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Introduction

Global ocean plastic waste originates from materials introduced in the 20th century to deliver wide-ranging benefits (Thompson et al. 2009). Plastics increased an era of disposability for products and packaging used for a short time and then thrown away. The result has been a dramatic rise in plastic waste, some of which leaks to the environment, including the ocean. Plastic waste has a range of adverse impacts, some of which are only beginning to be recognized and understood (MacLeod et al. 2021). Over the past decade, research on ocean plastic pollution has revealed that plastic waste is present in essentially almost every marine habitat, from the ocean surface (van Sebille et al. 2020) to deep-sea sediments (Barrett et al. 2020) and the ocean’s vast mid-water region (Choy et al. 2019). It also affects marine animals, including commercially important species of seafood, and ultimately humans (Barnes et al. 2009, Choy et al. 2019, Lusher et al. 2015, Santos, Machovsky-Capuska, and Andrades 2021).

The increasing visibility and scale of harmful effects of plastic pollution—from large items to microplastics—in freshwater and marine systems, along with related social and economic impacts, has brought the problem and the need for solutions to the forefront of public opinion and government concern. Global calls to action from all levels of government, the United Nations, civil society, and industry are translating to goals and plans of action at the national and international levels.¹ Local, state, and

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¹ See https://www.gpmarinelitter.org/what-we-do/action-plans.

federal governments are simultaneously testing new policies and laws in response to public concerns. Society is grappling with the massive and increasing scale of global plastic waste: beach cleanups, local bans, extended producer responsibility schemes (Abbott and Sumaila 2019), “circular economy” commitments (Ellen MacArthur Foundation 2017), country-level plans and commitments (European Commission 2018, 2020), and calls for a global treaty (CIEL 2020, Karasik et al. 2020).²

The urgency has also prompted explosive growth in research, pilot approaches, and technology innovation globally. These efforts are moving forward quickly and will continue to provide new information and insights after the release of this report. Decision makers are calling for reliable syntheses of scientific knowledge and of global and national data (Environment and Climate Change Canada and Health Canada 2020). This report is intended to provide such an assessment. Definitions of key terms used in this report are found in Box 1.1.

STUDY CONTEXT

Since the invention of plastics in the 20th century, the production and use of plastics, and the volume of resulting plastic waste, have rapidly risen. The annual global production of plastics grew from about 2 million metric tons (MMT) in 1950 to 381 MMT in 2015 (Geyer, Jambeck, and Law 2017) and is projected to continue to increase (World Economic Forum, Ellen MacArthur Foundation, and McKinsey & Company 2016). Figure 1.1 depicts historic and projected plastic production growth, using numbers from Geyer, Jambeck, and Law (2017) and World Economic Forum, Ellen MacArthur Foundation, and McKinsey & Company (2016). Despite growing political and social will to mitigate plastic waste and reduce fossil fuel consumption, the plastic industry expects continued, unfettered growth of plastics demand and production over the next several decades (CIEL 2018). The figure does not include the COVID-19 pandemic and its effects on plastic consumption. However, historical trends reveal conditions revert to the pre-crisis trend (e.g., consumption levels after the 2007–2008 financial crisis). Box 1.2 provides a historical overview of the production and use of plastics.

Plastics are widely utilized throughout society because they have many diverse and useful properties for a broad array of applications. For example, plastics used in piping and other delivery system components help ensure water safety during transport, while plastic packaging extends food preservation and prevents contamination (Andrady and Neal 2009, Matthews, Moran, and Jaiswal 2021, Millet et al. 2018, Sharma and Ghoshal 2018). Compared to other packaging materials, such as glass,

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² See https://usplasticspact.org/.

plastic packaging uses less material, due to its strength, and less energy during transport, due to its lightweight nature (Andrady and Neal 2009, Millet et al. 2018). In construction, plastics are widely used because of their durability. Plastics used in medical settings have improved patient and worker safety (e.g., nitrile gloves, disposable syringes, and sterile products such as intravenous bags and dialysis tubes) and have been used to advance healthcare treatments (e.g., absorbable sutures, controlled drug delivery systems, orthopedics, hearing aids, artificial corneas, and prostheses) (Millet et al. 2018, North and Halden 2013).

