Shaping a federal strategy for chemical recycling: Moving toward sensible applications of emerging technologies in US plastic waste management

Plastic waste management requires a diverse portfolio of strategies to avoid the most damaging environmental and social impacts of the plastic lifecycle and meet current national and international policy goals. The limitations of existing mechanical recycling methods for processing plastic waste have motivated the development and commercialization of chemical recycling processes. The novelty and diversity of such pathways beg critical questions of how these emerging technologies will fit within existing policy frameworks and contribute to recycling, plastic pollution, and waste management policy objectives. This work provides technical background into mechanical and chemical recycling methods, and policy background into differing modern approaches to chemical recycling at various levels of governance. Finally, this work summarizes key conflicts and crafts recommendations for future policy action on chemical recycling in three main areas: (1) defining an objective and identifying sensible applications for chemical recycling technologies, (2) filling gaps in existing knowledge and upholding environmental justice protections, and (3) implementing a suite of policies to complement chemical recycling's role in plastic waste management strategy.

They are constructed in long chains (known as polymers) from repeated chemical units (monomers).Plastics are ubiquitous, and have been applied to both necessary and unnecessary roles in the modern society.For example, the lightweight and flexible material properties of plastics make them favorable materials for manufacturing in many sectors, such as the automotive industry. 1Plastics are also critical for healthcare applications, where low-cost, massproducible, and sterile materials are necessary to prevent contamination and the spread of disease, including medical devices 2 and particularly personal protective equipment (PPE) for medical and everyday settings. 3 contrast to these sensible or necessary applications of plastics, the versatile materials have also been incorporated into many nonessential or single-use roles.With mass production of plastics reaching near 400 million tonnes annually and significant mismanagement around the world, 4 plastic pollution has become a global crisis.Meanwhile, global demand for plastics, and the products they make up, are only likely to expand with the growth of economic middle classes in key regions. 5However, plastic recycling-a key strategy to mitigate pollution-remains insufficiently practiced, with global recycling rates for plastic waste falling below 10% according to the Organization for Economic Co-Operation and Development (OECD) (see Figure 1).The OECD members, which include 38 of the world's traditionallyconsidered "developed countries" with high GDP and human development indices, represent 18% of the global population but produce almost half of all plastic waste. 6Thus, plastic waste is not only a global issue, but one which reflects existing socio-economic disparities.

| United States
Among OECD countries, the United States has the highest per-capita plastic waste production at 221 kg of plastic annually. 7According to the U.S. Environmental Protection Agency (EPA), plastic makes up roughly 12% of all US municipal solid waste (MSW). 8In 2018, over three-fourths (75.6%) of US waste plastics ended up in landfills, while 15.6% were incinerated and only 8.7% were recycled. 9Since 2018, changes in critical international waste import markets, as well as global pandemic disruptions, have decreased the nation's recycling rate to an estimated 5%. 10

| Consequences
Low recycling rates lead more plastic waste to be landfilled, incinerated, or mismanaged, contributing to plastic pollution of the terrestrial and marine biosphere.This has allowed for the accumulation of the so-called "legacy plastics" in marine litter in oceans, which disproportionately impact small island developing states and coastal regions. 11,12Left in the environment for long periods of time, plastics can break up into small components known as microplastics, defined as less than 5 mm in size. 13Microplastics are now ubiquitous across nature's extremes, having been found at the deepest point of the Mariana Trench, 14 near the summit of Mount Everest, 15 and in the fresh snow of Antarctica. 16croplastics are particularly dangerous in marine ecosystems, where they have been identified as contaminants that accumulate over time in organisms at all levels of the oceanic food web. 17Likewise, microplastics can accumulate in human adults and children through eating, drinking, and inhalation. 18Microplastics have been detected in human blood, 19 lungs, 20 and breast milk. 21All the while, the exact health impacts of long-term exposure to microplastics are not well understood. 22 addition, plastics can contain additives to modify their material properties, or nonintentionally added substances (NIAS) including side products and contaminants. 12Various common additives in plastic have been correlated to negative health outcomes: some have activity as endocrine disruptors, which have been linked to declining fertility, 23,24 and others have been identified as potential carcinogens, including certain phthalates. 25In some cases, the monomeric units of plastics themselves have carcinogenic links, such as vinyl chloride of PVC 26 and styrene of PS. 27 Toxic emissions occur throughout the life cycle of plastic products.Plastics produced today are predominantly "virgin" materials made directly from fossil fuels, while recycled content is incorporated into less than 6% of modern plastics. 7Fossil fuel extraction has its own significant environmental impacts, but the production of plastics also emits significant greenhouse gases, as well as toxic F I G U R E 1 The fate of plastic wastes in OECD and world averages. 7The United States fares among the worst in recycling, but also produces the most plastic waste per-capita.byproducts. 12,28At the end of the life cycle, plastic disposal methods also have environmentally damaging effects.When sent to landfills, plastics are allowed to break up into microplastics, leach toxic chemical additives, and produce toxic gases. 29When incinerated, plastics can release not only carbon dioxide, but toxic gases and chemicals that also contribute to climate change. 30| TECHNICAL BACKGROUND 2.1 | Mechanical recycling

| Process
Traditional recycling relies on mechanical methods that do not alter the fundamental chemical structure of waste plastics.In general, the process consists of several steps: first, input waste plastics are reduced in size via shredding or granulation.Second, contaminants of plastics are removed.Third, the resulting plastic flakes are separated by type. 31Often, the resulting products are melted and re-extruded into small, uniform pellet shapes, to be compatible with and blended into manufacturing processes that accept post-consumer recycled (PCR) plastic. 32

| Limitations
The primary limitations on mechanical recycling are the diversity and properties of plastics compared to other recyclable materials such as aluminum and paper.Plastics are rarely designed with recycling in mind, as manufacturers give priority to optimizing strength, durability, safety, cost, appearance, and other material and economic properties.
As a result, relatively few types of plastic are currently accepted by mechanical recycling systems. 33In the United States, PET and HDPE are considered mechanically recyclable, but make up less than a quarter of plastics found in municipal solid waste (MSW). 34Furthermore, the mechanical recycling process "downcycles" plastic waste: it involves harsh conditions (e.g.heat) which produce lower quality outputs relative to process inputs or similar virgin market products. 31It is estimated that up to 10% degradation to the plastic feedstock occurs in each cycle of mechanical recycling, 35 which means that plastics can only be mechanically recycled a finite number of times. 36Degradation can also occur through undesired side reactions in plastic, caused by contaminants from the use of plastic before its disposal. 37ntamination can also occur during sorting before disposal.
Because only certain types of plastic can be mechanically recycled, the US residents are commonly expected to sort plastics between recycling and trash streams before collection.Improper residential sorting of plastics can require additional sorting in the mechanical recycling process to remove "unrecyclable" plastics that could cause failures in the process. 37Incomplete sorting can also introduce unintended types of polymers into the recycled product, and even some toxic impurities. 38As a direct result of contamination and degradation, mechanically recycled plastics are usually not considered suitable for specialized applications, such as "food-grade" products, without further processing to meet the associated more stringent limits on total residual contaminants. 39astic sorting is largely dependent on standardized resin identification codes (RICs), as defined by the ASTM D7611 standard, 40 which are present on plastic commodities produced in the United States.The ATSM standard began as a voluntary initiative and has since become required on plastic products in many states (though the system was never formally adopted at the federal level 41 ), creating a de-facto presence of RICs on US plastic commodities.This system defines seven numerical categories, with #1-6 representing common plastic types and #7 representing all other plastic resins. 42 identifying types of plastics to recycle, local recycling programs may differ by what plastics they accept.In general, plastics #1 and #2 (PET and HDPE) are most commonly accepted for mechanical recycling, with 88% and 87% of US residents having access to recycling programs that accept bottles made from these plastics, according to a 2021 report by the Sustainable Packaging Coalition. 43However, programs have significant variability in accepting plastics by type as well as by shape: PET in non-bottle forms are only accepted by slightly over 50% of programs surveyed, and plastics made from LDPE, PP, and PS are all accepted at lower rates than bottle-form PET and HDPE.
The RIC system is not intuitive and requires specific education for consumers to know the meaning of each code.According to a 2019 survey of American adults, 92% of respondents did not correctly understand RICs, with as many as 68% assuming that all codes signified a recyclable plastic. 44The standard has changed over time in an effort to address consumer confusion and distance itself from implying recyclability for each plastic product.Under the most recent version of the standard (ASTM D7611M-20), RICs are depicted with a bold equilateral triangle outlining the number code, but previous versions of the standard invoked the well-known "chasing arrows" recycling symbol instead. 40Current options for RIC labeling on US plastic products are presented in Figure 2.
Furthermore, existing recycling infrastructure does not reach all consumers in the United States.From the same 2021 Sustainable Packaging Coalition report on recycling in the United States, 91% of US residents had access to either curbside (59%) or drop-off (32%) recycling programs, down from 94% in 2016. 43Though a strong majority of residents have recycling access for plastics in both cases, the report findings still illustrate gaps in our recycling infrastructure where recycling is not available, precipitating inefficient plastic disposal or pollution in these areas.At the same time, a reliance on foreign importation markets for plastic waste has historically disincentivized investment in new US recycling infrastructure or maintenance of existing facilities. 45However, this dependence has become particularly problematic in the wake of international policy shifts in nations such as China and Turkey that have banned waste plastic imports, forcing US recycling industries to respond to supply chain disruptions.

