Dietary exposure to polycyclic aromatic hydrocarbons in pets: Evidence from urinary biomonitoring

Little is known about the pet exposure to polycyclic aromatic hydrocarbons (PAHs), despite their shared indoor environments with humans. This study is the first to investigate PAH exposure in pets by analyzing paired dog food and urine samples. Specifically, levels and distributions of PAHs and their metabolites were determined in 47 commercial dried granule dog food samples and corresponding urine samples to assess exposure through dietary intake. Total PAHs and their metabolites were detected in all dog food (range: 0.308-55.0 ng/g, average: 10.7 ng/g) and urine samples (range: 565-10,094 ng/g creatinine, average: 4298 ng/g creatinine), respectively. Naphthalene (73 % of total PAHs) and its hydroxylated metabolite, 1-OH-naphthalene and 2-OH-naphthalene (79 % of total metabolites), were the predominant compounds identified in both dog food and urine samples. The concentrations of PAH metabolites in dog urine were comparable to those reported for the Korean population in the 2021-2023 cycle of the Korean National Environmental Health Survey (KoNEHS). Urinary concentrations of PAH metabolites positively correlated with body weight; however, no significant differences were observed based on age, gender, eating habit, or hair length. Notably, significant correlations were identified between the concentrations of ∑₄PAHs in dog food and their corresponding hydroxylated metabolite concentrations in urine samples, suggesting that dietary intake as one of contributors to the cumulative PAH burden in dogs. Nevertheless, the dietary contribution was relatively minor; the estimated daily intake through food consumption (EDI_food) accounted for only 1.57 % of the cumulative daily intake (CDI) calculated from urinary PAH concentrations. This key finding indicates that non-dietary exposure from the dogs' surrounding environment may be the predominant pathway for their overall PAH burden.