Key takeaway: A systematic review published Aug. 4 in Occupational and Environmental Medicine found that occupational exposure to pesticides—particularly herbicides and insecticides—is associated with a 61%–71% higher risk of ALS. The increased risk was larger for workers with high exposure and appeared stronger in men; studies did not show a clear increase for women. The authors call for interventions to reduce workplace exposure and for better measurement of pesticide exposure in future research.
New Review Links Occupational Pesticide Exposure to Higher ALS Risk — Men at Greater Risk
Stock image of a physiotherapist assisting a patient with ALS.Credit: Getty
New research suggests that workers in certain occupations — especially farming, landscaping and pest control — may face an increased risk of developing amyotrophic lateral sclerosis (ALS) after repeated occupational exposure to pesticides.
What the review found
A systematic review led by Sabrina Gravel of the Robert‑Sauvé Research Institute on Occupational Health and Safety (Montreal), published Aug. 4 in Occupational and Environmental Medicine, pooled decades of observational studies and found that occupational exposure to pesticides, particularly herbicides and insecticides, was associated with a 61%–71% higher likelihood of an ALS diagnosis.
Workers with high levels of pesticide exposure had larger estimated risks than those with lower exposure. The review also found that exposed men faced about twice the ALS risk compared with unexposed men, while the studies included did not demonstrate a clear increased risk for women.
Who was studied and how
Gravel and colleagues searched eight bibliographic databases for publications from 1990 through 2025 and selected observational studies that estimated ALS risk after occupational pesticide exposure. Data sources included neurology clinics and patient association registries. Because the primary studies used heterogeneous and often limited exposure metrics, the review could not perform a more refined dose‑response analysis.
Context and limitations
ALS (Lou Gehrig’s disease) is a rare, progressive neurological disorder marked by muscle weakness, difficulty speaking or swallowing, and impaired mobility. There is currently no cure, and the causes are not fully understood. The authors noted limitations across the evidence base: inconsistent exposure measurement, variable study designs, and potential confounding factors previously linked to ALS risk, such as head injuries, electrocution and drinking well water.
"Our results add to the evidence suggesting that occupational exposure to pesticides may increase the risk of ALS," the authors wrote, urging strategies to reduce workplace exposure.
Independent perspective
Dr. Rachel Tan, a motor neurone disease specialist not involved in the review, told Australia’s ABC that evidence remains mixed and that further research is needed to identify which specific pesticide chemicals or exposure patterns might be responsible and whether longer or cumulative exposure increases risk.
Implications
The review recommends implementing interventions to lower occupational pesticide exposure where possible and calls for improved, standardized exposure metrics in primary studies to better define which agents and exposure levels may drive risk. Until more definitive evidence identifies specific chemicals or mechanisms, awareness and exposure reduction remain prudent precautions for higher‑risk occupations.
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