| Consequences
US mechanical recycling systems face significant technical limitations, poor standardization of local infrastructure, and supply chain disruptions, all of which have challenged their ability to effectively capture and process plastic waste.As a result, the lobbyist group Beyond Plastics has noted that US recycling rates have decreased even further in recent years. 46These challenges mean that there is no guarantee those plastics will truly be recycled, even when consumers correctly sort recyclable plastics into the proper waste streams. 47Mechanical recycling systems lead a majority of mixed plastics (and even some recyclable plastics) to be disposed of via methods not specifically designed for plastic or for preventing plastic pollution, which can result in environmental pollution, including by landfill and by incineration.
One other disposal method, the dumping of plastic wastes in other countries, has significant social dimensions.Though US plastic waste exports have been declining due to international bans on importation (particularly in China), the United States exported 1.2 billion pounds of scrap plastic in 2021 to other countries, including Canada, Mexico, India, Malaysia, and Vietnam. 4 In the so-called "developing countries," waste importation has contributed to the development of informal "waste picker" economies that constitute a significant portion of local recycling efforts.However, the wastepickers themselves are exposed to toxic conditions and other health hazards, 48 and are minimally compensated for their work. 49

| Process
Chemical recycling technologies have been promoted as complements to the existing mechanical recycling systems.Though the term "chemical recycling" has not been used with consistent meaning, it is typically understood to include a handful of different classes of plastic reprocessing and recycling technologies.Several categories of chemical recycling technologies have been proposed and researched.Plastics Europe distinguishes between three categories that chemically break down plastics to different molecular levels, as presented in RIC key for plastics in the United States.Two slight variations of the RIC system are permissible under the current ASTM standards.As the EPA admits, the current equilateral triangle options still resemble the classic recycling symbol, but do not signal that a product is recyclable in a local context. 42I G U R E 3 The relationships between chemical recycling technologies. 58eployed for plastic including PVC, PS, PE, and PP, but as separate, homogeneous feedstocks. 50However, some processes (such as STRAP, or solvent-targeted recovery and precipitation) are under current research and development to treat multilayer flexible plastic films made up of several different resins using a variety of selective solvents. 51Given that purification is a new technology and waste plastics are typically mixed, several challenges will need to be addressed (including in some cases the separation of plastic wastes) for purification to be commercially viable. 50second category, depolymerization (also referred to as decomposition, chemolysis, or solvolysis), involves the chemical breakdown of plastics into small monomer units (the repeated molecular unit of longchain plastic polymers) or oligomers (short chains of monomers that combine into larger polymers). 50Current research suggests that depolymerization technologies are compatible with certain types of plastic including polyesters (PET, PCL, PLA, etc.) and polycarbonates (PC-BPA, PPC). 52Some types of depolymerization have been developed for specific plastic resin types, such as solvolysis for PET feedstocks. 53Because of its target, solvolysis would compete with existing mechanical recycling systems, which also accept PET.However, like purification, few types of depolymerization have been commercially proven. 54nally, conversion technologies do not directly produce plastic products, but instead form chemicals and industrial feedstocks, which can be reconverted into plastics with further processing.Conversion methods include pyrolysis, gasification, hydrocracking, and hydrothermal treatment of plastics, among others. 50One potential pathway to forming plastics after pyrolysis is steam cracking, which reduces the pyrolysis output oil product into monomeric hydrocarbon molecules, precursors to plastic polymers. 55Conversion technologies pyrolysis and gasification differ from incineration processes by limiting the amount of oxygen allowed to combine with plastic wastes in high heat conditions.While incineration is defined to occur under conditions of excess oxygen, pyrolysis is operated at conditions intended to limit oxygen input to the lowest possible levels, and gasification is operated with limited but less strictly controlled oxygen, 28 resulting in hydrocarbon oil products from pyrolysis and syngas (methane and carbon monoxide) from gasification.Still, other similarities between the three processes (e.g.high heat) are present.Conversion technologies are also versatile in the types of plastic they can accept, including plastics that cannot be easily depolymerized, 50 and many that cannot be mechanically recycled.However, certain plastics (such as PVC) result in particularly toxic emissions, including dioxins, 56 presenting an obstacle for conversion technologies that accept mixed plastic waste streams.
For greater clarity, these technologies can be reclassified according to their outputs. 7,57One class of chemical recycling technologies involves a plastic-to-plastic (P2P) transformation, in which the output products are plastics of identical or improved quality to the waste stream inputs, requiring a complex series of steps to achieve.All of the above three categories can theoretically result in plastic products, depending on the extent of additional processing involved. 58On the other hand, alternatives focus on plastic-to-fuel (P2F), where the feedstock products of conversion technologies are not converted back into plastics, and are instead used for other industrial processes or are eventually combusted to release energy. 33

| Opportunities
The chief benefit of deploying chemical recycling technologies is their versatility: while mechanical methods have been specialized for PET and HDPE (plastics #1 and #2), various chemical methods have been developed to treat all types of plastic.This capability could divert more types of plastic that are currently inaccessible to mechanical recycling systems from landfill and incineration disposal.Chemical recycling processes that accept mixed plastics could potentially circumvent the nonintuitive RIC system by reducing the consumer sorting burden.Furthermore, the products of chemical recycling after significant processing can be higher quality than those of mechanical recycling, and can be "indistinguishable" from virgin-grade plastics. 9This means that chemically recycled plastics are suitable for applications with among the most stringent health regulations, including food-grade products. 39Correspondingly, chemically recycled plastics have higher economic value to plastic markets.Recent analysis have suggested that such value could potentially offset chemical recycling's higher processing costs relative to mechanical recycling, allowing scaled chemical recycling systems to reach economic viability without other incentives. 55emical recycling allows a significant majority of mixed plastics, unusable under current mechanical recycling systems, to gain value as precursors to virgin-quality polymers.Thus, chemical recycling has the potential to increase the circularity of the plastics economy, as more types of plastic become accessible for recycling, requiring fewer virgin plastics and reducing fossil fuel consumption for plastic production.
These technologies could also fulfill the increasing demand for recycled content in plastic products by consumers and regulators, while boosting the US market for plastic wastes and recycled plastics.

