Occurrence of emerging contaminants in pet hair and indoor air: integrative health risk assessment using multiple ToxCast endpoints†

Indoor exposome is a growing concern, including a mixture of legacy and emerging contaminants. Recent studies suggest that indoor pollutants may accumulate in pet hair, a part of indoor exposome, increasing health risks to pet owners; however, the source and hazards of pollutants associated with pet hair are largely unknown. Here, we found that hydrophobic pollutants often had higher indoor concentrations than hydrophilic ones, and polycyclic aromatic hydrocarbons (PAHs) were the most dominant fractions (61.1%) in indoor air exposome while polycyclic musks (PCMs) had the highest concentrations among all contaminant classes in indoor dust (1559 ± 1598 ng g⁻¹ dw) and pet hair (2831 ± 2458 ng g⁻¹ dw). The levels of hygiene-related contaminants (PCMs, current-use pesticides (CUPs), and antibiotics) were higher in pet hair than dust due to direct contact during applications. Health risk assessment using toxicity thresholds from high-throughput screening data showed that human health risks from the five classes of indoor contaminants (PAHs, PCMs, organophosphate esters, CUPs, and antibiotics) via inhalation, ingestion, and dermal contact were within acceptable limits, but the children may be exposed to a higher risk than the adults. The thresholds estimated from the ToxCast data using endpoint sensitivity distribution make the exposome risk assessment feasible in the absence of benchmarks, which is beneficial for including a mixture of emerging pollutants in risk assessment.