Identification and characterization of quaternary ammonium compounds in Flemish indoor dust by ion-mobility high-resolution mass spectrometry

Reproductive & Developmental Toxicity of quaternary ammonium compounds

Quaternary ammonium compounds (QACs) are a class of chemicals commonly used as disinfectants in household and healthcare settings. Their usage has significantly increased in recent years due to the COVID-19 pandemic. In addition, QACs have replaced the recently banned disinfectants triclosan and triclocarban in consumer products. QACs are found in daily antimicrobial and personal care products such as household disinfectants, mouthwash, and hair care products. Due to the pervasiveness of QACs in daily use products, humans are constantly exposed. However, little is known about the health effects of everyday QAC exposure, particularly effects on human reproduction and development. Studies that investigate the harmful effects of QACs on reproduction are largely limited to high-dose studies, which may not be predictive of low dose, daily exposure, especially as QACs may be endocrine disrupting chemicals. This review analyzes recent studies on QAC effects on reproductive health, identifying knowledge gaps, and recommending future directions in QAC-related research.

Development and Application of a Multidimensional Database for the Detection of Quaternary Ammonium Compounds and Their Phase I Hepatic Metabolites in Humans

The COVID-19 pandemic has led to significantly increased human exposure to the widely used disinfectants quaternary ammonium compounds (QACs). Xenobiotic metabolism serves a critical role in the clearance of environmental molecules, yet limited data are available on the routes of QAC metabolism or metabolite levels in humans. To address this gap and to advance QAC biomonitoring capabilities, we analyzed 19 commonly used QACs and their phase I metabolites by liquid chromatography-ion mobility-tandem mass spectrometry (LC-IM-MS/MS). In vitro generation of QAC metabolites by human liver microsomes produced a series of oxidized metabolites, with metabolism generally occurring on the alkyl chain group, as supported by MS/MS fragmentation. Discernible trends were observed in the gas-phase IM behavior of QAC metabolites, which, despite their increased mass, displayed smaller collision cross-section (CCS) values than those of their respective parent compounds. We then constructed a multidimensional reference SQLite database consisting of m/z, CCS, retention time (rt), and MS/MS spectra for 19 parent QACs and 81 QAC metabolites. Using this database, we confidently identified 13 parent QACs and 35 metabolites in de-identified human fecal samples. This is the first study to integrate in vitro metabolite biosynthesis with LC-IM-MS/MS for the simultaneous monitoring of parent QACs and their metabolites in humans.

An exposure assessment of 27 quaternary ammonium compounds in pet dogs and cats from New York State, USA

Benzylalkyldimethylammonium (BACs), dialkyldimethylammonium (DDACs), and alkyltrimethylammonium compounds (ATMACs) are quaternary ammonium compounds (QACs) used widely as biocides, disinfectants, and sanitizers. Owing to their toxicity, human exposure to this class of chemicals is a concern. Pet animals are sentinels of human exposure to several indoor environmental chemicals. For the first time, we measured 7 BACs, 6 DDACs, 6 ATMACs, and 8 metabolites of BACs in urine and feces of pet dogs and cats from New York State, USA. We found widespread occurrence of QACs in feces, with median concentration of ∑All (sum concentration of all 27 QAC analytes) at 9680 and 1260 ng/g dry weight (dw) in dog and cat feces, respectively. BACs were the most abundant compounds among the four types of QACs, accounting for 64 % and 57 % of ∑All in dog and cat feces, respectively, followed by DDACs (33 % and 34 %, respectively), ATMACs (4 % and 9 %, respectively), and BAC metabolites (0.2 % and 0.3 %, respectively). However, in urine, only ω-carboxylic acid metabolites of BACs were found at median concentrations at 2.08 and 0.28 ng/mL in dogs and cats, respectively. Samples collected from animal shelters contained elevated levels of QACs than those from homes of pet owners. A significant positive correlation was found among the four types of QACs analyzed, which suggested usage of these chemicals in combination as mixtures. Based on the concentrations measured in feces, and through a reverse dosimetry approach, the median cumulative daily intakes (CDIs) of QACs were estimated to be 49.4 and 4.75 µg/kg body weight (BW)/day for dogs and cats, respectively. This study provides first evidence that pet dogs and cats are exposed to QACs at significant levels that warrant further attention.

High-Resolution Mass Spectrometry Screening of Quaternary Ammonium Compounds (QACs) in Dust from Homes and Various Microenvironments in South China

Despite their ubiquitous use, information regarding the presence of quaternary ammonium compounds (QACs) in various microenvironments remains scarce and only a small subset of QACs has been monitored using targeted chemical analysis. In this study, a total of 111 dust samples were collected from homes and various public settings in South China during the COVID-19 pandemic and were analyzed for traditional and emerging QACs using high-resolution mass spectrometry. The total traditional QAC concentrations in residential dust (∑traditional QAC, sum of 18 traditional QACs) ranged from 13.8 to 150 μg/g with a median concentration of 42.2 μg/g. Twenty-eight emerging QACs were identified in these samples, and the composition of ∑emerging QAC (sum of emerging QACs) to ∑QAC (sum of traditional and emerging QACs) ranged from 19 to 42% across various microenvironments, indicating the widespread existence of emerging QACs in indoor environments. Additionally, dust samples from cinemas exhibited higher ∑QAC concentrations compared to homes (medians 65.9 μg/g vs 58.3 μg/g, respectively), indicating heavier emission sources of QACs in these places. Interestingly, significantly higher ∑QAC concentrations were observed in dust from the rooms with carpets than those without (medians 65.6 μg/g vs 32.6 μg/g, p < 0.05, respectively). Overall, this study sheds light on the ubiquitous occurrence of QACs in indoor environments in South China.