Uptake of inhaled polychlorinated biphenyls (PCBs) in a human longitudinal cohort study and animal inhalation studies

PCBs are a group of 209 persistent organic pollutants whose carcinogenic and neurological toxicities are well established. PCB inhalation exposure assessments have been lacking for non-occupational conditions and for lower-Cl congeners. We assessed congener-specific inhalation and dietary exposure for 78 adolescent children and their mothers (n=68) in the Airborne Exposure to Semi-volatile Organic Pollutants (AESOP) Study. Congener-specific PCB inhalation exposure was modeled using 293 measurements of indoor and outdoor airborne PCB concentrations at homes and schools, analyzed via tandem quadrupole GS-MS/MS, combined with questionnaire data from the AESOP Study. Dietary exposure was modeled using Canadian Total Diet Survey PCBs and U.S. National Health and Nutrition Examination Survey food ingestion rates. For ∑PCB, including the higher-Cl congeners, dietary exposure dominated. For individual lower-Cl congeners, inhalation exposure was as high as one-third of the total dietary + inhalation exposure. Geometric mean ∑PCB inhalation was greater for urban mothers (7.1 µg yr^-1) and children (12.0 µg yr^-1) than for rural mothers (2.4 µg yr^-1) and children (8.9 µg yr^-1). AESOP Study schools had higher indoor PCB concentrations than did homes, and accounted for the majority of children9s inhalation exposure. Concurrent sub-chronic inhalation studies in rats using a complex PCB mixture that represents urban air demonstrated uptake from the lung resulting in alteration of thyroid hormones and increased oxidative stress. Although several PCB congeners were enriched in lung tissue, the lung was primarily a route of exposure rather than a target organ for inhaled PCBs.