The study is published in this month's issue of Neurology.
"This is the first study to link work-related exposure of 20 years or more to specific metals with any chronic neurodegenerative disorder," said the study's principal author, Jay M. Gorell, M.D. "Our findings suggest that chronic occupational exposure to these metals is associated with Parkinson's disease, and that the metals may act alone or together over time in some patients to help produce the disease."
Dr. Gorell heads the Division of Movement Disorders in the Department of Neurology at Henry Ford Hospital and is Director of the William T. Gossett Parkinson's Disease Center.
The study found that more than 20 years of work-related exposure to either copper or manganese, or dual combinations of lead, copper and iron, was significantly associated with acquiring Parkinson's disease. Combinations of lead, copper and iron exposures were associated with an even greater risk than any single metal investigated. These new findings may help shed light on the cause of this disabling disorder.
Parkinson's disease is a common degenerative disorder of the brain that produces slow bodily movements, rigid muscles, frequent tremor of limbs, and loss of balance. Of concern to patients and families are the costs of medications and other treatments of Parkinson's disease, along with the loss of independence of individuals with advanced cases.
The study consisted of 144 Henry Ford Health System patients who had been diagnosed with Parkinson's disease and another 464 patients as control subjects.
All patients were extensively interviewed by an industrial hygienist about their work history and worksite conditions on all jobs they had held for a period of six months or more since the age of 18. Occupational exposure to six metals was rated by the industrial hygienist.
The work was funded by the National Institute of Environmental Health Sciences, the Gossett Parkinson's Disease Center and the Louis Hayman Parkinson's Disease Research Fund.