote and implement solutions. Remaining inadequately informed and involved is no longer an option.

Handling editor: Seye Abimbola

Twitter: @thereshoke @fhi360research, @amyweissman

Contributors: Conceptualisation: DB, TH and AW. Writing of the original draft: DB and TH. Literature search for publications on plastics in the global health literature: AB, DB. Significant input and edits: AW, TBH, NN, KP, TTH, AB. All authors have reviewed the manuscript. All authors approved the version submitted. All Authors agreed to be personally accountable for all aspects of the accuracy and integrity of the work.

Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests: None declared.

Provenance and peer review: Not commissioned; externally peer reviewed.

Data availability statement

Ethics statements, patient consent for publication.

Not applicable.

Ethics approval

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Article Contents

Introduction, entanglement, impacts on nesting beaches, wider ecosystem impacts, future research, acknowledgements, plastic and marine turtles: a review and call for research.

Joint lead authors.

Handling editor: Howard Browman

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Sarah E. Nelms, Emily M. Duncan, Annette C. Broderick, Tamara S. Galloway, Matthew H. Godfrey, Mark Hamann, Penelope K. Lindeque, Brendan J. Godley, Plastic and marine turtles: a review and call for research, ICES Journal of Marine Science , Volume 73, Issue 2, January/February 2016, Pages 165–181, https://doi.org/10.1093/icesjms/fsv165

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Plastic debris is now ubiquitous in the marine environment affecting a wide range of taxa, from microscopic zooplankton to large vertebrates. Its persistence and dispersal throughout marine ecosystems has meant that sensitivity toward the scale of threat is growing, particularly for species of conservation concern, such as marine turtles. Their use of a variety of habitats, migratory behaviour, and complex life histories leave them subject to a host of anthropogenic stressors, including exposure to marine plastic pollution. Here, we review the evidence for the effects of plastic debris on turtles and their habitats, highlight knowledge gaps, and make recommendations for future research. We found that, of the seven species, all are known to ingest or become entangled in marine debris. Ingestion can cause intestinal blockage and internal injury, dietary dilution, malnutrition, and increased buoyancy which in turn can result in poor health, reduced growth rates and reproductive output, or death. Entanglement in plastic debris (including ghost fishing gear) is known to cause lacerations, increased drag—which reduces the ability to forage effectively or escape threats—and may lead to drowning or death by starvation. In addition, plastic pollution may impact key turtle habitats. In particular, its presence on nesting beaches may alter nest properties by affecting temperature and sediment permeability. This could influence hatchling sex ratios and reproductive success, resulting in population level implications. Additionally, beach litter may entangle nesting females or emerging hatchlings. Lastly, as an omnipresent and widespread pollutant, plastic debris may cause wider ecosystem effects which result in loss of productivity and implications for trophic interactions. By compiling and presenting this evidence, we demonstrate that urgent action is required to better understand this issue and its effects on marine turtles, so that appropriate and effective mitigation policies can be developed.

Between 1950 and 2015, the total annual global production of plastics grew from 1.5 million t to 299 million t ( PlasticsEurope, 2015 ). As a result, the abundance and spatial distribution of plastic pollution, both on land and at sea, is increasing ( Barnes et al. , 2009 ; Jambeck et al. , 2015 ). Indeed, plastic items have become the principal constituent of marine debris, the majority originating from land-based sources, such as landfill sites, with the remaining deriving from human activities, such as fishing ( Barnes et al ., 2009 ; Ivar do Sul et al ., 2011 ).

Of particular concern is the longevity of plastic debris and its wide dispersal ability ( Barnes et al. , 2009 ; Wabnitz and Nichols, 2010 ; Reisser et al. , 2014b ). It has been recorded worldwide in a vast range of marine habitats, including remote areas far from human habitation ( Barnes et al ., 2009 ; Ivar do Sul et al ., 2011 ). Transported across the globe by winds and oceanic currents, high concentrations of floating plastic can accumulate in convergence zones, or gyres, as well as exposed coastlines ( Cózar et al ., 2014 ; Reisser et al ., 2014b ; Schuyler et al ., 2014 ). Enclosed seas, such as the Mediterranean basin, also experience particularly high levels of plastic pollution due to densely populated coastal regions and low diffusion from limited water circulation ( Cózar et al. , 2015 ). Once seaborne, plastic persists in the marine environment, fragmenting into smaller pieces as a result of wave action, exposure to UV and physical abrasion ( Andrady, 2015 ). Small particles are highly bioavailable to a wide spectrum of marine organisms ( Lusher, 2015 ). Furthermore, the hydrophobic properties and large surface area to volume ratio of microplastics (fragments of <5 mm in diameter) can lead to the accumulation of contaminants, such as heavy metals and polychlorinated biphenyls (PCBs), from the marine environment. These chemicals, and those incorporated during production (such as plasticizers), can leach into biological tissue upon ingestion, potentially causing cryptic sublethal effects that have rarely been investigated ( Koelmans, 2015 ).

For some species, plastics could present a major threat through ingestion, entanglement, the degradation of key habitats, and wider ecosystem effects ( Barnes et al. , 2009 ; Vegter et al. , 2014 ; Gall and Thompson, 2015 ). Among these species are the marine turtles, whose complex life histories and highly mobile behaviour can make them particularly vulnerable to the impacts of plastic pollution ( Arthur et al. , 2008 ; Ivar do Sul et al. , 2011 ; Schuyler et al. , 2014 ). As concern grows for the issue of marine plastic and the associated implications for biodiversity, it is essential to assess the risks faced by key species ( Vegter et al. , 2014 ). Understanding vulnerability is necessary for setting research priorities, advising management decisions, and developing appropriate mitigation measures ( Schuyler et al. , 2014 ; Vegter et al. , 2014 ). This is particularly pertinent given that marine turtles are of conservation concern and often seen as “flagships” for marine conservation issues ( Eckert and Hemphill, 2005 ).

Here, we carry out a comprehensive review of the state of knowledge concerning this anthropogenic hazard and how it impacts marine turtles, and highlight a range of research and innovative methods that are urgently needed. To do so, we searched ISI Web of Knowledge and Google Scholar for the terms plastic, plastic pollution, marine debris, marine litter, ingestion, entanglement, entrapment, ghost nets and ghost fishing. Plastic and debris were also searched for in conjunction with beach, sand, coral reef, sea grass beds , and fronts . Alongside each search term, we also included the word turtle. We found that the number of peer-reviewed publications per year (between 1985 and 2014) has generally increased over time (Figure 1 a) and a descriptive overview of the 64 peer-reviewed studies is given in Table 1 (Ingestion) and Table 2 (Entanglement). We structure our review in five major sections looking at (i) ingestion, (ii) entanglement, (iii) impacts to nesting beaches, and (iv) wider ecosystem effects and then suggest priorities for (v) future research.

Summary of all studies on plastic ingestion by marine turtles.

CCL, curved carapace length.

Summary of all studies on entanglement in plastic debris by marine turtles.

Number of publications returned from literature search per (a) year (between 1985 and 2014), (b) life stage, (c) species (Lh, Loggerhead; Gr, Green; Lb, Leatherback; Hb, Hawksbill; Kr, Kemp's ridley; Or, Olive ridley; Fb, Flatback), and (d) Ocean basin.

There are two potential pathways by which turtles may ingest plastic; directly or indirectly. Direct consumption of plastic fragments is well documented and has been observed in all marine turtle species ( Carr, 1987 ; Bjorndal et al. , 1994 ; Hoarau et al. , 2014 ; Schuyler et al. , 2014 ; Figure 2 a). Accidental ingestion may occur when debris is mixed with normal dietary items. For instance, one study found that juvenile green turtles ( Chelonia mydas ) consumed debris because it was attached to the macroalgae they target directly ( Di Beneditto and Awabdi, 2014 ). Alternatively, plastic ingestion may be a case of mistaken identity. As turtles are primarily visual feeders, they may misidentify items, such as shopping bags, plastic balloons, and sheet plastic, as prey and actively select them for consumption ( Mrosovsky, 1981 ; Tomás et al. , 2002 ; Gregory, 2009 ; Hoarau et al. , 2014 ). Hoarau et al. (2014) found a high occurrence of plastic bottle lids in the loggerhead turtles ( Caretta caretta ) they examined and surmised that the lids' round shape and presence floating near the surface visually resemble neustonic organisms normally preyed upon. Laboratory trials have found that turtles are able to differentiate between colours and so the visual properties of plastic are likely to be important factors determining the probability of ingestion ( Bartol and Musick, 2003 ; Swimmer et al. , 2005 ; Schuyler et al. , 2012 ). A number of studies have found that white and transparent plastics are the most readily consumed colours ( Tourinho et al. , 2010 ; Schuyler et al. , 2012 ; Camedda et al. , 2014 ; Hoarau et al. , 2014 ). It is not certain, however, whether this trend is a result of selectivity by the turtles or due to the differing proportions of plastic types and colours in the environment ( Schuyler et al. , 2012 ; Camedda et al. , 2014 ). Aside from visual cues, perhaps microbial biofilm formation on plastic debris and the associated invertebrate grazers ( Reisser et al. , 2014a ) cause the particles to emit other sensory cues (such as smell and taste) which could lead turtles to consume them. This, however, remains to be investigated.

Plastics and marine turtles: (a) plastic fragments extracted from the digestive tract of a necropsied juvenile green turtle (inset), found stranded in northern Cyprus (photo: EMD); (b) plastic extruding from a green turtle's cloaca in Cocos Island, Costa Rica (photo: Cristiano Paoli); (c) loggerhead turtle entangled in fishing gear in the Mediterranean Sea (north of Libya) (photo: Greenpeace©/Carè©/Marine Photobank); (d) female green turtle attempting to nest among beach litter, northern Cyprus in 1992 before the commencement of annual beach cleaning (photo: ACB).

Indirect ingestion may occur when prey items, such as molluscs and crustaceans that have been shown to ingest and assimilate microplastic particles in their tissues ( Cole et al. , 2013 ; Wright et al. , 2013 ), are consumed by carnivorous species. Although not yet investigated for marine turtles, trophic transfer has been inferred in other marine vertebrates, specifically pinnipeds ( McMahon et al. , 1999 ; Eriksson and Burton, 2003 ). For example, the prey of the Hooker's sea lion ( Phocarctos hookeri ), myctophid fish, ingest microplastic particles. Subsequently, the otoliths (ear bones) of these fish have been found alongside plastic particles within the sea lion scat, suggesting a trophic link ( McMahon et al. , 1999 ). This indirect ingestion may lead to sublethal effects that are difficult to identify, quantify and attribute to plastic ingestion as opposed to other water quality issues ( Baulch and Perry, 2014 ; Vegter et al. , 2014 ; Gall and Thompson, 2015 ). These are discussed later in this section.

It is likely that feeding ecology and diet, as well as habitat use in relation to areas of high plastic density, determine the likelihood and consequences of plastic ingestion ( Bond et al. , 2014 ). These differ among turtle life stages, regional populations and species, meaning that there are likely to be inter- and intraspecies variation in the densities and types of plastic encountered and potentially consumed ( Schuyler et al. , 2014 ).

Both the likelihood of exposure to and consequences of ingestion differ across life stage. Post-hatchlings and juveniles of six of the seven marine turtle species undergo a period of pelagic drifting, known as the “ lost year ”. Although flatback turtles ( Natator depressus ) lack an oceanic dispersal stage, their habitat use during the post-hatchling phase is still likely to be influenced by bathymetry and coastal currents ( Hamann et al. , 2011 ). Currents transport hatchlings away from their natal beaches, often to oceanic convergence zones, such as fronts or downwelling areas ( Bolten, 2003 ; Boyle et al. , 2009 ; Scott et al. , 2014 ). These areas can be highly productive and act as foraging hotspots for many marine taxa, including fish, seabirds, and marine turtles ( Witherington, 2002 ; Scales et al. , 2014 ; Schuyler et al. , 2014 ). However, along with food, advection also draws in and concentrates floating anthropogenic debris, increasing the likelihood of exposure to plastic. This spatial overlap potentially creates an ecological trap for young turtles ( Carr, 1987 ; Tomás et al. , 2002 ; Battin, 2004 ; Witherington et al. , 2012 ; Cózar et al. , 2014 ). Their vulnerability is further intensified by indiscriminate feeding behaviour, often mistaking plastic for prey items or accidentally ingesting debris while grazing on organisms that are encrusted on such items ( McCauley and Bjorndal, 1999 ; Schuyler et al. , 2012 ; Hoarau et al. , 2014 ). Additionally, turtles in early life history stages, that are small in size, may be at higher risk of mortality from plastic ingestion due to their smaller, less robust, digestive tracts ( Boyle, 2006 ; Schuyler et al. , 2012 ). During our literature search, we found that of all the life stages, young “ lost year ” juveniles are the most data deficient, but potentially the most vulnerable (Figure 1 b).

