Inhalation Risk Assessment for Ambient Air Toxic Concentrations Monitored in Berks County, Pennsylvania

摘要

An inhalation human health risk assessment was conducted to estimate the chronic risks (excess lifetime cancer risk and noncancer health effects) associated with contaminants measured in the ambient air at two monitoring sites in Berks County, Pennsylvania. Two air toxic monitoring sites have been operating in Berks County from 2007-2012 in response to concerns about elevated levels of air toxics in the region due to the proximity of diverse industrial sources including two secondary lead smelters, a specialty stainless steel manufacturer, a cement plant, and a coal-fired power plant. Excess lifetime cancer and non-cancer risks were calculated using inhalation unit risk factors (URFs) and reference concentrations (RfCs) that were obtained from peer-reviewed sources with the primary source being the U.S. EPA Integrated Risk Information System (IRIS). Inhalation cancer risks associated with the ambient air toxic concentrations measured in Berks County over the 2008-2011 period are consistent with cancer risks computed at other Pennsylvania ambient air toxic monitoring sites and with modeled ambient concentrations in the U.S. EPA's most recent 2005 National Air Toxic Assessment (NATA). Lead concentrations measured at the two Berks County monitoring sites over the 2008 - 2011 period were well below the 2008 National Ambient Air Quality Standard (NAAQS) of 0.15 micrograms per cubic meter. Inhalation non-cancer risks were elevated (i.e., Hazard Quotient ＞ 1.0) due to consistently high measured concentrations of acrolein, but the acrolein concentrations measured in Berks County were consistent with levels measured at other Pennsylvania monitoring sites and at U.S. EPA school outdoor air toxic monitoring sites. Inhalation cancer risks computed based on annual average air toxic concentrations decreased over the 2008-2011 period at both Berks County monitoring sites. Non-cancer risks did not show any apparent trend over the 2008-2011 period and have been driven by acrolein concentrations since 2009 when this chemical started to be analyzed.