A human health risk assessment of exposure to polycyclic aromatic hydrocarbons (PAHs) in coal-tar sealcoats

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Title: A human health risk assessment of exposure to polycyclic aromatic hydrocarbons (PAHs) in coal-tar sealcoats
Author: Mocka, Corey
Abstract: ABSTRACT MOCKA, COREY ADAM. A human health risk assessment of exposure to polycyclic aromatic hydrocarbons (PAHs) in coal-tar sealcoats. (Under the direction of Dr. Stephen Graham and Ms. Linda Taylor). Polycyclic aromatic hydrocarbons (PAHs) are organic molecules that consist of two or more fused benzene rings. They are natural components of coal or petroleum products and also formed by the incomplete combustion of organic matter, making them ubiquitous environmental contaminants. The United States Environmental Protection Agency (EPA) currently classifies seven PAHs as B2 chemicals (probable human carcinogens) and, considering their presence in most environmental exposure media (e.g., soil, sediment, water, air) PAHs are a significant concern to environmental and human health professionals. Coal-tar sealcoats are black, shiny coatings that are adhered to driveway and parking lots to increase pavement life and improve aesthetics. Recent studies by the United States Geological Survey (USGS) have determined that certain PAH concentrations in settled dust on the coal-tar seal coated parking lots were 5,300 times greater than concentration limits recommended for designated superfund sites. The research herein consisted of two parts: (1) background research on recent coal-tar sealant data to determine individual PAH concentrations, and (2) an initial human health risk assessment (HHRA) for selected exposure pathways. In order to determine the exposure point concentration (EPC) of PAHs, two calculation methods were used based on the EPA’s 1993 relative potency factors (RPFs) and the more recent 2010 RPFs. This comparison of RPFs was essential to demonstrate the impact of the EPA possibly implementing an expanded PAH risk assessment. Of the three scenarios examined, worker exposure to volatilized PAHs in the air presented the largest LADD and cancer risk values of 3.25E-06 mg/kg-day and 2.37E-05, respectively, when using the 2010 RPF values for the calculations. These results have upheld the hypothesis of the potential PAH risk of certain populations that may become exposed to coal tar sealcoats.
Date: 2012-12
URI: http://www.lib.ncsu.edu/resolver/1840.4/8154


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