After the post-hatchling pelagic stage, most populations of chelonid (hard-shelled) species, such as loggerheads, greens, and hawksbills ( Eretmochelys imbricata ), undergo an ontogenetic shift in feeding behaviour where they may switch to benthic foraging in neritic areas (although some populations forage pelagically even in larger size classes; Tomás et al. , 2001 ; Witherington, 2002 ; Hawkes et al. , 2006 ; Arthur et al. , 2008 ; Schuyler et al. , 2012 ). Some foraging areas experience higher concentrations of plastic debris due to physical processes, for example, frontal systems or discharging rivers, and when such accumulations overlap with turtle foraging grounds, high rates of ingestion may be observed ( González Carman et al. , 2014 ). Indeed, González Carman et al. (2014) reported that 90% of the juvenile green turtles examined had ingested anthropogenic debris and postulated that, aside from the high concentrations of debris, poor visibility (caused by estuarine sediment) and therefore a reduced ability to discriminate among ingested items may also be a factor.

The results from our literature search show that, of all peer-reviewed publications (between 1985 and 2014; n = ∼6668) looking at marine turtles, the proportion that investigated occurrences of plastic ingestion is relatively low, ranging from 1 to 2% depending on species. We found that the majority of these studies focused on loggerhead ( n = 24; 44%) and green turtles ( n = 23; 43%) in contrast to a small number of reports on the leatherback ( Dermochelys coriacea ; n = 7, 13%), Kemp's ridley ( Lepidochelys kempii ; n = 7; 13%), hawksbill ( n = 3; 6%), olive ridley ( Lepidochelys olivacea ; n = 2; 4%), and flatback turtles ( n = 2; 4%; Figure 1 c). These biases, however, are broadly reflected by those observed for general turtle studies (green = 35%, loggerhead = 31%, leatherback = 14%, hawksbill = 9%, olive ridley = 5%, kemps ridley = 4%, and flatback = 1%). This relationship demonstrates the need for caution when interpreting apparent patterns based on the number of observations of plastic ingestion among species.

We also found that the majority of research was carried out in the Atlantic Ocean basin ( n = 28 of 55 publications on plastic ingestion by turtles; Figure 1 d). These strong biases towards certain species/regions demonstrate a need to expand research to better understand plastic ingestion for the taxon, globally.

Among marine turtles, there are profound interspecific differences in feeding strategies, diet, and habitat use that could result in varying likelihoods of exposure to and consequences of plastic ingestion ( Bjorndal, 1997 ; Schuyler et al. , 2014 ). For example, the generalist feeding strategy of loggerhead turtles seems to put them at high risk of ingesting plastic, but their ability to defecate these items, due to a wide alimentary tract, however, demonstrates a certain degree of tolerance (in adults and subadults; Bugoni et al. , 2001 ; Tomás et al. , 2001 , 2002 ; Hoarau et al. , 2014 ). This, though, may not mitigate the sublethal effects which may occur as a result of plastic ingestion (see the Ecological effects section). Although not heavily studied when compared with the other turtle species (Figure 1 c), ingestion rates by Kemp's ridley turtles appear to be low. This may be because they specialize in hunting active prey, such as crabs, which plastic debris is less likely to be mistaken for ( Bjorndal et al. , 1994 ). Nonetheless, a potential issue for benthic feeding, carnivorous marine turtle species, such as Kemp's ridley, olive ridley, loggerhead, and flatback turtles, is indirect ingestion of microplastics through consumption of contaminated invertebrate prey, such as molluscs and crustaceans ( Parker et al. , 2005 ; Casale et al. , 2008 ) and any associated sediments. Green turtles too are mostly benthic feeders but are largely herbivorous ( Bjorndal, 1997 ). Their preference for sea grass or algae may lead to a greater likelihood of ingesting clear soft plastics resembling their natural food in structure and behaviour. A study in southeastern Brazil found that 59% of juvenile green turtles stomachs contained flexible and hard plastic debris (clear, white, and coloured) and Nylon filaments ( Di Beneditto and Awabdi, 2014 ); another found that 100% of green turtle stomachs examined contained at least one plastic item ( Bezerra and Bondioli, 2011 ). Hawksbills, although omnivorous, prefer to consume sponges and algae, acting as important trophic regulators on coral reefs ( León and Bjorndal, 2002 ). While clean-up surveys on coral reefs show that plastic is present in such habitats ( Abu-Hilal and Al-Najjar, 2009 ), data on the ingestion rates and selectivity for hawksbills are lacking (Figure 1 c). Peer-reviewed studies investigating ingestion by flatbacks are also scarce, but we found reports that in 2003, a flatback turtle died following ingestion of a balloon ( Greenland and Limpus, 2003 ) and in 2014, four out of five stranded post-hatchling flatback turtles had ingested plastic fragments ( StrandNet Database, 2015 ). Pelagic species that forage on gelatinous prey, such as leatherbacks, are also susceptible to plastic ingestion and Mrosovsky et al. (2009) estimated that approximately one-third of all adult leatherbacks autopsied from 1968 to 2007 had ingested plastic. This is thought to be due to similarities to prey items, such as jellyfish, acting as sensory cues to feed ( Schuyler et al. , 2014 ).

Ecological effects

The effects of plastic ingestion can be both lethal and sublethal, the latter being far more difficult to detect and likely more frequent ( Hoarau et al. , 2014 ; Schuyler et al. , 2014 ; Gall and Thompson, 2015 ). Tourinho et al. (2010) reported that 100% of stranded green turtles ( n = 34) examined in southeastern Brazil had ingested anthropogenic debris, the majority of which was plastic, but the deaths of only three of these turtles could be directly linked to its presence. Damage to the digestive system and obstruction is the most conspicuous outcome and is often observed in stranded individuals (Figure 2 b; Camedda et al. , 2014 ). The passage of hard fragments through the gut can cause internal injuries and intestinal blockage ( Plotkin and Amos, 1990 ; Derraik, 2002 ). Accidental ingestion of plastic fishing line may occur when turtles consume baited hooks (e.g. Bjorndal et al. , 1994 ). As the line is driven through the gut by peristalsis, it can become constricted, causing damage, such as tearing to the intestinal wall ( Parga, 2012 ; Di Bello et al. , 2013 ).

In some cases, the sheer volume of plastic within the gut is noticeable during necropsy or possibly via X-ray or internal examination. Small amounts of anthropogenic debris, however, have been found to block the digestive tract ( Bjorndal et al. , 1994 ; Bugoni et al. , 2001 ; Schuyler et al. , 2014 ; Santos et al. , 2015 ). For example, Santos et al. (2015) found that only 0.5 g of debris (consisting of mainly soft plastic and fibres) was enough to block the digestive tract of a juvenile green turtle, ultimately causing its death. Additionally, hardened faecal material has been known to accumulate as a result of the presence of plastic and the associated blockage to the gastrointestinal system ( Davenport et al. , 1993 ; Awabdi et al. , 2013 ). On the contrary, it is possible for significant amounts of plastic to accumulate and remain within the gut without causing lethal damage ( Hoarau et al. , 2014 ). For example, Lutz (1990) reported that plastic pieces remained in the gut of a normally feeding captive turtle for four months. In the long term, however, a reduction in feeding stimulus and stomach capacity could lead to malnutrition through dietary dilution which occurs when debris items displace food in the gut, reducing the turtles ability to feed ( McCauley and Bjorndal, 1999 ; Plot and Georges, 2010 ; Tourinho et al. , 2010 ). Experimental evidence has shown that dietary dilution causes post-hatchling loggerheads to exhibit signs of reduced energy and nitrogen intake ( McCauley and Bjorndal, 1999 ). Post-hatchlings and juvenile turtles are of particular concern because their smaller size means that starvation is likely to occur more rapidly which has consequences for the turtle's ability to obtain sufficient nutrients for growth ( McCauley and Bjorndal, 1999 ; Tomás et al. , 2002 ).

The presence of large quantities of buoyant material within the intestines may affect turtles' swimming behaviour and buoyancy control. This is especially crucial for deep diving species, such as the leatherbacks ( Fossette et al. , 2010 ) and small benthic foragers, such as flatbacks. Additionally, plastic ingestion can compromise a female's ability to reproduce. For example, plastic was found to block the cloaca of a nesting leatherback turtle, preventing the passage of her eggs ( Plot and Georges, 2010 ; Sigler, 2014 ).

Long gut residency times for plastics may lead to chemical contamination as plasticizers, such as Bisphenol A and phthalates, leach out of ingested plastics and can be absorbed into tissues, potentially acting as endocrine disrupters ( Oehlmann et al. , 2009 ). Additionally, due to their hydrophobic properties, plastics are known to accumulate heavy metals and other toxins, such as PCBs, from the marine environment which can also be released during digestion ( Cole et al. , 2015 ; Wright et al. , 2013 ). Such contaminants have been shown to cause developmental and reproductive abnormalities in many taxa, such as egg-shell thinning and delayed ovulation in birds as well as hepatic stress in fish ( Azzarello and Van Vleet, 1987 ; Wiemeyer et al. , 1993 ; Oehlmann et al. , 2009 ; Rochman et al. , 2013a , b ; Vegter et al. , 2014 ). To date, the knowledge base regarding these issues in marine turtles is limited.

Indirectly ingested microplastics may pass through the cell membranes and into body tissues and organs where they can accumulate and lead to chronic effects ( Wright et al. , 2013 ). The implications of trophic transfer, of both the microplastics and their associated toxins, are as yet unknown ( Cole et al. , 2013 ; Wright et al. , 2013 ; Reisser et al. , 2014a ) and worthy of investigation.

It is possible that the sublethal effects of plastic ingestion, including dietary dilution, reduced energy levels, and chemical contamination, may lead to a depressed immune system function resulting in an increased vulnerability to diseases, such as fibropapillomatosis ( Landsberg et al. , 1999 ; Aguirre and Lutz, 2004 ). Stranded juvenile green turtles in Brazil exhibit both high occurrence of plastic ingestion and incidences of this disease ( Santos et al. , 2011 ). Additionally, plastic ingestion may impact health and weaken the turtle's physical condition which could impair the ability to avoid predators and survive anthropogenic threats, such as ship strikes and incidental capture by fisheries, issues which already threaten many marine turtle populations ( Lewison et al. , 2004 ; Hazel and Gyuris, 2006 ; Hoarau et al. , 2014 ). Other longer term consequences could include reduced growth rates, fecundity, reproductive success, and late sexual maturation which could have long-term demographic ramifications for the stability of marine turtle populations ( Hoarau et al. , 2014 ; Vegter et al. , 2014 ).

In summary, the potential effects of plastic ingestion on marine turtles are diverse and often cryptic, making it difficult to identify a clear causal link. The sheer scale of possibilities, though, makes this topic one that is in urgent need of further research.

