People who come into regular contact with pesticides at work - such as farmers and pesticide sprayers - appear to have a slightly higher risk of developing Parkinson’s disease, according to new study findings released Monday.

However, the study is relatively small, and the possibility that the relationship between past exposure to pesticides and Parkinson’s could be due to chance cannot be ruled out, lead author Dr. Jordan A. Firestone of the University of Washington in Seattle told AMN Health.

Nevertheless, “I think there very likely may be” an increased risk of developing Parkinson’s after heavy exposure to toxic pesticides, Firestone noted.

Previous laboratory research has shown that certain pesticides can damage the brain. People who ingest large doses of pesticides can develop symptoms such as seizures, confusion, or coma, Firestone explained.

However, it’s less clear what effects chronic, low-level exposures - perhaps through daily contact - can have on the brain, he added. “Lower levels of many exposures ... whether those accumulate to cause problems, that’s not so clear,” Firestone said.

To investigate, he and his colleagues asked 250 men and women with Parkinson’s disease and 388 people without to recall their lifetime exposure to pesticides.

They found that pesticide workers who applied the chemicals had approximately twice the risk of developing the disease. Animal and crop farmers also had a slightly higher risk of being diagnosed, the researchers note.

Exposure to pesticides at home did not appear to influence the risk of Parkinson’s, although lifelong drinking of well water did, Firestone and his team report in the Archives of Neurology.

In an interview, Firestone explained that farm workers typically have higher exposures to pesticides than people who eat fruits and vegetables because they come in direct contact with produce sooner after spraying, and handle the produce before it is washed and prepared.

However, he noted that there may still be “a possible risk” of Parkinson’s from eating produce sprayed with pesticides, and the risk will be higher or lower for people with different genetic susceptibilities.

“By definition,” organic foods are supposed to contain fewer - if any - pesticides, Firestone added, but noted that early research shows that people who opt for organic foods still have some pesticides in their bodies.

Biologically, some pesticides may affect the brain by disrupting a system that is important for normal brain function, and one that is also disrupted in people with Parkinson’s, Firestone noted. The chemicals may also cause harm by affecting energy production within brain cells, he added.

Firestone noted that another study is currently looking at Parkinson’s risk among thousands of former pesticide sprayers, and may offer more clues about the risk from these chemicals.

SOURCE: Archives of Neurology, January 2005.