State of the
science
on plastic
chemicals
Identifying and addressing chemicals and polymers of concern
Frequently Asked Questions
What is a plastic chemical?
While some stakeholders attempt to frame the issue of chemicals in plastics very narrowly to so-called additives (chemicals intentionally added to impose some functionality to the final product), we applied a more comprehensive definition of a plastic chemical that includes starting substances, processing aids, additives and non-intentionally added substances (NIAS). Given that all these can be present in the final plastic product, such broader scope is required to safeguard human health and the environment.
The specific definition we developed is: Plastic chemicals are “all chemicals that can be present in plastic materials and products, including the polymer backbone, intentionally added substances (i.e., starting substances, processing aids, additives), and NIAS (e.g., impurities, unreacted intermediates, reaction by-products, and degradation products). The fact that some plastic chemicals may have additional uses in non-plastic applications has no bearing on their inclusion. Contaminants sorbing to plastics during use or end-of-life are not considered plastic
chemicals” (Monclús et al., 2025).
Are there really >16 000 chemicals in plastics? That seems like (too) many.
As a matter of fact, the actual number of chemicals in plastics is unknown, including to the manufacturers of plastics. This has two main reasons: First, the plastics industry does not publicly disclose which chemicals are intentionally used in their products. Second, plastics contain non-intentionally added substances (NIAS), basically contaminants introduced during the production and use of plastics. They are difficult to analyze and assess because most NIAS are unknown. Government experts have estimated that there are far more NIAS in plastics than intentionally added chemicals, but their number and identity remain largely unknown.
To address these challenges, the goal of PlastChem was to build a database of all chemicals that can potentially be present in plastics (we refer to them as plastic chemicals). This nuance is important because, due to the reasons mentioned above, it is impossible for the public to know the exact chemical composition of a plastic product. Accordingly, our aim was to provide a comprehensive overview of all plastic chemicals.
We compiled information on all plastic chemicals from six peer-reviewed scientific studies and one government source. These sources have identified chemicals that can be present in plastics using rigorous methodologies and relying on regulatory information (e.g., chemicals approved for use in plastics by governments) and empirical evidence (e.g., chemicals that have been detected in plastics). We used these sources because they are authoritative, that means of high quality, and because they are public and thus verifiable.
As a result, the PlastChem database contains 16,325 plastic chemicals. This represents the most comprehensive estimate to date of how many chemicals can potentially be present in plastics.
There are, however, some uncertainties to this estimate. First, we took great care to remove duplicates (e.g., identical chemicals with slightly different names) but cannot rule out that some duplicates remain. That would result in an overestimation of the number of plastic chemicals. Conversely, we identified 1,616 substances without CAS registry numbers, that include for instance complex chemical mixtures and some polymers. These are listed in the PlastChem database but not counted towards the 16,325 plastic chemicals. Accordingly, the number of plastic chemicals could be underestimated.
Some chemicals listed in PlastChem do not seem to make sense. Are these really plastic chemicals?
We accepted a chemical as being a “plastic chemical” if it was classified as such by one of the scientific or government sources we used to compile the PlastChem database. Accordingly, we did not validate whether individual chemicals “make sense” in the context of plastics as clearly indicated in Monclús et al. (2025). The reason for this is simple: A verifiable ground truth of which chemicals are present in plastics does not exist, except for the 4,129 chemicals that have been detected in plastics in scientific studies. In addition, a manual curation would have introduced biases because it would need to rely on expert judgment whether a chemical is a plastic chemical or not. Such judgments would not be verifiable independently, a situation we wanted to avoid.
Instead, we made each chemical entry in the PlastChem traceable to its original source. This allows users to assess which previous source has classified a chemical as being associated with plastics. In some cases, the chemicals may be counterintuitive (e.g., pesticides or pharmaceuticals). We note that these compounds may be non-intentionally added substances (NIAS) that originate from contamination during production, such as the use of recycled plastics. Importantly, when seemingly non-sensical chemicals are detected in PlastChem it can help to inform the curators of the original sources to understand why it is listed there.
Aren't all plastic chemicals tightly regulated?
This depends on the context. Our work was conducted to support policymakers and stakeholders to create a global plastics treaty that protects human health and the environment. Hence, PlastChem had an international scope, and we focused on the global regulation of plastic chemicals. We found that few plastic chemicals are regulated globally, mainly because established Multilateral Environmental Agreements, such as the Stockholm Convention or the Montreal Protocol, are not specifically designed to cover chemicals in plastics.
The situation on a national level might be different with more specific laws in place. While our objective was not to comprehensively map the national regulation of plastic chemicals, we found that countries with well-established chemicals’ regulation (e.g., European Union, South Korea, Japan) address relatively few plastic chemicals as well. However, we note that the geographical scope is limited, and we only integrated easily accessible lists in PlastChem. Accordingly, additional regulations may exist but are not included.
PlastChem suggests a hazard-based identification of chemicals of concern. How is that different from a risk-based approach?
Assessing the risks of a plastic chemical requires extensive knowledge of its hazards (e.g., its toxicity) as well as the exposure, that is, its levels in plastics, foodstuffs, the environment and biota, including humans. Since such exposure information is often not available or very uncertain, PlastChem decided to identify chemicals of concern in plastics based on their hazards to enable a timely removal of harmful chemicals. The rationale is simple: First, hazardous chemicals should not be present in plastics to efficiently protect human health and the environment. Second, exposure to plastic chemicals is likely because most of them are not chemically bound to the material and can easily be released. Third, performing risk assessments for all plastic chemicals is not feasible in a timely fashion and often not suitable because of data gaps, blind spots, and high implementation costs. Accordingly, we argue that a hazard-based approach is sufficient to identify chemicals of concern in plastics, noting that their subsequent management can contain elements of exposure if the required data are available. Please read the following publication for more details: Hader et al. (2025).
Which expertise flowed into PlastChem?
The team behind PlastChem has a diverse set of scientific expertise, including analytical chemistry, toxicology, chemicals management and regulation as well as data science. Members of our team have worked on plastic chemicals for many years, some of them for decades, producing previous databases of plastic chemicals that we used for creating PlastChem (FPF, Empa, Eawag), investigating the chemicals and toxicity of plastic products experimentally (NTNU) and supporting chemical’s management in Europe and beyond (all partners). Taken together, the PlastChem team has published more than 100 scientific studies on chemicals in plastics.
Why was the plastics industry not involved in PlastChem?
We decided against involving plastic manufacturers or other industry experts because our aim was to produce an open and verifiable database of all plastic chemicals. While industry representatives possess valuable insight into the chemical composition of plastics, they are bound by confidentiality rules and, hence, would be unable to contribute to making relevant information publicly available.
How was PlastChem funded?
The project was funded by the Norwegian Environment Agency via an open call for proposals managed by the Norwegian Research Council. This means that our team was awarded the funding for PlastChem after a competitive process and peer review. This also means that the project was independent of the political positions of the Norwegian government, which had no role in the design, execution, and interpretation of the research performed in PlastChem.