Measured and modeled personal exposures to and risks from volatile organic compounds

We developed a personal exposure model using volatile organic compound data collected for teachers and office workers as part of the Boston Exposure Assessment in Microenvironments (BEAM) study. We included participant-specific time-activity and concentration measurements of residential outdoor, residential indoor, and workplace microenvironments, along with average concentrations in various dining, retail, and transportation microenvironments. We used a series of time-weighted personal exposure models to compare measured personal concentrations using median regression models, with bias estimates representing the difference between measured and modeled personal exposures. Incorporating only the outdoor microenvironment results in an unbiased estimate of personal exposure only for carbon tetrachloride. Adding the residential indoor microenvironment provides an unbiased estimate for trichloroethene as well. A model incorporating residential outdoor, indoor, and workplace microenvironments provides an unbiased estimate for the above compounds and chloroform, 1,4-dichlorobenzene, benzene, and alpha-pinene, and adding the transportation microenvironment adds ethylbenzene. A fully saturated model, including outdoor, indoor, workplace, transportation, and all other microenvironments, provides an unbiased estimate for the previously listed compounds along with tetrachloroethene and styrene. MTBE, toluene, o-xylene, d-limonene, formaldehyde, and acetaldehyde were not fully characterized even in the saturated model, emphasizing that additional time-activity and concentration information would more fully characterize personal exposure.