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, 38 (4), 748-759

Aryl Hydrocarbon Receptor-Mediated Activity of Gas-Phase Ambient Air Derived From Passive Sampling and an in Vitro Bioassay

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Aryl Hydrocarbon Receptor-Mediated Activity of Gas-Phase Ambient Air Derived From Passive Sampling and an in Vitro Bioassay

Carrie A McDonough et al. Environ Toxicol Chem.

Abstract

The gaseous fraction of hydrophobic organic contaminants (HOCs) in ambient air appears to be responsible for a significant portion of aryl hydrocarbon receptor (AhR)-mediated activity, but the majority of compounds contributing to this activity remain unidentified. The present study investigated the use of polyethylene passive samplers to isolate gaseous HOCs from ambient air for use in in vitro bioassays and to improve our understanding of the toxicological relevance of the gaseous fraction of ambient air in urban and residential environments. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and organic flame retardants were measured in polyethylene passive sampler extracts. Extracts were also analyzed using an in vitro bioassay to measure AhR-mediated activity. Bioassay-derived benzo[a]pyrene (BaP) equivalents (BaP-Eqbio ), a measure of potency of HOC mixtures, were greatest in the downtown Cleveland area and lowest at rural/residential sites further from the city center. The BaP-Eqbio was weakly correlated with concentrations of 2-ring alkyl/substituted PAHs and one organophosphate flame retardant, ethylhexyl diphenyl phosphate. Potency predicted based on literature-derived induction equivalency factors (IEFs) explained only 2 to 23% of the AhR-mediated potency observed in bioassay experiments. Our results suggests that health risks of gaseous ambient air pollution predicted using data from targeted chemical analysis may underestimate risks of exposure, most likely due to augmentation of potency by unmonitored chemicals in the mixture, and the lack of relevant IEFs for many targeted analytes. Environ Toxicol Chem 2019;38:748-759. © 2019 SETAC.

Keywords: Aryl hydrocarbon receptor; Flame retardants; Mixture toxicology; Organophosphate esters; Passive sampler; Polycyclic aromatic hydrocarbons.

Figures

FIGURE 1.
FIGURE 1.
Concentration and composition of PAHs and OPEs in PE extracts (A and B; ng/μL) and ambient air (C and D; ng/m3). Site name abbreviations are BLK: PE Blank; CUY: Cuyahoga National Park; KENT: Kent; FHL: Fairport Harbor Lakefront; UH: University Heights; CLH: Cleveland Downtown 3; CLT: Cleveland Downtown 2; CLF: Cleveland Lakefront 1; CLE: Cleveland Lakefront 2; CLD: Cleveland Downtown 1
FIGURE 2.
FIGURE 2.
Concentration-response curves for triplicate cell exposures to PE extract dilution curves, including the PE Blank. Concentrations are expressed as the mass of PE extracted per mL DMSO in each dosing solution. Activity is expressed as the ratio of the response to the PE extract as compared to the response of the positive control (120 nM BaP).
FIGURE 3.
FIGURE 3.
Map of BaP-Eqbio, total PAH concentrations (Σ40PAH), and total OPE concentrations (Σ12OPE) in PE extracts from each site. The size of each circle represents the value at each site, with the smallest and largest circles representing the minimum and maximum, of the range of values.
FIGURE 4.
FIGURE 4.
Relative contribution of PAHs to BaP-EQchem, based on IEFs from Machala et al. (2001). Compound abbreviations are FLRA: fluoranthene; PYR: pyrene; BAA: benzo[a]anthracene; CHRY: chrysene; DIMEBAA: 7,12-dimethylbenz[a]anthracene; BBJKFLRA: benzo[b,j,k]fluoranthene; BAP: benzo[a]pyrene; IND: indeno[1,2,3-c,d]pyrene; DIBA: dibenz[a,h]anthracene. Place name acronyms are defined in the caption for Figure 1.

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