| Challenges
Directly hindering all chemical recycling conversations, the terminology surrounding these emerging technologies is not standardized, and many terms are used synonymously.While "upcycling" is favored by some university research centers, 59 some industry groups prefer "advanced recycling" 60 or "molecular recycling" 61  The ISO definition unites disparate processes with very different end products under one label, and furthermore introduces yet another synonym ("feedstock recycling") for the same set of technologies.The many groupings currently in use can obscure differences between processes under the shared "chemical recycling" term.Such generalizations can also lead to confusion and misinformation about specific process technical details, allowing industry to claim that such processes are recycling, while some environmental groups dispute their nature as closer to environmentally harmful processes like incineration. 63ide from terminology, several challenges face the implementation of chemical recycling on a meaningful scale.Though these technologies produce higher value products than mechanical recycling, their operating and processing costs are correspondingly higher.Furthermore, chemical recycling would require significant capital expenditures to implement, as minimal suitable infrastructure exists today.
Industry sources currently tout that over 40 US projects have been announced, with the potential to divert nearly 8 million metric tonnes of plastic waste from landfills annually. 60However, according to a 2022 National Resource Defense Council (NRDC) report, the United States only has eight chemical recycling facilities currently in operation, most of which are P2F and do not produce plastic. 64 short, despite studies suggesting that economic viability of chemical recycling is within reach, no US implementation of P2P yet exists to demonstrate commercial success.Furthermore, the projected 8 million tonnes of processing capacity is small relative to the totality of US annual plastic waste production, which was closer to 36 million tonnes in 2018. 4In the global community, Plastics Europe reports that 44 chemical recycling projects in 13 EU countries are also planned. 58These investments demonstrate strong interest in chemical recycling in the future, but do not represent a network of chemical recycling infrastructure ready today.
The scale of such investments also signals that chemical recycling technologies may not be practical in small island developing states, developing countries, or other regions without significant resources to invest in recycling networks, some of which instead rely on informal waste picking economies.
The requirement for new physical infrastructure to support chemical recycling also raises significant environmental justice concerns.
Plastics manufacturing plants are frequently located in low-income and/or communities of color who face barriers to resisting industrial construction plans.These plants result in "sacrifice zones" with heavily concentrated industrial presence, and significant local environmental impacts through ground and source pollution.Industrial plants generate "pollution hotspots" that disproportionately impact nearby "fenceline communities," who lack proper protection against industrial impacts. 65,66Chemical recycling in the United States appears to be developing according to a similar trend: of the eight operational chemical recycling facilities identified in the 2022 NRDC report, five were located in disproportionately low-income communities, and seven with disproportionate communities of color. 64Though industrial plants are required to obtain permits based on their contributions to certain pollution metrics, community participation in the process is essential.Communities' approval of a chemical recycling plant would be incomplete without comprehensive understanding of its environmental impacts, which is not yet available for many chemical recycling processes.
Chemical recycling technologies face technical limitations as well.
For example, conversion technologies under the chemical recycling umbrella (pyrolysis and gasification) cannot selectively produce either feedstocks or fuel.Instead, their products are split between the two categories 55 and cannot exclusively fulfill a P2P purpose, leading to lower contributions to plastics circularity.Chemical recycling technologies, and recycling systems in general, also have difficulty addressing toxic pollutants such as PFAS and other "forever chemicals" that may appear as NIAS in plastic waste feedstocks. 67,68It is also not clear how the PCR content of plastic products that incorporate chemically recycled feedstocks should be measured.Various industrial stakeholders have proposed a "mass balance" measurement, in which PCR is a simple fraction of the input feedstock that ends up in the final product.However, the mass balance method could afford significant discretion to producers in marketing certain segments of their products as containing significant recycled content, which may not authentically reflect the true distribution of recycled feedstock in the process, as demonstrated in Figure 4. 69 Crucially, significant gaps in understanding exist for the totality of environmental impacts from each chemical recycling process.Many chemical recycling technologies carry risks of toxic emissions and hazardous waste creation from the use of chemical solvents or other process elements, 56 which generate further environmental justice concerns.However, environmental impact calculations under a life cycle assessment (LCA) approach rely heavily on modeling assumptions and other methodological choices, so it can be challenging to reach definitive environmental conclusions about a specific industry or process. 62While some LCA studies have estimated that chemical recycling technologies present environmental benefits relative to incineration 70 and similar global warming potentials to mechanical recycling, 71 others have concluded that chemical recycling has greater environmental impacts than existing methods. 72Chemical recycling impacts are complicated further by the uncertainty surrounding microplastics, which are difficult to measure and are rarely considered as emissions of recycling processes. 73It is clear from these uncertainties that more research is needed in to accurately determine the environmental impacts of chemical recycling technologies. 74

| Current developments, projections, and stakeholders
Nevertheless, chemical recycling has received significant investment from industry and strong promotion from industry associations, such as the American Chemistry Council Plastics Division. 60The independent market research firm IDTechEx forecasted that in the next 10 years (by 2033), two key technologies considered to be chemical recycling (pyrolysis and depolymerization) will use over 20 million tonnes per year of plastic waste globally. 62Once again, this represents only a small fraction of current (<5%) global plastic waste production, which will continue expanding in the near future. 5anwhile, chemical recycling remains the subject of government-funded research 59 and of broader interest to the international community in discussions on how to mitigate global plastic pollution.Recent works have reviewed the currently favored chemical recycling strategies and challenges facing each major type of plastic found in post-consumer waste. 75These efforts include addressing the degradation problems of mechanical recycling for plastics #1 and #2 by applying chemical recycling strategies, as well as pioneering the recycling of currently unrecyclable plastics.Within this second area of focus, much attention has been directed to the development of advanced catalysts to further refine and improve the selectivity of chemical recycling products from mixed plastic wastes. 76Other reviews have highlighted the extent of LCA work devoted to various chemical recycling pathways, identifying a clear concentration of efforts around well-established P2F pathways such as pyrolysis. 77But serious questions remain about how the technologies should be defined and regulated, whether they can sufficiently address environmental justice concerns, and what potential complementary policies could be implemented to ensure that chemical recycling does not allow plastic production and pollution to continue business-as-usual.

| Promotion of chemical recycling
A recent, coordinated movement at the state level has established protections for the so-called "advanced recycling" (here taken as a synonym of chemical recycling) into law.The American Chemistry Council's (ACC) Plastics Division have championed such legislation: as of April 2023, 24 states had enacted new laws to support advanced recycling. 78One such state, Kansas, passed bill SB 114 in the 2023 session, which defines the term "advanced recycling" as: a manufacturing process where already sorted postuse polymers and recovered feedstocks are purchased and then converted into basic raw materials, feedstocks, chemicals, and other products through processes that include, but are not limited to, pyrolysis, gasification, depolymerization, catalytic cracking, reforming, hydrogenation, solvolysis, chemolysis, and other similar technologies. 79is definition hinges on the reclassification of "post-use polymers" (mixed plastics separated from the rest of MSW but not into pure streams) as a manufacturing feedstock rather than a waste product, allowing chemical recycling to be considered a "manufacturing" process rather than "waste management."Furthermore, this definition explicitly excludes the "incineration of plastics or waste-to-energy processes," and states that "products sold as fuel are not recycled products". 79The 24th state, Indiana, passed similar "advanced recycling" legislation with SB 472, which contains related language and also promotes a third-party process to certify advanced recycling based on simple mass-balance determinations. 80der ACC-backed legislation, "advanced recycling" processes are not required to produce virgin-quality plastic from waste plastic.
Despite their very different technical details and purposes, chemical recycling categories of purification, depolymerization, and conversion have the potential to be treated equivalently under this legislative approach.In addition, the signal that the defined list of technologies that qualify is not exhaustive ("…but are not limited to…") creates regulatory uncertainty in an area where innovation and the development of new distinct chemical recycling processes will continue to occur.By leaving this door open, the definition places very few limits on what can be considered chemical recycling An example implementation of the mass balance method when the recycled feedstock is spread across all output units, but outputs are segregated into two distinct segments, "regular" and "green."Though they contain the same proportion of recycled content, the mass balance method allows recycled content to be reallocated among the outputs. 69n the future, regardless of the process specifications or environmental and social impacts.
Furthermore, this definition excludes the sale of products as fuel, but includes conversion technologies such as pyrolysis and gasification, which produce chemical feedstocks that can be used as fuel, absent further processing. 50This draws an arbitrary regulatory distinction between the immediate incineration of plastics for fuel and the sale of fuels made from plastics for later use, where in both cases, plastic matter is eventually combusted for energy.
Finally, ACC-backed legislation classifies chemical recycling plants as manufacturing facilities rather than waste management facilities, which affects the permitting process and could reduce regulatory requirements for facility operators. 36Some states have gone further, as Oklahoma, South Carolina, and Virginia have all passed legislation that defines chemical recycling explicitly as "recycling". 81Given that not all chemical recycling processes produce plastic from plastic (P2P), these definitions are not technically accurate.
The ACC has not been successful in passing this legislation in all states.In 2022, a similar bill was introduced in the Rhode Island legislature but failed to pass both chambers after resistance from House leadership.The ACC blamed this failure on "misinformation" regarding the details of the chemical recycling technologies involved. 82ACC has also attempted to pressure New York lawmakers into passing similar legislation, in one instance by citing strong support among New York voters for "advanced recycling". 83This is likely a result of framing their processes of interest as "recycling," which does have broad public support. 84But as stated, it is clear that not all "advanced recycling" pathways truly recycle plastic.The final legislation in New York (S7891 in the 2021-2022 session) failed to advance out of committee. 85netheless, the adoption of such legislation in nearly half of US states speaks to a coordinated interest among industry and some policymakers in supporting chemical recycling technologies.This pattern of state-by-state adoption creates a nonuniform regulatory environment for these emerging technologies and may contribute to misinformation about what chemical recycling technologies actually accomplish.The potential for uncertainty and arbitrary distinctions in this state-level policy means that these definitions for chemical recycling deserve reconsideration and could benefit from stronger standardization at the federal level.