The durability of plastics, and their resulting persistence in the environment, creates a particularly challenging ocean waste problem, as described below. At present, plastic waste is the least recycled and recyclable of all persistent solid waste (glass, metal) in the waste stream and the environment (Coe, Antonelis, and Moy 2019). Moreover, with population growth and consumption per capita increasing worldwide, plastics will continue to pollute the marine environment (Jambeck and Johnsen 2015, Jambeck et al. 2015).

Understanding the Problem of Oceanic Plastic Waste

When plastics are taken out of use, whether intentionally or unintentionally, they become plastic waste. An estimated 8 MMT of plastic waste enters the world’s ocean each year—the equivalent of dumping a garbage truck of plastic waste into the ocean every minute (Jambeck et al. 2015). Plastic waste that enters the ocean includes single-use items (designed to be used once before disposal, such as packaging, water bottles, or straws) and durable items. If current practices continue, the amount of plastics discharged into the ocean could reach up to 53 MMT per year by 2030, roughly half of the total weight of fish caught from the ocean annually (Borrelle et al. 2020, Jambeck and Johnsen 2015, Pauly and Zeller 2016).

The United States is a major contributor to global plastic waste: in 2016, the country generated an estimated 42 MMT of plastic waste—the largest mass of plastic waste generated by any country. The European Union (28 countries) generated the second highest amount of waste at 30 MMT, followed by India (26 MMT) and China (22 MMT) (Law et al. 2020) (Table 1.1).

Plastics deployed as “single-use” products or packaging, about 45% of the total produced each year, become plastic waste quickly, often within the year of manufacture (Geyer, Jambeck, and Law 2017). Other plastics remain in use for decades, sometimes repurposed from their original application. Eventually, all plastics are intentionally or accidentally “retired” from use and become waste.

Impacts of Oceanic Plastic Waste

Plastics have been lauded for their durability, convenience, and affordability. These same attributes make plastics a primary and pervasive environmental contaminant with widespread biological, ecological, and economic impacts (Andrady 2011, Beaumont et al. 2019, Mæland and Staupe-Delgado 2020, Wright, Thompson, and Galloway 2013). When plastics and plastic waste are inadequately managed, their impacts are seemingly as diverse as the types of plastic itself (Bucci, Tulio, and Rochman 2020). The full ramifications of our reliance on and exposure to plastics continue to be investigated.

Impacts of aquatic plastic waste range from entanglement and ingestion by marine life (Kühn and van Franeker 2020) to associated ecotoxicological effects on a wide variety of taxa (Anbumani and Kakkar 2018, Guzzetti et al. 2018), including humans (see Singh and Li 2012 as one example). Plastic waste also affects microbial ecology as microplastics in wastewater treatment plants have been shown to enrich antibiotic resistance genes and serve as a vector for human and wildlife pathogens (Pham, Clark, and Li 2021). Exposure to marine plastic waste via seafood is likely to be greater for populations that depend heavily on seafood for nutrition. The contributions of environmental plastic waste to blue carbon—carbon captured by the oceans, marine plants and algae, and coastal ecosystems—and impacts on blue carbon sinks relating to biogeochemical cycling and climate change warrant further attention. Finally, the nexus between plastics (production, use, and waste) and socioeconomic factors has varied direct and indirect effects. One example is the ecosystem devaluation and loss of tourism from increased marine debris (Leggett et al. 2014, 2018). Orange County, California would add $137 million to recreational expenditures and the regional economy if it reduced marine debris to zero. Conversely, if marine debris doubles, it would cost

TABLE 1.1 Plastic Waste Generation Values Across Countries

^a Refined estimate for the United States.

^b EU-28 countries are reported collectively.

SOURCE: Law et al. (2020).