Entanglement in marine debris, such as items from land-based sources and lost fishing gear (known as “ghost gear”), is now recognized as a major threat to many marine species (Figure 2 c; Gregory, 2009 ; Wilcox et al. , 2013 ; Vegter et al. , 2014 ). Their sources are difficult to trace, but their widespread distribution indicates that ocean currents and winds may be dispersal factors ( Santos et al. , 2012 ; Jensen et al. , 2013 ; Wilcox et al. , 2013 ). Entanglement is one of the major causes of turtle mortality in many areas including northern Australia and the Mediterranean ( Casale et al. , 2010 ; Jensen et al. , 2013 ; Wilcox et al. , 2013 ; Camedda et al. , 2014 ). Despite this, quantitative research on mortality rates is lacking and a large knowledge gap exists in terms of implications for global sea turtle populations ( Matsuoka et al. , 2005 ). Our literature search returned just nine peer-reviewed publications directly referring to marine debris entanglement and turtles ( Bentivegna, 1995 ; Chatto, 1995 ; Lopez-Jurado et al. , 2003 ; Casale et al. , 2010 ; Santos et al. , 2012 ; Jensen et al. , 2013 ; Wilcox et al. , 2013 , 2014 ; Barreiros and Raykov, 2014 ) and of these, seven are related to ghost fishing gear. For individual turtles, the effects of entanglement are injuries, such as abrasions, or loss of limbs; a reduced ability to avoid predators; or forage efficiently due to drag leading to starvation or drowning ( Gregory, 2009 ; Barreiros and Raykov, 2014 ; Vegter et al. , 2014 ). From a welfare perspective, entanglement may cause long-term suffering and a slow deterioration ( Barreiros and Raykov, 2014 ). In some cases, injuries are so severe that amputation or euthanasia are the only options for rehabilitators ( Chatto, 1995 ; Barreiros and Raykov, 2014 ).

Ghost nets—mostly consisting of synthetic, non-biodegradable fibres, such as Nylon—may persist in the marine environment for many years, indiscriminately “fishing” an undefinable number of animals ( Bentivegna, 1995 ; Wilcox et al. , 2013 , 2014 ; Stelfox et al. , 2014 ). Some nets, which may be several kilometres long, drift passively over large distances ( Brown and Macfadyen, 2007 ; Jensen et al. , 2013 ), eventually becoming bio-fouled by marine organisms and attracting grazers and predators, such as turtles ( Matsuoka et al. , 2005 ; Gregory, 2009 ; Jensen et al. , 2013 ; Stelfox et al. , 2014 ). Although this widespread problem is not unique to turtles, as a taxon, they appear to be particularly vulnerable. For example, a study by Wilcox et al. (2013) reported that 80% of the animals found in lost nets off the Australian coast were turtles. It may be, however, that the physical attributes of marine turtles mean they are more persistent in these nets. For example, their robust carapaces are likely to degrade more slowly and could be easier to identify than carcasses of other marine animals.

More recently, Wilcox et al. (2014) found that nets with large mesh sizes but smaller twine sizes are more likely to entangle turtles, and larger nets seemed to attract turtles, further increasing their catch rates.

Aside from lost or discarded fishing gear, turtles may become trapped in debris from land-based sources. For example, a juvenile loggerhead was found off the island of Sicily trapped in a bundle of polyethylene packaging twine ( Bentivegna, 1995 ) and a juvenile flatback turtle stranded in Australia after becoming trapped in a woven plastic bag ( Chatto, 1995 ). Reports of such incidences in scientific literature are scarce and it is likely that many individual cases of entanglement are never published (BJG, pers. obs.). Thus, the rates of entanglement in debris, such as sheet plastic and Nylon rope, from land-based sources may be greatly underestimated.

There are few investigations into the susceptibility of the various life stages, but one study found that for olive ridleys, the majority of trapped animals were subadults and adults ( Santos et al. , 2012 ). There could be several reasons for this. First, the smaller size of young juveniles enhances their ability to escape. Second, it may be that their carcasses are more readily assimilated into the environment through depredation and decomposition and therefore the evidence of their entanglement is less likely to be discovered. Lastly, it may be that nets are impacting migrating or breeding areas rather than juvenile habitats. The lack of published literature means that the scale of entanglement-induced mortality is unknown, as are the population level impacts of such mortality.

Nesting beaches are extremely important habitats for marine turtles and are already under pressure from issues such as sea-level rise and coastal development ( Fuentes et al. , 2009 ). Sandy shorelines are thought to be sinks for marine debris whereby litter, after becoming stranded, is eventually trapped in the substrate or is blown inland ( Poeta et al. , 2014 ). As such, various sizes and types of plastic accumulate on marine turtle nesting beaches ( Ivar do Sul et al. , 2011 ; Turra et al. , 2014 ). Developed or remote beaches may experience similar levels of contamination but inaccessible beaches, which are not cleaned may experience greater densities of plastic pollution (Figure 2 d; Özdilek et al. , 2006 ; Ivar do Sul et al. , 2011 ; Triessnig, 2012 ). From large fishing nets to tiny microscopic particles, this debris presents a threat to nesting females, their eggs, and emerging hatchlings ( Ivar do Sul et al. , 2011 ; Triessnig, 2012 ; Turra et al. , 2014 ), further limiting and/or degrading the amount of habitat available for reproduction.

Female marine turtles are philopatric, returning to their natal region to lay eggs in the sand ( Bowen and Karl, 2007 ). Large debris obstacles may impede females during the nest site selection stage, causing them to abort the nesting attempt and return to the sea without depositing eggs ( Chacón-Chaverri and Eckert, 2007 ). Alongside this, entanglement is a risk when debris, such as netting, monofilament fishing line, and rope, is encountered ( Ramos et al. , 2012 ). Additionally, macro-plastic within the sand column itself may prevent hatchlings from leaving the egg chamber, trapping them below the surface (Authors', pers. obs.).

On emergence from the nest, hatchlings must orient themselves towards the sea and enter the water as quickly as possible to avoid depredation and desiccation ( Tomillo et al. , 2010 ; Triessnig, 2012 ). The presence of obstacles may act as a barrier to this frenzy crawl, not only trapping and killing the hatchlings but increasing their vulnerability to predators and causing them to expend greater amounts of energy ( Özdilek et al. , 2006 ; Triessnig, 2012 ).

The physical properties of nesting beaches, particularly the permeability and temperature, are known to be altered by the presence of plastic fragments and pellets ( Carson et al. , 2011 ). These authors found that adding plastic to sediment core samples significantly increased permeability, and sand containing plastics warmed more slowly, resulting in a 16% decrease in thermal diffusivity ( Carson et al. , 2011 ). This, and the fact microplastics have been found up to 2 m below the surface ( Turra et al. , 2014 ), indicates potential ramifications for turtle nests. Hatchling sex-ratios are temperature-dependent; consequently, eggs that are exposed to cooler temperatures produce more male hatchlings than females within the clutch ( Witt et al. , 2010 ; Carson et al. , 2011 ; Vegter et al. , 2014 ). Eggs buried beneath sediment containing a high plastic load may also require a longer incubation period to develop sufficiently ( Carson et al. , 2011 ). Increased permeability may result in reduced humidity which could in turn lead to desiccation of the eggs ( Carson et al. , 2011 ). Other possible impacts include sediment contamination from absorbed persistent organic pollutants or leached plasticizers ( Oehlmann et al. , 2009 ; Carson et al. , 2011 ; Turra et al. , 2014 ). For example, the physiological processes of normal gonad development in red-eared slider turtles ( Trachemys scripta ) at male-producing incubation temperatures were altered by PCB exposure, resulting in sex ratios that were significantly biased towards females ( Matsumoto et al. , 2014 ).

Marine turtles utilize a variety of aquatic habitats that are both neritic and oceanic ( Bolten, 2003 ), but the presence of marine plastics may reduce productivity and cause detrimental changes in ecosystem health ( Richards and Beger, 2011 ). Here, we outline the possible impacts of plastic pollution on two key types of habitats.

Neritic foraging habitats

Coral reefs are relied upon by turtles for food, shelter from predators, and the removal of parasites by reef fish at “cleaning stations” ( León and Bjorndal, 2002 ; Blumenthal et al. , 2009 ; Sazima et al. , 2010 ; Goatley et al. , 2012 ). Richards and Beger (2011) found a negative correlation between the level of hard coral cover and coverage of marine debris as it causes suffocation, tissue abrasion, shading, sediment accumulation, and smothering; all of which may lead to coral mortality ( Matsuoka et al. , 2005 ; Brown and Macfadyen, 2007 ; Richards and Beger, 2011 ). Additionally, high densities of marine debris appear to impact both the diversity and functioning of coral reef communities, which may lead to a further reduction in biodiversity ( Matsuoka et al. , 2005 ; Richards and Beger, 2011 ). Furthermore, scleractinian corals have been shown to ingest and assimilate microplastics within their tissues, suggesting that high microplastic concentrations could impair the health of coral reefs ( Hall et al. , 2015 ). For turtles, changes to these assemblages may lead to a reduced availability of food, a greater predation risk, and an increase in epibiotic loads, such as barnacles ( Sazima et al. , 2010 ).

Sea grass beds and macroalgae communities are important foraging habitats for the herbivorous green turtle but are sensitive to habitat alterations; the impacts of which are often observed in the form of reduced species richness ( Santos et al. , 2011 ). As highly competitive species become dominant, some marine herbivores are forced to consume less-preferred algal species which in turn reduces the dietary complexity of those organisms ( Santos et al. , 2011 ). Balazs (1985) found that this resulted in reduced growth rates of juvenile turtles.

Oceanic fronts

As previously discussed, features such as mesoscale thermal fronts and smaller coastal eddies act as foraging hotspots for many marine organisms and are an important micro-habitat for pelagic or surface feeding coastal turtles ( Scales et al. , 2014 , 2015 ). However, these features are likely sink areas for both macro and microplastics which degrade the quality of these critical habitats, not only in terms of increasing the risk of direct harm through ingestion and entanglement, but by indirectly altering the abundance and quality of the food available ( González Carman et al. , 2014 ). Small particles of plastic are known to affect the reproduction and growth rates of low trophic level organisms, for example, zooplankton ( Cole et al. , 2013 ). Finally, there is a possibility that the accumulation of such plastic debris can inhibit the gas exchange within the water column, resulting in hypoxia or anoxia in the benthos, which in turn can interfere with normal ecosystem functioning and alter the biodiversity of the seabed ( Derraik, 2002 ).

There are many worthy lines of investigation that would further aid our understanding of the expanding issue of marine plastic pollution and its impact on marine turtles. These are discussed below and summarized in Table 3 .

Summary of recommended research priorities.

Given the variability in the scale and extent of plastic pollution within the marine environment, there is a clear need to improve our knowledge of relative risk. To achieve this, we advocate for further research to better understand the species, populations, and size classes that have either high likelihood of exposure or high consequences of ingestion. There are a number of biases that need to be eliminated in our knowledge base.

Studies from the Atlantic are as many as those from all other oceans combined. There clearly needs to be much further work from the Indo-pacific.

Although the relative distribution of studies in some way maps to the overall research effort across species, there clearly needs to be more work on species other than loggerhead and green turtles. Of particular interest are hawksbill, leatherback, and olive ridley turtles, given their cosmopolitan distribution and the largely oceanic nature of the latter two species. For Kemp's ridleys and flatbacks, despite their limited geographic range, there is clearly room for a better understanding of this problem, especially given the conservation status of the former.

It is suggested that young turtles residing in or transiting convergence zones, where high densities of plastics are known to occur, are at greater risk from ingesting plastic debris. As such, these areas could act as a population sink ( Witherington, 2002 ; Witherington et al. , 2012 ; González Carman et al. , 2014 ). As the development and survivorship of young turtles is critical for species persistence, it must be emphasized to generate greater understanding of the impacts of plastics for this life stage and therefore future population viability. Further sampling of frontal zones and knowledge concerning the oceanic developmental stage or “lost years” is also needed. Particularly as the detectability of mortality rates in these post-hatchling turtles is likely to be low ( Witherington, 2002 ; Witherington et al. , 2012 ).

We found only one study that compared ingestion between the sexes, the results of which showed that the frequency of occurrence of debris ingestion was significantly higher in females. Further studies are needed to investigate whether this pattern is observed elsewhere and if so, whether this sex-based difference in plastic ingestion is biologically significant ( Bjorndal et al. , 1994 ).

