An Ecological Evaluation of Vinyl Chloride Exposure and Liver Cancer Incidence and Mortality in Texas

The goal of this analysis was to evaluate the association between county-level ambient vinyl chloride (VC) and county-level liver cancer incidence and mortality rates in Texas. Modeled county-level ambient VC data were obtained from the National Air Toxics Assessment. Age-adjusted county-level liver cancer incidence rates were abstracted from the Texas Cancer Registry and age-standardized county-level liver cancer mortality rates were obtained from the peer-reviewed literature. Multivariable imputation was utilized to impute incidence rates in counties with suppressed liver cancer incidence rates. Negative binomial and Poisson regression models were utilized to evaluate the association between county-level ambient VC and county-level liver cancer incidence and mortality rates, respectively, adjusted for county-level heavy drinking prevalence, hepatitis mortality rates, median income, and race (percent Hispanic). County-level ambient VC was not associated with county-level liver cancer incidence or mortality rates. Specifically, when compared to the lowest tertile of ambient VC, the middle (relative risk [RR]: 1.06, 95% confidence interval [CI]: 0.95-1.19) and highest (RR: 1.03, 95% CI: 0.90-1.17) tertiles of ambient VC were not associated with liver cancer incidence. Similarly, county-level ambient VC in the middle (RR: 0.95, 95% CI: 0.85-1.05) and highest (RR: 0.93, 95% CI: 0.82-1.05) tertiles were not associated with liver cancer mortality. This analysis suggests that county-level ambient VC is not associated with liver cancer incidence or mortality in Texas. Our study provides novel results regarding liver cancer risk from low-level non-occupational exposure to ambient VC.