Quaternary Ammonium\nCompounds in Paired Samples of\nBlood and Indoor Dust from the United States

Previous studies\nof quaternary ammonium compounds (QACs)\nin the\nindoor environment have reported widespread presence of QAC in indoor\ndust. However, there are limited data on the contribution of dust\ningestion to the QAC body burden. In this study, 18 QACs (6 benzylalkyldimethylammonium\ncompounds [BACs], 6 dialkyldimethylammonium compounds [DADMACs], and\n6 alkyltrimethylammonium compounds [ATMACs]) were analyzed in 81 paired\nsamples of blood serum and dust collected in Indiana, United States.\nQACs were detected in 51–100% of the dust samples with the\ntotal QAC concentrations (∑QAC) ranging from 0.613 to 427 μg/g\n(median 56.9 μg/g). In contrast to dust samples, QACs were detected\nless frequently in blood serum with a median ∑QAC concentration\nof 3.66 ng/mL. The relative source contribution (RSC) of dust ingestion\nto serum levels was calculated using the PROTEX (PROduction-To-EXposure)\nmodel and was estimated as less than 1%, suggesting that hand-to-mouth\ncontact, dietary intake, or inhalation could be more important exposure\nroutes than dust ingestion. This is the first study to simultaneously\nmeasure QAC concentrations in indoor dust and blood, providing comprehensive\nassessment of the role of dust ingestion in QAC human exposure.