In terms of practical methods for identifying temporal and spatial patterns of plastic ingestion by turtles, Schuyler et al. (2014) found necropsy to be the most effective method. Its application, however, is constrained by small sample sizes because data collection is limited to dead animals. Therefore, every opportunity to examine by-caught and stranded individuals should be utilized ( Bjorndal et al. , 1994 ). Alongside gut contents from necropsied turtles, faecal and lavage samples from live specimens should also be analysed. Although not currently a commonly used practise, this may offer insights into survival, partial or total digestion, and comparisons with dead turtles with plastic loads ( Witherington, 2002 ; Hoarau et al. , 2014 ). Integrating body condition indices into necropsy practices will generate a better understanding of the sublethal impacts of plastic ingestion, such as malnutrition and the absorption of toxins ( Bjorndal et al. , 1994 ; Gregory, 2009 ; Labrada-Martagón et al. , 2010 ). It may also be useful to record conditions such as the presence of fibropapillomatosis or epibiotic loads (such as barnacles) as they are also often used as indicators of health ( Aguirre and Lutz, 2004 ; Stamper et al. , 2005 ).

When surveying the literature on plastic debris and marine turtles, it must be emphasized to recognize that published studies do not necessarily represent a randomized sample of the rates of interactions between marine turtles and plastic debris. It is unlikely that researchers who find no evidence of plastic in their study (either in habitats or during necropsies) report negative findings—we found only two studies that did so ( Flint et al. , 2010 ; Reinhold, 2015 ). Data on the absence of marine turtle interactions with plastic debris form an important complement to other datasets, and will facilitate a better understanding of spatio-temporal trends in rates of interactions. We strongly encourage researchers to publish both positive and negative results related to plastics and marine turtles.

We suggest that the endeavours above would be greatly facilitated by a global open access database of necropsy results with regard to plastics. At its simplest, this would be date, location, species, size, state of decomposition, likely cause of death, and some basic descriptors of presence or absence of plastic ingestion or entanglement with associated metadata. This way, workers with a single or small number of cases could still contribute to the global endeavour. Currently, seaturtle.org hosts a Sea Turtle Rehabilitation and Necropsy Database, STRAND, which allows users to upload gross necropsy reports.

To complement this, it will be important to investigate the passage of plastics through the gut, their degradation, and in addition the transport and bioavailability of bioaccumulative and toxic substances ( Campani et al. , 2013 ). Few studies have been conducted on the bioaccumulation and trophic transfer of microplastics. Most have focused on invertebrates in controlled laboratory experiments and none focus on the higher trophic level organisms such as marine turtles ( Wright et al. , 2013 ). Future studies should sample turtle prey species for the presence of microplastics, examine trophic transfer from prey species containing microplastics, and test for the presence of the contaminants associated with these particles in tissues of necropsied turtles.

To ensure data are comparable, the measurements used to quantify plastic abundance should be standardized. Currently, a variety of metrics are employed, making comparisons among studies difficult. The most common approach is to record total numbers and/or size of fragments. There is a possibility, however, that plastic may break down within the gut or become compressed to appear smaller. Therefore, it is more accurate and comparable to record the total dry weight once extracted ( Schuyler et al. , 2012 ; Camedda et al. , 2014 ). Additionally, a wider, more global application of the European Marine Strategy Framework Directive (MSFD) “toolkit” for classification would allow a better comparison of the properties and types of ingested plastics. Furthermore, although not currently included in the MSFD toolkit, efforts to classify colour and/or shape would aid selectivity studies and offer insights as to whether these properties influence the levels of ingestion by turtles ( Lazar and Gračan, 2011 ; Hoarau et al. , 2014 ). The colour and shape should then be compared with those of plastic pieces found in the environment of the species/life stage investigated. Systematic collection of photos with a scale bar could allow computer-based analytical techniques to be used to classify plastics and compare data across studies.

Debris–turtle interactions often occur in remote locations, far from human habitation and the chronic effects of plastic ingestion may present themselves long after the items were first encountered ( Witherington, 2002 ; Ivar do Sul et al. , 2011 ; Schuyler et al. , 2014 ). The use of tracking technologies, such as satellite telemetry, has already been successfully employed to identify foraging habitats and migration corridors for all sea turtle species. Such data are now being used to develop niche models that can offer a synoptic view of the distribution of a whole segment of a population by season ( Pikesley et al. , 2013 ) and can help predict where these ranges may be in the future ( Pikesley et al. , 2014 ). Combining such data with plastic debris concentrations using remote sensing methods may identify threat hotspots leading to more effective conservation recommendations ( Barnes et al. , 2009 ). At present, the tracking devices used on subadult and adult turtles are not yet available for hatchlings, but technological advances mean they will most likely be available soon as small turtles are now being tracked ( Abecassis et al. , 2013 ; Mansfield et al. , 2014 ). In the interim, direct sampling of juveniles in situ with subsequent assessment of plastic loads during a period of captivity would seem a reasonable approach. Alternative methods, such as ocean circulation modelling, can be used to predict the migratory trajectories of hatchling turtles to understand their movements in the open ocean ( Putman et al. , 2012 ). Additionally, such methods could also be employed to simulate marine debris dispersal. The development of sophisticated three-dimensional oceanographic models will enable substantial improvements to our understanding of debris transport and turtle movements.

The analysis of trace elements may be used to broadly infer the locations of foraging areas and deduce possible interactions with high concentrations of plastics ( López-Castro et al. , 2013 ). A study by López-Castro et al. (2013) tentatively identified six oceanic clusters as foraging locations for Atlantic green turtles. As it stands this method needs refinement but with further development, fine-scale mapping may become feasible, offering valuable insights in terms of the spatial overlap with plastic debris distribution.

In addition to the horizontal spatial overlap between turtles and plastics, it would also be beneficial to understand the vertical distribution of quantities and sizes of plastics as this will influence the degree to which marine biodiversity is affected, particularly for those taxa who breathe air and forage near the surface ( Reisser et al. , 2014b ).

In a study by Wilcox et al. (2013) , the spatial degree of threat posed by ghost net entanglement was predicted by combining physical models of oceanic drift and beach clean data with data concerning marine turtle distributions in northern Australia. This process identified high-risk areas so that recommendations for monitoring and remediation could be made ( Wilcox et al. , 2013 ). This approach could be replicated on a global scale but would only be possible where such data exist. As such, a greater research effort is urgently needed ( Matsuoka et al. , 2005 ). Indeed, the MSFD Technical Subgroup on Marine Litter is developing a dedicated monitoring protocol for their next report ( MSFD GES Technical Subgroup on Marine Litter, 2011 ). Additionally, fisheries layers, such as vessel monitoring system (VMS) data, may help outline areas of high fishing pressure ( Witt and Godley, 2007 ). To determine the amount of time debris has drifted, Jensen et al. (2013) suggest recording the abundance of epibionts as well as the presence and decomposition state of any entangled turtles.

It would be beneficial to test for any variation in entanglement rates among species and life stages to better understand vulnerability ( Wilcox et al. , 2013 ), particularly for small or isolated populations ( Jensen et al. , 2013 ). Stranding networks, where dead or alive turtles washed up on beaches are recorded, offer an opportunity to carry out research, not only in terms of debris entanglement but for other anthropogenic issues such as fisheries bycatch and ship strike ( Casale et al. , 2010 ). In obvious cases of entanglement, such data can provide valuable insights into the temporal and spatial trends in mortality. However, it can be difficult for the lay-person, and even experts, to confidently determine the cause of death for accurate recording ( Casale et al. , 2010 ). For those turtles that strand alive, information should be gathered on health status and post-release mortality. Currently, there are indications that species, time, depth, and severity of entanglement affect the probability of post-release survival ( Snoddy et al. , 2009 ).

During our literature search, we found that the majority of publications on turtle entanglement focus on the issue of ghost fishing by lost gear and few report entrapment in other forms of marine debris, for example, those originating from land-based sources ( n = 2 of 9). Exploration into why this may be seems a pertinent next step for research. Additionally, to overcome the lack of peer-reviewed material, efforts should be made to gather and synthesize all relevant grey literature (for example, Balazs, 1984 , 1985 ) in a manner that is suitable for peer-reviewed publication.

As per ingestion, a global open access database of entanglements (and animals discovered without entanglement) would greatly facilitate research efforts.

Impacts to nesting beach

Few studies exist whereby the extent of debris-induced mortality, or even interactions, for emerging hatchlings is investigated ( Özdilek et al. , 2006 ; Triessnig, 2012 ). Observational monitoring programmes could be developed for the many conservation projects operating globally on turtle nesting beaches. This could also be applied to nesting adult females. Currently, most observations are anecdotal ( Özdilek et al. , 2006 ; Triessnig, 2012 ). Standardized protocols for monitoring and data collection would help facilitate comparisons across studies and over time ( Velander and Mocogni, 1999 ). Additionally, the establishment of a globally accessible database of marine debris surveys on nesting beaches would help facilitate an improved understanding of the impacts of plastics on sea turtles that use sandy beaches. Oceanographic modelling could be used to forecast how and when key coastal areas are likely to be impacted in the future.

To date, most studies on coastal microplastic distributions have focused on surface densities. As illustrated by Turra et al. (2014) , this may lead to a mis-representation of their overall concentrations. To better quantify this, and develop a greater understanding of the potential impacts on marine turtles and their eggs, three-dimensional sampling should be carried out, investigating the distribution of microplastics at depth ( Turra et al. , 2014 ).

Additionally, the relationship between marine plastics and hatchling sex ratios, both in terms of chemical contamination and nest environments, requires greater clarification. This is of interest due to the potential large-scale impacts on turtle populations, particularly as climate change is already predicted to significantly alter female to male ratios ( Hawkes et al. , 2009 ).

Wider ecosystems effects

Due to the importance of marine habitats such as coral reefs, sea grass beds, and mesoscale thermal fronts for marine turtles, it is essential that we understand the scale of impact from marine debris. Data concerning the distribution and abundance of plastics within these key ecosystems will provide an environmental baseline, a method by which patterns, trends, and, potentially solutions, may be identified. As both coral reefs and seagrass beds are often frequented by divers, utilizing citizen science-based approaches, such as volunteer surveys, may be an affordable and effective method of collecting such data ( Smith and Edgar, 2014 ). Offshore sampling at oceanic fronts may require greater resources but collaboration between research disciplines and industries may help to minimize duplication of effort and expense. As the presence of plastics within the marine environment is of concern not only for biodiversity conservation but for fisheries, tourism, and human health and well-being (through contamination of seafood, a commercially important resource), it is likely that research into this area will grow. As such, it would seem appropriate that those concerned should cooperate to tackle the issue, sharing data where possible.

To better understand the ecosystem level effects of marine plastics, micro- and mesocosm experiments are useful methods of replicating natural environmental systems in controlled conditions ( Benton et al. , 2007 ). So far, the majority of such studies have looked only at single taxa, but these study systems allow for investigation into how the links between different marine environments may be affected. As such, further studies should focus on bentho-pelagic coupling to explore the impacts of plastics on the relationships themselves, providing an indication of what influences this foreign debris may have on ecosystem functioning.

Currently, there is little clear evidence to demonstrate that interactions with plastics cause population level impacts for marine turtles. This, however, should not be interpreted as a lack of effect ( Gall and Thompson, 2015 ). Their widespread distribution, complicated spatial ecology, and highly mobile lifestyles make studying turtles difficult and the development of monitoring programmes that deliver statistically robust results challenging. This coupled with the diffuse nature of marine plastic pollution further exacerbates the difficulty in identifying a direct causal link to any potential impacts. In this review, we have demonstrated the widespread and diverse pathways by which plastics may affect turtles. These include ingestion, both directly and indirectly; entanglement; alterations to nesting beach properties; wider ecosystem effects. Although it is evident that this issue could have far-reaching ramifications for marine biodiversity, the lack of focused scientific research into this topic is a major hindrance to its resolution. Policy-makers require robust, comparable, scale-appropriate data (including negative results) on which to develop appropriate and effective mitigation recommendations, something which, as it stands, are severely lacking ( Brown and Macfadyen, 2007 ). We encourage open reporting of plastic–turtle interactions and urge such observations to be submitted for peer-reviewed publication where ever possible. Furthermore, cooperation among scientists, industry, governments, and the general public is urgently needed to confront this rapidly increasing form of pollution.

