Superfund Research Program
Development and Application of Biomarkers of Exposure
Project Leader: Stephen M. Rappaport (University of California-Berkeley)
Grant Number: P42ES005948
Funding Period: 1995 - 2011
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants that are present in most waste sites on the National Priorities List identified by the Environmental Protection Agency. These chemicals are also in air, water, and food throughout the world. Although epidemiologic studies have shown that PAH exposures are associated with cancers, exposure-response relationships are unclear due to the lack of quantitative exposure data for the hundreds of individual PAH compounds emanating from a particular source. In this project, the researchers are developing and applying biomarkers of exposure to PAHs to quantify better exposures of PAHs in humans. A host of biomarkers is being applied, including protein adducts of reactive intermediates of PAH metabolism, unmetabolized PAHs in urine, and PAH metabolites in urine. These biomarkers are being measured in several hundred specimens of blood and urine collected from persons exposed to PAHs in various environments, namely, coke and steel factories, the trucking industry, the asphalt industry, and homes where coal is used for fuel. Using state-of-the-art mass spectrometry, they have developed assays to measure protein adducts of PAHs, unmetabolized PAHs in urine, and urinary metabolites of PAHs, with extremely high sensitivity and specificity. These methods will facilitate the quantitation of PAH exposures in epidemiology studies of health effects. For example, current work with samples of urine from asphalt workers indicates that levels of hydroxylated phenanthrene, a three-ring PAH, is a particularly good surrogate for exposures to all PAHs from a given source and can also differentiate PAH exposures arising from inhalation and dermal absorption. This work has important implications for the assessment of low levels of PAH exposures among persons in the workplace and in the general population.