Incense burning is one of the common traditions or religious offerings in Chinese communities. Incense is burned indoor as well as in some public places like temples. Studies have shown that burning incense emits lots of volatile organic compounds (VOCs) and particulates which contribute to a significant portion of indoor air pollutants, and their potential health impacts have been increasingly concerned. The aim of this study is to determine the acute toxic effect exemplified by cell death and inflammatory response of VOCs emitted from incense during burning on the human lung epithelial cells A549. An air-liquid interface exposure system, which simulates the inhalation exposure pattern in the lung, is employed for the exposure studies. VOCs were also collected with multisorbent tubes (...[ Read more ]

Incense burning is one of the common traditions or religious offerings in Chinese communities. Incense is burned indoor as well as in some public places like temples. Studies have shown that burning incense emits lots of volatile organic compounds (VOCs) and particulates which contribute to a significant portion of indoor air pollutants, and their potential health impacts have been increasingly concerned. The aim of this study is to determine the acute toxic effect exemplified by cell death and inflammatory response of VOCs emitted from incense during burning on the human lung epithelial cells A549. An air-liquid interface exposure system, which simulates the inhalation exposure pattern in the lung, is employed for the exposure studies. VOCs were also collected with multisorbent tubes (Anasorb GCB2/GCB1/Carbosieve S-III, SKC) and analyzed with automated thermal desorption gas chromatography-mass spectrometer (ATD-GC/MS, PE). The major VOCs species identified were benzene, toluene, methyl vinyl ketone, 3-methylfuran, 2-methylfuran and 2,5-dimethylfuran . Due to the limitation of the sorbent tube used, compounds smaller than C4 and some polar carbonyl VOCs were not able to quantify.

The acute toxic effect was assessed with the extent of cell death or cell viability upon exposure. Cell viability decreased significantly in a dose and time-dependent manner after exposure of the cells to incense VOCs. The median lethal dosage (LD₅₀) derived is 42.3-44.3μg (benzene equivalent) which corresponds to concentration of 14.1-14.8mg/m³ for one hour exposure suggesting that at this level of incense VOCs, it is likely that acute toxic effect will result in cell death. The inflammatory effects of incense VOCs on A549 cells were studied at sub-lethal dosage (50) and parameterized with the level of the reactive oxygen species (ROS) generated and the induction of interleukin-8 (IL-8) which served as a marker for oxidative stress and inflammation, respectively. The results of these two markers showed that lung inflammation was induced when incense VOCs concentration is at around 200μg/m³ and an exposure time of 15-30min. The changes in the ROS and IL-8 profiles in relation to the incense VOCs concentration also suggested the incense VOCs stimulate the generation of ROS in the cells, the ROS will in turn induce the inflammatory response through the induction of the IL-8 level.

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