Chronic low-dose exposure to chlorpyrifos reduces life span in a wild fish by accelerating aging.

Low concentrations of chemicals are widespread in the environment, but exploration of the effects of their chronic exposures on animal life span in the wild is limited. Field investigations showed that fish populations of lake skygazer (Culter dabryi) with chronic low-dose chlorpyrifos loads had shortened telomeres and truncated age structures. Laboratory experiments confirmed that chronic low-dose chlorpyrifos exposure induced telomere degradation and reduced survival in a dose- and physiological age–dependent manner, whereas acute high-dose exposure did not. Together, these studies provide evidence that chronic low-level chlorpyrifos exposure reduces life span and population viability in a wild fish by accelerating physiological aging. Given the pervasive presence of low pesticide concentrations in the environment and the conserved mechanisms of aging across vertebrates, these findings raise concerns that even low doses of pesticides may pose long-term risks to longevity. Editor's summary: Most studies of the negative effects of pesticides focus on acute lethality, but we are increasingly recognizing that chronic, low-dose exposure has pernicious effects. Huang et al. studied the effects of low but chronic exposure to the pesticide chlorpyrifos on the lake skygazer, a predatory fish common in lake ecosystems in China. They found that in lakes with persistent low-dose exposure, these fish had shorter telomeres, and the population was made up of mostly younger fish. Experiments in the lab confirmed that exposing fish to low doses of the pesticide shortened telomeres. —Sacha Vignieri [ABSTRACT FROM AUTHOR]