WEDNESDAY, April 6 (HealthDay News) -- Manganese in welding fumes may affect welders' brains over time, according to a new, small study.

Previous research has found a link between manganese and neurological disorders, including Parkinson's disease-like symptoms.

This study included 20 welders with no symptoms of Parkinson's disease, 20 Parkinson's disease patients who were not welders, and 20 healthy people who were not welders. The welders worked at shipyards and a metal fabrication plant in the Midwest and had an average of 30,000 hours of lifetime welding exposure. Their average manganese levels were two times the upper limits of normal.

All 60 participants underwent brain PET and MRI scans and motor skills tests, and were examined by a movement disorder specialist.

Compared to non-welders, the welders had an average 11.7 percent reduction in a marker of the neurotransmitter dopamine in the same area of the brain affected by Parkinson's disease. Dopamine helps nerve cells communicate.

The researchers also found that welders had mild movement disorders. However, the results merely show an association, not cause and effect.

"There are over one million workers who perform welding as part of their job functions in the United States," study author Dr. Brad A. Racette of the Washington University School of Medicine in St. Louis said in a journal news release. "If a link between neurotoxic effects and these fumes were proven, it would have a substantial public health impact for the U.S. workforce and economy," he said.

But one expert said it's too early to draw firm conclusions from the study.

"The dopaminergic reductions [observed] were not as dramatic as those seen in Parkinson's disease patients nor was the nature of the reduction exactly like that typically seen in Parkinson's," said Dr. Michael Pourfar, director of the division of movement disorders at North Shore-LIJ Health System, Great Neck, NY. He agreed that right now, all the findings suggest is an association with dopamine function.

"That is to say, exposure to manganese may affect dopamine function and cause a parkinsonian syndrome but it does not clearly cause the same classic Parkinson's that most people are familiar with," Pourfar said. "The number of subjects in the study was relatively small and prior PET studies have not consistently demonstrated the same findings, so many questions remain about the nature of the association between manganese and parkinsonism," he added.

The study appears online April 6 in the journal Neurology.

More information

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