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