Even small doses of pesticides shorten fish lifespans

Modern agriculture uses pesticides to protect crops from pests and minimize economic losses. Compounds lethal to insects enter watercourses and there – quietly – continue killing. Scientists from the University of Notre Dame have shown that a once widely used pesticide, even in small amounts, causes aging and death in fish.

Chronic poisoning as a cause of premature aging

The study, the results of which were published on 15 January this year in the journal Science, focused on analyzing the long-term effects of small doses of chlorpyrifos on populations of silver carp (Culter dabryi), a freshwater fish from the carp family. Unfortunately, most chemical regulations focus on the short-term effects of large doses of tested compounds – pesticides that appear safe are given the green light and enter widespread use.

A team of scientists led by biologist Jason Rohr from the University of Notre Dame in the United States decided to focus on something different – the chronic effects of small amounts of chlorpyrifos present in water on organisms. The research was conducted in China, where an interesting pattern was observed – in lakes with water contaminated by pesticides, older individuals were missing, although populations were not clearly smaller than elsewhere.

A detailed analysis of fish tissues showed that living in water containing chlorpyrifos leads to telomere shortening and changes in the way lipofuscin accumulates in the liver of fish. Both of these physiological factors are widely recognized markers of the aging process. Fish of the same chronological age age faster in contaminated lakes than in clean ones – commented Jason Rohr.

Chlorpyrifos – withdrawn and reinstated

CPS, or chlorpyrifos, is an organophosphate pesticide that for many years was used to control chewing and piercing-sucking pests in cereals, rapeseed, potatoes, vegetables and fruit trees – practically everywhere. Repeated reports of the toxic effects of higher doses on human health led to its gradual withdrawal from use. It was banned in the United Kingdom in 2016 and across the entire European Union in 2020.

The United States also introduced a ban on the use of CPS on food crops in 2021. However, the decision was opposed by more than 80 agricultural groups, which filed a lawsuit against the US Environmental Protection Agency (EPA). As a result, in 2023 chlorpyrifos was reinstated by a decision of the Court of Appeals. However, a necessary condition was added – the conduct of in-depth studies on its actual impact. Only selected states, including California and Oregon, maintained the ban on the use of CPS in food crops.

Pesticides still underestimated

The study by scientists from Notre Dame shows that low concentrations of pesticides in the environment are a persistent and underestimated threat to living organisms. Their conclusions can easily be extended to other groups of vertebrates dependent on aquatic environments. Unfortunately, as the example of the court battle in the United States shows, decisions on the approval and withdrawal of controversial insecticidal substances are often subject to particular pressures.

Meanwhile, the results of a study published in November 2025 by scientists representing the Center for Environmental and Sustainability Research suggest that high amounts of the already banned compound p,p’-DDT are still found in 31 percent of soil samples collected in Europe. This problem was particularly noticeable in Poland and Greece. Worryingly high were also the concentrations of permitted pesticides: boscalid (in 36 percent of samples) and epoxiconazole (32 percent). Both compounds, although relatively safe for humans, pose a serious threat to aquatic organisms and bees.

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Sources:

Kai Huang et al., Chronic low-dose exposure to chlorpyrifos reduces life span in a wild fish by accelerating aging. Science 391,275-279(2026).DOI:10.1126/science.ady4727

Carvalho R, Guedes P, Mateus EP et al. Soil contamination in Europe unveiled: A review of pesticides and metabolites to watch [version 1; peer review: 1 approved, 1 approved with reservations]. Open Res Europe 2025, 5:257 (https://doi.org/10.12688/openreseurope.20475.1)