By Adam Marcus
HealthSCOUT Reporter

If you work in a rubber plant, paint for a living or otherwise expose yourself to hydrocarbon solvents, you may be upping your risk of Parkinson's disease, new research shows.

European scientists say their study of nearly 1,000 Italian patients with the nerve disorder found that those routinely exposed to solvents on the job developed Parkinson's disease sooner and more severely than those who weren't close to the hazardous chemicals.

A report on the finding appears in the latest issue of the journal Neurology.

"Hydrocarbons are implicated in the development of Parkinson's disease," says Dr. Jennifer Hartwig, who prepared the English version of the study.

While case reports have hinted at a link between hydrocarbons and Parkinson's, the latest work is the first on a large scale to suggest the connection.

However, Hartwig notes, the scientists had to rely on what the patients themselves said in order to assess their exposure to the chemicals -- a potentially significant pitfall of the study, since memories fade and actual exposures may differ from perception.

Led by Dr. Gianni Pezzoli of the Parkinson Institute in Milan, Italy, the researchers compared age of onset and severity of symptoms in 990 men and women with the degenerative nerve disorder, 188, or roughly 20 percent, of whom reported a history of on-the-job exposure to hydrocarbon solvents.

People who worked with solvents -- an average of 10 hours a week for 10 years -- developed symptoms of Parkinson's three years earlier, on average, than people not exposed to the chemicals, at age 55 vs. 58. Their symptoms were generally worse than their unexposed peers.

Nine careers accounted for more than 90 percent of the solvent exposure. Plastic, petroleum and rubber workers had the most contact with hydrocarbons, and painters, mechanics and lithographers also worked frequently with the chemicals.

Dr. Robert G. Feldman, a neurologist at Boston University who is familiar with the research, calls it an "interesting observation" but one that needs more proof. "To say that this particular study conclusively indicates a causal relationship between exposure to hydrocarbons and Parkinson's is premature," he says.

A more definitive study would compare rates of Parkinson's disease in a large group of people exposed to solvents. And it would look not just at two clinics in single city, as the Italian research did, but across a much larger region.

Even so, he says, evidence suggests that the nerve ailment, which affects as many as 1 million Americans, may be tied to environmental risk factors such as hydrocarbons, pesticides and other poisonous chemicals. Although scientists haven't found genes for inherited forms of the disease, it's possible that people may carry so-called susceptibility genes that switch on in the presence of these and other toxins.

Feldman and his colleagues at Harvard University are now looking for susceptibility genes linked to iron and lead, two metals that appear to increase the risk of Parkinson's-like symptoms, which include tremors, jerky and rigid motion, confusion and poor balance.

What To Do

The Italian study has a few major drawbacks, especially the fact that exact exposures were never actually measured.

The American Lung Association has this fact sheet on how solvents can affect your health.

For more on Parkinson's disease, try the American Parkinson Disease Association and The National Parkinson Foundation, where you can find a simple test to see if you may have the disease.