Research: Low-Dose Pesticides Cut Wild Fish Lifespan

Even at amounts considered safe under regulatory frameworks, chronic exposure to the pesticide chlorpyrifos accelerates physiological aging and shortens the life spans of wild fish, according to a new study based in China. The findings raise concerns about the long-term impacts of low-level environmental pesticide contamination. Traditionally, to define risk, chemical safety regulations have relied on the acute dangers of short-term exposure to high doses. While this method captures immediate toxicity, it assumes that exposure to much lower concentrations is more or less harmless. However, low concentrations of chemical pollutants, like pesticides, are widespread in the environment, and the effects of chronic low-dose exposure on animal life span in the wild are poorly understood. To assess how low-level pesticide exposure affects wild fish, Kai Huang combined field observations of 24,388 lake stargazer fish (Culter Dabryi) from lakes in China with persistent low levels of the common pesticide chlorpyrifos, with laboratory experiments involving exposing fish to controlled doses of this chemical over time. Huang et al. found that fish from pesticide-impacted lakes showed shortened telomeres; they also exhibited truncated population structures, dominated by younger individuals, suggesting that chronic, low-dose chlorpyrifos exposure is associated with accelerated physiological aging and shortened life spans. These findings were confirmed in laboratory experiments that revealed chronic low-dose exposure reduced fish survival and degraded telomeres in a dose- and physiological age-dependent manner – effects which were not seen with acute high-dose exposure. "Given the conserved mechanisms of telomere biology across vertebrates, chronic low-dose exposure to these chemicals may pose similar aging-related risks in humans, potentially contributing to age-associated diseases," Huang et al. write.