Associations of welding and manganese exposure with Parkinson disease: review and meta-analysis.

Abstract

OBJECTIVE:

To examine associations of welding and manganese exposure with Parkinson disease (PD) using meta-analyses of data from cohort, case-control, and mortality studies.

METHODS:

Epidemiologic studies related to welding or manganese exposure and PD were identified in a PubMed search, article references, published reviews, and abstracts. Inclusion criteria were 1) cohort, case-control, or mortality study with relative risk (RR), odds ratio (OR), or mortality OR (MOR) and 95 confidence intervals (95% CI); 2) RR, OR, and MOR matched or adjusted for age and sex; 3) valid study design and analysis. When participants of a study were a subgroup of those in a larger study, only results of the larger study were included to assure independence of datasets. Pooled RR/OR estimates and 95% CIs were obtained using random effects models; heterogeneity of study effects were evaluated using the Q statistic and I(2) index in fixed effect models.

RESULTS:

Thirteen studies met inclusion criteria for the welding meta-analysis and 3 studies for the manganese exposure meta-analysis. The pooled RR for the association between welding and PD for all study designs was 0.86 (95% CI 0.80-0.92), with absence of between-study heterogeneity (I(2) = 0.0). Effect measures for cohort, case-control, and mortality studies were similar (0.91, 0.82, 0.87). For the association between manganese exposure and PD, the pooled OR was 0.76 (95% CI 0.41-1.42).

CONCLUSIONS:

Welding and manganese exposure are not associated with increased PD risk. Possible explanations for the inverse association between welding and PD include confounding by smoking, healthy worker effect, and hormesis.

• Authors: James A Mortimer, Amy R Borenstein, Lorene M Nelson
• Journal: Neurology (Neurology) Vol. 79 Issue 11 Pg. 1174-80 (Sep 11 2012) ISSN: 1526-632X [Electronic] United States
• PMID: 22965675 (Publication Type: Journal Article, Meta-Analysis, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Review)

Chemical References

• Manganese

Topics

• Humans
• Manganese (toxicity)
• Occupational Exposure
• Parkinson Disease (etiology)
• Welding