The authors thank two anonymous reviewers for their valuable and insightful comments that improved our manuscript. BJG and ACB receive support from NERC and the Darwin Initiative and BJG and PKL were funded by a University of Exeter—Plymouth Marine Laboratory collaboration award which supported EMD. We acknowledge funding to TSG from the EU seventh framework programme under Grant Agreement 308370 and PKL and TSG receive funding from a NERC Discovery Grant (NE/L007010/1).

Abecassis M. Senina I. Lehodey P. Gaspar P. Parker D. Balazs G. Polovina J. 2013 . A model of loggerhead sea turtle ( Caretta caretta ) habitat and movement in the oceanic north Pacific . PLoS ONE , 8 : e73274 .

Google Scholar

Abu-Hilal A. Al-Najjar T. 2009 . Marine litter in coral reef areas along the Jordan Gulf of Aqaba, Red Sea . Journal of Environmental Management , 90 : 1043 – 1049 .

Aguirre A. A. Lutz P. L. 2004 . Marine turtles as sentinels of ecosystem health: is fibropapillomatosis an indicator ? EcoHealth , 1 : 275 – 283 .

Allen W. 1992 . Loggerhead dies after ingesting marine debris . Marine Turtle Newsletter , 58 : 10 .

Andrady A. L. 2015 . Persistence of plastic litter in the oceans . In Marine anthropogenic litter , pp. 57–72. Ed. by M. Bergmann, L. Gutow and M. Klages. Springer, Berlin .

Arauz Almengor M. Morera Avila R. A. 1994 . Ingested plastic implicated in death of juvenile hawksbill . Marine Turtle Newsletter , 64 : 13 .

Arthur K. E. Boyle M. C. Limpus C. J. 2008 . Ontogenetic changes in diet and habitat use in green sea turtle ( Chelonia mydas ) life history . Marine Ecology Progress Series , 362 : 303 – 311 .

Awabdi D. R. Siciliano S. Di Beneditto A. P. M. 2013 . First information about the stomach contents of juvenile green turtles, Chelonia mydas , in Rio de Janeiro, south-eastern Brazil . Marine Biodiversity Records , 6 : e5 .

Azzarello M. Van Vleet E. 1987 . Marine birds and plastic pollution . Marine Ecology Progress Series , 37 : 295 – 303 .

Balazs G. H. 1985 . Status and ecology of marine turtles at Johnston Atoll . Atoll Research Bulletin , 285 : 1 – 46 .

Balazs G. 1984 . Impact of ocean debris on marine turtles: entanglement and ingestion . In Proceedings of the workshop on the fate and impact of marine debris , pp. 387 – 430 .

Google Preview

Bane G. 1992 . First report of a loggerhead sea turtle from Alaska . Marine Turtle Newsletter , 58 : 1 – 2 .

Barnes D. K. A. Galgani F. Thompson R. C. Barlaz M. 2009 . Accumulation and fragmentation of plastic debris in global environments . Philosophical Transactions of the Royal Society B , 364 : 1985 – 1998 .

Barreiros J. P. Barcelos J. 2001 . Plastic ingestion by a leatherback turtle Dermochelys coriacea from the Azores (NE Atlantic) . Marine Pollution Bulletin , 42 : 1196 – 1197 .

Barreiros J. P. Raykov V. S. 2014 . Lethal lesions and amputation caused by plastic debris and fishing gear on the loggerhead turtle Caretta caretta (Linnaeus, 1758). Three case reports from Terceira Island, Azores (NE Atlantic) . Marine Pollution Bulletin , 86 : 518 – 522 .

Bartol S. Musick J. 2003 . Sensory biology of sea turtles . In The Biology of Sea Turtles , 2 , pp. 79 – 102 . Ed. by Lutz J. Musick P. L. Wyneken J. A. . CRC Press , Boca Raton, FL .

Battin J. 2004 . When good animals love bad habitats: ecological traps and the conservation of animal populations . Conservation Biology , 18 : 1482 – 1491 .

Baulch S. Perry C. 2014 . Evaluating the impacts of marine debris on cetaceans . Marine Pollution Bulletin , 80 : 210 – 221 .

Bentivegna F. 1995 . Endoscopic removal of polyethylene cord from a loggerhead turtle . Marine Turtle Newsletter , 71 : 5 .

Benton T. G. Solan M. Travis J. M. J. Sait S. M. 2007 . Microcosm experiments can inform global ecological problems . Trends in Ecology and Evolution , 22 : 516 – 521 .

Bezerra D. P. Bondioli A. C. V. 2011 . Ingestão de resíduos inorgânicos por Chelonia mydas na área de alimentação do Complexo Estuarino Lagunar de Cananéia . In Proceedings of the V Jornada sobre Tartarugas Marinhas do Atlântico Sul Ocidental , São Paulo, Brasil , pp. 51 – 54 .

Bjorndal K. A. 1997 . Foraging ecology and nutrition of sea turtles . In The Biology of Sea Turtles , pp. 397 – 409 . Ed. by Lutz P. L. Musick J. . CRC Press , Boca Raton, FL .

Bjorndal K. A. Bolten A. B. Lagueux C. J. 1994 . Ingestion of marine debris by juvenile sea turtles in coastal Florida habitats . Marine Pollution Bulletin , 28 : 154 – 158 .

Blumenthal J. M. Austin T. J. Bothwell J. B. Broderick A. C. Ebanks-Petrie G. Olynik J. R. Orr M. F. et al.  2009 . Diving behavior and movements of juvenile hawksbill turtles Eretmochelys imbricata on a Caribbean coral reef . Coral Reefs , 28 : 55 – 65 .

Bolten A. 2003 . Variation in sea turtle life history patterns: neritic vs. oceanic developmental stages . In The Biology of Sea Turtles , 2 , pp. 243 – 257 . Ed. by Musick J. Wyneken J. Lutz P. L. . CRC Press , Boca Raton, FL .

Bond A. L. Provencher J. F. Daoust P-Y. Lucas Z. N. 2014 . Plastic ingestion by fulmars and shearwaters at Sable Island, Nova Scotia, Canada . Marine Pollution Bulletin , 87 : 68 – 75 .

Bowen B. W. Karl S. A. 2007 . Population genetics and phylogeography of sea turtles . Molecular Ecology , 16 : 4886 – 4907 .

Boyle M. C. 2006 . Post-hatchling sea turtle biology . PhD thesis . 128 pp .

Boyle M. C. Fitzsimmons N. N. Limpus C. J. Kelez S. Velez-Zuazo X. Waycott M. 2009 . Evidence for transoceanic migrations by loggerhead sea turtles in the southern Pacific Ocean . Proceedings of the Royal Society B , 276 : 1993 – 1999 .

Boyle M. C. Limpus C. J. 2008 . The stomach contents of post-hatchling green and loggerhead sea turtles in the southwest Pacific: an insight into habitat association . Marine Biology , 155 : 233 – 241 .

Brown J. Macfadyen G. 2007 . Ghost fishing in European waters: impacts and management responses . Marine Policy , 31 : 488 – 504 .

Bugoni L. Krause L. Petry M. V. 2001 . Marine debris and human impacts on sea turtles in southern Brazil . Marine Pollution Bulletin , 42 : 1330 – 1334 .

Burke V. Morreale S. Standora E. 1994 . Diet of the Kemp's ridley sea turtle, Lepidochelys kempii , in New York waters . US National Marine Fisheries Service Fishery Bulletin , 92 pp .

Camedda A. Marra S. Matiddi M. Massaro G. Coppa S. Perilli A. Ruiu A. et al.  2014 . Interaction between loggerhead sea turtles ( Caretta caretta ) and marine litter in Sardinia (Western Mediterranean Sea) . Marine Environmental Research , 100 : 25 – 32 .

Campani T. Baini M. Giannetti M. Cancelli F. Mancusi C. Serena F. Marsili L. et al.  2013 . Presence of plastic debris in loggerhead turtle stranded along the Tuscany coasts of the Pelagos Sanctuary for Mediterranean Marine Mammals (Italy) . Marine Pollution Bulletin , 74 : 225 – 230 .

Cannon A. C. 1998 . Gross necropsy results of sea turtles stranded on the upper Texas and western Louisiana coasts, 1 January–31 December 1994 in characteristics and causes of Texas marine strandings , pp. 81 – 85 . US National Oceanic and Atmospheric Administration (NOAA) .

Carr A. 1987 . Impact of nondegradable marine debris on the ecology and survival outlook of sea turtles . Marine Pollution Bulletin , 18 : 352 – 356 .

Carson H. S. Colbert S. L. Kaylor M. J. McDermid K. J. 2011 . Small plastic debris changes water movement and heat transfer through beach sediments . Marine Pollution Bulletin , 62 : 1708 – 1713 .

Casale P. Abbate G. Freggi D. Conte N. Oliverio M. Argano R. 2008 . Foraging ecology of loggerhead sea turtles Caretta caretta in the central Mediterranean Sea: evidence for a relaxed life history model . Marine Ecology Progress Series , 372 : 265 – 276 .

Casale P. Affronte M. Insacco G. Freggi D. Vallini C. Pino D'Astore P. Basso R. et al.  2010 . Sea turtle strandings reveal high anthropogenic mortality in Italian waters . Aquatic Conservation: Marine and Freshwater Ecosystems , 20 : 611 – 620 .

Chacón-Chaverri D. Eckert K. L. 2007 . Leatherback sea turtle nesting at Gandoca beach in Caribbean Costa Rica: management recommendations from fifteen years of conservation . Chelonian Conservation and Biology , 6 : 101 – 110 .

Chatto R. 1995 . Sea turtles killed by flotsam in northern Australia . Marine Turtle Newsletter , 69 : 17 – 18 .

Cole M. Lindeque P. Fileman E. Halsband C. Galloway T. S. 2015 . The impact of polystyrene microplastics on feeding, function and fecundity in the marine copepod Calanus helgolandicus . Environmental Science and Technology , 49 : 1130 – 1137 .

Cole M. Lindeque P. Fileman E. Halsband C. Goodhead R. Moger J. Galloway T. S. 2013 . Microplastic ingestion by zooplankton . Environmental Science and Technology , 47 : 6646 – 6655 .

Cózar A. Echevarría F. González-Gordillo J. I. Irigoien X. Ubeda B. Hernández-León S. Palma A. T. et al.  2014 . Plastic debris in the open ocean . Proceedings of the National Academy of Sciences of the United States of America , 111 : 10239 – 10244 .

Cózar A. Sanz-Martín M. Martí E. González-Gordillo J. I. Ubeda B. Gálvez J. Á. Irigoien X. et al.  2015 . Plastic accumulation in the mediterranean sea . PLoS ONE , 10 : e0121762 .

da Silva Mendes S. de Carvalho R. H. de Faria A. F. de Sousa B. M. 2015 . Marine debris ingestion by Chelonia mydas (Testudines: Cheloniidae) on the Brazilian coast . Marine Pollution Bulletin , 92 : 8 – 10 .

Davenport J. Balazs G. H. Faithfull J. Williamson D. A. 1993 . A struvite faecolith in the leatherback turtle Dermochelys coriacea Vandelli. A means of packaging garbage? Herpetological Journal , 3 : 81 – 83 .

Derraik J. G. B. 2002 . The pollution of the marine environment by plastic debris: a review . Marine Pollution Bulletin , 44 : 842 – 852 .

Di Bello A. Valastro C. Freggi D. Lai O. R. Crescenzo G. Franchini D. 2013 . Surgical treatment of injuries caused by fishing gear in the intracoelomic digestive tract of sea turtles . Diseases of Aquatic Organisms , 106 : 93 – 102 .

Di Beneditto A. P. M. Awabdi D. R. 2014 . How marine debris ingestion differs among megafauna species in a tropical coastal area . Marine Pollution Bulletin , 88 : 86 – 90 .

Duguy R. Moriniere P. Meunier A. 2000 . L'ingestion des déchets flottants par la tortue luth Dermochelys coriacea (Vandelli, 1761) dans le Golfe de Gascogne . In Annales de la Société des Sciences Naturelles de la Charente-Maritimes , pp. 1035 – 1038 .

