Le HQ, et al. - Researchers conducted a review of studies of occupational titanium dioxide (TiO2) exposure, and summarized the results from the three industry-based cohort mortality studies via meta-analysis. Using random effects models, they derived summary standardized mortality ratios (SSMR) and summary Cox regression coefficients from exposure-response models. Combined results from studies of 24,312 TiO2 production workers yielded no clear evidence of a link between occupational exposure to TiO2 and lung cancer.