More Pesticide/Parkinson's Links

More Pesticide/Parkinson's Links

Exposure to a combination of two commonly used agricultural pesticides has been shown to cause brain damage in mice.

According to a recent study, exposure to a mixture of the herbicide paraquat and the fungicide maneb caused extensive damage to brain cells known as dopamine neurons.

The damage to dopamine neurons in the mice is identical to that found in people suffering from Parkinson's disease, a degenerative brain disorder affecting 1.5 million people in the United States.

Paraquat is used on corn, soybeans, cotton and other crops. Maneb is applied to potatoes, tomatoes, lettuce and corn. Both pesticides are used by farmers on millions of acres in the United States.

A team of researchers from the University of Rochester School of Medicine and Dentistry injected mice twice weekly over a period of six weeks with a mixture of paraquat and maneb.

The mice showed immediate reductions in motor activity. Further examination showed selective, irreversible damage to the neurochemical system, specifically the area of the brain known as the migrostriatal system.

According to the study's principle author Deborah Cory-Slechta, Ph.D., the mice in the study appeared to represent an early stage in the disease.

Several previous epidemiological studies have shown a link between pesticides and Parkinson's. These studies have shown that farmers, people who live in rural areas and people who drink well water are more likely to have the disease than people who do not.

A comparison of regions where maneb and paraquat are commonly used revealed that people are more likely to die of Parkinson's disease in these areas.

A recent study by the National Parkinson Foundation found that the states of Iowa, Minnesota, Nebraska and the Dakotas had rates (that were nearly twice the national average) of one Parkinson's case per 250 residents.

Another study by Stanford University neuroepi-demiologist Dr. Lorene Nelson showed that people exposed to in-home insecticides are 70% more likely to develop Parkinson's disease and that exposure to garden insecticides assumes
a 50% increase in likelihood for developing the disease.

While most scientists agree that exposures to these pesticides do not cause Parkinson's on their own, there is agreement that a combination of genetic susceptibility and environmental agents may be involved in the disease.

The study's findings corroborate this notion as well as show that exposures to combinations of chemicals have different health implications than exposures to individual chemicals.

Source: Pesticides and You, Volume 20(4) 2000-2001. Reprinted from the Global Pesticide Campaigner, a publication of Pesticide Action Network North America