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Rodent cancer bioassays are currently required by regulatory authorities for the carcinogenicity assessment of industrial chemicals, agrochemicals, food additives, pharmaceuticals, and environmental pollutants. In these tests, at least 480 rats and 400 mice are forced to ingest or inhale chemicals every day for 18 to 24 months and then killed to assess the effects of chemical exposure.
Over the past 50 years, we have learned a great deal about cancer biology, but our approach to testing chemicals for carcinogenic potential in humans has not kept up. Rodent cancer bioassays are expensive, time-consuming, and of questionable relevance to humans and require the use of many animals. Fortunately, scientists are now modernising carcinogenicity assessment through mechanistic approaches that reduce testing on animals and provide information that is more relevant to protecting human health.
Projects
The Rethinking Carcinogenicity Assessment for Agrochemicals Project (ReCAAP) is led by experts from PETA Science Consortium International, government, and industry who are developing a strategy to move away from a “check-box” approach that includes bioassays to one based on human-relevant mechanisms of disease and other sources of information.
Details about this project are available in our 2022 publication in Regulatory Toxicology and Pharmacology, a poster we presented at the 11th World Congress on Alternatives and Animal Use in the Life Sciences and the EuroTox2021 Congress, and our 2024 publication in Frontiers in Toxicology on how to use the framework, in which examples with specific chemicals are provided.
In 2024, following vetting and approval by its participating member countries, the Organisation for Economic Co-operation and Development published a document describing two examples of how to use a weight of evidence approach to protect against chronic toxicity and carcinogenicity without relying on the lifetime rodent cancer bioassay. The document was co-authored by the Science Consortium, Syngenta, and Exponent.
In addition to the above project, there are many others aiming to help make the transition away from the bioassay, including those led by the following groups and initiatives:
- The European Partnership for Alternative Approaches to Animal Testing
- The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) S1B(R1) Addendum to S1B Testing for Carcinogenicity of Pharmaceuticals: Guidance for Industry
- The FDA Center for Food Safety and Applied Nutrition and SOT (“Redesigning the Rodent Bioassay for the 21st Century” workshop)
- The Health and Environmental Sciences Institute’s Emerging Systems Toxicology for Assessment of Risk (eSTAR) Committee
- The National Toxicology Program’s National Toxicology Health Effects Initiative (“Converging on Cancer” workshop)
- The Organisation for Economic Co-operation and Development (integrated approach to testing and assessment of non-genotoxic carcinogens)
For more information on carcinogenicity, see here.