Analysis of human exposure to benzo(a)pyrene via inhalation and food ingestion in the Total Human Environmental Exposure Study (THEES)

The Total Human Environmental Exposure Study (THEES) focuses on benzo(a)pyrene (BaP) as an example of a combustion-generated polycyclic aromatic hydrocarbon (PAH) compound. Primary pathways for environmental exposures to BaP are inhalation and ingestion. This program of field studies was conducted in Phillipsburg, New Jersey, a small, industrial city in the Delaware River valley. The study protocols included direct monitoring of BaP exposures via inhalation and ingestion pathways during three separate periods, each lasting 14 days. BaP concentrations in air were sampled at outdoor and in-home locations, with personal air sampling added during the latter two phases. Cooked food samples from each household were acquired, using a constant portion "second plate" of each meal prepared at home. Ambient levels were 4-10 times higher during the cold months compared with the late summer study period. Space heating and regional aerosol were major contributors to community levels of BaP in the air during the wintertime. Penetration of outdoor air, cooking activities, combustion appliances, and cigarette smoke were important sources of indoor air exposures. Cooking activities, besides releasing BaP-enriched particles indoors, produced food imbued with BaP and added substantially to exposure via the ingestion route. Among the study subjects, the range and magnitude of dietary exposures (2 to 500 ng/d) were much greater than for inhalation (10 to 50 ng/d). Nevertheless, there were ample individual cases where inhalation of BaP was the predominant exposure route. Indoor air BaP levels were closely correlated with ambient levels in most of the homes. For some individuals, measured personal air BaP exposures were adequately predicted by time-weighting of microenvironmental (i.e., outdoor and in-home) concentrations. However, enormously high exposures for ingestion or inhalation were detected only by direct observation, not from microenvironmental data.