| Addressing plastic production
An integrated plastic waste management system may require a combination of many strategies.In the "waste management hierarchy" endorsed by the US EPA (see Figure 5), recycling programs are considered more beneficial than energy recovery from waste or alternative end-of-life disposal.In contrast, several waste prevention strategies, including source reduction and reuse of products, are preferred to waste management strategies such as recycling, based on their lower required inputs and environmental impacts. 86urce reduction can be achieved through a variety of policy interventions.A small number of states have embraced measures Fund.Of the collected funds, 40% of which will be appropriated to conservation, restoration, and monitoring efforts related to plastic pollution, and 60% of which will be appropriated to addressing and monitoring environmental injustice related to plastic production.Furthermore, PROs are required to meet additional goals in source reduction of plastic packaging and promote plastic recyclability. 87handful of US states have implemented similar EPR programs for plastic packaging: Oregon passed the first explicitly plastic EPR law in August 2021, 88,89 followed by Colorado 36,90 and Washington 91 in 2022.Additionally, Maine has implemented an EPR law for the recycling of paper products and packaging 89 which has since been expanded to plastic.91 Other states are also currently considering several plastic EPR bills, such as New York with SB S1064.92 Figure 6 presents a map of states with such programs.
EPR measures are frequently connected to other policy measures, such as incentives or mandates for the use of PCR content in new plastics produced in certain categories. 36As of October 2020, California implemented the first statewide PCR mandate, also with SB 54. 87 Since then, Washington and New Jersey have followed with PCR targets for plastic beverage bottles. 89A common feature of such PCR laws is that requirements increase incrementally over time, though New Jersey's law increments much more slowly than either California F I G U R E 5 A traditional "Waste Management Hierarchy" in an inverted pyramid structure to represent most preferred and least preferred methods of waste management. 86r Washington. 93However, current research has highlighted a potential conflict between PCR mandates and existing bans on toxic intentionally added substances such as PFAS, 68 as modern recycling processes face technical limitations in addressing such contaminants.
Several states and municipalities in the United States have also piloted a variety of small-scope programs to influence consumer behavior.For example, plastic bags have become targets of bans in 10 states, 94 as well as charges in Washington, DC, and some localities of Virginia. 95A further 10 states have facilitated plastic product reuse through the passage of "bottle bills," which establish charges on certain bottles and other containers (including plastic material) but offer deposit-refund systems to consumers to incentivize packaging reuse. 96However, just as some states have banned plastic bags, 18 states have enacted laws to preempt bans at the local level. 94elve of these states (Arizona, Florida, Indiana, Iowa, Michigan, Mississippi, Missouri, Ohio, Oklahoma, Tennessee, Texas, and Wisconsin) have also enacted legislation with ACC's favored definition of "advanced recycling."Figure 7 presents a map of states who have implemented ACC legislation and/or preemption bans focused on promoting processing solutions to plastic waste management challenges.
Finally, some states have undertaken initiatives to improve transparency in advertising and labeling of plastic products.In particular, California law requires the proper labeling of products using standardized "recyclable," "biodegradable," and "compostable" designations. 99,100These measures help to address challenges with the RIC system by instituting nomenclature specific to recycling and waste disposal.Short of adjusting marketing standards, many states and local groups have instead invested in general recycling education and outreach, which regularly includes region-specific information about RICs and recyclability of certain plastics.
F I G U R E 6 A map of state policy environments for addressing plastic production. 91,94I G U R E 7 A map of state policy environments for supporting chemical recycling and deemphasizing source reduction. 97,98.2 | International policy

| Plastic import and export
US plastic waste is regularly exported internationally, 4 but irresponsible exportation practices have created legitimate environmental justice concerns for the importing countries and their ability to manage plastic waste.In an effort to prevent such outcomes, the international Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal provides restrictions on the destinations to which waste materials can be shipped, requiring the "prior written consent" of any countries accepting imports and any countries through which waste travels.The Basel Convention was amended to include plastic wastes from January 1, 2021.The United States is not a party of the Basel Convention, but trade in plastic waste to Basel parties is still restricted, unless in the presence of another trade agreement (for example, the United States has one such agreement with Canada, which is a Basel party). 101portation markets are of significant importance to US plastics recycling: the materials which the United States has insufficient infrastructure to recycle itself (often plastic waste) are regularly exported to countries who accept waste. 45When key markets close, plastic waste becomes less valuable and incentives to invest in plastic waste collection and recycling decrease.The historically most prominent importer, China, stopped accepting US plastic waste under the National Sword policy in January 2018 due to the low quality and high level of contamination present in imported waste. 102In the past, plastic exported to China had been counted as "recycled" in the United States, skewing actual recycling rates. 10The closure of this market has impacted US recycling rates and, despite an overall trend toward reducing the US plastic waste exports, has shifted the importation burden to other countries rather than forcing a reduction in dependence on international waste importers. 4

| The United Nations
Chemical recycling has received interest at the intergovernmental organizations such as the United Nations, which is in the process of negotiating a landmark plastic pollution treaty by 2024 in a series of five global meetings of an Intergovernmental Negotiating Committee (INC).The second meeting (INC-2) took place in June 2023, to authorize a "zero draft" on the desired treaty. 103Prepared documents for INC-2 refer to chemical recycling in two contexts: as a potentially danger practice to prohibit, and as a potential avenue for addressing plastic pollution meriting further research. 104These conflicting assessments demonstrate awareness of chemical recycling's promise, but lack depth or specific stances on roles for the technologies.Furthermore, the UN Environmental Programme's related report on plastic production ahead of INC 2, Turning Off the Tap: How the world can end plastic pollution and create a circular economy, identifies several challenges facing chemical recycling.The report projects chemical recycling (P2P) to only occupy a small portion of plastic waste management from now until 2040.In addition, the report argues that chemical recycling requires global standards to ensure "safety and sustainability," and clarify when various kinds of chemical recycling (e.g.conversion technologies) are appropriate. 57

| The European Union
Chemical recycling is also receiving consideration from European nations for the role it may play in reaching a circular economy.In the EU's 2020 Circular Economy Action Plan, chemical recycling is one strategy identified for further exploration, 105 reflecting international interest in the promise of the technology, but a lack of comprehensive knowledge on process impacts that prevent more concrete recommendations.
The EU regulatory body directly involved with chemical regulation is the European Chemicals Agency (ECHA).ECHA was founded by the EU REACH program, which institutes chemical safety requirements for member states, including mandated testing for toxins. 5Such requirements apply to manufacturing and industrial processes, but ECHA has identified a lack of consideration for REACH rules in discussion of chemical recycling. 106In a report commissioned by ECHA to study chemical recycling, the authors correctly identified that "chemical recycling" is not homogeneous, and lacks "clarity and consistency" in its terminology, particularly with regard to the use of the term "recycling" for all associated technologies. 107As a result, the agency recommends chemical recycling technologies be assessed on a "caseby-case" basis for the purposes of regulation, and to "avoid mistaken generalizations of advantages/disadvantages of one technology to the whole field of chemical recycling.". 108The report also identifies gaps in the existing knowledge about how chemical recycling processes can address toxic substances introduced with plastic waste feedstocks, and recommends process-specific investigations to determine these outcomes. 107 addition, the EU's Packaging and Packaging Waste Directive (PPWD) establishes general targets for the recyclability of packaging products and other measures. 109As part of the PPWD, the EU has initiated an accounting system for PCR content in recycled products, which is necessary to enable transparency in chemical recycling and recycling at large.In particular, the EU Single-Use Plastics Directive (SUPD) Implementing Act sets standards for calculating and verifying recycled content in plastic products.The EU industry stakeholders have asked for clarity on how these standards will apply to chemical recycling processes, while expressing a preference for a simple mass balance accounting approach. 110The SUPD also implements several complementary policies to address the broader problem of plastic pollution, including bans on certain single-use plastic products, EPR measures, and encouragement of product redesign to facilitate plastics recycling. 111In order to meet goals under the 2020 Circular Economy Action Plan, a revision to the PPWD was proposed in November 2022 to expand its measures further and improve harmonization between EU members in areas such as recyclability labelling and the implementation of EPR schemes. 109

| Canada
Just as with the UN and EU, chemical recycling is receiving interest in Canada's environmental and recycling policy.In 2022, the Environment and Climate Change Canada (ECCC) sought public feedback on measures to require minimum PCR measures in certain plastic products manufactured in the country.In a technical issues paper, chemical recycling was identified as one option to meet these proposed requirements for its promise to recycle plastics that are currently inaccessible to traditional mechanical processes.However, the authors acknowledged two major areas of concerns surrounding chemical recycling technologies: process environmental impacts, and measurement of chemically recycled content.Nonetheless, the ECCC vowed to consider whether the outputs of chemical recycling technologies should be allowed to meet PCR regulations. 112is is generally consistent with the level of consideration afforded to chemical recycling in other "developed nations" and international organizations.Governments and regulatory agencies seem aware of chemical recycling, and the claims demonstrating its promise, but are also aware of counterclaims over negative local and environmental impacts.The tone of these international documents is largely exploratory and uncertain, seeking to maintain a balance between opposing environmentalist and industry stakeholders while leaving a firmer determination to be made in the future.They demonstrate that a foundation for international discussion around chemical recycling exists, but must be quickly developed if we are to determine its role in the near future to meet plastic pollution mitigation goals.

| Corporations
In recent years, many large corporations have made pledges related to plastic recycling and packaging.In the consumer packaged goods industry, more than 80 global companies have committed to reaching anywhere between 15% and 50% recycled content in their packaging by 2025. 113However, a literature review of 973 companies reveals little focus on actual source reduction to accompany these recycled content goals. 114Corporate pledges, while representing progress, often exist for only the most convenient to achieve goals, and do very little to approach a cohesive national strategy on plastics.

