Novel insight into quaternary ammonium compounds in combined 13 environmental and human matrices: Occurrence, associations, and exposure pathways

Quaternary ammonium compounds (QACs) are widely used as antimicrobials and surfactants, with their potential risks to human health attracting increasing attention. To address the knowledge gap regarding the associations of QACs across multiple environmental and human-associated matrices, as well as the dominant exposure pathways of QACs, 30 QACs were measured in 13 environmental and human-associated matrices. These included hand wipes (median: 26,000 ng/m²), desktop wipes (18,900 ng/m²), wristbands (18,800 ng/m²), back wipes (17,300 ng/m²), floor wipes (9,580 ng/m²), tape strips (4,660 ng/m²), fingernails (8,020 ng/g), hair (6,650 ng/g), toenails (2,220 ng/g), food (85.8 ng/g), personal PM_2.5 (5.4 ng/m³), sputum (151 ng/mL), and urine (15.3 ng/mL). Emerging QACs were prevalent in food, personal PM_2.5, sputum, and urine, whereas traditional QACs were predominant in other matrices. Additionally, distinct gender differences in exposure levels and QAC compositions were observed. QACs in nails, hair, and sputum were significantly correlated (r = 0.57-0.59, p < 0.05) with skin wipes, floor wipes, and personal PM_2.5, respectively, indicating these human matrices could serve as indicators of external exposure. Furthermore, the stratum corneum and wristbands can serve as indicators of dermal exposure. Based on exposure assessment, dietary intake and dermal absorption were the dominant exposure pathways to QACs.