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Cite This: Environ. Sci. Technol. 2019, 53, 7177−7179
The Plastic Cycle: A Novel and Holistic Paradigm for the Anthropocene Michael S. Bank*,†,‡ and Sophia V. Hansson§ †
Department of Contaminants and Biohazards, Institute of Marine Research, Bergen, Norway Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts United States § Department of Bioscience, Aarhus University, Frederiksborgvej 399 Roskilde, DK-4000, Denmark transport of pollutants in a biogeochemical, toxicological, and human health context. For example, carbon, nitrogen, mercury, lead, as well as water, all follow environmental or biogeochemical cycles that are relatively well understood with regard to the major principles governing their fate and transport within and across ecosystem compartments and environmental reservoirs. Here we suggest a novel paradigm for the research and management of plastics in all size class fractions (macro, micro, and nano) and suggest that a further understanding of the plastic biogeochemical cycle must be developed in order to effectively address this ubiquitous, global problem. Previous conceptual plastic fate and transport models4 largely only include transfer from land to ocean and often do not continue through the processes occurring in the ocean and to human exposure. Our proposed cycling approach is founded sequentially on atmospheric sciences and biogeochemistry, trophic transfer, and human health and exposure. Here we formally define the plastic cycle (Figure 1) as the continuous and complex movement of plastic materials between dif ferent abiotic and biotic ecosystem compartments, including humans. Recent research has shown that atmospheric transport of lthough plastic pollution in aquatic ecosystems was microplastics can even reach and impact remote, pristine areas5 1 identified nearly half a century ago, recently, over the without any local point sources of plastic (within a distance of past decade, this issue has garnered significant interest from approximately up to 95 km). Additionally, ocean circulation 2 policymakers, scientists, the public, and the media. Several patterns, marine currents, and microplastic drift have been governments, universities, and research institutions have shown to be important drivers in the distribution of plastic in identified plastic pollution, particularly micro and nanoplastics, Arctic environments.6 Collectively, these findings are notable as an important priority with regard to seafood safety as well as and highlight the broad spatiotemporal scales of the processes environmental and human health. Although the scientific that influence the sources, fate, transport, and effects of micro community has made important scientific and policy strides and nanoplastics on the environment and its inhabitants, toward reducing, managing, and studying plastics, many facets including humans. Migratory wildlife, rivers, wind,7,8 and of this global issue remain poorly understood. One of the surface waters in general are also considered important vectors major limitations of current perspectives on plastic pollution and strongly influence the flux mechanisms and source-sink research is the lack of harmonization of data and methoddynamics of plastic pollution in different ecosystems including ologies that are widely used within the research community. transfer from terrestrial to marine environments9 (Figure 1). However, this is improving as scientists have now developed Several recent investigations have focused on the life cycle of formal definitions to ensure transferability and reproducibility 3 plastics, which is important. However, by extending this “cradle of research results. to the grave” perspective to include the steps that occur after In addition to data and methodological harmonization for plastic materials are discarded (i.e., landfill, recycling, and abiotic and biotic matrices, the recognition of the plastic processing) and continuing to follow their fate and transport pollution problem as a biogeochemical cycle (Figure 1) will likely through the various ecosystem processes it undergoes, up to be a critical component in the development of risk assessment and including human exposure, via air, drinking water and and mitigation strategies and relevant research approaches to seafood, will be more purposeful. Thus far, this holistic and address the global nature of this environmental problem. Plastic pollution is a product of the Anthropocene era, and the concept of cycling is widespread in environmental research and Received: May 16, 2019 is especially relevant in studies of the sources, fate and Published: June 14, 2019
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A
© 2019 American Chemical Society
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DOI: 10.1021/acs.est.9b02942 Environ. Sci. Technol. 2019, 53, 7177−7179
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Environmental Science & Technology
Figure 1. Conceptual model of the plastic pollution cycle and the interactions between biogeochemistry, trophic transfer, and human health and exposure. Note that arrows and artwork are not to scale and are for descriptive purposes only. Expanded, adapted, and redrawn, in part, from Rochman et al. (2019) with permission.
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integrative approach has not been widely used nor adapted, although some models do exist.10 Some of the challenges facing the development of the plastic cycle model is the fact that plastics, and especially microplastics and nanoplastics, truly occur as a mixture of diverse chemical compounds.11 Since microplastics are so diverse and are comprised of a wide array of polymers with varying structural characteristics their fate, transport, and potential toxicological effects are driven by a complex series of poorly understood processes that likely interact with other anthropogenic and natural stressors, such as climate change and other pollutants and predation stress, respectively. Also, of major concern to hindering our understanding of the plastic cycle is the issue of sampling, measuring and investigating nanoplastics within the atmosphere, hydrosphere, lithosphere, and biosphere. Due to their incredibly small size, nanoplastics present a series of complicated toxicological and analytical challenges. This is an important concept since it is likely that plastic particles at each end of the spectrum, macro and nano, are the most hazardous to biota. In conclusion, the concept of viewing the plastic pollution problem as an environmental or biogeochemical cycle will have important ramifications for policy and management of this issue. Moreover, this approach will also aid in identifying and understanding the relationships between plastic manufacturing and pollution to other serious environmental problems such as climate change, species loss, marine oxygen minimum zones, coral disease,12 pathogens and parasites,13 and antibiotic resistance.14 Just as the carbon cycle has been instrumental in identifying the factors related to climate change, we feel that the development of a new paradigm (i.e., the perspective of viewing plastic pollution as an environmental or biogeochemical cycle) will serve as a foundation for the development of thoughts, ideas, and hopefully, sustainable solutions to address this important global problem in the Anthropocene.
