Repeated Measures of County Level Toxic Releases are Associated with Increased Circulatory Disease Mortality

Abstract

BACKGROUND AND AIM: Cardiovascular disease (CVD) is the leading cause of death from environmental exposures. Although exposure to PM2.5 is an established risk factor for CVD, the contribution of other hazardous pollutant exposure to CVD is less clear. METHODS: To examine the relationship between environmental exposures and CVD, we used the publicly available Toxic Release Inventory data and age-adjusted circulatory disease mortality rates from the National Center for Health Statistics between 2002 and 2012. We built longitudinal mixed models using an aggregate quantity-based exposure and risk-based exposure, the county sum and the risk sum, respectively. The county sum is the sum of all chemicals released in pounds in each county, each year, independent of the chemical toxicity. The risk sum is the sum of the product of each chemical release in pounds and the inverse of the reportable quantity of the chemical. To identify the potentially toxic chemicals associated with circulatory disease mortality rates in a cross-section of the data, in year 2012, we used the variable selection elastic net approach. Models were adjusted for county percent male, percent White, percent Hispanic, and percent less than a high school diploma earned, median household income, alcohol, smoking, frequency of National Priority List Superfund sites, and PM2.5. RESULTS:For every 25% increase in annual county sum, we found a 2.8% (1.2, 4.4; p-value=0.0006) increase in circulatory disease mortality rate. In addition, for every 25% increase in annual risk sum, there was a 3.0% (95%CI 1.3, 4.6; p-value=0.0003) increase in circulatory mortality. The elastic net model identified that five out of 467 potentially toxic chemicals: bromoform, dichlorobromomethane, dichlorotrifluoroethane, nitrophenol, and thallium may be contributing to excessive CVD mortality. CONCLUSIONS:These results identify 5 reactive chemicals of concern and suggest that county-wide releases of toxic chemicals may be significant contributors to CVD mortality. KEYWORDS: Cardiovascular diseases, Mortality, Multi-pollutant, Air Pollution