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.