2. Relevance to Public Health 2.1 Background and Environmental Exposures to Cresols in the United States

Cresols are widely distributed in the environment and the general population may be exposed to low levels of cresols mainly through the inhalation of contaminated air. Cresols are readily degraded in the atmosphere; atmospheric concentrations outside of source-dominated areas are typically low. Since cresols are released via automobile exhaust, areas of high traffic and gas stations are likely to have increased atmospheric levels of cresols. Cresols are also the product of combustion of coal, wood, and municipal solid waste; therefore, residents near coal and petroleum fueled facilities, as well as residents near municipal waste incinerators, may have increased exposure to cresols. There are limited air monitoring data for cresols; a median concentration of 1.5 μg/m o-cresol was detected in air samples from 3 locations, the range of p-cresol at 11 locations was 0.5–20 μg/m, and m-cresol was not detected in air samples from 2 locations. A national emissions study conducted from 1990 to 1998 reported a county-level estimated ambient average concentration of 31.7 ng/m for all cresol isomers combined.