| Credits
Another voluntary solution to mitigate and track plastic pollution involves credit systems.Certain private providers have begun to offer "plastic credits" in the vein of carbon credits, 115 but such systems have deep flaws and little methodological accountability, making them prone to overstate their environmental worth.7][118] Due to these challenges, environmental groups advise against allowing recyclable content (PCR) to be transferable or otherwise act like a currency. 69

| Standards
Chemical recycling has been tentatively defined by voluntary standards organizations such as the ISO.As mentioned, the ISO definition makes a similar exclusion of waste-to-energy and incineration from chemical recycling as ACC-backed legislation, 62 but is still problematic by generalizing very distinct processes which should more appropriately be treated differently according to their technical details and outputs.Relevant to the broader plastics economy, ASTM D7611M-60 provides the latest standard on RICs, as discussed in Figure 2.
Though D7611M-60 began as voluntary, many US states have integrated the standard by reference into law. 414 | Federal policy

| Canonical federal laws
To provide a brief summary, a majority of US regulations relevant to plastic pollution and recycling derive from older environmental protection legislation. 11,119In particular, the Clean Air Act, or CAA, 120 authorizes EPA to set limits on emissions of certain substances into air from industrial facilities through a permitting process. 121Some particular substances are designated as "criteria pollutants," which include carbon monoxide (CO), particulate matter (PM), ozone (O 3 ), nitrogen oxides (NO x ), sulfur dioxide (SO 2 ), and lead (Pb).Under the CAA, an additional 189 hazardous air pollutants (HAPs) are incorporated with criteria pollutants into the National Emission Standards for Hazardous Air Pollutants (NESHAP). 122The EPA's list of criteria pollutants does not include microplastics (which are of particular concern for processes that involve plastics manufacturing or recycling), but are instead considered a type of PM under the CAA.The EPA sets and periodically reviews emission standards for two kinds of particular matter, including PM10 (particles less than 10 μ in size) and PM2.5 (less than 2.5 μ in size) in the National Ambient Air Quality Standards (NAAQS), available in 40 CFR Part 50. 123Microplastics are often small enough to fall under the PM2.5 category, but technical limitations in monitoring and sampling methods prevent CAA procedures, originally developed for chemical pollutants, from being directly applied to particle microplastic pollutants.Furthermore, existing regulation systems are largely risk-based, and given the scientific uncertainty over the effects of microplastic exposure, risk-based calculations for thresholds and acceptable levels of microplastics remain challenging. 124 a set of emerging technologies, it is unclear how chemical recycling should fit into existing CAA regulations.Recent discussions of how to regulate pyrolysis and gasification (conversion technologies that fall under chemical recycling) are particularly illustrative of this issue.Section 129 of the CAA provides air pollution emissions controls for facilities considered Other Solid Waste Incineration (OSWI). 120Recent EPA rulemaking has considered whether to exclude pyrolysis and gasification from this category of regulation.The question is technical: pyrolysis and gasification do not meet the accepted technical definition of incineration because they exclude or restrict, respectively, the presence of intentionally added oxygen in the process.On this technical basis, in 2020, the EPA proposed removing these two technologies from OSWI regulatory definition. 125However, this proposal amounted to opening a regulatory gap for these technologies under the CAA.Without a clear federal regulatory approach to chemical recycling, individual states have more discretion to classify chemical recycling as a manufacturing process (an objective of the ACC) for less stringent regulation.
In response, congressional members sent a letter on this subject to EPA director Michael Regan, urging reconsideration and full regulation of chemical recycling technologies. 126A subsequent congressional letter reinforced this message and further urged the removal of "harmful chemical recycling technologies" from consideration under a National Recycling Strategy. 127Furthermore, a committee report prepared for the Consolidated Appropriations Act of 2023 128 included cautionary language regarding chemical recycling technologies pyrolysis and gasification, urging the EPA to consider the "emissions, disproportionate impacts, and lack of circularity" of said processes. 129ough the report ultimately recommended that pyrolysis and gasification continue to be regulated as incineration units under the Clean Air Act, its language was not included in the final appropriations bill.
In June 2023, the EPA withdrew its proposed change, but final rulemaking is still ongoing after the agency received many public comments on the subject of appropriate regulation. 130milarly, the Clean Water Act, or CWA, 131 focuses on discharges of conventional, toxic, and nonconventional pollutants into surface waters. 122CWA institutes the National Pollutant Discharge Elimination System (NPDES) for permitting discharge into surface waters, and like the CAA, devises New Source Pollution Standards (NSPS) for the construction of new facilities.In contrast to the CAA, microplastics are slightly better accounted for in the existing CWA regulatory framework for emissions to surface waters under standards for total suspended solids (TSS), a conventional pollutant under CWA Section 304(a)(4). 132Related water quality legislation, the Safe Drinking Water Act, or SDWA, 133 also establishes turbidity standards for drinking water that include microplastics. 11,119 particular relevance to plastic solid waste is the Resource Conservation and Recovery Act, or RCRA, 134 which amended the Solid Waste Disposal Act of 1965 with defined categories of waste, representing different levels of toxicity and regulation.More strict regulations apply to wastes that can be considered hazardous, or possess ignitable, corrosive, reactive, or toxic properties. 122Most discarded plastics are not considered hazardous waste, though this prevailing policy has been challenged.For example, polyvinyl chloride (PVC, or plastic #6) contains vinyl chloride, a known carcinogen, 135 and can also contain phthalate plasticizers, which have been characterized as endocrine disruptors. 136Despite this, PVC is only considered hazardous waste in limited circumstances, a policy that the US EPA recently reaffirmed in rejecting a suit brought by the Center for Biological Diversity. 137In its decision, the EPA cited a lack of evidence that regulation as a hazardous waste in all circumstances would reduce toxic emissions from discarded PVC, and a constraint on resources which encouraged the agency to pursue other priorities. 138There is also broader interest in reclassifying microplastics as hazardous wastes under RCRA, given the presence of toxic chemicals, risk to ecosystems, and uncertainty over the effects of long-term exposure.In May 2023, over 70 lawmakers signed a letter urging the EPA to adopt this reclassification for microplastics. 139der the Toxic Substances Control Act, or TSCA, 140 the EPA gained the authority to require pre-manufacture notifications of new chemical substances produced in the United States, and issue Significant New Use Rules (SNURs) for substances of concern that present novel risks of exposure or release from facilities.Furthermore, the EPA must be able to minimize the dangers to human health and environmental systems of new chemicals proposed for manufacture, or must require further testing to clarify the impacts of a new chemical. 141The Act provides relevant regulatory mechanisms for oversight of new chemical recycling facilities, particularly conversion technologies that produce novel fuels and feedstocks from plastic waste. 142CA was amended in 2016 by the Lautenberg Chemical Safety Act 143 which places more focus on the evaluation of existing chemicals, risk-based assessments, and public transparency.These federal laws, and their relevance to emerging chemical recycling technologies, are summarized in Table 1.

| Recent federal laws
Though many bills related to plastics pollution and recycling have been introduced in recent Congresses, only a select few have negotiated the bipartisan support needed to become law.Chief among them is the Save Our Seas 2.0 Act, 145 a 2020 expansion of the original law signed in 2018 which mostly focused on marine debris cleanup. 146ve Our Seas 2.0 reflects greater interest in addressing the sources of marine pollution, including plastic.In particular, the Act creates the Solid Waste Infrastructure for Recycling (SWIFR) Grant Program administered by the EPA. 147Under SWIFR, states, territories, and DC can apply for grant funding to develop and improve, collect data regarding, or support the implementation of recycling plans.In general, operation and maintenance costs are ineligible for funding, while construction and equipment costs are only eligible in US territories.Thus, SWIFR is rather intended for planning, educating, and implementing complementary recycling strategies.
The SWIFR program was funded by the Infrastructure Investment and Jobs Act of 2021 (IIJA), or Bipartisan Infrastructure Law. 148Of the $1.2 trillion made available in the IIJA, 149 $30 million were allocated to the EPA SWIFR program in 2023. 150The IIJA also provided $75 million over 2022-2026 for the EPA to operate a Consumer Recycling Education and Outreach Grant program, for which states, territories, local governments, tribes, nonprofits, and public-private partnerships are eligible to apply. 151Furthermore, the Save Our Seas 2.0 Act directed the US EPA to prepare several reports for Congress, including one on the subject of microfiber pollution (a type of microplastic often from textiles). 152After a period of public comment, the report is currently being finalized. 153e Microbead-Free Waters Act of 2015 represents a limited application of a national plastics ban. 154It was signed into law to ban manufacturers from intentionally adding microbeads from cosmetic and personal care products, toothpaste, and over-the-counter drugs. 13e Act addresses one particular and relatively straightforward source of plastics pollution, as microbeads are intentionally added and are not natural products of plastics breakup.The ban likely draws much of its success from its limited scope, whereas legislation for microplastics more broadly would face significantly greater logistical challenges.

