Welding Occupations and Mortality from Parkinson's Disease and Other Neurodegenerative Diseases Among United States Men, 1985–1999

Abstract

Metal welding produces gaseous fumes that contain manganese, resulting in potential occupational exposure to welders. It has been hypothesized that occupational exposure among welders could increase risk of Parkinson's disease and other neurodegenerative diseases. The present study examines welding occupation and mortality from neurodegenerative diseases among men in the United States using the National Cause of Death databases 1985 to 1999. Information was abstracted from death certificates for states that collected data on occupation. Of 4,252,490 men who died during the study period, 107,773 had welding-related occupations. Multivariable logistic regression models were used to calculate mortality odds ratios (MOR) and 95% confidence intervals (CI) for odds of dying from Parkinson's disease or other neurodegenerative diseases among men who were welders as compared with men of other occupations, adjusting for attained age, race, region of residence, and year of death. During the study period, 49,174 deaths were attributed to Parkinson's disease, 54,892 to Alzheimer's disease, and 19,018 to presenile dementia. There was no evidence of an increased odds of Parkinson's disease mortality among welders as compared with men with other occupations (MOR = 0.83, 95% CI 0.78–0.88). Furthermore, welding occupation was unrelated to the odds of mortality from Alzheimer's disease (MOR = 0.94, 95% CI 0.89–1.00) or presenile dementia (MOR = 0.96, 95% CI 0.87–1.06). Earlier research suggested that welding exposures could predispose individuals to earlier onset Parkinson's disease. However, there was no evidence in this data of an increased mortality odds ratio associated with welding occupations among men younger than 65 (MOR = 1.03, 95% CI 0.74–1.44); while there was a suggestion of a lower odds Parkinson's disease death among men age 65 years and older (MOR = 0.82, 95% CI 0.77–0.88). Data from this large study do not support an association between welding occupations and death from Parkinson's disease or other neurodegenerative diseases, nor that welders are at increased odds of dying from Parkinson's disease at a younger age.

Keywords:

• age at onset
• Alzheimer's disease
• Parkinson's disease
• welding and welders

ACKNOWLEDGMENT

The project was supported in part through a consulting agreement with a group of manufacturers of welding consumables who had no role in the analysis, or in preparing this report, did not see any draft of this manuscript prior to submission for publication, and had no control over any aspect of the work or its publication.

Notes

^AWelding occupation (1): Welders and cutters, only (occupational code 783).

^BWelding occupation (2): Millwrights (occupational code 544), supervisors: plumbers, pipefitters, steamfitters (557), plumbers, pipefitters, steamfitters (585), apprentice: plumbers, pipefitters, steamfitters (587), structural metal workers (597), boilermakers (643), and welders and cutters (783).

^AAdjusted for age at death (continuously) and age at death squared, using unconditional logistic regression.

^BAdjusted for age at death (continuously), age at death squared, race (white, black, other), region (south, midwest, west), and year of death, using unconditional logistic regression.

^CReference group.

^DToo few events among welders to calculate stable estimates of mortality odds ratios.

^AWelding occupation (1): Welders and cutters only (occupational code 783).

^BWelding occupation (2): Millwrights (occupational code 544), supervisors: plumbers, pipefitters, steamfitters (557), plumbers, pipefitters, steamfitters (585), apprentice: plumbers, pipefitters, steamfitters (587), structural metalworkers (597), boilermakers (643), and welders and cutters (783).