Eckert K. L. Hemphill A. H. 2005 . Sea turtles as flagships for protection of the wider Caribbean region . Mast , 3 : 119 – 143 .

Eckert K. L. Luginbuhl C. 1988 . Death of a giant . Marine Turtle Newsletter , 43 : 2 – 3 .

Eriksson C. Burton H. 2003 . Origins and biological accumulation of small plastic particles in fur seals from Macquarie Island . AMBIO: A Journal of the Human Environment , 32 : 380 – 384 .

Flint M. Patterson-Kane J. C. Limpus C. J. Mills P. C. 2010 . Health surveillance of stranded green turtles in Southern Queensland, Australia (2006–2009): An epidemiological analysis of causes of disease and mortality . EcoHealth , 7 : 135 – 145 .

Foley A. M. Singel K. E. Dutton P. H. Summers T. M. Redlow A. E. Lessman J. 2007 . Characteristics of a green turtle ( Chelonia mydas ) assemblage in northwestern Florida determined during a hypothermic stunning event . Gulf of Mexico Science , 25 : 131 – 143 .

Fossette S. Gleiss A. C. Myers A. E. Garner S. Liebsch N. Whitney N. M. Hays G. C. et al.  2010 . Behaviour and buoyancy regulation in the deepest-diving reptile: the leatherback turtle . The Journal of Experimental Biology , 213 : 4074 – 4083 .

Frick M. G. Williams K. L. Bolten A. Bjorndal K. Martins H. 2009 . Foraging ecology of oceanic-stage loggerhead turtles Caretta caretta . Endangered Species Research , 9 : 91 – 97 .

Frick M. G. Williams K. L. Pierrard L. 2001 . Summertime foraging and feeding by immature loggerheads sea turtles ( Caretta caretta ) from Georgia . Chelonian Conservation and Biology , 4 : 178 – 181 .

Fuentes M. Limpus C. Hamann M. Dawson J. 2009 . Potential impacts of projected sea-level rise on sea turtle rookeries . Aquatic Conservation: Marine and Freshwater Ecosystems , 20 : 132 – 139 .

Gall S. C. Thompson R. C. 2015 . The impact of debris on marine life . Marine Pollution Bulletin , 92 : 170 – 179 .

Garnett S. Price R. Scott F. 1985 . The diet of the green turtle, Chelonia mydas (L.), in Torres Strait . Australian Wildlife Research , 12 : 103 – 112 .

Goatley C. H. R. Hoey A. S. Bellwood D. R. 2012 . The role of turtles as coral reef macroherbivores . PLoS ONE , 7 : e39979 .

González Carman V. Acha E. M. Maxwell S. M. Albareda D. Campagna C. Mianzan H. 2014 . Young green turtles, Chelonia mydas , exposed to plastic in a frontal area of the SW Atlantic . Marine Pollution Bulletin , 78 : 56 – 62 .

Greenland J. A. Limpus C. J. 2003 . Marine wildlife stranding and mortality database annual report 2003 III . Marine Turtles. Conservation Technical and Data Report, 2003 .

Gregory M. R. 2009 . Environmental implications of plastic debris in marine settings-entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions . Philosophical Transactions of the Royal Society B , 364 : 2013 – 2025 .

Guebert-Bartholo F. Barletta M. Costa M. Monteiro-Filho E. 2011 . Using gut contents to assess foraging patterns of juvenile green turtles Chelonia mydas in the Paranagua Estuary, Brazil . Endangered Species Research , 13 : 131 – 143 .

Hall N. M. Berry K. L. E. Rintoul L. Hoogenboom M. O. 2015 . Microplastic ingestion by scleractinian corals . Marine Biology , 162 : 725 – 732 .

Hamann M. Grech A. Wolanski E. Lambrechts J. 2011 . Modelling the fate of marine turtle hatchlings . Ecological Modelling , 222 : 1515 – 1521 .

Hasbún C. R. Lawrence A. J. Samour J. H. Al-Ghais S. M. 2000 . Preliminary observations on the biology of green turtles, Chelonia mydas , from the United Arab Emirates . Aquatic Conservation: Marine and Freshwater Ecosystems , 10 : 311 – 322 .

Hawkes L. A. Broderick A. C. Coyne M. S. Godfrey M. H. Lopez-Jurado L. F. Lopez-Suarez P. Merino S. E. et al.  2006 . Phenotypically linked dichotomy in sea turtle foraging requires multiple conservation approaches . Current Biology , 16 : 990 – 995 .

Hawkes L. Broderick A. Godfrey M. Godley B. 2009 . Climate change and marine turtles . Endangered Species Research , 7 : 137 – 154 .

Hazel J. Gyuris E. 2006 . Vessel-related mortality of sea turtles in Queensland, Australia . Wildlife Research , 33 : 149 – 154 .

Hoarau L. Ainley L. Jean C. Ciccione S. 2014 . Ingestion and defecation of marine debris by loggerhead sea turtles, Caretta caretta , from by-catches in the South-West Indian Ocean . Marine Pollution Bulletin , 84 : 90 – 96 .

Ivar do Sul J. A. Santos I. R. Friedrich A. C. Matthiensen A. Fillmann G. 2011 . Plastic pollution at a sea turtle conservation area in NE Brazil: contrasting developed and undeveloped beaches . Estuaries and Coasts , 34 : 814 – 823 .

Jambeck J. R. Geyer R. Wilcox C. Siegler T. R. Perryman M. Andrady A. Narayan R. et al.  2015 . Plastic waste inputs from land into the ocean . Science , 347 : 768 – 771 .

Jensen M. Limpus C. Whiting S. Guinea M. Prince R. Dethmers K. Adnyana I. et al.  2013 . Defining olive ridley turtle Lepidochelys olivacea management units in Australia and assessing the potential impact of mortality in ghost nets . Endangered Species Research , 21 : 241 – 253 .

Kaska Y. Celik A. Bag H. Aureggi M. Ozel K. Elci A. Kaska A. et al.  2004 . Heavy metal monitoring in stranded sea turtles along the Mediterranean coast of Turkey . Fresenius Environmental Bulletin , 13 : 769 – 776 .

Koelmans A. A. 2015 . Modeling the role of microplastics in bioaccumulation of organic chemicals to marine aquatic organisms. A critical review . In Marine anthropogenic litter , pp. 309 – 324 . Ed. by M. Bergmann, L. Gutow and M. Klages. Springer, Berlin .

Labrada-Martagón V. Méndez-Rodríguez L. C. Gardner S. C. López-Castro M. Zenteno-Savín T. 2010 . Health indices of the green turtle ( Chelonia mydas ) along the Pacific coast of Baja California Sur, Mexico. I. Blood Biochemistry Values . Chelonian Conservation and Biology , 9 : 162 – 172 .

Landsberg J. H. Balazs G. H. Steidinger K. A. Baden D. G. Wada M. Work T. M. Rabalais N. N. et al.  1999 . The potential role of natural tumor promoters in marine turtle fibropapillomatosis . Journal of Aquatic Animal Health , 11 : 199 – 210 .

Lazar B. Gračan R. 2011 . Ingestion of marine debris by loggerhead sea turtles, Caretta caretta , in the Adriatic Sea . Marine Pollution Bulletin , 62 : 43 – 47 .

León Y. M. Bjorndal K. A. 2002 . Selective feeding in the hawksbill turtle, an important predator in coral reef ecosystems . Marine Ecology Progress Series , 245 : 249 – 258 .

Lewison R. Crowder L. Read A. Freeman S. 2004 . Understanding impacts of fisheries bycatch on marine megafauna . Trends in Ecology and Evolution , 19 : 598 – 604 .

Limpus C. Limpus D. 2001 . The loggerhead turtle, Caretta caretta , in Queensland: breeding migrations and fidelity to a warm temperate feeding area . Chelonian Conservation and Biology , 4 : 142 – 153 .

López-Castro M. C. Bjorndal K. A. Kamenov G. D. Zenil-Ferguson R. Bolten A. B. 2013 . Sea turtle population structure and connections between oceanic and neritic foraging areas in the Atlantic revealed through trace elements . Marine Ecology Progress Series , 490 : 233 – 246 .

Lopez-Jurado L. F. Varo-Cruz N. Lopez-Suarez P. 2003 . Incidental capture of loggerhead turtles ( Caretta caretta ) on Boa Vista (Cape Verde Islands) . Marine Turtle Newsletter , 101 : 14 – 16 .

López-Mendilaharsu M. Gardner S. C. Seminoff J. A. Riosmena-Rodriguez R. 2005 . Identifying critical foraging habitats of the green turtle ( Chelonia mydas ) along the Pacific coast of the Baja California peninsula, Mexico . Aquatic Conservation: Marine and Freshwater Ecosystems , 15 : 259 – 269 .

Lucas Z. 1992 . Monitoring persistent litter in the marine environment on Sable Island, Nova Scotia . Marine Pollution Bulletin , 24 : 192 – 198 .

Lusher A. 2015 . Microplastics in the marine environment: distribution, interactions and effects . In Marine anthropogenic litter , pp. 245 – 307 . Ed. by M. Bergmann, L. Gutow and M. Klages. Springer, Berlin .

Lutz P. 1990 . Studies on the ingestion of plastic and latex by sea turtles . In Proceedings of the Second International Conference on Marine Debris , pp. 2 – 7 . Ed. by Shomura R. S. Godfrey M. L. . US Department of Commerce NOM Tech Memo, NMFS. NOM-TM-NMFS-SUFSC-15 , Honolulu, Hawaii .

Mansfield K. L. Wyneken J. Porter W. P. Luo J. 2014 . First satellite tracks of neonate sea turtles redefine the “lost years” oceanic niche . Proceedings of the Royal Society B , 281 : 20133039 .

Mascarenhas R. Santos R. Zeppelini D. 2004 . Plastic debris ingestion by sea turtle in Paraiba, Brazil . Marine Pollution Bulletin , 49 : 354 – 355 .

Matsumoto Y. Hannigan B. Crews D. 2014 . Embryonic PCB exposure alters phenotypic, genetic, and epigenetic profiles in turtle sex determination, a biomarker of environmental contamination . Endocrinology , 155 : 4168 – 4177 .

Matsuoka T. Nakashima T. Nagasawa N. 2005 . A review of ghost fishing: scientific approaches to evaluation and solutions . Fisheries Science , 71 : 691 – 702 .

McCauley S. J. Bjorndal K. A. 1999 . Dietary dilution from debris ingestion: sublethal effects in post-hatchling loggerhead sea turtles . Conservation Biology , 13 : 925 – 929 .

McMahon C. R. Holley D. Robinson S. 1999 . The diet of itinerant male Hooker's sea lions, Phocarctos hookeri , at sub-Antarctic Macquarie Island . Wildlife Research , 26 : 839 – 846 .

Mrosovsky N. 1981 . Plastic jellyfish . Marine Turtle Newsletter , 17 : 5 – 7 .

Mrosovsky N. Ryan G. D. James M. C. 2009 . Leatherback turtles: the menace of plastic . Marine Pollution Bulletin , 58 : 287 – 289 .

MSFD GES Technical Subgroup on Marine Litter . 2011 . Marine Strategy Framework Directive . 91 pp . http://www.ices.dk/news-and-events/themes/Managementreports/TG2Report_Final_vII.pdf (last accessed 14 September 2015) .

Oehlmann J. Schulte-Oehlmann U. Kloas W. Jagnytsch O. Lutz I. Kusk K. O. Wollenberger L. et al.  2009 . A critical analysis of the biological impacts of plasticizers on wildlife . Philosophical Transactions of the Royal Society B , 364 : 2047 – 2062 .

Özdilek H. G. Yalçin-Özdilek Ş. Ozaner F. S. Sönmez B. 2006 . Impact of accumulated beach litter on Chelonia mydas L. 1758 (green turtle) hatchlings of the Samandaǧ coast, Hatay, Turkey . Fresenius Environmental Bulletin , 15 : 1 – 9 .

