New study shows no link between welding and Parkinson's

February 2, 2006

The Welding Information Center today announced that a new epidemiological study published in the February 2006 issue of Occupational and Environmental Medicineconcluded that no link exists between welding or exposure to welding fumes and an increased risk of Parkinson's disease or any other similar movement disorder. Entitled "Parkinson's Disease and Other Basal Ganglia or Movement Disorders in a Large Nationwide Cohort of Swedish Welders," the study is purported to be the most comprehensive epidemiological cohort study of Parkinson's disease and other movement disorders undertaken among men employed as welders ever conducted.

The study compared 49,488 male welders and flame cutters with 489,572 men from the general Swedish population assembled from the Swedish National Census Register. Medical history information was obtained from public health records, including the Swedish Cause of Death Register and the Swedish Hospital Discharge Register, which contains information on all hospital admissions countrywide since 1964 and nationwide since 1987.

"This is the most powerful study I have seen on the issue of welding and movement disorders," stated Dr. Mark Roberts, Fellow of the American College of Occupational and Environmental Medicine. "The sheer size of the cohort and the control group, combined with the inherent reliability and accuracy in the collected data, help make this study without question the most rigorous and informative study on the issue to date. As a physician and a former welder, this study gives me further comfort that there is no association between welding and movement disorders."

Incidence rates in the welders cohort and the comparison cohort were not statistically significantly different for basal ganglia and movement disorders overall, nor specifically for Parkinson's disease, secondary Parkinsonism, other degenerative diseases of the basal ganglia, dystonia, or other extrapyramidal and movement disorders. Further analyses for Parkinson's disease stratified by attained age, time period of follow-up, geographical area of residency, and education level were unremarkable, and a subcohort analysis of shipyard welders with presumably higher exposure to welding fumes showed no increased rate of Parkinson's disease or other movement disorders.

Dr. Roberts continued, "The availability of detailed health and occupational information about this Swedish population allowed these scientists to conduct a methodologically rigorous study that not only compared the incidence of movement disorders among welders to that of the general population, but also analyzed data from a subcohort of welders who worked in shipyards—environments with potentially higher levels of welding fumes—and concluded that shipyard welders also bore no increased risk. This study compliments the recent study of Danish welders, and adds to the growing body of scientific literature that demonstrates that no causal link exists between welding or exposure to welding fumes and an increased risk of Parkinson's disease or any other similar neurodegenerative disorders."

The study concluded "this well defined, large, nationwide cohort of Swedish welders with up to 40 years of follow up did not reveal any statistically significantly increased risks for Parksinson's disease or other basal ganglia and movement disorders for welders compared with an age and geographically matched general population comparison cohort," and noted its clinical significance by saying, "this nationwide linkage study offers no support for a relation between welding and Parkinson's disease or any other specific basal ganglia and movement disorders."

The lead author of the study was epidemiologist Dr. C.M. Fored of the Clinical Epidemiology Unit, Karolinska University Hotel, Stockholm, Sweden. This study was financed by a grant from the International Epidemiology Institute, an independent biomedical research organization, which in turn received funding from a grant provided by a group of current and former manufacturers of welding consumables. This group of manufacturers was not involved in any aspect of the study design, data collection or interpretation.

More information can be found here.