The Total Human Environmental Exposure Study (THEES) to benzo(a)pyrene: comparison of the inhalation and food pathways

The assessment of human exposure to an environmental contaminant requires the measurement of levels present in each pathway of possible contact. In this paper, the design considerations and Phase I results of a human exposure study focused on Benzo(a)pyrene (BaP) are discussed. This study site, located in Phillipsburg, New Jersey, is a city that contains a metal pipe foundry, which is a suspected major source of BaP. Three outdoor PM-10 samplers (used to collect BaP-containing particles with an aerodynamic size of less than or equal to 10 micron) were located in residential areas surrounding the foundry. Ten homes were sampled indoors for PM-10. Some homes have indoor combustion sources, e.g., cigarette smoke or a coal burning stove. The indoor and outdoor samples were 24 hr in duration. The mean outdoor concentration of BaP was 0.9 ng/m3, and the indoor concentrations ranged from 0.1-8.1 ng/m3. Food samples were acquired from family meals each day. They represented a one-third portion of each meal eaten at home. The range of BaP per gram of wet weight of food was between 0.004 and 1.2 ng/g. Of the 20 wk of exposure (10 x 2 wk), 10 had higher food exposures and the other 10 had higher inhalation exposures. Of the two groups, the higher food exposures usually had a greater number of ng of BaP/wk. The dominance of one or the other pathway appeared to depend upon personal eating habits and indoor combustion source use. In some instances, outdoor air pollution led to a major portion of indoor air BaP exposures. Water appears to be a minor source of BaP exposures in the study area.