Chronic low-dose exposure to chlorpyrifos reduces lifespan in a wild fish by accelerating aging

Low-concentration chemicals are widespread in the environment, but exploration of the effects of their chronic exposures on animal lifespan in the wild is limited. Field investigations showed that fish populations of 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 lifespan and population viability in a wild fish by accelerating physiological aging. Given the pervasive nature of low concentrations of pesticides in the environment and the conserved mechanisms of aging across vertebrates, these findings raise concerns about the potential long-term risks to longevity of pesticides, even at low doses.

Methods
This repository contains the code and data to run the analyses from K Huang et al., “Chronic low-dose exposure to chlorpyrifos reduces lifespan in a wild fish by accelerating aging”.  We performed a four-year field survey in three adjacent lakes with different levels of pesticide burdens, namely Niushan Lake (NSL, reference lake), West Liangzi Lake (WLL), and East Liangzi Lake (ELL), to characterize the aging phenotypes (e.g., telomere degradation, lipofuscin deposition, reduced lifespan, and truncated age structures) of C. dabryi populations. We further measured the concentrations of 96 pesticides in these fish, investigated the associations between pesticide contamination and fish aging, and identified the main causal agent. Laboratory chronic exposure experiments were conducted to confirm the chronic aging effects of pesticides observed in the field, and the possible acute exposure was ruled out.