1287

Individuals living in an indoor environment are typically exposed to a greater variety of air pollutants than in an outdoor environment. Numerous sources of chemical emissions are found in the indoor environment, depending on the building materials as well as the lifestyle of the occupants. The quality of the indoor environment considerably impacts public health. Japan has established Indoor Air Quality guidelines (IAQGs) for 13 chemicals, including formaldehyde, acetaldehyde, xylene, ethylbenzene, styrene, 1,4-dichlorobenzene, and toluene. However, the pollutant types and concentrations have been inconsistent over time because of altered lifestyles and the development of novel household products and building materials. Therefore, a comprehensive approach and action plan for the overall reduction of health risks because of indoor air pollutants are required for public health protection. To determine the high-risk indoor air pollutants that should be reduced, a preliminary risk assessment using data from nationwide exposure assessments and existing hazard data was conducted. As the result, 11 indoor air pollutants: 2-ethyl-1-hexanol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether, 3-methoxy-3-methylbutanol, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol monomethyl ether acetate, and methyl isobutyl ketone were identified. Subsequently, we reviewed the hazard or toxicological data for the 13 chemicals with established IAQGs and the 11 novel chemicals without established IAQGs to update their hazard assessments. The reference values for acute and chronic effects were determined from the reviewed information. The process and result of the preliminary risk assessment and the progress of the updated hazard assessments are reported.