Orange County $304 million (Abt Associates 2019). Importantly, many of these socioeconomic impacts disproportionately affect marginalized communities and are recognized as environmental justice issues (see Box 1.3 for more information, UNEP 2021b).

Environmental and Human Health Impacts

Exposure to the jarring, tragic images of iconic megafauna entangled in marine debris is, for many, their introduction to, and remains synonymous with, the ocean plastic waste problem. As early as the 1970s, entanglement in, and ingestion of, marine debris by ocean life was widely observed and recognized as an emerging concern (Laist 1997, Shomura and Yoshida 1985). Presently, 914 species are known to have entanglement or ingestion records (Kühn and van Franeker 2020).

Plastic waste interferes with animal health when it is mistaken for food or is incidentally consumed during feeding activities (see Santos, Machovsky-Capuska, and Andrades 2021 for a recent review). It can range from large plastic pieces ingested by whales to microplastics ingested by organisms of all sizes (Kühn and van Franeker 2020, López-Martínez et al. 2021). How plastic exposure, via ingestion or other routes, affects organisms is a subject of ongoing research. As one example, interactions of corals with plastics have shown reduced growth (Reichert et al. 2018), impaired feeding (Savinelli et al. 2020), decreased fitness (Savinelli et al. 2020), and reduced calcification (Chapron et al. 2018), among many other negative outcomes (Rocha et al. 2020). Ingestion of plastics entrains plastic pollution in the food web, with potential for bioaccumulation in predators that consume plastic-contaminated prey.

Marine plastic waste can also impact services provided by ocean ecosystems, from provisioning services to carbon sequestration. For example, it is impairing the cycling of nutrients and the biological carbon pump, which negatively impacts the ocean’s carbon sink capacity (Galgani and Loiselle 2021, Kumar et al. 2021, Shen et al. 2020, Villarrubia-Gómez, Cornell, and Fabres 2018). There is a wide range of processes by which this occurs. A few examples include marine plastic waste affecting phytoplankton photosynthesis (Galgani and Loiselle 2021, Shen et al. 2020); a thicker barrier hindering air-sea gas exchange (Galgani and Loiselle 2021); microplastics increasing the sinking rates of zooplankton fecal pellets, thereby altering the vertical flow of carbon and nutrients (Cole et al. 2016, Villarrubia-Gómez, Cornell, and Fabres 2018); and plastic particles accumulating on the seafloor and affecting long-term carbon storage (Villarrubia-Gómez, Cornell, and Fabres 2018).

Some effects of plastic ingestion may be attributed to chemicals used to manufacture plastics, which can leach from plastics into animal tissues (Engler 2012, Jarosova et al. 2009, Koelmans, Besseling, and Foekema 2014, Teuten et al. 2007). Leaching of chemicals may vary by plastic type, weathering of plastics in seawater, or by reactions with digestive fluids. By 2010, more than 120 scientific studies on the role of plastics and their additives in human and animal health—largely through these compounds’ actions as endocrine disrupters—had been published (Halden 2010). From animal studies, endocrine-disrupting effects from plastics-associated compounds, including reproductive disease, sperm epimutations, and obesity, have been found to transmit to offspring (Manikkam et al. 2013). Recently, microplastics have been found in human placentas examined after birth, despite a plastic-free birthing protocol (Ragusa et al. 2021).

Adsorption of exogenous chemicals, metals, and persistent organic pollutants on plastic litter also introduces toxins to the food web when plastics are ingested, although mechanisms and quantities of transfer and their impacts are still being investigated (Amaral-Zettler, Zettler, and Mincer 2020, Kögel et al. 2020, Mato et al. 2001, Rios, Moore, and Jones 2007, Rochman et al. 2013, Rochman, Hentschel, and Teh 2014, Saliu et al. 2019, 2021, Santana-Viera et al. 2021, Teuten et al. 2007, Wright, Thompson, and Galloway 2013). Trophic transfer of microplastics through both juvenile and adult salmon predation on zooplankton containing plastics, for example krill and copepods, is estimated at up to 91 plastic particles daily (Desforges, Galbraith, and Ross 2015).

