MODELING THE EFFECTS OF WATER USAGE AND CO-BEHAVIOR ON INHALATION EXPOSURES TO CONTAMINANTS VOLATILIZED FROM HOUSEHOLD WATER

The volatilization of volatile organic chemicals during domestic water usage can result in significant indoor air concentrations, and the su bsequent inhalation of these contaminants is an important route of exp osure. The magnitude of these exposures is highly dependent on the act ivities undertaken by the exposed individual, as well as the activitie s of other occupants of the home. The indoor air quality-exposure Mode l for the Analysis of Volatiles and Residential Indoor Air Quality (MA RVIQ) was used to ascertain the impact of water-use activities on the potential contaminant dose to household members. Human time-activity p atterns of various population groups were sampled for om the Californi a Air Resources Board database, applying distributions of water-use oc currence and water-use duration to each activity based on survey resul ts. Indoor air concentrations in a sample house and the resulting pote ntial inhalation dose to the occupants were computed for different ind ividuals and pairs of individuals to test for exposure and coexposure effects. The simulated daily exposure is well described by a simplifie d equation that is a function of the amount of time the individual spe nds in the shower the bath, and the bathroom; the total water usage in the home; and the function of time the individual is at home. These r esults can be used to identify high-risk populations, individuals, and households. The study also demonstrates the importance of further res earch on joint time-activity patterns in multiperson households for as sessment of exposure and coexposure effects.