A 2026 study by researchers from China and the US has linked chronic low-dose chlorpyrifos exposure to accelerated telomere shortening and aging in wild lake fish.

Background

Chlorpyrifos is an organophosphorus insecticide, which is in use for decades in agriculture worldwide. While European countries, China, the US and some others have restricted the use, it is still applied in many other parts of the world. A study that appeared in Science on 16.1.2026 has now linked low dose exposure to chlorpyrifos with telomere length in a fish species (lake sky gazer, Culter dabryi) and aging.

What was done

The scientists from China and the US measured the levels of several pesticides in livers of the fish over many years and were able to link the liver pesticide levels in three lakes in China differing in their pesticide pollution with telomere length in the fish. Telomeres are important in the coding of DNA and shorten throughout the lifetime of a species. This study now showed an accelerated telomere shorting in response to chronic low dose chemical exposure. From their field results they gained some evidence that the insecticide chlorpyrifos was the likely candidate for the effects.

Laboratory confirmation

To proof their hypothesis, they subsequently tested low chlorpyrifos concentrations (10 and 50 ng/L) in the lab and found that exactly the same effects on chromosomal telomere length as documented in the field appeared in the lab. This elegant combination of field and lab approaches is rare in ecotoxicology, but adds a striking and very convincing case to the debate of low-dose chronic pesticide effects on relevant endpoints in wildlife. 

Relevance to Chlorpyrifos research at Landau

This new work nicely links in with studies conducted in Landau in different ways: We have shown some years ago (Stehle et al. 2018), the low chlorpyrifos exposure this used indeed is below the 20th percentile of chlorpyrifos concentrations measured in surface waters worldwide. In other words, it is likely that the results in the new study are indeed relevant in at least 80% of surface global waters in which chlorpyrifos is detected.

Chronic Chlorpyrifos occurrences

The importance of chronic occurrence of chlorpyrifos was shown in another study from Landau (Herrmann et al. 2023) which analysed large scale pesticide data from Europe for the longer-term re-occurrence of these contaminants in the environment. Chlorpyrifos was one of the pesticides in this large dataset which most consistently occurred chronically in surface waters. 

Have a look at the new study in Science and enjoy reading it! 

Reference to the study:

Huang, K., Zhang, Z., Han, G., Kong, R., Qin, H., Zhang, H., Letcher, R.J., Qiu, W., Liu, C., Shi, J., Rohr, J.R. (2026): Chronic low-dose exposure to chlorpyrifos reduces life span in a wild fish by accelerating aging. Science, https: doi.org/10.1126/science.ady4727

Other cited studies:

Herrmann, L.Z., Bub, S., Wolfram, J., Stehle, S., Petschick, L.L., Schulz, R. (2023) Large monitoring datasets reveal high probabilities for intermittent occurrences of pesticides in European running waters. Environmental Sciences Europe 35, 90, https://doi.org/10.1186/s12302-023-00795-4.

Stehle, S., Bub, S., Schulz, R. (2018) Compilation and analysis of global surface water concentrations for individual insecticide compounds. Science of the Total Environment 639, 516-625, https://doi.org/10.1016/j.scitotenv.2018.05.158.

Article by: Prof. Dr. Ralf Schulz