Zebrafish Embryos, Fruit Fly Larvae and our Science Advisory Board
Written by Karen Thomas, TURI EHS Support Specialist
Regardless of how you feel about animals (mostly rodents) being used for industrial chemical health and safety testing, it is becoming a thing of the past. Following multiple decades of it being standard practice, the Environmental Protection Agency (EPA) recently pledged to eliminate all mammalian testing by 2035. The methods to fill this knowledge gap have been improving for decades and somewhere along the way they became known as “new approach methods” (NAMs). NAMs are a combination of: computational modeling, termed “in silico,” to mathematically predict toxicity; “in vitro” testing on human, animal and bacterial cells; and “in vivo” testing on non-mammalian model organisms such as on zebrafish larvae.
“In silico” methods often use the concept of grouping chemicals, such as those with similar chemical structures, to indicate potentially similar toxicological outcomes or biological behaviors of all group members based on known outcomes of one group member. Performed on a microscale level, “in vitro” testing exposes multiple concentrations of a chemical to cells and an outcome (e.g., cell damage, mutation, etc.) is measured. Also on the microscale level but looking at whole-organism changes (e.g., skeletal abnormalities, lethargy, organ weight), “in vivo” testing can be performed on many organisms like fruit flies or roundworms.
The results of animal testing were never perfect for many reasons including: animal results do not translate perfectly to humans; testing doses are typically higher than would normally be encountered; and it’s difficult to simulate the chronic outcomes like cancer that develop over a long time. In addition, animal testing is resource intensive in animals, cost, and time. However, scientists and regulators depended on the results because they trusted the standards and established methods such that comparison of relative hazards between chemicals was possible.
At this time, the most developed NAMs endpoints are skin (sensitization and irritation), eye (damage and irritation) and cell mutation (as a possible precursor to cancer). These are being followed by more complex endpoints such as endocrine disruption and developmental toxicity which are in more nascent stages. In addition to these methods not being fully developed, they also do not paint a complete picture of the potential hazards associated with a chemical. They don’t adequately capture repeat and long-term exposure outcomes, complex physiological contributions, safety (e.g., reactivity, flammability) and environmental (e.g., persistence) hazards to name a few.
In this landscape of evolving toxicological methods, the highly accomplished, devoted (and volunteer!) members of our Toxics Use Reduction Science Advisory Board are hard at work applying multi-disciplinary, consensus decision-making approaches to the complex relative hazard questions of today’s industrial chemicals. Their contributions to understanding how to use the available toxicological information at this pivotal time is very important to our program and much appreciated. Bravo and thank you Board members!
For more information:
Trump EPA Takes New Action to Eliminate Animal Testing – goal of eliminating all mammalian testing by 2035. https://www.epa.gov/newsreleases/trump-epa-takes-new-action-eliminate-animal-testing
Barbara L.F. Kaplan, Alan Hoberman, Simone H. Stahl, George E.N. Kass, William Slikker, Identifying the gaps and opportunities for NAMs application in regulatory toxicology, Current Opinion in Toxicology, Volume 47, 2026,100591, ISSN 2468-2020. https://doi.org/10.1016/j.cotox.2026.100591
