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.

Effects of time, temperature, and sebum layer on migration rate of plasticizers in polyvinyl chloride products.

Large amounts of plasticizers, such as di(2-ethylhexyl) phthalate (DEHP) and dioctyl terephthalate (DOTP), are added to various polyvinyl chloride (PVC) products. To assess the human exposure to these plasticizers on using PVC products, it is important to know their migration rate. However, conventional migration tests conducted at a fixed time and temperature are often insufficient for determining possible variations in migration rates with respect to time, temperature, and sebum layer. In this study, the migration rates of DEHP and DOTP from five PVC products were measured using a polydimethylsiloxane (PDMS) sampler at different times and temperatures, in the presence and absence of artificial sebum. Although the migrated mass of the plasticizers increased over time, the average migration rate decreased. The average migration rates increased with increasing temperature and in the presence of an artificial sebum layer between the product and the PDMS sampler. When the artificial sebum layer was added, the average migration rate increased considerably by a factor of 1.5-14, suggesting that sebum should be considered to avoid the underestimation of dermal exposure to highly hydrophobic plasticizers, such as DEHP and DOTP. Based on the measured values, a conceptual analysis was conducted to quantitatively assess the difference in the migration rate of plasticizers caused by the difference between the time set for the migration test and the exposure time when the product is used. To reduce uncertainties and the potential underestimation of dermal exposure, an appropriate time for the experiment should be set to simulate the exposure scenario of a given product.