PAH Metabolites

Hydroxylated polyaromatic hydrocarbons (OH-PAHs) have been PAH metabolites of interest for many years as biomarkers for asphalt production, coal smoke, and aerosols, as well as other industrial uses. The presence of these compounds in human urine is an indication of exposure to PAHs from industrial sources, and the Centers for Disease Control and Prevention (CDC) has been studying human exposure to PAHs from combustion for many years. Read more: CDC’s PAHs factsheet. 

PAHs are absorbed through ingestion, inhalation, and dermal contact. They are predominantly metabolized to epoxides, which are converted to dihydrodiol derivatives and phenols. The hydroxylated metabolites of the PAHs are excreted in human urine both as free hydroxylated metabolites and as hydroxylated metabolites conjugated to glucuronic acid and sulfate. 

During 1999-2002, the CDC measured 22 hydroxy-PAH urinary metabolites as part of the Third National Report on Human Exposure to Environmental Chemicals in the National Health and Nutrition Examination Survey (NHANES). Since then, CDC has focused on 10 target hydroxy-PAH urinary metabolites for which CIL has developed calibration solutions and spikes. Other laboratories will be able to use these new standards to follow the CDC’s procedures and compare data acquired using the same standards as used by the CDC. The data gathered in these studies provide physicians with a reference range for PAH exposures, and eliminate one source of variability in these complex analyses. 

CIL has been developing a wide variety of OH-PAH standards for a project for the CDC. This has required the formulation of many new OH-PAH standards with several new mixtures expected to be finished in 2012.