Subchronic Inhalation Exposure Study of an Airborne Polychlorinated Biphenyl Mixture Resembling the Chicago Ambient Air Congener Profile

Abstract

Although inhalation of atmospheric PCBs is the most universal exposure route and has become a substantial concern in urban areas, research is lacking to determine the body burden of inhaled PCBs and consequent health effects. To reflect the Chicago airshed environment and mimic the PCB profile in Chicago air, we generated vapors from a Chicago Air Mixture (CAM). Sprague-Dawley rats were exposed to the CAM vapor for 1.6 hr/day via nose-only inhalation for 4 wks, 520±10 μg/m3. Congener-specific quantification in tissue and air samples was performed by GC/MS/MS. In contrast to the lower-chlorinated congener enriched vapor, body tissues mainly contained tri- to hexachlorobiphenyls. Congener profiles varied between vapor and tissues, and among different organs. The toxic equivalence (TEQ) and neurotoxic equivalence (NEQ) were also investigated for tissue distribution. We evaluated a variety of endpoints to catalog the effects of long-term inhalation exposure, including immune responses, enzyme induction, cellular toxicity and histopathologic abnormalities. GSSG/GSH ratio was increased in blood of exposed animals, accompanied by elevation of hematocrit. This study demonstrated that inhalation contributed to the body burden of mostly tri- to hexachlorobiphenyls and produced a distinct profile of congeners in tissue, yet minimal toxicity was found at this exposure dose estimated at 134 μg/rat.

Elimination of Inhaled 3,3′-Dichlorobiphenyl and the Formation of the 4-Hydroxylated Metabolite

“…Pure CB11 vapor was generated into our exposure system as previously described for PCB mixtures (23). Briefly, clean dry air (4.0 L/min) was bubbled through neat CB11 in an impinger held at 25.0°C in a precision water bath (Thermo Scientific, Portsmouth, NH).…”

Metabolism and metabolites of polychlorinated biphenyls

“…Initial laboratory studies with animals and plants have demonstrated the potential of PCB 11 to become bioavailable to humans through inhalation and to be accessible for biotransformation (Hu et al, 2013, Zhu et al, 2013, Hu et al, 2012, Hu et al, 2010b, Hu et al, 2014). In 2013, PCB 11 was reportedly detected in human serum for the first time, thereby further emphasizing the need for a better understanding of the exposure, metabolism and toxicities of nonlegacy PCBs (Marek et al, 2013b).…”

Chiral polychlorinated biphenyls: absorption, metabolism and excretion—a review

“…The observation that certain C-PCBs have considerable concentrations in indoor air from US schools represents a particular public health concern (Thomas et al 2012). Recent nose-only inhalation studies demonstrate the PCBs, including some C-PCBs, are absorbed in the lung and distributed systemically in rats (Hu et al 2010, Hu et al 2012b). The uptake of PCBs in the lung appears to be highly efficient, with a 99.8% pulmonary uptake of an inhaled, radiolabeled PCB reported in rats (Hu et al 2014).…”