Exposure To Pesticides Increases Risk Of Developing Parkinson's Disease
May 28, 2013

Exposure To Pesticides Increases Risk Of Developing Parkinson’s Disease

Brett Smith for redOrbit.com - Your Universe Online

In what might be considered cause for concern among farm workers — a new research review in the journal Neurology has found a link between Parkinson´s disease and exposure to chemical weed or bug killers.

The review included over 100 studies from around the world and calculated between a 33 to 80 percent increased risk of developing the disorder as exposure to certain weed or bug killers increased. Prolonged exposure to the weed killer paraquat or the fungicides maneb and mancozeb doubled the risk of contracting the disease.

"Due to this association, there was also a link between farming or country living and developing Parkinson's in some of the studies," said co-author Dr. Emanuele Cereda, with the IRCCS University Hospital San Matteo Foundation in Pavia, Italy.

For the review, Cereda and his colleague Dr. Gianni Pezzoli, with the Parkinson Institute — Istituti Clinici di Perfezionamento (ICP), Milan, examined studies from around the world that looked at human exposure to insecticides, weed killers, fungicides, dichlorodiphenyltrichloroethane (DDT) and other chemicals used in agriculture. The pair of researchers focused on the length of time that individuals were exposed to chemicals and the subjects´ proximity to agriculture.

The team was able to make a direct correlation between the duration of exposure to these chemicals and the risk for developing Parkinson´s disease. They also found a one-third higher risk for those directly working in agricultural jobs.

"We didn't study whether the type of exposure, such as whether the compound was inhaled or absorbed through the skin and the method of application, such as spraying or mixing, affected Parkinson's risk," Cereda said. "However, our study suggests that the risk increases in a dose response manner as the length of exposure to these chemicals increases."

"I think the study is actually a big advance in our research knowledge of the relation between chemical exposures and the basic neurological injuries," Dr. Arch Carson, associate professor at the University of Texas School of Public Health (UT-SPH) in Houston, told Medpage Today. "This report is the first to show that there is a positive relationship between not only insecticides and herbicides but also some other solvent chemicals to which many people are exposed and the development of Parkinson's syndrome."

Although the review found a relationship between many agricultural chemicals and risk for Parkinson´s, the scientists weren´t able to establish that relationship for DDT, which has been banned in the United States for decades.

Parkinson's disease is a neurodegenerative disorder that results from a significant loss of dopamine-producing brain cells. Because dopamine affects motor skills and other functions, people lose control of their movements leading to trembling, balance issues, and rigidity. Those with Parkinson´s may also experience vivid dreams due to sleep disorder, an altered sense of smell, constipation, and depression.

In the US alone, 50,000 to 60,000 new cases of Parkinson's are diagnosed each year, according to the National Parkinson Foundation — making it the 14th leading cause of death in the country. The disease can be managed, but is currently incurable.