Farmers who use herbicides are almost two-and-a-half times more likely to seek treatment for depression compared to farmers who do not use herbicides, according to a new study published in the American Journal of Epidemiology.

Furthermore, the greater the length of time that a farmer is exposed to herbicides, the stronger the risk for depression. These findings raise more concerns regarding the damage that farming chemicals can inflict on mental health.

For the study, researchers surveyed 567 farmers from France, questioning them on the frequency of their use of fungicides, insecticides, and herbicides, to determine how pesticide exposures were linked to the risk of developing clinical depression.

Lead researchers and associate professor at the Harvard School of Public Health, Marc Weisskopf, Ph.D., said while the results are unclear, they “suggest we should not be ignoring herbicides just because they’re targeting plants.”

Earlier studies have already shown that pesticides, particularly organophosphates, cause a variety of serious neurological health problems, including Parkinson’s disease.

For the new study, researchers conducted interviews, surveyed old pesticide containers, and even examined records for pesticide purchases. They also questioned whether farmers had ever been treated for depression.

The findings revealed that among 567 farmers, 83 self-reported treatment or hospitalization for depression — nearly 15 percent. After adjusting for age and health factors, the researchers found that farmers who use herbicides were more than twice as likely to have been treated for depression.

Also, those farmers who were exposed to herbicides for a longer period of time — either more hours of exposure or for a greater number of years — were more likely to be treated for depression than those with less exposure.

Interestingly, the study found no connection between depression and farmers who had used fungicides or insecticides compared to those who had not. Weisskopf suggested that this may be because farmers are more aware of the harm fungicides and insecticides have on human health.

“If (herbicides) are considered in general safer and people take less precautions because people think they’re not as bad, then that poses a problem,” he said.

Although the research shows a strong link between herbicides and mental health, it does not definitively prove cause and effect. Researchers accounted for age and cigarette smoking in their correlation; however, there may be still be other unknown health conditions or external circumstances that affected work conditions or made the farmers more susceptible to depression.

“This still has to be considered a relatively first, small study. There’s more work to do, but it raises concerns that need to be looked into more fully,” said Weisskopf.

Sources: American Journal of Epidemiology



Barrels of herbicide sitting in a field photo by shutterstock.

Herbicides Linked to Depression in Farmers