Parga M. L. 2012 . Hooks and sea turtles: a veterinarian's perspective . Bulletin of Marine Science , 88 : 731 – 741 .

Parker D. Cooke W. Balazs G. 2005 . Diet of oceanic loggerhead sea turtles ( Caretta caretta ) in the central North Pacific . Fishery Bulletin , 103 : 142 – 152 .

Parker D. M. Dutton P. H. Balazs G. H. 2011 . Oceanic diet and distribution of haplotypes for the green turtle, Chelonia mydas , in the Central North Pacific . Pacific Science , 65 : 419 – 431 .

Parra M. Deem S. L. Espinoza E. 2011 . Green turtle ( Chelonia mydas ) mortality in the Galápagos Islands, Ecuador during the 2009–2010 nesting season . Marine Turtle Newsletter , 130 : 10 – 15 .

Peckham S. H. Maldonado-Diaz D. Tremblay Y. Ochoa R. Polovina J. Balazs G. Dutton P. H. et al.  2011 . Demographic implications of alternative foraging strategies in juvenile loggerhead turtles Caretta caretta of the North Pacific Ocean . Marine Ecology Progress Series , 425 : 269 – 280 .

Pikesley S. K. Broderick A. C. Cejudo D. Coyne M. S. Godfrey M. H. Godley B. J. Lopez P. et al.  2014 . Modelling the niche for a marine vertebrate: a case study incorporating behavioural plasticity, proximate threats and climate change . Ecography , 38 : 001 – 010 .

Pikesley S. K. Maxwell S. M. Pendoley K. Costa D. P. Coyne M. S. Formia A. Godley B. J. et al.  2013 . On the front line: integrated habitat mapping for olive ridley sea turtles in the Southeast Atlantic . Diversity and Distributions , 19 : 1518 – 1530 .

Plastics – the facts 2015 (PlasticsEurope, Brussels, Belgium, 2015). http://www.plasticseurope.org/Document/plastics-the-facts-20142015.aspx?FolID=2 (last accessed 14 September 2015) .

Plot V. Georges J-Y. 2010 . Plastic debris in a nesting leatherback turtle in French Guiana . Chelonian Conservation and Biology , 9 : 267 – 270 .

Plotkin P. T. Amos A. F. 1988 . Entanglement in and ingestion of marine debris by sea turtles stranded along the South Texas coast . In Proceedings of the Eighth Annual Workshop on Sea Turtle Biology and Conservation , pp. 79 – 82 . Ed. by Schroeder B. A. . NOAA Technical Memorandum NMFS-SEFC-214 , Forth Fisher, South Carolina .

Plotkin P. Amos A. 1990 . Effects of anthropogenic debris on sea turtles in the Northwestern Gulf of Mexico . In Proceedings of the Second International Conference on Marine Debris , pp. 736 – 743 . NOAA Technical Memorandum NMFS-SEFC-154 , Honolulu, Hawaii .

Plotkin P. T. Wicksten M. K. Amos A. F. 1993 . Feeding ecology of the loggerhead sea turtle Caretta caretta in the Northwestern Gulf of Mexico . Marine Biology , 115 : 1 – 5 .

Poeta G. Battisti C. Acosta A. T. R. 2014 . Marine litter in Mediterranean sandy littorals: spatial distribution patterns along central Italy coastal dunes . Marine Pollution Bulletin , 89 : 168 – 173 .

Poli C. Lopez L. Mesquita D. Saska C. Mascarenhas R. 2014 . Patterns and inferred processes associated with sea turtle strandings in Paraíba State, Northeast Brazil . Brazilian Journal of Biology , 74 : 283 – 289 .

Putman N. F. Verley P. Shay T. J. Lohmann K. J. 2012 . Simulating transoceanic migrations of young loggerhead sea turtles: merging magnetic navigation behavior with an ocean circulation model . Journal of Experimental Biology , 215 : 1863 – 1870 .

Quiñones J. Carman V. G. Zeballos J. Purca S. Mianzan H. 2010 . Effects of El Niño-driven environmental variability on black turtle migration to Peruvian foraging grounds . Hydrobiologia , 645 : 69 – 79 .

Ramos J. Pincetich C. Adams L. Santos K. C. Hage J. Arauz R. 2012 . Quantification and recommended management of man-made debris along the sea turtle nesting beach at Playa Caletas, Guanacaste, Costa Rica . Marine Turtle Newsletter , 134 : 12 – 17 .

Reinhold L. 2015 . Absence of ingested plastics in 20 necropsied sea turtles in Western Australia . Marine Turtle Newsletter , 144 : 13 – 15 .

Reisser J. Proietti M. Shaw J. Pattiaratchi C. 2014a . Ingestion of plastics at sea: does debris size really matter ? Frontiers in Marine Science , 1 : 1 – 2 .

Reisser J. Slat B. Noble K. Plessis K. Epp M. Proietti M. 2014b . The vertical distribution of buoyant plastics at sea . Biogeosciences Discuss , 11 : 16207 – 16226 .

Revelles M. Cardona L. Aguilar A. Borrell A. Fernández G. Félix M. S. 2007 . Stable C and N isotope concentration in several tissues of the loggerhead sea turtle Caretta caretta from the western Mediterranean and dietary implications . Scientia Marina , 71 : 87 – 93 .

Richards Z. T. Beger M. 2011 . A quantification of the standing stock of macro-debris in Majuro lagoon and its effect on hard coral communities . Marine Pollution Bulletin , 62 : 1693 – 1701 .

Rochman C. M. Browne M. A. Halpern B. S. Hentschel B. T. Hoh E. Karapanagioti H. K. Rios-Mendoza L. M. et al.  2013a . Classify plastic waste as hazardous . Nature , 494 : 169 – 171 .

Rochman C. M. Hoh E. Kurobe T. Teh S. J. 2013b . Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress . Scientific Reports , 3 : 3263 .

Ross J. P. 1985 . Biology of the green turtle, Chelonia mydas , on an Arabian feeding ground . Journal of Herpetology , 19 : 459 – 468 .

Russo G. Di Bella C. Loria G. R. Insacco G. Palazzo P. Violani C. Zava B. 2003 . Notes on the influence of human activities on sea chelonians in Sicilian waters . Journal of Mountain Ecology , 7 : 37 – 41 .

Sadove S. Morreale S. 1989 . Marine mammal and sea turtle encounters with marine debris in the New York Bight and the northeast Atlantic . In Proceedings of the 2nd International Conference on Marine Debris , pp. 2 – 7 . National Oceanic and Atmospheric Administration , Honolulu .

Santos A. J. B. Bellini C. Bortolon L. F. Coluchi R. 2012 . Ghost nets haunt the olive ridley turtle ( Lepidochelys olivacea ) near the Brazilian Islands of Fernando de Noronha and Atol das Rocas . Herpetological Review , 43 : 245 – 246 .

Santos R. G. Andrades R. Boldrini M. A. Martins A. S. 2015 . Debris ingestion by juvenile marine turtles: an underestimated problem . Marine Pollution Bulletin , 93 : 37 – 43 .

Santos R. G. Martins A. S. Farias J. D. N. Horta P. A. Pinheiro H. T. Torezani E. Baptistotte C. et al.  2011 . Coastal habitat degradation and green sea turtle diets in Southeastern Brazil . Marine Pollution Bulletin , 62 : 1297 – 1302 .

Sazima C. Grossman A. Sazima I. 2010 . Turtle cleaners: reef fishes foraging on epibionts of sea turtles in the tropical Southwestern Atlantic, with a summary of this association type . Neotropical Ichthyology , 8 : 187 – 192 .

Scales K. L. Miller P. I. Embling C. B. Ingram S. N. Pirotta E. Stephen C. Votier S. C. 2014 . Mesoscale fronts as foraging habitats: composite front mapping reveals oceanographic drivers of habitat use for a pelagic seabird . Journal of the Royal Society Interface , 11 : 20140679 .

Scales K. L. Miller P. I. Varo-Cruz N. Hodgson D. J. Hawkes L. A. Godley B. J. 2015 . Oceanic loggerhead turtles Caretta caretta associate with thermal fronts: evidence from the Canary Current Large Marine Ecosystem . Marine Ecology Progress Series , 519 : 195 – 207 .

Schuyler Q. Hardesty B. D. Wilcox C. Townsend K. 2012 . To eat or not to eat? Debris selectivity by marine turtles . PLoS ONE , 7 : e40884 .

Schuyler Q. Hardesty B. D. Wilcox C. Townsend K. 2014 . Global analysis of anthropogenic debris ingestion by sea turtles . Conservation Biology , 28 : 129 – 139 .

Scott R. Biastoch A. Roder C. Stiebens V. A. Eizaguirre C. 2014 . Nano-tags for neonates and ocean-mediated swimming behaviours linked to rapid dispersal of hatchling sea turtles . Proceedings of the Royal Society B , 281 : 20141209 .

Seminoff J. Resendiz A. Nichols W. 2002 . Diet of east Pacific green turtles ( Chelonia mydas ) in the central Gulf of California, México . Journal of Herpetology , 36 : 447 – 453 .

Seney E. E. Musick J. A. 2007 . Historical diet analysis of loggerhead sea turtles ( Caretta caretta ) in Virginia . Copeia , 2 : 478 – 489 .

Shaver D. J. 1991 . Feeding ecology of wild and head-started Kemp's ridley sea turtles in south Texas waters . Journal of Herpetology , 25 : 327 – 334 .

Shaver D. J. 1998 . Sea turtle strandings along the Texas coast, 1980–94 . In Characteristics and Causes of Texas Marine Strandings , pp. 57 – 72 . US National Oceanic and Atmospheric Administration (NOAA) Technical Report, 143. National Marine Fisheries .

Sigler M. 2014 . The effects of plastic pollution on aquatic wildlife: current situations and future solutions . Water, Air, and Soil Pollution , 225 : 2184 .

Smith S. D. A. Edgar R. J. 2014 . Documenting the density of subtidal marine debris across multiple marine and coastal habitats . PLoS ONE , 9 : e94593 .

Snoddy J. E. Landon M. Blanvillain G. Southwood A. 2009 . Blood biochemistry of sea turtles captured in gillnets in the lower Cape Fear river, North Carolina, USA . Journal of Wildlife Management , 73 : 1394 – 1401 .

Stahelin G. Hennemann M. Cegoni C. Wanderlinde J. Lima E. Goldberg D. 2012 . Ingestion of a massive amount of debris by a green turtle ( Chelonia mydas ) in Southern Brazil . Marine Turtle Newsletter , 135 : 6 – 8 .

Stamper M. A. Harms C. Epperly S. P. Braun-McNeill J. Avens L. Stoskopf M. K. 2005 . Relationship between barnacle epibiotic load and hematologic parameters in loggerhead sea turtles ( Caretta caretta ), a comparison between migratory and residential animals in Pamlico Sound, North Carolina . Journal of Zoo and Wildlife Medicine , 36 : 635 – 641 .

Stelfox M. Balson D. Hudgins J. 2014 . Olive ridley project: actively fighting ghost nets in the Indian Ocean . Indian Ocean Turtle Newsletter 23 – 26 .

StrandNet Database . 2015 . https://www.ehp.qld.gov.au/wildlife/caring-for-wildlife/strandnet-reports.html#marine_turtles (last accessed 14 September 2015) .

Swimmer Y. Arauz R. Higgins B. McNaughton L. McCracken M. Ballestero J. Brill R. 2005 . Food color and marine turtle feeding behavior: can blue bait reduce turtle bycatch in commercial fisheries ? Marine Ecology Progress Series , 295 : 273 – 278 .

Tomás J. Aznar F. J. Raga J. A. 2001 . Feeding ecology of the loggerhead turtle Caretta caretta in the western Mediterranean . Hippocampus , 255 : 525 – 532 .

Tomás J. Guitart R. Mateo R. Raga J. A. 2002 . Marine debris ingestion in loggerhead sea turtles, Caretta caretta , from the Western Mediterranean . Marine Pollution Bulletin , 44 : 211 – 216 .

Tomillo P. S. Paladino F. V. Suss J. S. Spotila J. R. 2010 . Predation of leatherback turtle hatchlings during the crawl to the water . Chelonian Conservation and Biology , 9 : 18 – 25 .

