Increased risk of parkinsonism associated with welding exposure

• Published in: Neurotoxicology (Park Forest South) Vol. 33; no. 5; pp. 1356 - 1361
• Main Authors: Racette, Brad A., Criswell, Susan R., Lundin, Jessica I., Hobson, Angela, Seixas, Noah, Kotzbauer, Paul T., Evanoff, Bradley A., Perlmutter, Joel S., Zhang, Jing, Sheppard, Lianne, Checkoway, Harvey
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2012; Elsevier
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Case-Control Studies; Chemical and industrial products toxicology. Toxic occupational diseases; Cross-Sectional Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Female; Humans; Male; Manganese; Medical sciences; Metals and various inorganic compounds; Middle Aged; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Occupational Diseases - chemically induced; Occupational Diseases - epidemiology; Occupational Exposure - adverse effects; Occupational exposures; Parkinson disease; Parkinsonian Disorders - epidemiology; Parkinsonian Disorders - physiopathology; Parkinsonism; Retrospective Studies; Severity of Illness Index; Toxicology; Welding; Parkinsonism; Parkinson disease; Occupational exposures; Welding; Manganese; Nervous system diseases; Transition metal; Occupational exposure; Cerebral disorder; Central nervous system disease; Risk factor; Degenerative disease; Occupational medicine; Extrapyramidal syndrome
• ISSN: 0161-813X; 1872-9711
• DOI: 10.1016/j.neuro.2012.08.011

► We found a high prevalence of parkinsonism in welders compared to non-welders. ► Dose–response of welding years and parkinsonism was U-shaped. ► Parkinsonian phenotype in welders was similar to that of newly diagnosed PD patients. Manganese (Mn), an established neurotoxicant, is a common component of welding fume. The neurological phenotype associated with welding exposures has not been well described. Prior epidemiologic evidence linking occupational welding to parkinsonism is mixed, and remains controversial. This was a cross-sectional and nested case–control study to investigate the prevalence and phenotype of parkinsonism among 811 shipyard and fabrication welders recruited from trade unions. Two reference groups included 59 non-welder trade workers and 118 newly diagnosed, untreated idiopathic PD patients. Study subjects were examined by a movement disorders specialist using the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3). Parkinsonism cases were defined as welders with UPDRS3 score ≥15. Normal was defined as UPDRS3<6. Exposure was classified as intensity adjusted, cumulative years of welding. Adjusted prevalence ratios for parkinsonism were calculated in relation to quartiles of welding years. The overall prevalence estimate of parkinsonism was 15.6% in welding exposed workers compared to 0% in the reference group. Among welders, we observed a U-shaped dose–response relation between weighted welding exposure-years and parkinsonism. UPDRS3 scores for most domains were similar between welders and newly diagnosed idiopathic Parkinson disease (PD) patients, except for greater frequency of rest tremor and asymmetry in PD patients. This work-site based study among welders demonstrates a high prevalence of parkinsonism compared to nonwelding-exposed workers and a clinical phenotype that overlaps substantially with PD.