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welders disease: Researchers Suspect Link Between Welding and Parkinson’s Disease
According to a press release from Washington University School of Medicine, in 2001 concerning welders disease, researches identified the first clue that welding fume inhalation might trigger Parkinson’s disease (PD) in welders. A research team led by neurologist Brad A. Racette, M.D., found that 15 professional welders developed typical clinical and neurological signs of the disease (welders disease) an average of 15 years earlier than the general population. The study is featured in the January issue of the journal Neurology with an accompanying editorial.
"This research doesn’t prove that welding causes PD," (or welders disease) explains Racette, an assistant professor of neurology at Washington University School of Medicine in St. Louis. "But it’s suspicious that the majority of these patients were welders and had a much younger age of onset of welders disease (PD). Our theory is that we have identified a group of people who probably would have developed welders disease eventually, but something in the welding environment caused them to develop symptoms earlier." Other studies have shown that the fumes from the heavy metals, such as manganese are at the core of welders disease (weldor's disease).
"One clue, though, is that manganese miners are susceptible to a condition called manganism because they inhale large amounts of the mineral manganese. The disease is classified as a Parkinson syndrome because it bears a resemblance to PD. But both the symptoms and brain pathology are significantly different." Thus, the link to manganese is the likely cause of welders disease.
Welding fumes also contain high levels of manganese. But when a young welder walked into Racette’s office and said he was suffering from manganism, Racette knew something was fishy.
"Manganism (welders disease) is a very different disease. To me, this patient clearly looked as if he had PD," Racette says.
He soon discovered a lore that welding may lead to PD; material data safety sheets even list welders disease as a possible hazard. But there is little scientific evidence to back up the idea.
Racette and colleagues therefore set out to determine whether welding is in fact an environmental contributor to PD and welders disease. They identified 15 professional welders among patients in the school’s Movement Disorders Center. Then they compared the welders’ medi cal history and clinical symptoms with those of control PD patients.
They found no clinical differences between the welders and typical PD patients. The two groups had the same severity and frequency of symptoms and responded similarly to levodopa, a drug used to treat PD.
The only statistically significant difference was average age of onset: 45 for the welders or 15 years younger than for the control group.
Racette and colleagues also imaged the brains of two of the welding patients for welders disease and 13 control patients for PD. People with PD typically have lower levels of a neurotransmitter called dopamine in certain regions of their brain. Using a technique called fluorodopa positron emission tomography (FDOPA PET), the researchers determined how much dopamine the brain could take up. With that information, they assessed the extent of Parkinson-like deterioration. The FDOPA PET scans revealed no significant difference between the welding and control groups. Therefore, the welders appeared to have typical PD.
"These results are really exciting because we may soon be able to identify the first environmental cause of PD," says Racette. "Our first goal is to show that welding truly does cause this disease. Then we can figure out which aspect of welding is responsible." This information, Racette argues, will help determine whether welders should take precautionary measures to avoid welders disease and also will help researchers begin to unlock the underlying cause of this debilitating disorder.
In the editorial that accompanies the paper, Canadian neurologist Ali H. Rajput, M.B.B.S., F.R.C.P.C., likens the search for environmental causes of PD to looking for a needle in a haystack. "By narrowing the focus to one environmental group, Racette et al. have chosen a smaller stack and, therefore, have a greater chance of finding whether there is a needle or not," he says.
Racette BA, McGee-Minnich L, Moerlein SM, Mink JW, Videen TO, Perlmutter JS. Welding-related parkinsonism: Clinical features, treatment, and pathophysiology. Neurology, 56, 8-13, Jan. 9, 2001.
Funding from the National Institutes of Health, the American Parkinson’s Disease Association, the Charles A. Dana Foundation and the McDonnell Center for the Study of Higher Brain Function supported this study.
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