Pesticide exposure on the job could sharply increase the risk of ALS, with men and heavily exposed workers facing the greatest danger.
Regular contact with pesticides may carry risks that do not become apparent until years later. A new review suggests that people exposed to these chemicals at work face a substantially greater likelihood of developing amyotrophic lateral sclerosis, or ALS, a rare disease that gradually destroys the nerve cells needed for movement.
The analysis linked occupational pesticide exposure with a 60% to 70% higher risk of ALS. The association was especially pronounced among men, who appeared twice as likely to develop the disease if they had encountered pesticides on the job.
ALS is the most common form of motor neuron disease. It damages the specialized nerve cells that control voluntary muscles, eventually affecting a person’s ability to walk, speak, swallow, and breathe. The condition progresses rapidly, is usually fatal, and currently has no cure.
Although ALS remains uncommon, its incidence has risen in recent years, making the search for preventable environmental and workplace risk factors increasingly important.
How Pesticides May Affect ALS Risk
Pesticides have long been known to cause immediate toxic effects on the nervous system, particularly after substantial insecticide exposure. Their possible consequences decades later, however, are much harder to investigate. Researchers must often reconstruct a person’s past exposure from job histories, questionnaires, or memories rather than direct measurements.
To evaluate the evidence more systematically, researchers searched eight scientific databases for observational studies published between 1990 and 2025. They also considered peer-reviewed theses and scientific reports.
From 767 screened articles, they selected eight case-control studies involving 1,734 people with ALS. Three additional studies included 457 people diagnosed with an unspecified motor neuron disease.
When the results of six studies were combined, people with any occupational pesticide exposure had a 60% higher risk of ALS than those with no reported exposure.
Exposure Level, Pesticide Type, and Sex
The amount of exposure also appeared to matter. Based on three studies, workers with high exposure levels faced nearly three times the risk of those who had not been exposed. Even lower exposure was associated with approximately double the risk.
The pattern remained when researchers examined different types of pesticides. Herbicide exposure was linked to a 70% increase in risk, while insecticides and fungicides were each associated with a 60% increase.
A notable sex difference emerged from the available data. In three studies that analyzed men and women separately, exposed men had twice the risk recorded among unexposed men. The review found no corresponding increase among women.
Study Limits and Workplace Implications
The relatively small number of eligible studies adds uncertainty. Better research would require more detailed employment records, improved exposure measurements, carefully chosen comparison groups, and stronger adjustment for other possible ALS risk factors.
“To strengthen the evidence on risk factors for ALS, primary studies particularly need methodological improvements on exposure assessment, on the selection of reference groups, and on adjustment for potential confounders, including analysis for interactions between risk factors,” the researchers emphasize.
“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,” the researchers conclude.
Reference: “Occupational exposure to pesticides increases the risk of amyotrophic lateral sclerosis: a systematic review and meta-analysis” by France Labrèche, Pamela Prud’homme, Maryse Gagnon, Nicolas Dupré and Sabrina Gravel, 4 August 2026, Occupational and Environmental Medicine.
DOI: 10.1136/oemed-2025-110662
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