Exposure to Quaternary Ammonium Compounds (QACs) in Assisted Living Facilities: Implications for Older Adults

Quaternary ammonium compounds (QACs) are commonly used in disinfecting and personal care products for their antimicrobial, surfactant, and preservative properties. This study provides the first comprehensive assessment of QACs in assisted living facilities through the analysis of 19 QACs from three different QAC subgroups in indoor dust and air samples collected from three assisted living facilities in Indiana, United States (US), as well as in wristbands worn by the residents and staff of these facilities. The medians of the total QAC concentrations (∑QAC, the sum of 19 QAC concentrations) were 151,000 ng/g in dust, 3.17 ng/m³ in air, and 2,290 ng/g in wristbands. Benzylalkyldimethylammonium compounds (BACs) were the most abundant QAC group in all three matrices and contributed 58-87% to the ∑QAC concentrations. The QAC distribution patterns found in dust, air, and wristbands were similar to those reported for disinfecting products, suggesting these products could be an important indoor source in assisted living. QAC concentrations in wristbands worn by staff during their work shift were significantly higher than those in wristbands worn by residents (p < 0.05). In addition, the levels found in dust from assisted living were several times higher than those previously reported in US residential households. Concentrations of C12-, C14-, and C16-BACs in dust, air, and wristbands significantly and positively correlated, suggesting common sources in the indoor environment. Estimated daily intake (EDI) of QACs suggests that accidental dust ingestion is the predominant exposure route, accounting for approximately 62% of the total QAC intake. The elevated QAC concentrations in assisted living facilities are of concern for the residents and staff of these facilities because of the potential health risks associated with exposure to these chemicals, such as respiratory effects.