1e:T40d,Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are globally distributed, persistent, toxic, and are found in human blood and serum. Exposure pathways are not well characterized. To better understand indoor dust ingestion as a potential pathway for human exposure, we determined the concentrations of these compounds in dust collected from 10 houses, 38 apartments, 10 day care centers, 10 offices, and 5 cars. Samples were prepared using a rapid extraction and cleanup method and analyzed using LC-MS/MS. PFOS and PFOA were found in dust samples from all microenvironments and their concentrations were significantly positively correlated to each other. Highest median concentrations were seen in offices (PFOS: 110 ng/g dry weight) and apartments (PFOA: 93 ng/g dw). Adult and toddler dust ingestion exposures were estimated and compared to dietary exposure data from Canada and Spain. Results show that diet is the most important exposure route, but in a worst case scenario, dust ingestion may also be significant.1f:T4ec,Quaternary ammonium compounds (QACs or "quats") make up a class of chemicals used as disinfectants in cleaning and other consumer products. While disinfection is recommended for maintaining a safe environment during the COVID-19 pandemic, the increased use of QACs is concerning as exposure to these compounds has been associated with adverse effects on reproductive and respiratory systems. We have determined the occurrence of 19 QACs in residential dust collected before and during the COVID-19 pandemic. QACs were detected in >90% of the samples collected during the pandemic at concentrations ranging from 1.95 to 531 μg/g (n = 40; median of 58.9 μg/g). The total QAC concentrations in these samples were significantly higher than in samples collected before the COVID-19 pandemic (p < 0.05; n = 21; median of 36.3 μg/g). Higher QAC concentrations were found in households that generally disinfected more frequently (p < 0.05). Disinfecting products commonly used in these homes were analyzed, and the QAC profiles in dust and in products were similar, suggesting that these products can be a significant source of QACs. Our findings indicate that indoor exposure to QACs is widespread and has increased during the pandemic.20:T5f3,

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