| Recent federal bills
Despite the lack of direct legislative progress on plastics and recycling, numerous federal measures have been proposed.One of the most comprehensive plastics bills introduced recently is Senator Jeff Merkley's Break Free From Plastic Pollution Act (BFFPPA) of 2021, which represents an ambitious collection of programs, many inspired by action at the state level.Its main components include a national EPR scheme, container deposit programs, the phasing out of common single-use plastics, fees on plastic bags, PCR mandates, more transparent and accessible plastic labeling, microplastics and microfiber filtration of wastewater, prevention of irresponsible plastic waste export, protections for states that enact more stringent plastic pollution regulations, and a pause on the approval of new plastic facilities. 155Furthermore, the BFFPPA explicitly defines recycling to exclude pyrolysis, gasification, and other P2F technologies, taking an opposite position to the ACC-backed legislation on "advanced recycling."Senator Merkley's BFFPPA highlights a dispute over whether pyrolysis and gasification produce fuel or feedstocks.From a technical standpoint, these processes can do both.The outputs of pyrolysis in particular can be used to manufacture virgin-quality plastics, but as analyzed by the NRDC, no implemented US plants currently follow the additional processing pathway required to do so. 64Thus, by examining pyrolysis and gasification as solitary processes which do not by themselves produce plastic, the BFFPPA definition of recycling is more technically accurate, but the definition offers no exceptions for implementations where additional processing is employed to create plastics from conversion technologies.Furthermore, the BFFPPA's measure to revamp recycling labeling is a timely and relevant suggestion according to consumer sentiment.In the same 2019 survey that revealed widespread confusion among the public regarding RICs, 74% of respondents agreed that state or nationally standardized rules for recycling would bring greater clarity to recycling systems. 44nator Sheldon Whitehouse's REDUCE Act, introduced in 2021, represents another perspective on reducing plastic production and promoting recycling.Chiefly, the REDUCE Act would enact an excise tax on certain categories of virgin plastics.The Act also establishes a Plastic Waste Reduction Fund, to be funded by the excise tax, to "carry out reduction and recycling activities, plastic waste and marine debris reduction, detection, monitoring, and cleanup activities, and address environmental justice and pollution impacts from plastic products". 156The excise tax value increases rapidly over time, to be paid by manufacturers, producers, and importers of covered plastic goods, but could lead to increases in plastic prices for consumers.
The Protect Communities from Plastics Act was proposed in 2022 by Senator Cory Booker and others with greater considerations T A B L E 1 Summary of canonical environmental protection laws administered by the EPA and their relevance to the regulation of chemical recycling. 11,119,122,144

Law
Brief summary Potential relevance to chemical recycling CAA Authorizes the EPA to set emissions standards for criteria pollutants and HAPs and require permits for various types of industrial facilities.
Chemical recycling processes need to be categorized into the existing CAA industry types to clear up regulatory uncertainty.The EPA recently reversed a proposal to exempt conversion technologies from regulation as solid waste incinerators.The CAA regulates PM, but monitoring and testing methods originally designed for chemical pollutants must be adapted to fit microplastics.

CWA
Authorizes the EPA to set discharge standards and require permits for pollutants to surface waters.
Subject to studies of process impacts, chemical recycling facilities may require surface water discharge permits.CWA regulates TSS, which more successfully accounts for microplastics than CAA methods.

SDWA
Authorizes the EPA to set pollutant standards for public drinking water.
The SDWA regulates turbidity, a measure of water quality that covers microplastics, which is a potential pollutant from recycling processes.

RCRA
Defines categories of solid waste, including hazardous waste, and the levels of regulatory requirements.
Neither plastic nor microplastics are considered.hazardous wastes, but there has been federal interest in revising this approach, which could provide motivation for recycling or impact the regulatory requirements for processes that produce microplastic waste.In some cases, process byproducts may be subject to hazardous waste regulations.

TSCA
Mandates the EPA to approve SNURs for chemicals manufactured in the United States.
TSCA approval may be required for the products of certain chemical recycling processes, particularly P2F pathways.
toward environmental justice.The Act goes further than the BFFPPA by explicitly excluding "pyrolysis, gasification, or similar chemical recycling technologies" from playing a role in the National Recycling Strategy, and requiring more study into the impacts of chemical recycling technologies. 157Finally, equitable access to recycling, and closing gaps in the existing recycling programs identified in the 2021 SPC report, have also received attention from members of Congress.One proposed bill, the Recycling Infrastructure and Accessibility Act of 2022, would establish an EPA recycling grant program to expand access to recycling in underserved communities. 158

| Executive agency action
With little legislative success, federal action on the plastics crisis has largely been confined to the executive branch, where to date, executive agencies have focused on exerting their direct authority over a limited federal jurisdiction and adjusting their enforcement of existing laws to reflect national-scale strategies.This approach involves large sectors of the executive branch: by executive order, President Biden formed an Interagency Policy Committee (IPC) on Plastic Pollution and a Circular Economy in April 2023, 159 in order to "coordinate federal efforts on plastic pollution, prioritizing public health, economic development, and equity to ensure that the benefits of acting on plastic pollution-including jobs, minimized exposure to harmful chemicals, and clean communities-are available to all". 160The same executive order also bolstered executive agency commitments to environmental justice with new accountability measures, building on the environmental justice foundation of the existing executive orders. 161rthermore, the EPA has taken recent steps toward the development of two relevant National Strategies in order to fulfill mandates established by the 2020 Save Our Seas 2.0 Act on marine plastic pollution and its 2020 goal for a national recycling rate of 50% by 2030. 162In the first, the EPA released a Draft National Recycling Strategy in November 2021, 163 which mentions chemical recycling as one potential option among a suite of policies to improve recycling. 164rthermore, the 2021 draft clearly excludes plastic-to-fuel (P2F) processes from the official EPA definition of "recycling." The EPA reaffirmed this exclusion in its Draft National Strategy to Prevent Plastic Pollution, released in April 2023, while also bringing environmental justice concerns back to the forefront.According to the Draft: EPA now understands that some of these technologies, produce fuels and/or intermediate materials used in the manufacturing or processing of fuel or fuel substitutes.EPA reaffirms that the Agency does not consider activities that convert non-hazardous solid waste to fuels or fuel substitutes ("plastics-to-fuel") or for energy production to be "recycling" activities.EPA also aims to ensure that a U.S. circular economy approach for plastic products reduces greenhouse gas emissions and protects overburdened communities from facilities that can increase the generation of hazardous waste and other forms of pollution.

47
Along these lines, the EPA has also proposed new rules under the TSCA that reflect concern over the presence of additional toxins in fuels made from plastics, 165 indirectly responding to new scientific knowledge demonstrating the potential for contamination in chemical recycling processes. 67cognizing roadblocks for new plastics legislation, some lawmakers have urged the EPA to further expand its actions on plastics.
In a June 2023 letter, 66 members of the House and Senate sought federal commitments beyond those included in the Draft National Strategy to Prevent Plastic Pollution, such as a timeline to phase out single-use plastics from the entire government, a reduction in federal use of PVC and PS (considered particularly toxic plastics), an expansion of environmental justice considerations for plastics industrial projects, and further direct rulemaking on microplastic pollution. 166ward these goals, the phasing out of single-use plastics has already begun on public lands through a June 2022 Department of Interior initiative, 167 and throughout the federal government via rulemaking initiated by the General Services Administration (GSA) to reconsider the use of plastics in packaging, shipping, and other uses in September 2022. 168e marketing of recycled products falls under the jurisdiction of the Federal Trade Commission (FTC), which is responsible for corporate advertising guidelines and preventing greenwashing.To this purpose, the FTC prepares and maintains the Green Guides, a set of best practices to avoid deceptive environmental claims about products. 169This includes guidance on the use of RICs and the "chasing arrows" recycling symbol on plastic products.According to the most recent Green Guides from 2012, these two symbols are allowed to be on the same product in an "inconspicuous location" without constituting a recyclable claim.During a recent period of public comment for the FTC to update the Green Guides, the EPA suggested that FTC adopt the current ASTM standard for RICs (which removed the chasing arrows symbol) in an effort to address consumer confusion. 170 mentioned, the US government currently funds research into chemical recycling through the Department of Energy, which additionally has signed a Memorandum of Understanding (MOU) with the ACC to collaborate on plastics recycling innovation. 171However, some EPA programs have also directly supported chemical recycling technologies.In 2023, the EPA finalized a Renewable Fuel Standard (RFS) program to approve the production of several "biofuels" as alternatives to petroleum, in an effort to reduce greenhouse gas emissions. 142ProPublica reports that of 34 recently approved biofuels, 16 are made from waste, including some from plastic waste in P2F processes. 172spite the intent of promoting chemical recycling for its climate change benefits, clear gaps in this approval process exist that reflect insufficient consideration of local impacts.Such gaps are highlighted by ProPublica's reporting on the EPA's recent approval of a Chevron P2F facility in Pascagoula, Mississippi.In August 2022, the EPA approved Chevron's submitted Pre-Manufacture Notice for a New Chemical Substance for the jet-fuel to be produced at its Mississippi P2F location, despite the facility carrying an estimated 1 in 4 lifetime risk of cancer for residents exposed to smokestack emissions of the facility, or 250,000 times the risk typically acceptable for EPA approval under the TSCA (1 in 1 million).According to Greenwire reporting, the Pascagoula plan approval now faces a probe and a lawsuit from community groups. 173,174This conflict represents continuity with ongoing conflicts over the siting of traditional chemical manufacturing industries.Recent proposals for new or expanded plastics facilities have attracted environmental-justice based investigations from the EPA or have had their CAA permits challenged or canceled in court for environmental justice related concerns. 161These developments demonstrate that environmental justice is being actively implemented at federal and state levels, and must be considered in the siting of future chemical recycling projects.