Tourinho P. S. Ivar do Sul J. A. Fillmann G. 2010 . Is marine debris ingestion still a problem for the coastal marine biota of southern Brazil ? Marine Pollution Bulletin , 60 : 396 – 401 .

Triessnig P. 2012 . Beach condition and marine debris: new hurdles for sea turtle hatchling survival . Chelonian Conservation and Biology , 11 : 68 – 77 .

Turra A. Manzano A. B. Dias R. J. S. Mahiques M. M. Barbosa L. Balthazar-Silva D. Moreira F. T. 2014 . Three-dimensional distribution of plastic pellets in sandy beaches: shifting paradigms . Scientific Reports , 4 : 4435 .

Vegter A. Barletta M. Beck C. Borrero J. Burton H. Campbell M. Costa M. et al.  2014 . Global research priorities to mitigate plastic pollution impacts on marine wildlife . Endangered Species Research , 25 : 225 – 247 .

Velander K. Mocogni M. 1999 . Beach litter sampling strategies: is there a “best” method ? Marine Pollution Bulletin , 38 : 1134 – 1140 .

Wabnitz C. Nichols W. J. 2010 . Plastic pollution: an ocean emergency . Marine Turtle Newsletter , 129 : 1 – 4 .

Wiemeyer S. N. Bunck C. M. Stafford C. J. 1993 . Environmental contaminants in bald eagle eggs—1980–84—and further interpretations of relationships to productivity and shell thickness . Archives of Environmental Contamination and Toxicology , 24 : 213 – 227 .

Wilcox C. Hardesty B. Sharples R. Griffin D. Lawson T. Gunn R. 2013 . Ghostnet impacts on globally threatened turtles, a spatial risk analysis for northern Australia . Conservation Letters , 6 : 247 – 254 .

Wilcox C. Heathcote G. Goldberg J. Gunn R. Peel D. Hardesty B. D. 2014 . Understanding the sources and effects of abandoned, lost, and discarded fishing gear on marine turtles in northern Australia . Conservation Biology , 29 : 198 – 206 .

Witherington B. E. 1994 . Flotsam, jetsam, post-hatchling loggerheads, and the advecting surface smorgasbord . In Proceedings of the Fourteenth Annual Symposium on Sea Turtle Biology and Conservation . Ed. by Bjorndal K. A. Bolten A. B. Johnson D. A. Eliazar P. J. . NOAA Technical Memorandum NMFS-SEFSC-351 (Vol. 166168) .

Witherington B. E. 2002 . Ecology of neonate loggerhead turtles inhabiting lines of downwelling near a Gulf Stream front . Marine Biology , 140 : 843 – 853 .

Witherington B. Hirama S. Hardy R. 2012 . Young sea turtles of the pelagic Sargassum-dominated drift community: habitat use, population density, and threats . Marine Ecology Progress Series , 463 : 1 – 22 .

Witt M. J. Godley B. J. 2007 . A step towards seascape scale conservation: using vessel monitoring systems (VMS) to map fishing activity . PLoS ONE , 2 : e1111 .

Witt M. J. Hawkes L. A. Godfrey M. H. Godley B. J. Broderick A. C. 2010 . Predicting the impacts of climate change on a globally distributed species: the case of the loggerhead turtle . The Journal of Experimental Biology , 213 : 901 – 911 .

Wright S. L. Thompson R. C. Galloway T. S. 2013 . The physical impacts of microplastics on 1089 marine organisms: a review . Environmental Pollution , 178 : 483 – 492 .

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Emerging research trends in plant-plastic interactions: A thorough analysis

• Feng, Wanju

Plants are integral components of ecosystems and key sources of food, medicine, and other resources for human societies. The interactions between micro(nano)plastics and plants have garnered significant attention in recent years due to the pervasive nature of plastic pollution and its potential impact on terrestrial and aquatic ecosystems. This study aims to analyze the current understanding, critical knowledge gaps and future perspectives on the interactions between plants and plastic residues, including microplastics, nanoplastics, microfiber, and microbeads. Data was gathered from the Web of Science Core Collection database, with 1049 documents indexed from 2009 to 2023 for further analysis. Co-citation analysis combined with co-word network analysis was utilized. The findings indicate a notable increase in publication productivity on plastic-plant interactions over the past decade, with China, India, Italy, Korea, and Spain as the core research countries in the field. Chinese universities and research institutions, particularly Naikai University and the Chinese Academy of Sciences, are the major research drivers. Weitao Liu from Naikai University was the most productive author up to 2023. Science of the Total Environment, Environmental Pollution, and Journal of Hazardous Materials were the top three journal that published the most articles. The most frequently cited article titled "Microplastics can change soil properties and affect plant performance" published in Environmental Science & Technology in 2019. The co-citation network highlights the interconnectedness of plant-plastic interactions, while burst analysis and thematic mapping suggest that future research will focus on the impact of emerging contaminants like microplastics and nanoplastics on soil health in the plastisphere. More long-scale and long-term interdisciplinary studies including plant species and polymer types at field condition are needed to a better understanding the plant-plastic interactions. This study offers a thorough and unbiased real-time analysis of plant-plastic interactions, highlighting current trends and outlining future research directions and priorities.

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What is the life-cycle approach and how can it help tackle plastic pollution?

Later this year, negotiators will gather in the Republic of Korea for a fifth round of discussions aimed at developing a legally binding international agreement to end plastic pollution.   

The negotiations are designed to help counter the mounting toll plastic pollution is taking on the planet. Every year, the world produces around 430 million tonnes of plastic, most of which soon becomes waste. This rising tide of plastic debris damages fragile ecosystems, stokes climate change and can result in human exposure to harmful chemicals .  

Central to any solution to plastic pollution is a concept known as the life-cycle approach . It aims to go beyond recycling and reduce the environmental toll that plastic pollution takes at every stage of the life cycle of plastics, from production to its use and disposal. In March 2022, UN Member States agreed to forge an international agreement on plastic pollution embracing the approach .   

“Plastic pollution is a wide-ranging problem and there are many solutions that include shifting away from single-use and short-lived plastic, to ensuring the prolonged use of plastic through reuse systems, to better waste management and recycling,” said Sheila Aggarwal-Khan, the director of the Industry and Economy Division with the United Nations Environment Programme (UNEP). “Recycling alone will not get us out of the plastic pollution crisis. We need a combination of approaches working in tandem across the life cycle of plastic to have a world free of plastic pollution.”  

So, what exactly is the life-cycle approach and how can it help the world deal with plastic pollution in a systemic way? Read on to find out. 

Why is plastic pollution so damaging?  

Plastic products often need to have chemicals added to them to give them their functionality. Some of these are harmful chemicals and may enter the environment or human bodies depending on the production practices, use and disposal. As a result, there is a risk of pollution to the soil, groundwater, the marine environment, or harm to human health. The production of plastic is also responsible for more than 3 per cent of global greenhouse gas emissions, contributing to the climate crisis. This all makes plastic pollution a driver of the triple planetary crisis of climate change , nature and biodiversity loss , and pollution and waste .  

When people talk about the life cycle of plastic, what do they mean?  

Experts refer to the extraction of raw materials, their conversion into products, and use and disposal of a product as its life cycle. In the case of plastic, the story usually begins in the ground . For most of plastic that is fossil fuel based, oil and gas are extracted from the earth and sent to refineries. There, they are transformed into plastic polymers, which are then moulded into products from water bottles and other single-use packaging material—including containers for food and beverage commodities—to fishing gear and products for use in agriculture or in transportation . After they have served their purpose, such products usually find their way to one of four places: a landfill (although often an uncontrolled dumpsite), an incinerator, a recycling or re-use centre and, most damagingly, the environment. 

What is the life-cycle approach to plastic pollution?  

The life-cycle approach looks to limit the potential problems caused by plastic products at every stage of their life, from their production to their disposal. UNEP research has found there are dozens of things that governments and businesses can do to accomplish that goal.  

For example, countries could ban or restrict single-use plastic products or incentivize the development of plastic alternatives. Governments could provide the necessary regulation to send the signal to manufacturers to reduce and eliminate single-use plastic products, and change the product design to ensure plastic products are made of materials that are reusable, prolong their useful life, and that can be recycled at the end of their use. This means having plastic products designed to reduce environmental and human exposure to harmful chemicals across the life cycle of these products.   

Since the plastics sector depends on legions of people around the world, including millions of informal waste pickers , the life-cycle approach also aims to balance socio-economic needs with concerns over plastic pollution.  

Why is the life-cycle approach important?  

Plastic is deeply embedded in our lives and our economies – and plastic pollution continues to mount. Research shows the life-cycle approach could save governments US$70 billion in waste management expenses, and save society US$4.5 trillion in social and environmental costs by 2040. It could also massively reduce the volume of plastics entering the ocean.  

These benefits could be achieved by using the life-cycle approach to inform common design standards, create market incentives and disincentives, and expand reuse schemes, among other things. 

The life-cycle approach is also essential to delivering on key multilateral environmental agreements, such as the Paris Agreement on climate change, and to achieving the United Nations Sustainable Development Goals.  

Why can’t we solve plastic pollution with recycling?  

Recycling is important but it alone isn’t enough to end the plastic pollution crisis. For a start, close to 80 per cent of the plastic in single-use plastic products is not economically viable to recycle . This can be due to design decisions for a plastic product, such as the type of polymer used, and absence of adequate recycling infrastructure, the use of colour additives and combination of materials in a single product, or the use of additives that if harmful, can also pose a health threat to workers in waste management and recycling.  

Additionally, more than 2.7 billion people do not have access to solid waste collection and scaling up recycling infrastructure is challenging.  

“To phase out and ultimately end plastic pollution, there needs to be a combination of solutions across the life cycle of plastics,” said Aggarwal-Khan. “The only way to do that, is with the life-cycle approach.” 

To fight the pervasive impact of pollution on society, UNEP launched #BeatPollution , a strategy for rapid, large-scale and coordinated action against air, land and water pollution. The strategy highlights the impact of pollution on climate change, nature and biodiversity loss, and human health. Through science-based messaging, the campaign showcases how transitioning to a pollution-free planet is vital for future generations.

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Effect of plastic mulch residue on plant growth performance and soil properties

Affiliations.

• 1 The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
• 2 Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
• 3 River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
• 4 School of Geography and Tourism, Shaanxi Normal University, Xi'an, 710119, China.
• 5 The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan. Electronic address: [email protected].
• 6 Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
• PMID: 38160772
• DOI: 10.1016/j.envpol.2023.123254

Plastic mulch is widely utilized for weed control, temperature regulation, soil erosion prevention, disease management, and soil structure improvement, ultimately enhancing crop quality and yield. However, a significant issue with conventional plastic mulches is their low recycling rates, which can cause plastic residue to build up, thereby damaging soil quality and reducing crop yield. The emergence of biodegradable films offers a promising solution to mitigate this issue and reduce soil pollution. However, its potential effects on soil properties and plant performance remain unclear. In this study, low-density polyethylene (LDPE) and poly (butylene succinate-co-butylene adipate) (PBSA) were used to observe the effect of plastic mulch residues on soil properties and plant growth performance via potting experiment. Additionally, the interaction effects of compost and biochar as soil amendments with plastic mulch residues were also evaluated. The result of this study revealed that the type of plastic significantly affected the total nitrogen and magnesium uptake; however, the morphological traits of the tested plant (Japanese mustard spinach) were not significantly affected. The addition of compost and biochar led to a significant increase in both shoot and total dry weight of the plant, indicating a positive effect on its growth. The results of the two-way ANOVA indicated a significant influence of plastic type on dissolved phosphate (PO 4 3- ) levels and soil dehydrogenase activity (DHA). The interaction effect (plastic type with soil amendment) was statistically significant only for soil DHA. Neither plastic mulch residues nor soil amendments significantly affected other soil chemical properties. However, long-term experiments to systematically investigate the long-term effects of plastic residues are necessary.

Keywords: Amendment; Biodegradable mulch; Plant performance; Plastic contamination; Polyethylene film; Soil properties.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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