People who are exposed to pesticides through their work may face a significantly higher risk of developing amyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND), according to a new review of international research.
The study, published in the journal Occupational & Environmental Medicine, analysed evidence from eight case-control studies involving 1,734 people with ALS. Researchers found that workers who had ever been occupationally exposed to pesticides were around 60% more likely to develop the disease than those who had not.
ALS is a progressive neurological condition that damages the nerve cells controlling voluntary muscle movement. It has no cure, and while some genetic causes have been identified, many cases are thought to result from a combination of genetic and environmental factors.
The researchers reviewed studies published between 1990 and 2025, assessing the quality of the evidence before combining the results in a meta-analysis. Overall, occupational exposure to pesticides was associated with a 1.6-fold increase in ALS risk.
The findings suggest the level and type of exposure may also matter. Workers exposed to high levels of pesticides had almost three times the risk of developing ALS compared with those who had never been exposed. Herbicides were linked to the greatest increase in risk, although insecticides and fungicides were also associated with elevated risks.
The authors caution that the evidence remains limited, with only a small number of studies meeting the criteria for inclusion. They also found differences in how exposure was measured, with studies relying on workers’ own recollections tending to report stronger associations than those using job records or expert assessments.
Despite these limitations, the researchers say the review strengthens the evidence that occupational pesticide exposure could be an important risk factor for ALS.
They conclude that more high-quality studies are needed to identify which specific pesticides or chemical groups pose the greatest risk and to better understand how exposure contributes to the development of the disease.
The findings also highlight the importance of measures to reduce pesticide exposure in workplaces, particularly in sectors such as agriculture, horticulture and grounds maintenance, where regular contact with these chemicals is common. The researchers say improving exposure monitoring and strengthening workplace protections could help reduce the risk while further research continues.
The full research can be read here.
Photo: Igor Omilaev
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