Determination of personal exposure to volatile organic compounds and their health risks after the use of mosquito repellents in residential environments using passive sampling.

The ubiquitous use of mosquito repellents in homes across Asia, Africa, and South America is related with human exposure to indoor volatile organic compounds (VOCs). There are three primary types of mosquito repellents: those in the form of coils, mats, and liquids. The repellent mechanisms of these products are distinct, resulting in the generation of varying types of VOCs during the repellent process. In this study, the emission characteristics of commercial coil-, mat-, and liquid-type mosquito repellents were observed in a laboratory chamber using real-time measurement. A previously developed personal passive sampler, ePTFE PS, was used to quantify personal exposure to indoor VOCs while 86 volunteers habitually used those three representative types for 3 h in their residence. Notable increase of indoor benzene was observed for coil- and mat-type mosquito repellents, while α-pinene concentration increased significantly following the use of liquid-type mosquito repellent. The average incremental cancer risks for benzene were 10-6 to 10-4 for adults following the use of coil- and mat-type mosquito repellents. The average non-cancer risks for all chemicals were <1 after the use of three types of mosquito repellents. Considering the potential human health risks associated with byproducts (e.g., particulate matter or carbon monoxide from incomplete combustion) emitted after mosquito coil use, further research on this topic is warranted.

Increase of the indoor concentration of volatile organic compounds after the use of incense and scented candle in studio apartments determined using passive sampling.

Burning incenses and scented candles may provide harmful chemicals. Although many studies have evaluated volatile organic chemicals emitted by their use and related health risks, extension of our understanding for guiding appropriate use under various use conditions is necessary. In this study, emission characteristics of commercial incenses and scented candles were evaluated in a laboratory chamber using real-time measurement and the time-weighted average exposure concentrations of monoaromatic compounds and monoterpenes were assessed using passive samplers while volunteers living in a studio apartment use them. After burning incense, the average levels of benzene increased from 1.4 to 100 µg m-3. The presence of a wood core in commercial incense products was the main cause of high benzene emission by burning them although the increase in benzene was also influenced by factors such as the brand of the products, the number of incense sticks burned, the duration of each burning session, and ventilation period. Electrical warming of scented candles increased the levels of monoterpenes by factors of 16-30 on average. Considering the emission characteristics found in this study, exposure to benzene and monoterpenes could be mitigated by cautious use of those products in residential areas.

Determination of terpene levels after the use of essential oil diffusers in vehicles and studio apartments using passive sampling.

The exposure levels of selected terpenes (limonene, α- and ß-pinenes, and γ-terpinene) emitted by essential oil diffusers in vehicles and studio apartments were assessed using a passive sampling method. A previously developed passive sampler composed of an expanded polytetrafluoroethylene membrane and adsorbent (ePTFE PS) was enlarged and made wearable. Before field deployment, the sampling performance of the modified ePTFE PS for selected terpenes was compared with that of active sampling in a lab-scale 5 m3 test chamber under constant exposure conditions, supporting that passive sampling provides reasonable estimates of the time-weighted exposure concentration. Fifty volunteers were recruited and asked to wear the ePTFE PS while using an essential oil diffuser inside their own vehicle while commuting and in their studio apartment while sleeping. Terpene levels without an essential oil diffuser were very low in vehicles and 47, 3.6, 1.6, and 0.62 µg m-3 for average concentrations of limonene, α- and ß-pinenes, and γ-terpinene in studio apartments, respectively, close to those reported in previous studies. The indoor concentrations of all selected terpenes in vehicles and studio apartments were elevated by the use of essential oil diffusers, especially in vehicles. The average concentration of limonene in vehicles after the use of essential oil diffusers was 11 µg m-3, which was greater than that before use by a factor of 30. Therefore, cautious usage of essential oil diffusers indoors where the volume is limited, such as a vehicle, is needed to reduce exposure to terpenes.

Personal Passive Air Samplers for Chlorinated Gases Generated from the Use of Consumer Products.

Various chlorine-based disinfectants are being used during the COVID-19 pandemic; however, only a few studies on exposure to harmful gases resulting from the use of these disinfectants exist. Previously, we developed a personal passive air sampler (PPAS) to estimate the exposure level to chlorine gas while using chlorinated disinfectants. Herein, we investigated the color development of the passive sampler corresponding to chlorine exposure concentration and time, which allows the general population to easily estimate their gas exposure levels. The uptake and reaction rate of PPAS are also explained, and the maximum capacity of the sampler was determined as 1.8 mol of chlorine per unit volume (m3) of the passive sampler. Additionally, the effects of disinfectant types on the gas exposure level were successfully assessed using passive samplers deployed in a closed chamber. It is noteworthy that the same level of chlorine gas is generated from liquid household bleach regardless of dilution ratios, and we confirmed that the chlorine gas can diffuse out from a gel-type disinfectant. Considering that this PPAS reflects reactive gas removal, individual working patterns, and environmental conditions, this sampler can be successfully used to estimate personal exposure levels of chlorinated gases generated from disinfectants.

Liposome leakage and increased cellular permeability induced by guanidine-based oligomers: effects of liposome composition on liposome leakage and human lung epithelial barrier permeability.

Over the decades, guanidine-based oligomer groups have been one of the most widely used antimicrobial agents. Reportedly, these cationic oligomers cause serious damage to microorganisms but have low toxicity to humans. However, public concerns regarding the guanidine group have rapidly grown after the fatal misuse of these oligomers as humidifier disinfectants, which resulted in thousands of fatalities in South Korea. Herein, we investigated liposome leakage and cellular permeability changes caused by polyhexamethylene guanidine (PHMG) and polyhexamethylene biguanide (PHMB), both representative guanidine-based oligomers. The leakage of zwitterionic liposomes, induced by cationic oligomers, was more extensive than that of negative liposomes, indicating that oligomer adsorption onto lipid head groups via electrostatic interaction cannot fully explain the induced lipid membrane damage. Furthermore, lipid packing parameters, including intrinsic curvature, cholesterol content, and lipid phases, affected liposome leakage, particularly for PHMG. Cellular permeability tests were performed using an A549 cell monolayer model and a respiratory 3D tissue model, revealing that PHMG and PHMB damaged cell membranes and reduced cell barrier function. Furthermore, liposome leakage induced by PHMG and PHMB was higher in human lung surfactant-mimicking liposomes than that observed in Escherichia coli-mimicking liposomes. These results indicated that human cells are susceptible to guanidine-based oligomers. Considering that the interaction of oligomers and cell membranes is a major mechanism of toxicity initiation, this study provides crucial insights into the action of these disinfectants on mammalian cells.