A recent study on fish development published in the Journal of Hazardous Materials found that the chemicals in microplastics are more toxic than the physical particles themselves, and that exposure to both together is even worse. The study analyzed the effects of microplastics from particles that wear off of tires and are washed into waters where fish breed.
In short:
- Atlantic cod eggs were exposed to tire wear microplastics and the chemicals that leach from these particles, both separately and in combination.
- The chemical leachates alone and in combination with the particles decreased hatching success and survival, and affected larvae development.
- The chemicals were the primary driver of car tire rubber toxicity.
Key quote:
“The observed …. alterations in Atlantic cod larvae suggest potential long-term implications for fish populations exposed to tire wear particles and their associated chemicals, which could influence ecosystem dynamics and services.”
Why this matters:
While numerous studies have identified harmful effects of microplastics, it is still unclear what’s primarily responsible for those impacts: the physical particles or the chemicals that leach out of them. This study shows that the chemicals are most responsible for the harmful effects on fish development, although the particles themselves also enhance the toxicity of these chemicals. This research has implications for not only fish health, but also for microplastic research at large.
Related EHN coverage:
- Weathering and size influence the health effects of microplastics
- Car tire chemicals are killing salmon and steelhead
- Record levels of harmful particles found in Great Lakes fish
More resources
- University of California San Francisco: I’m a Microplastics Researcher. Here’s How To Limit Their Dangers
- EPA: Where the Rubber Meets the Road: Opportunities to Address Tire Wear Particles In Waterways
Piarulli, Stefania et al. for Journal of Hazardous Materials Aug. 15, 2025
