Enabling a circular economy for plastics in Europe and beyond is an ambitious goal. To reach a fully closed loop, numerous challenges and knowledge gaps need to be overcome. This review provides a list of more than 6000 chemicals reported to be found in plastics and an overview of the challenges and gaps in assessing their impacts on the environment and human health along the life cycle of plastic products. We further identified 1518 plastic-related chemicals of concern, which should be prioritized for substitution by safer alternatives. At last, we propose five policy recommendations, including the need of a global and overarching regulatory framework for plastics and related chemicals, in support of a circular economy for plastics and of target 12.4 of the UN Sustainable Development Goals.
State of knowledge of chemicals in plastics
Overview of chemical additives
The production of chemicals for plastics is continuously increasing in terms of both quantity and diversity, with several thousand chemicals used across many material applications. Estimating global additives production is not an easy task, because these data are usually not publicly available. However, with a global plastic production of 368 Mt in 2019, and assuming 1–10% additives mass fraction for nonfibre plastics, the total amount of additives used in 2019 might be around 20 (3.6–36.8) Mt. If plastic production follows current increasing trends, it is estimated that we will have produced 2000 Mt of additives by the end of 2050. Plasticizers are the most used additives and together with flame retardants cover almost 50% of globally applied additives. Owing to their wide-ranging application and high-production volumes, these two types of additives have been receiving special attention (e.g. Commission Regulation (EU) 2018/2005).
Additives are applied during the production process at different concentrations based on the specific function that they need to fulfil. It provides an overview of functions, typical material application, chemical classes, and application ranges. For example, plasticizer application ranges vary across materials, and can reach up to 60–70% of the plastic mass in soft PVC resin products. Other additives are usually applied at much lower concentrations, such as 0.7–25% for flame retardants or 0.05–5% for stabilizers and antioxidants. The concentration of unintentional residues is typically <1%. Generally, it is accepted to consider as NIAS only compounds with a mass <1000 Da, assuming that substances with a higher molecular weight cannot be absorbed in the body (EU No 10/2011, although there might be some uptake in the gut).
Chemicals reported in plastics
As of today, there is no publicly available database containing a complete and detailed list of chemicals used in the various plastic products, specifying typical function, plastic types, and mass fraction ranges. In an attempt to provide such an overview, we used the mapping of plastic additives conducted by the European Chemical Agency (ECHA), and expanded it with data from 35 additional sources. The considered sources include—amongst others—Annex I of Commission Regulation (EU) No 10/2011, also called the Union list, which is a positive list of monomers and additives authorized for use in plastic-based food contact materials, the work conducted by Groh et al., and the Chemicals and Product Categories database (CPCat; actor.epa.gov/cpcat), which contains information across different categories and materials
As a result, It provides a list of more than 6000 functional additives, pigments and other substances found (both currently and in the past) in plastics. For each substance, we provide CAS number, main chemical function, typical application range, and polymer type (when available). For building the data set, we checked and harmonized where needed the reported chemical names, CAS numbers, and functions. Chemicals were classified according to their specific function in plastic materials based on the information reported in the considered sources. Wherever such information was missing, we retrieved the function from other references.
It aims at providing a comprehensive overview of chemicals found in plastics across different polymers and product applications. It contains various types of substances reported to be found in plastics; consequently, it is not limited to additives but also includes NIAS, solvents, unreacted monomers, starting substances, and processing aids.
Challenges and gaps in assessing plastic-related chemicals’ impacts in a circularity context
The goal of a circular economy is to move.
Sodium carbonate, activated carbon and copper-impregnated aluminium are used to absorb the sulphur without the use of water. They give efficiencies of absorption of 85–90% and have the advantage of not cooling the stack gases. The gases will then rise upwards from the top of the stack and disperse more widely in the atmosphere.