Jobs involving exposure to common solvents can put workers at risk for developing symptoms of Parkinson's disease earlier in life and more severe disease symptoms throughout its course, according to a recent study in Neurology, the scientific journal of the American Academy of Neurology.

Italian researchers studying 900 Parkinson’s patients found that those exposed to hydrocarbon solvents, found in petroleum-based products such as paints and glues, were an average of three years younger at first sign of disease symptoms. The severity of disease symptoms was found to be directly related to the amount of hydrocarbon exposure that was experienced.

Researchers identified nine jobs within the study group that accounted for more than 91 percent of the hydrocarbon solvent exposure. The most common occupations of those exposed were petroleum, plastic and rubber workers. Others found to have frequent hydrocarbon exposure were painters, engine mechanics and lithographers.

Parkinson's disease is a slowly progressive, neurodegenerative disease caused when a small group of brain cells die that control body movement. Symptoms generally include tremor in arms and legs, rigid muscles, slowness of movements and impaired balance. Parkinson's disease affects more than 500,000 Americans.