Researchers report in Science that long-term exposure to low concentrations of a common agricultural insecticide can accelerate physiological ageing and shorten lifespan in fish. The study, led by University of Notre Dame biologist Jason Rohr, began with field surveys in China that sampled thousands of fish over several years. Populations from contaminated lakes lacked older individuals, while lakes with little contamination contained many older fish; the team interpreted this pattern as earlier death rather than reduced reproduction.
Chemical analyses of tissues showed chlorpyrifos was the only compound consistently linked to biological markers of ageing. The researchers documented shortened telomeres—protective chromosome ends that shorten with age—and increased lipofuscin deposition, a build-up of old proteins and metals in long-lived cells, especially in the liver. To test causation, the team ran controlled laboratory experiments using chlorpyrifos concentrations similar to those measured in the wild. Chronic low-dose exposure caused progressive telomere shortening, greater cellular ageing and reduced survival, with the strongest effects in fish from already contaminated lakes. By contrast, short-term exposure to much higher doses produced rapid toxicity and death but did not accelerate telomere loss or lipofuscin accumulation, indicating that long-term accumulation of low concentrations drove the observed ageing.
Loss of older individuals can undermine reproduction, genetic diversity and population stability in aquatic ecosystems. The authors note that telomere biology and ageing mechanisms are highly conserved across vertebrates, including humans, so the findings carry broader concern. Chlorpyrifos is largely banned in the European Union but remains in use in China, parts of the United States and many other countries, and the observed ageing effects occurred at concentrations below current US freshwater safety standards.
- Funding: National Science Foundations (US and China)
- Additional support: Illinois-Indiana Sea Grant
- Additional support: Frontiers Research Foundation
Difficult words
- accelerate — make a process happen faster over time
- physiological — relating to normal functions of organisms
- telomere — protective end of a chromosometelomeres
- lipofuscin — cellular waste made of old proteins and metals
- chlorpyrifos — an insecticide used in agriculture
- chronic — lasting a long time or recurring often
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How might the finding that ageing effects occur below current US freshwater safety standards influence environmental policy or regulation?
- What ecological consequences could follow from the loss of older individuals in fish populations? Give examples.
- The authors note ageing mechanisms are conserved across vertebrates. What further research would you propose to assess possible risks to humans?
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