Pesticides may drastically shorten fish lifespans, study finds | Fish

The lifespan of fish appears to be significantly reduced by pesticides, a study suggests.

Even low levels of common agricultural pesticides can delay the long-term lifespan of fish, according to a study led by Jason Rohr, a biologist at the University of Notre Dame in Indiana.

According to the study published in Science, signs of aging accelerate when fish are exposed to chemicals, which could have implications for other organisms.

Chemical safety regulations tend to focus on short-term exposure to high doses of pesticides and other chemicals, but the study focused on long-term exposure. Low doses of pesticides are widely distributed in the environment, so their effects need to be studied and understood, the authors say.

Researcher Kai Huang, who also worked on the study, combined field observations of more than 20,000 observer fish from Chinese lakes with persistent low levels of chlorpyrifos, a common pesticide.

The research found that fish from pesticide-affected lakes had shortened telomeres, the caps at the ends of chromosomes known as the biological clock of aging.

When they shorten, it is a sign of cellular aging and a decline in the body’s regenerative capacity.

The lake’s populations were made up of younger fish, indicating that pesticides helped shorten lives. Laboratory experiments confirmed these results and showed that chronic exposure to low doses reduced fish survival and degraded telomeres. These effects were not observed during acute exposure to high doses.

“Given the conserved mechanisms of telomere biology in vertebrates, chronic low-dose exposure to these chemicals may present similar aging-related risks in humans, potentially contributing to age-associated diseases,” the researchers write.

Rohr said: “When we looked at telomere length and lipofuscin deposition in fish livers – well-established biological markers of aging – we found that fish of the same chronological age aged more quickly in contaminated lakes than in clean lakes.

Chemical analysis showed that chlorpyrifos, banned in the United Kingdom and the European Union but used in the United States and China, was the only compound found in fish tissues that was consistently associated with signs of aging. These included shortened telomeres and lipofuscin deposits – a buildup of insoluble proteins often described as cellular “waste.”

The worrying effects of aging occurred at concentrations below current U.S. freshwater safety standards, Rohr said, suggesting that the effects of chemicals and pesticides could occur at low levels over the long term.

He said: “Our results challenge the assumption that chemicals are safe if they do not cause immediate harm. Low-level exposures can silently accumulate damage over time by accelerating biological aging, highlighting that chemical safety assessments must go beyond short-term toxicity testing to adequately protect the environment and human health.”

Although short-term exposure to high doses did not appear to be causing these aging problems – although it did cause high toxicity and fish deaths – the researchers concluded that it was long-term exposure to low doses that was causing these changes.

The scientists added that reduced lifespans were particularly problematic because older fish often contribute disproportionately to reproduction, genetic diversity and population stability.