An investigation of the relationship between air emissions of volatile organic compounds and the incidence of cancer in Indiana counties

Cancer is a health endpoint influenced by a multitude of factors, including genetic history, individual behavior, and environmental insults. The ubiquity of toxicants in the environment has raised questions about the extent of their role in causing cancer in humans. More specifically, it is desirable to understand the cancer incidence due to airborne toxicants in anthropogenic pollution. One particular class of such pollutants is volatile organic compounds (VOCs). This paper reports an epidemiological investigation of the incidence of cancer in the 92 counties of Indiana. We evaluated the relationship between the amount of VOCs released in each county, as reported by the Toxic Release Inventory, and the county-by-county incidence of various types of cancer, especially those of less common organ systems not directly associated with the absorption or distribution of toxicants. Our evaluation considered chlorinated versus nonchlorinated emissions as well as stack versus fugitive emissions. We evaluated three models: linear, quadratic, and polynomial. Of these, the quadratic model appeared to be the best predictor (highest r2) for most endpoints for which there was a positive correlation. However, the linear model was the most sensitive (lowest P-value) for skin, melanoma, and endocrine-related cancers, including female genital system cancers. Our results indicate a relationship between emissions of VOCs and the incidence of some types of cancers. Most notable were strong correlations between VOC emissions and cancers of the brain, nervous system, endocrine system, and skin.