Economic Impacts

The true economic impact of global ocean plastic waste remains largely unknown, but work to date suggests the costs are substantial. The physical removal of coastal marine debris is costly (Stickel, Jahn, and Kier 2012), but these estimations do not routinely include nonmarket ecosystem service valuations or the depreciation of environmental services and resources. Economic impacts of plastic waste also do not include the costs associated with properly managing waste through the use and ultimate discard of the plastics manufactured.

Inextricably linked to ocean plastic pollution’s impacts on individuals, communities, and species are its effects on ecosystems and its economic ramifications. One estimate places the economic damage to marine ecosystems from plastics at a minimum of $13 billion annually (UNEP 2018). Beaumont et al. (2019) show that plastics negatively affect the ability of the marine ecosystem to function fully and therefore reduce its ability to continue to provide marine ecosystem services such as provision of fisheries, carbon sequestration, cultural heritage, and recreation. The authors estimated that the economic cost of marine plastic pollution is $3,300 to $33,000 per metric ton of plastic waste already in the ocean per year.

Economic impacts of mismanaged plastic waste can also be estimated from studies of the ecosystem service values the plastic waste may impact. For example, the perceived value of a beach is intimately linked with its overall cleanliness (Leggett et al. 2018), and local plastic hotspots from river influx threaten water quality (Keswani et al. 2016). A study in California determined that removing 50–100% of the litter on Orange County beaches could yield California residents $67–$148 million during the 3 months of summer (Leggett et al. 2014). When nonmarket values are unaccounted for and the degradation of ecosystem services is not considered, there is a failure to comprehensively interpret the total economic value.

ORIGIN OF THIS STUDY

Research on marine plastic pollution has grown at an exponential rate in the past few years along with increased public, governmental, and legislative interest into the causes of plastic pollution and potential interventions. One legislative instrument was the Save Our Seas 2.0 Act, which was sponsored by a bipartisan group of 19 senators and passed into law on December 18, 2020, in the 116th Congress (Public Law Number 116-224). This law stipulates requirements and incentives to address marine debris and expands the reach of the first Save Our Seas Act (Public Law Number 115-265).

This study, among other studies called for in the Save Our Seas 2.0 law, examines U.S. contributions to global oceanic plastic waste. The study was sponsored by the National Oceanic and Atmospheric Administration’s Marine Debris Program.

STUDY SCOPE AND APPROACH

This report focuses on those aspects of the uses of plastics and the oceanic waste they generate that are laid out in the statement of task for this study (Box 1.4). The rapid growth and evolution of the salient literature and the sheer scope of the issues involved required that the committee focus the report on the most pressing issues in need of attention.

Conversely, the statement of task does not cover all important topics on plastics, such as other Earth system components impacted by plastics, human and environmental impacts of ocean plastic pollution (including microplastics), sources and impacts of derelict fishing gear, detailed impacts of environmental equity, or impacts of land-based waste disposal or incineration methods. The scholarship on these areas is expansive and, where relevant, summaries and references to articles and reports on these topics are included in the text.

Chapter 2 discusses plastic production and global trade in the United States (statement of task [SOT] 1, 2a, 3a). Chapter 3 examines how plastic waste is managed (SOT 2a, 3b, 3c, 3d). Chapter 4 details the transport mechanisms of plastics and the pathways they encounter from source to the ocean (SOT 1, 2a, 2b). Chapter 5 starts off with an overview of global ocean plastic waste and then examines distribution and fate of plastics in the ocean, from estuaries to the open ocean (SOT 1, 2c). Chapter 6 considers tracking and monitoring systems (SOT 4a, 4b). Throughout Chapters 2–6, recommendations of prioritized knowledge gaps and means to reduce plastic waste are explored (SOT 5). Chapter 7 closes the report and provides intervention categories for how the United States might reduce global ocean plastic waste contributions (SOT 6).

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