| Facilitating a centralized chemical recycling strategy
Despite the recent legislative and executive considerations for plastic waste management, no federal agency, board, or committee is currently considering chemical recycling from a coordinated systems perspective.A variety of government structures could be employed to rectify this gap.Commonly, Federal Advisory Committees, or FACs, are established according to the Federal Advisory Committee Act 175 to provide balanced expertise on issues that are relevant to federal policies, and can also open up opportunities for public participation. 176Though FACs can be established by Congress, the President, or executive agencies, FACA requires strong consideration of whether the new committee is truly needed, or the responsibilities of interest fall under the purview of an existing FAC, or an existing FAC can be expanded in scope to meet the need.FACs must be chartered in detail by agencies and are automatically terminated after 2 years if not renewed.Additionally, the Congress has the authority to review active FACs and suggest mergers or abolitions. 177 the EPA, 21 FACs are currently chartered in 2023 on a variety of subjects. 178However, no FACs are clearly or directly associated with chemical recycling, or even with plastic wastes.Instead, currently chartered FACs associated with the EPA deal with diverse issues including child health protection, clean air science, pesticides, and others.Two EPA FACs deal directly with environmental justice concerns: the National Environmental Justice Advisory Council (NEJAC), whose charter was renewed for 2 years in August 2022, 179 and the White House Environmental Justice Advisory Board, established by executive order. 180Currently, NEJAC operates several workgroups based on charges issued by the EPA on farmworkers and pesticides, implementation of NEPA, water infrastructure, and an environmental justice cumulative impacts framework. 181In recent reports, the NEJAC has issued recommendations on the EPA's management of forever chemicals (a possible contaminant in chemical recycling) and implementation of its PFAS roadmap. 182Meanwhile, the WHEJAC has workgroups focused on environmental justice screening and measurement tools, indigenous peoples, climate preparedness, and carbon management. 183Given the environmental justice considerations involved in chemical recycling infrastructure, either of these two advisory boards could take up chemical recycling for in-depth recommendations in the future, but this could strain the limited staff and resources available to either committee.Furthermore, questions of defining and standardizing chemical recycling have significant technical components that these FACs may not be equipped to address.
Another FAC established under the EPA is the Science Advisory Board (SAB).The SAB has broader scope than other FACs, and is intended to review technical information used in regulations and EPA research programs, as well as provide scientific advise. 184The SAB was originally authorized under the Environmental Research, Development, and Demonstration Authorization Act, or ERDDAA. 185As an FAC, the SAB has its charter renewed biannually, and it reviews regulations under EPA laws including but not limited to the CAA, CWA, SDWA, RCRA, and TSCA.The SAB will also decide which proposed rules do not require their review, often if they do not include new scientific content.
There is also precedent for small, single-purpose, and independent agencies for technical issues of extreme importance.The Nuclear Waste Technical Review Board (NWTRB), established by 1987 amendments to the Nuclear Waste Policy Act of 1982, 186 serves as a model for this type of government structure. 187The NWTRB was created in a very specific context: the responsibility for nuclear waste dis-

| Recommendations
There is an urgent need to standardize and specify terminology surrounding chemical recycling.The ISO definition of chemical recycling, for example, is too broad and includes technologies that do not always result in plastic products on their own without further processing.
Industry synonyms, such as advanced recycling and molecular recycling, have the effect of further confusing and complicating the technical details of the processes they describe.
The foundations of the discourse, up to and including the use of the umbrella term "chemical recycling," must be revisited to facilitate discussions over the roles such technologies should play in a National Recycling Strategy and an international plastic pollution treaty.While the term provides a convenient identifier for emerging technologies that are distinct from existing mechanical recycling systems, more technically accurate and informative classifications have been devised by industry and subject matter experts.This includes the binary P2F-P2P distinction and also the three-category framing of purification, depolymerization, and conversion-both of which have a strong technical basis in the products or chemical transformations of each type of process.
The development of new formal standards through a relevant independent standards body or through ongoing negotiations over the UN plastic pollution treaty should be undertaken to create uniform terminology and taxonomy surrounding chemical recycling processes.The standards-making methodology is a lengthy but comprehensive process for seeking input from industry and academic expertise through the formation of focused working committees and subcommittees.Independent standards bodies are also democratic, finding technical consensus through a system of drafts, objections, and approval votes.Standards could eventually be used to formally define and codify chemical recycling categories, using purification, depolymerization, and conversion as starting points.Given the thorough nature of the process, the making of such standards should be treated as a long-term goal, so additional federal action to strategize around chemical recycling is needed for the near term.
For instance, it is clear that not all technologies currently considered under the "chemical recycling" designation should legally qualify as true "recycling" or are worthy of that connotation.This determination should be made based in part on whether waste plastic inputs are converted to valuable virgin-quality plastic outputs (P2P, which has a clear argument to be considered recycling), to feedstocks and fuels (P2F, which does not), or to other forms of energy recovery.Thus, the recycling definition set out in EPA's Draft National Strategy to Prevent Plastic Pollution is correct, but could be revised with more nuance in recognizing that conversion technologies can produce plastic when their feedstock products are input to further processing.
However, it is necessary to expand our consideration of chemical recycling past simple assessments of inputs and outputs, and examine processes within the context of their limited niche applications, as well as their environmental and social impacts.
Likewise, we must reorient our thinking about the regulation of chemical recycling technologies in terms of their roles in integrated systems, rather than in terms of specific unit operations.Setting aside explicit technologies to always qualify as recycling, which has been the strategy of certain state-level legislation, is not resilient to future innovation in the industry.This rethinking will facilitate a broader agreement on which chemical recycling technologies should be deemphasized, and which should be considered "part of the solution" in the National Recycling Strategy toward reaching a circular economy for plastic wastes.Subject to a more detailed study of process environmental impacts, technologies which produce virgin-quality plastic from plastic waste meet the criteria of recycling and contributors to a circular economy.These include depolymerization and purification technologies, though both currently have feedstock constraints.
Conversion technologies such as pyrolysis and gasification, which are generally understood to better handle mixed plastic streams, should be considered conditionally "part of the solution" only when combined with further processing to selectively convert their products back into plastic polymers, rather than feedstocks to other processes or fuels.However, the considerations of additional processing may make these strategies environmentally noncompetitive.In total, it is recommended that the advisory committee have the following responsibilities: • Develop and maintain a shared language of reference terminology and taxonomy resources to describe chemical recycling processes for use in regulatory discussions (within the context of ongoing treaty negotiations).
• Conduct or commission environmental impact research using the operational chemical recycling facility data.
• Collect information on the commercial status and economic viability of various chemical recycling pathways, with an emphasis on P2P systems.
• Monitor the state of chemical recycling research (particularly government-funded) and encourage considerations of policy and regulations earlier in the research process.
• Advise the current regulatory problem of whether and how to regulate conversion technologies of pyrolysis and gasification as other solid waste incinerators, and other future considerations of the EPA on chemical recycling regulation.
• Produce recommendations on fitting emerging chemical recycling processes into existing regulatory frameworks, using regulatory strategies oriented toward the process technical details, product outputs (P2F vs. P2P), and environmental and social impacts.
• Advise the ongoing development and revision of the National Recycling Strategy and the role of chemical recycling technologies in that strategy document.
• Conduct reviews of EPA permit approvals for new plants that utilize processes traditionally considered chemical recycling.
• Produce data-based recommendations on the potential for various chemical recycling technologies to contribute to a circular economy and national recycling strategy.
• Contribute expertise to an independent standards body on the eventual creation of new formal standards chemical recycling terminology and taxonomy.Finally, the implementation of chemical recycling could benefit from the development of further standards not explicitly related to its definition and taxonomy.For example, the inadequacy of RICs for plastics identification-which began as the voluntary ASTM standards and became adopted by reference in many states-has been clearly documented.While the ASTM clarifies that RICs were only ever meant to standardize the properties of plastic resins, and never to signal whether a product was recyclable, RICs have taken on that role as one of the only markers present on most plastic commodities.At the very least, there is cause to federally adopt the most recent ASTM RIC standard.A more broadly beneficial strategy would be for the EPA to assist the ASTM or another relevant independent standards body in devising a new system explicitly meant as a recycling aid to foster more consumer-friendly plastic.The differences in input feedstock requirements to various chemical recycling processes reflect that plastic sorting will continue to play an important role in the future of recycling, and thus, further tools to reduce the sorting burden currently placed on consumers are needed.Furthermore, improved standardization for labeling will increase transparency of recycling measurements in product advertising and help to prevent greenwashing and other misleading claims about recycled content that could be facilitated by adopting a simple mass balance or allowing PCR to function as a tradable credit.
Such measures will protect the integrity of recycling while assuring a smooth transition toward assessing chemical recycling technologies in their appropriate roles.

