Workplace pesticide exposure linked to 60% higher ALS risk

Clinical takeaway: Ask about occupational pesticide use when reviewing a patient’s exposure history, and counsel exposed workers on practical strategies and programs to help reduce contact.

Workplace pesticide exposure can involve absorption of high doses of active ingredients and additives over short periods, mainly through inhalation and skin contact. The acute neurotoxic effects of pesticides, particularly insecticides, have been recognized for decades, but the long-term effects of chronic exposure on the nervous system remain less certain.

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal disease of central and peripheral motor neurons, and occupational pesticide exposure has been investigated as a possible risk factor since 1980, with prior reviews reaching inconsistent conclusions. To clarify the association, investigators pooled eight case-control studies involving 1,734 ALS cases published from 1990 through 2025.

Any workplace pesticide exposure was associated with about 60% higher ALS risk than no exposure across six studies. Herbicide exposure was linked to 71% higher risk and insecticide exposure to 57% higher risk; the fungicide estimate was similar but not statistically significant. Across three studies, high exposure was associated with a 2.68-fold risk and low exposure with a 1.94-fold risk, although the difference between those estimates was not statistically significant. Exposed men had roughly twice the risk of unexposed men, while no increase was evident among women.

Investigators searched eight databases for observational studies comparing ALS risk in workers with and without pesticide exposure. They favored adjusted estimates, excluded estimates based on fewer than five exposed cases or controls, assessed study quality, and pooled comparable findings while accounting for differences among studies.

Future studies need more precise, individual-level exposure assessment that distinguishes specific pesticides and captures exposure intensity, along with better-selected unexposed groups and fuller adjustment for other ALS risk factors. The review also supports implementing and evaluating workplace interventions that measurably reduce pesticide exposure.

“The findings of this review add to the evidence that occupational exposure to pesticides may increase the risk of ALS and should encourage the implementation of interventions aimed at reducing exposure during occupational pesticide use,” conclude the authors.

Source: Labrèche, et al (2026 Aug 4). Occup Environ Med. Occupational exposure to pesticides increases the risk of amyotrophic lateral sclerosis: a systematic review and meta-analysis