Occurrence of Current-Use Pesticides in Paired Indoor Dust, Drinking Water, and Urine Samples from the United States: Risk Prioritization and Health Implications

Despite being regarded as safer alternatives to legacy pesticides, current-use pesticides (CUPs) are now identified as emerging contaminants with growing evidence of their toxicity to wildlife and humans. In this study, we collected matched samples of indoor dust, drinking water, and urine from 81 households in Indiana, United States, and analyzed these samples for 82 CUPs, including 48 insecticides, 25 herbicides, and 9 fungicides. Of these, 47 CUPs were identified across samples of indoor dust, drinking water, and urine with median total CUP (∑CUP) concentrations of 18 300 ng/g, 101 ng/L, and 2.93 ng/mL, respectively. Notably, concentrations of neonicotinoids (NEOs) in indoor dust were higher than those reported in other studies. Herbicides were the most abundant CUPs detected in drinking water, constituting 55% of the ∑CUP concentrations. Insecticides were the most abundant CUP group detected in urine (median total insecticide concentration: 2.30 ng/mL), followed by herbicides (median: 0.409 ng/mL) and fungicides (median: 0.0531 ng/mL). The highest estimated daily intake (EDI) from drinking water and dust exposure was found for imidacloprid, with a median value of 1.00 ng/kg of body weight/day. Our results show that indoor dust is a significant exposure pathway for most insecticides and fungicides, while herbicides are mainly consumed through drinking water. In addition, the toxicity equivalent factor model, incorporated with data retrieved from the ToxCast database, indicated that imidacloprid poses the greatest health risk based on its high exposure levels and toxicity. This study underscores the importance of monitoring CUPs in indoor environments and sheds light on their potential health risks.