September 05, 2002

NEW YORK (Reuters Health) - Farm workers poisoned by industrial strength agricultural pesticides containing organophosphates face a nearly sixfold increased risk of suffering depression in the months following their exposure, new study findings show.

Organophosphates are extremely toxic and easily absorbed into the bloodstream through the skin, nose, eyes, gut and lungs. Immediately after being poisoned, a person may experience vomiting, abdominal pain, fatigue, headaches and blurred vision, among other symptoms.

There have also been reports of organophosphate poisoning leading to neurological problems such as anxiety, depression, irritability and restlessness, according to study authors Dr. Lorann Stallones and Cheryl Beseler of Colorado State University in Fort Collins.

"In some states, farmers have been reported to have higher rates of depression than other population groups," the authors write in the August issue of the Annals of Epidemiology. However, "little work has been done to describe the effects of exposure to organophosphate compounds and depressive symptoms among the farming population."

To investigate the relationship, the two researchers interviewed 761 farm residents, operators and their spouses living in Colorado between 1992 and 1997. All participants completed interviews assessing various aspects of their physical and mental health, as well as their organophosphate exposure.

Sixty-nine study participants reported having been sickened by pesticide poisoning, the report indicates.

After accounting for other known depression risk factors such as age, marital status, education level and alcohol use, farmers who reported organophosphate poisoning were 5.8 times more likely to score high on tests measuring level of depression than farmers who did not report having been poisoned, the authors found.

"The findings reported here provide further support for evidence of an association between mental health and pesticide poisoning," Stallones and Beseler write.

But further research is needed to establish a causal link, they conclude.

SOURCE: Annals of Epidemiology 2002;12:389-394.