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Sophia V. Hansson: 0000-0001-5874-0720 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was supported by the Norwegian Ministry of Trade, Industry and Fisheries to M.S.B.
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REFERENCES
(1) Carpenter, E. J.; Smith, K. L., Jr. Plastics on the Sargasso Sea surface. Science 1972, 155, 1240−1241. (2) Sedlak, D. L. 2017. Three lessons for the microplastics voyage. Environ. Sci. Technol. 2017, 51 (14), 7747−7748. (3) Hartmann, N. B.; Hüffer, T.; Thompson, R. C.; Hassellöv, M.; Verschoor, A.; Daugaard, A. E.; Rist, S.; Karlsson, T.; Brennholt, Matthew Cole M.; Herrling, M. P.; Hess, M. C.; Ivleva, N. P.; Lusher, A. L.; Wagner, M. Are we speaking the same language? Recommendations for a definition and categorization framework for plastic debris. Environ. Sci. Technol. 2019, 53 (3), 1039−1047. (4) Horton, A.; Dixon, S. Microplastics: An introduction to environmental transport processes. Wiley Interdisciplinary Reviews: Water 2017, e1268. (5) Allen, S.; Allen, D.; Phoenix, V. R.; Le Roux, G.; Jiménez, P. D.; Simonneau, A.; Binet, S. Atmospheric transport and deposition of microplastics in a remote mountain catchment. Nat. Geosci. 2019. In Press. 12339 (6) Onink, V.; Wichmann, D.; Delandmeter, P.; Sebille, E. The role of Ekman currents, geostrophy, and stokes drift in the accumulation of floating microplastic. J. Geophys. Res.: Oceans 2019, 124, 1474−1490. (7) Jambeck, J. R.; Andrady, A.; Geyer, R.; Narayan, R.; Perryman, M.; Siegler, T.; Wilcox, C.; Lavender Law, K. Plastic waste inputs from land into the ocean. Science 2015, 347, 768−771. (8) Hurley, R.; Woodward, J.; Rothwell, J. J. Microplastic contamination of river beds significantly reduced by catchment-wide flooding. Nat. Geosci. 2018, 11, 251−257. (9) Windsor, F. M.; Durance, I.; Horton, A. A.; Thompson, R. C.; Tyler, C. R.; Ormerod, S. J. A catchment-scale perspective of plastic pollution. Glob. Change Biol. 2019, 25, 1207−1221. (10) CIEL. Plastic & Health: The Hidden Costs of a Plastic Planet; Center for International Environmental Law Technical Report, 2019.
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[email protected]. 7178
DOI: 10.1021/acs.est.9b02942 Environ. Sci. Technol. 2019, 53, 7177−7179
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Environmental Science & Technology (11) Rochman, C. M.; Brookson, C.; Bikker, J.; Djuric, N.; Earn, A.; Bucci, K.; Athey, S.; Huntington, A.; McIlwraith, H.; Munno, K.; De Frond, H.; Kolomijeca, A.; Erdle, L.; Grbic, J.; Bayoumi, M.; Borrelle, S. B.; Wu, T.; Santoro, S.; Werbowski, L. M.; Zhu, X.; Giles, R. K.; Hamilton, B. M.; Thaysen, C.; Kaura, A.; Klasios, N.; Ead, L.; Kim, J.; Sherlock, C.; Ho, A.; Hunga, C. Rethinking microplastics as a diverse contaminant suite. Environ. Toxicol. Chem. 2019, 38 (4), 703−711. (12) Lamb, J. B.; Willis, B. L.; Fiorenza, E. A.; Couch, C. S.; Howard, R.; Rader, D. N.; True, J. D.; Kelly, L. A.; Ahmad, A.; Jompa, J.; Harvell, C. D. Plastic waste associated with disease on coral reefs. Science 2018, 359 (6374), 460−462. (13) Vethaak, A. D.; Leslie, H. A. 2016. Plastic Debris Is a Human Health Issue. Environ. Sci. Technol. 2016, 50 (13), 6825−6826. (14) Parthasarathy, A.; Tyler, A. C.; Hoffman, M. J.; Savka, M. A.; Hudson, A. O. Is Plastic Pollution in Aquatic and Terrestrial Environments a Driver for the Transmission of Pathogens and the Evolution of Antibiotic Resistance? Environ. Sci. Technol. 2019, 53 (4), 1744−1745.
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DOI: 10.1021/acs.est.9b02942 Environ. Sci. Technol. 2019, 53, 7177−7179