| CONCLUSION
The vast scale of plastic waste production, and the necessary roles that plastic products will continue to play in the global economy, demand comprehensive policies to protect ecosystems and vulnerable communities from the worst impacts of plastic pollution.Recycling continues to be a necessary strategy for achieving a circular plastics economy where reducing plastic production, consumption, and disposal is not possible.Given the technical limitations of traditional mechanical recycling methods, many technologies described by chemical recycling have the potential to complement existing systems by processing currently inaccessible plastics into higher quality products.
However, chemical recycling is not homogeneous.The overall discourse of chemical recycling is significantly held back by a lack of standardization in its terminology and taxonomy, which has generated uncertainty around chemical recycling's details and disagreement over its potential contributions to a circular economy.As a result, an uneven regulatory environment has developed at the state level, compounding uncertainty about the future development of chemical recycling.As a set of emerging technologies with promise to treat currently inaccessible plastic wastes, chemical recycling not only deserves, but could benefit significantly from a uniform regulatory approach that would alleviate uncertainty for stakeholders and push the international community past its present exploratory state of policy considerations.
There is room for the federal government to assist in chemical recycling strategy and policy considerations in a more centralized and intentional manner, primarily through the formation of an EPA Federal Advisory Committee focused on chemical recycling as one element of the integrated system of plastic waste management and pollution prevention.This work will involve analyzing distinct processes for their Plastics are a diverse set of materials with countless applications in packing, construction, textiles, electronics, safety, and healthcare.

Figure 3 .
Figure 3. First, purification (or dissolution) technologies dissolve plastics in solvents to remove additives and contaminants, usually leaving the plastic polymer chains intact.Purification technologies are typically to differentiate these methods of recycling as novel and chemical in nature.Furthermore, the International Standards Organization (ISO) definition of chemical recycling currently reads as follows: (ISO 472: 2013: 2.1690) feedstock (=chemical) recycling: recycling of plastic waste: conversion to monomer or production of new raw materials by changing the chemical structure of plastic waste through cracking, gasification, or depolymerization, excluding energy recovery and incineration.
codifying extended producer responsibility (EPR) schemes for plastic manufacturers.A model EPR implementation was established in California with the passage of SB 54 in 2022, under which plastic manufacturers must join a Producer Responsibility Organization (PRO) to sell products in the state.The PRO collects membership fees and other charges from manufacturers, which translates to a tax on plastic packaging products.SB 54 requires that the established PRO pays an annual $500 million surcharge to the State starting in 2027, to be deposited in a new California Plastic Pollution Mitigation

178 4 | POLICY RECOMMENDATIONS 4 . 1 |
position was originally claimed by the Department of Energy in the original 1982 Act, but after Congress selected Yucca Mountain as a designated nuclear waste site in 1987, the establishment of NWTRB was suggested in tandem with this decision to provide an avenue for public awareness and participation in the process going forward.Its advantages as an independent advisory agency are to provide transparency, oversight, and legitimacy through unbiased technical review of DOE activities surrounding nuclear waste disposal.The NWTRB is a thoroughly unique agency: "Technical Review Board" has no standard definition in the US government188 and has not been replicated for other issues or other types of wastes.Its Board Members hold part-time positions and are qualified experts from academic and consulting backgrounds in a broad range of relevant subjects.The barriers to establishing a new, independent agency are significant, as such an action would require new enabling legislation, and a bipartisan agreement laying out the scope of the agency's mission.However, the actual agency would not strain US appropriations or resources: the NWTRB had a budget of $5.48 million for Fiscal Year 2023, a negligible fraction of the annual US budget.189This demonstrates that a new single-purpose independent advisory agency would require relatively low monetary investment to achieve its missions (but in comparison, the 21 EPA FACs together cost less than $10 million in Fiscal Year 2022).Strategies and standards for chemical recycling4.1.1 | ConflictThe nature of chemical recycling is disputed, in part because the term has been adapted as a catch-all for many distinct processes that accept waste plastic feedstocks and use methods different from existing mechanical recycling systems.Complicating the discourse, different stakeholders prefer different terms (advanced recycling, feedstock recycling, molecular recycling, and upcycling) that are all generally synonymous with unclear implied distinctions.At the state level, industry stakeholders have led a coordinated campaign to secure support for a vision of chemical recycling that includes a broad and vague range of technologies, while issuing blanket statements that all qualify as recycling, and all contribute to a circular economy.Some environmental groups, for their part, have suggested that chemical recycling technologies are equivalent to incineration of plastics.Others are generally skeptical of industry and suggest that promoting chemical recycling as "recycling" amounts to greenwashing.Furthermore, as a set of emerging technologies, it is unclear how the many forms of chemical recycling should be regulated under canonical environmental law at the federal level.Current efforts to fit chemical recycling into existing regulations have focused on only a handful of processes and have been challenged by technical questions.A lack of cohesion at the federal level has allowed a regulatory patchwork to develop: today, nearly half of all US states have adopted legislation to promote chemical recycling and reduce its regulatory obligations, while the remaining states have not.Without federal coordination, states may find economic incentive in reducing regulatory burdens to attract the chemical recycling industry.Current state legislation also picks explicit winners and losers by singling out specific processes without strong basis in environmental impact studies, while generalizing the nature of purification, depolymerization, and conversion technologies all under the same category of chemical recycling.

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schemes (modeled by California's SB-54) could be expanded to the national scale, creating systems to require the establishment of regional or national PROs, who would fund plastic pollution and environmental injustice mitigation activities through a new national plastic pollution mitigation fund.A national EPR scheme would additionally facilitate the achievement of national recycling goals and possible PCR content targets.However, there is also an opportunity for PRO technological and commercial readiness, as well as environmental and social impacts, to guide near-term advice on the regulation of chemical recycling in the United States.In long term, the Committee can assist with disentangling these diverse processes from underneath the single existing label of chemical recycling, correcting generalizations about process technical details, and reaching a data-driven consensus about the roles that individual technologies should play in a national recycling strategy.Chemical recycling processes also deserve further research aimed to comprehensively describe and quantify their environmental impacts, and existing environmental justice advisory committees of the federal government can play a role in upholding protections for fenceline communities in the face of emerging technologies.Finally, we must recognize that plastic pollution is a defining challenge, and recycling cannot be the only strategy employed to mitigate its harms.Just as chemical recycling technologies offer to complement mechanical recycling systems, we need a suite of strong complementary policies from the upper level of the waste management hierarchy to address single-use and unnecessary plastics.The United States can look to states and the international community for model ideas and implementations of such programs, so that the nation can move toward the development of a truly integrative and comprehensive plastics strategy that addresses plastic production, assists consumers, and supports recycling technologies in sensible waste management applications.AUTHOR CONTRIBUTIONS Evan Erickson: Investigation; writingoriginal draft; writingreview and editing; conceptualization; visualization.ACKNOWLEDGMENTS I would like to sincerely thank the mentors and resources I met through the WISE program, including program coordinator Erica Wissolik, faculty member-in-residence Logen Johnson, AIChE sponsoring society representative Heather Yuengling, and AIChE program mentor Dale Keairns.I would also like to thank Mary Ellen Ternes, Martin Abraham and the anonymous reviewers for helping to improve this manuscript.Finally, I would like to thank my fellow interns (Ryan, Sarah, Courtney, Abbey, Chris, Aicha, and Jean-Luc) for their friendship and my family for their support during an amazing summer to remember in Washington, DC.
long-term effects, and there is interest in regulating these pollutants as hazardous waste to more fully account for their risk to human and ecosystem health.Finally, gaps in the cur- regulations to matter and particle contaminants relevant to chemical recycling is challenging (see Table1and above discussion of the existing US environmental protection law).Microplastics, of particular concern for any process involving plastics or plastics recycling, are not directly a criteria pollutant of the CAA, a toxic pollutant of the CWA, or a hazardous waste under RCRA regulations.However, exposure to microplastics has uncertain can potentially inform regulatory strategies surrounding the pollutant and identify further knowledge gaps.The improvement of microplastics pollution regulations will rectify our current underestimation of environmental and health risks that allow plastic waste to be mismanaged, and could promote further mechanical and chemical recycling as waste management methods.singand capital costs for these emerging technologies may prevent chemical recycling from being explored in many countries, while their implementation in nations such as the United States may be hampered by existing gaps in our national recycling infrastructure.With an international treaty on plastic pollution expected by 2024, it may not be practical or timely to develop chemical recycling as a central component of a US plastic pollution mitigation strategy.