Risks of brain tumors in rubber workers: A metaanalysis

Objective: To better understand whether rubber industry workers suffer increased risks of brain tumor, a concern that has persisted for over 40 years despite numerous well-conducted studies. Methods: We performed a formal metaanalysis of brain tumor risk estimates reported in cohort studies of rubber and tire workers. Twenty unique cohorts were identified who met a priori inclusion criteria. Metaanalysis was performed using the general variance-based method; the variance of risk estimates was calculated for each study using a chi-squared method. Homogeneity was tested by means of the Q statistic. Results: The metaanalysis determined an overall relative risk of 0.90 (95 % CI = 0.79-1.02). Conclusions: The analytical results are consistent with a conclusion that risks of brain tumor are not increased as a result of occupational exposures in the rubber and tire industry.