Parkinson’s disease and other basal ganglia or movement disorders in a large nationwide cohort of Swedish welders
- 1Clinical Epidemiology Unit, Karolinska University Hospital, Stockholm, Sweden
- 2The International Epidemiology Institute, Rockville, MD, and Department of Medicine, Vanderbilt University, Nashville, TN, USA
- 3Division of Occupational Medicine, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
- 4Work Environment Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
- Correspondence to: Dr C M Fored Clinical Epidemiology Unit, Department of Medicine, Karolinska University Hospital, Site M9:01, SE-171 76 Stockholm, Sweden;
- Accepted 14 October 2005
Introduction: Although it has been hypothesised that metal welding and flame cutting are associated with an increased risk for Parkinson’s disease due to manganese released in the welding fume, few rigorous cohort studies have evaluated this risk.
Methods: The authors examined the relation between employment as a welder and all basal ganglia and movement disorders (ICD-10, G20–26) in Sweden using nationwide and population based registers. All men recorded as welders or flame cutters (n = 49 488) in the 1960 or 1970 Swedish National Census were identified and their rates of specific basal ganglia and movement disorders between 1964 and 2003 were compared with those in an age and geographical area matched general population comparison cohort of gainfully employed men (n = 489 572).
Results: The overall rate for basal ganglia and movement disorders combined was similar for the welders and flame cutters compared with the general population (adjusted rate ratio (aRR) = 0.91 (95% CI 0.81 to 1.01). Similarly, the rate ratio for PD was 0.89 (95% CI 0.79 to 0.99). Adjusted rate ratios for other individual basal ganglia and movement disorders were also not significantly increased or decreased. Further analyses of Parkinson’s disease by attained age, time period of follow up, geographical area of residency, and educational level revealed no significant differences between the welders and the general population. Rates for Parkinson’s disease among welders in shipyards, where exposures to welding fumes are higher, were also similar to the general population (aRR = 0.95; 95% CI 0.70 to 1.28).
Conclusion: This nationwide record linkage study offers no support for a relation between welding and Parkinson’s disease or any other specific basal ganglia and movement disorders.
- ICD, International Classification of Diseases
- ISCO, International Standard Classification of Occupations
- MAG, metal arc gas welders
- MMA, manual metal arc welders
- NRN, national registration number
- NYK, Nordic Occupational Classification
- occupational exposure
- Parkinson disease
- cohort studies
- basal ganglia diseases
Funding: the study was financed by a grant from the International Epidemiology Institute, an independent biomedical research organisation, which in turn received funding from a grant provided by a group of current and former manufacturers of welding consumables. This group of manufacturers of welding consumables was not involved in any aspect of the study design, data collection, or interpretation.
Competing interests: none.