Deep Dive into Plastic Monomers, Additives, and Processing Aids

CASRNs = Chemical Abstracts Service Registry Numbers; SMILES = simplified molecular-input line-entry system; REACH = Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals; PBT = persistent, bioaccumulative and toxic; EU = European Union.Initial categories and associated keywords were defined for functions (using definitions in industrial handbooks),(6,8,9,63) compatible polymer types, and industrial sectors of use (based on recent plastic material flow analyses).(1,64,65) Keywords included synonyms (e.g., “HDPE” for high-density polyethylene), hyponyms (e.g., “fridge” for electronics and “milk bottle” for food packaging), and hypernyms [for example, “polyolefin” for (high- and low-density) polyethylene]. Only their total production volumes for all uses (including ones other than in plastics) are available.Under any of the regulations considered in this study (Sheet S2 in Supporting Information S1).The percentage of the total number of chemicals within that hazard group.The percentage of the number of chemicals from regulator-harmonized hazard data within that hazard group.There is a general lack of transparency regarding substances present in plastics.(66,67) Existing practices of national/regional chemical inventories provide limited help on this matter, due to (1) limited public accessibility of production and use information (e.g., only three of the 21 investigated inventories made use information public; much of the information reported in these three inventories is claimed to be “confidential business information”) and (2) incompleteness (e.g., reduced reporting requirements for low production volume or “non-hazardous” chemicals(62)). Currently, several initiatives targeting better communication of information on chemicals in products along supply chains have been initiated, for example, the EU Sustainable Product Policy Initiative,(67,68) the Substances of Concern In articles or Products database (SCIP database) hosted by the European Chemicals Agency (ECHA),(69) and the HolyGrail Project led by P&G (under the New Plastics Economy program of the Ellen MacArthur Foundation).(70) However, their effective implementation is currently hindered by factors such as (claims of) complex supply chains, diverging interests and technical capacities of actors within supply chains, and data storage and transfer issues.(71,72)Not all data in the public domain are readily machine-accessible and processable; in this study, substances for which the assigned CASRNs are not provided are excluded from the analysis, including ions for ionizable substances or structural isomers (see Section 2.2). Concerted efforts to address these problems are necessary to improve, harmonize, and foster nonambiguous reporting of substance identities and use patterns by all stakeholders across the world, building on existing initiatives.(3,73−76) In addition, advances in information technologies (such as optical character recognition, natural language processing, and cheminformatics tools) to unambiguously recognize different types of chemical identifiers in the text and convert between them may help collect information that currently requires manual processing.(77−81)Besides the intentionally added substances considered in this study, also NIASs are highly relevant for plastics because (1) they have been frequently reported in measurements, (2) plastics in many applications are prone to contamination from production, processing, and use, and (3) substance transformation is an integral part of fulfilling specific functions (e.g., formation of quinones from oxidization of phenolic antioxidants).(10,41,82−84) However, NIASs are not yet comprehensively understood, their identification remains challenging, not least because of a dearth of clarity on plastic compositions and conditions during production and use, and analytical difficulties of unequivocally identifying substances at low concentrations remain.(10,11,41) To improve NIAS identification and quantification, measures such as increasing product transparency through company reporting, obligatory provision of analytical standards, and standardization of sample treatment, separation, and data treatment procedures may be taken.(41)Reported uses may be incomplete, outdated, or inaccurate. For example, ulterior motives may play a role in the comprehensiveness and accuracy of reporting (such as missed or wrong reporting of risk-related information and exaggeration of the number of applicable uses).(93,94)The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.1c00976.Excel file with large tables presenting data sources and retrieval, keywords for the categorization, and overviews of all substances and substances of potential concern (ZIP)PDF file presenting details on methods, additional results, and additional discussion on chemicals on the global market (PDF)Excel file with large tables presenting data sources and retrieval, keywords for the categorization, and overviews of all substances and substances of potential concern (ZIP)PDF file presenting details on methods, additional results, and additional discussion on chemicals on the global market (PDF)Most electronic Supporting Information files are available without a subscription to ACS Web Editions. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.1c00976.Excel file with large tables presenting data sources and retrieval, keywords for the categorization, and overviews of all substances and substances of potential concern (ZIP)PDF file presenting details on methods, additional results, and additional discussion on chemicals on the global market (PDF)Excel file with large tables presenting data sources and retrieval, keywords for the categorization, and overviews of all substances and substances of potential concern (ZIP)PDF file presenting details on methods, additional results, and additional discussion on chemicals on the global market (PDF)Most electronic Supporting Information files are available without a subscription to ACS Web Editions.