A toxicological risk assessment of per- and polyfluoroalkyl substances at a contaminated site in gustavus, alaska

Abstract

The use of fluoroalkyl-based aqueous film forming foams (AFFF) at an airport in Gustavus, Alaska has led to per- and polyfluoroalkyl substances (PFAS) contamination in the groundwater. Numerous drinking water wells have been contaminated, presenting a risk for exposure to PFAS chemicals. PFAS are a class of federally unregulated pollutants that show extreme persistence once leached into the environment. Fluoroalkyl exposure has been associated with increased risk for adverse health impacts such as thyroid disease, disruptions to the immune system, testicular cancer, and kidney cancer. A preliminary toxicological risk assessment was conducted for evaluating possible impacts to human health in Gustavus. This analysis focused on the most prevalent PFAS compounds, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Measurements of PFOA and PFOS from drinking water wells were collected by the State of Alaska's Department of Transportation and Public Facilities. These values were used to estimate hazard quotients. The calculation of hazard quotients was based upon values established by the U.S. Agency for Toxic Substances and Disease Registry (ATSDR). Estimation of blood serum levels for PFOA were based upon correlation values published by Harvard University. The percentage of tested wells containing hazardous levels (HQ > 0.1) of PFOA and PFOS were 7.9% and 31.7%, respectively. The concentrations found in these wells present increased risk for adverse health impacts. The linear relationship associating hazard quotient and drinking water concentration was used to calculate estimated values for protective levels of PFOA and PFOS. Drinking water containing more than 7.75 ng/L PFOA or 5.18 ng/L PFOS would have a hazard quotient above 0.1, presenting increased risk for adverse health effects.