In a new study done in France, researchers discovered that farmers that put weedkillers on their fields were over two times as likely to have depression than farmers that did not use these chemicals.
While it is not clear whether the weedkilling chemicals are the cause of the depression or not, Marc Weisskopf, lead author of the study, and associate professor with the Harvard School of Public Health, says that the results suggest that herbicides should not be ignored just because they target plants.
According to Weisskopf, earlier research has linked depression to pesticides, especially organophosphates, which have been shown to be toxic for nerve cells. The insecticide that caused 23 school aged fatalities in India in July, called Monocrotophos, is an organophosphate.
Pesticide use has also been known to cause Parkinson’s disease in farmers.
For the study on Parkinson’s disease, Weisskopf, as well as his colleagues worked to determine the depression risks when exposed to any type of pesticides by providing a survey to 567 French farmers regarding their practices of using insecticides, herbicides and fungicides.
The researchers also went to the homes of the farmers so they could get a detailed description of the amount of chemicals the farmers were exposed to. They went so far as to examine pesticide purchase bills, and looking through the calendars of the farmers. They even inspected old containers of pesticides.
Then, the researchers asked farmers if they had ever had to be treated for depression.
According to Weisskpf and his colleagues, in a report published in the American Journal of Epidemiology, said that 83 farmers, or about 15 percent, reported that they had at some time taken medication for their depression. Out of the 83, 47 reported that they had never added pesticides to their fields, but 36 of them had.
In the farmers that did not have Parkinson’s disease, 37 of those that had never added herbicides to their fields, and 20 of those that had added chemicals to their fields said that they had gotten depression treatment.
When the researchers accounted for other factors, including cigarette smoking and depression, they found that the farmers that used weedkillers were still two and a half times more likely to experience depression. Also, the farmers that had more exposure, either for longer years or hours to herbicides, also experienced a higher chance of experiencing depression than the farmers that used herbicides less often.
While this study does not apply to the average home gardener, it is still important that people seriously consider the potential risks of using weedkillers in any situation.