Many agree that chemicals of concern in plastics need to be addressed by regulation, for instance, under the United Nations’ forthcoming Global Plastics Treaty (FPF reported and here). A recent PlastChem Project study identified more than 4,200 plastic chemicals are of concern, using a hazard-based approach (FPF reported). However, disagreements continue to exist around whether hazard-based or risk-based approaches should be used to identify chemicals of concern in plastics.
In a peer-reviewed perspective article published on July 30, 2025, in the journal Environmental Science & Technology, John D. Hader from Empa (The Swiss Federal Laboratories for Materials Science and Technology), and co-authors including PlastChem Project team members outline the advantages of a hazard-based over a risk-based approach to identify chemicals of concern in plastics. Under a hazard-based approach, chemicals are identified as of concern solely based on their intrinsic hazard properties, while a risk-based approach considers chemicals’ hazard properties and level of exposure to humans and wildlife.
Why a risk-based approach is not fit for purpose
First, the scientists summarize why a risk-based approach can delay and complicate identifying plastic chemicals of concern while also bearing uncertainties. Specifically, they highlight
- the large number of plastic chemicals (> 16,000, FPF reported) whose use (in mixtures) varies between products, applications, regions, and in time.
- a lack of transparency concerning chemical identity and quantity in specific products.
- analytical challenges to characterize many of the plastic chemicals, e.g., due to missing analytical standards and capacities.
- systemic limitations of exposure and risk assessment, such as the difficulty of linking adverse outcomes to chemical exposures, and the frequent refinement of what is considered a ‘safe’ level of exposure.
Benefits of applying a hazard-based approach
Subsequently, the authors describe how to efficiently and soundly manage plastic chemicals of concern under regulatory frameworks such as the Global Plastics Treaty. They suggest applying a hazard-based approach and using the Stockholm Convention and other international treaties as orientation. They recommend using predefined robust hazard criteria to identify chemicals of concern. If a chemical is of concern, it would be checked whether it provides an essential function in the plastic product (FPF reported and here). Functionally unnecessary chemicals could easily be phased out, while functionally essential ones would be replaced with well-tested, safe alternatives, if possible. For essential chemicals of concern without safe alternatives, the scientists propose the integration of exposure and risk assessment to inform measures that reduce exposure, and that these chemicals be prioritized for removal or replacement as quickly as possible.
Further recommendations towards safer plastics
Besides using a hazard-based approach to identify plastic chemicals of concern, the authors recommend enhancing transparency of the identity and quantity of plastic chemicals in specific applications as well as traceability. Lastly, they echo calls from previous studies to transition to new plastics/materials with “simplified, standardized, and safe plastic chemicals” (FPF reported).
As plastic chemicals can have impacts along the entire life cycle of plastics, chemicals of concern need to be considered also at the very beginning and very end of the plastic life cycle, the authors point out. This includes, for example, chemicals used in fossil extraction all the way to the chemicals created during open burning of plastic wastes. The scientists further emphasized that eliminating chemicals of concern from plastic and other materials is important to enable a safe and sustainable circular economy, to prevent unintended exposure from recycled products and recycling processes, and to ensure recycled materials are of high quality.
Putting it into perspective
The authors conclude that given the complexity of plastic chemicals “the hazard-based approach to identifying which of these chemicals are of concern offers an efficient, simple, and fit-for-purpose solution to take a timely first step toward enabling a safer use of plastic chemicals. More complex exposure and risk assessments should be reserved only for subsequent steps to develop concerted action on plastic chemicals of concern.”
Lead author of the article John Hader says “If you come across a snake in the woods, your first thought is almost always ‘is this a venomous snake?’ That is a hazard-based approach to identifying a snake as a concern. You don’t take a risk-based approach, which would mean investing time to also research and assess how much of the venom it would take to cause you harm, if the anti-venom is likely to be available at a local hospital, etc. We should apply this same approach to identifying chemicals of concern in plastics – if it is hazardous, it is of concern.”
Reference
Hader, J. D. et al. (2025). “A Hazard-Based Approach Enables the Efficient Identification of Chemicals of Concern in Plastics.” Environmental Science & Technology. DOI: 10.1021/acs.est.5c02912
