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Five subjects were exposed to nine volatile organic compounds (VOCs) at concentrations that can be encountered in everyday life. Breath samples were collected during a 10-h uptake phase and a 24-h decay phase. It was possible to determine four distinct slopes in the decay curve for each chemical. The distribution in the body and residence times in different tissues were calculated using a linear four-compartment mass-balance model. The model was used to predict breath concentrations for two subjects in a second chamber experiment including the same nine VOCs, representing three chemical classes (aromatic, aliphatic, and chlorinated compounds). Predicted values were generally within 25% of those observed, suggesting that the model parameters calculated here could be useful in estimating exposure and body burden to other VOCs in these three classes. Median residence times for the nine VOCs ranged from 3-12 min for compartment 1 (metabolizing); 0.3-2 h for compartment 2; 2-5 h for compartment 3; and 1-4 d for compartment 4. The fraction of the parent compound exhaled at equilibrium was estimated to range from 0.06-0.16 for four aromatic compounds and decane; 0.22-0.23 for trichloroethylene and dichloromethane; 0.35 for hexane; and 0.88 for 1,1,1-trichloroethane. Limited blood measurements were obtained for six of the nine VOCs in two subjects simultaneously with the breath samples over four-hour decay periods. Blood/breath ratios agreed well between the two subjects, but were higher than human blood/air partition coefficients reported in subjects exposed to high concentrations. This observation is consistent with results from other studies at relatively low concentrations.

Several volatile organic compounds, including tetrachloroethylene, have been found to be nearly ubiquitous in residential indoor environments during previous TEAM studies. Eleven homes in New Jersey were monitored over three or five days to examine the effect of bringing freshly dry-cleaned clothes into the home on indoor air levels and personal exposures to tetrachloroethylene. Indoor air, personal air, and breath concentrations were measured over multiple 12-hrs periods before and after dry-cleaned clothes were introduced into nine of the homes. No dry-cleaned clothes were introduced into the two remaining homes. Outdoor air tetrachloroethylene concentrations were measured at six of the eleven homes. Indoor/outdoor concentration ratios and source strengths were calculated at the six homes with outdoor measurements. Elevated indoor air levels and human exposures to tetrachloroethylene were measured at seven of the nine homes with dry-cleaned clothes. Indoor air concentrations reached 300 micrograms/m3 in one home and elevated indoor levels persisted for at least 48 hrs in all seven homes. Indoor/outdoor tetrachloroethylene concentration ratios exceeded 100 for the four homes with both dry-cleaned clothes and outdoor measurements. Maximum source strengths ranged from 16 to 69 mg/hr in these homes and did not directly correspond to the number of dry-cleaned garments brought into the home. Breath levels of tetrachloroethylene increased two to six-fold for participants living in seven homes with increased indoor air levels. Indoor air, personal air, and breath tetrachloroethylene concentrations were significantly related (0.05 level) to the number of garments introduced divided by the home volume.

Breath measurements offer the potential for a direct and noninvasive evaluation of human exposure to volatile organic compounds (VOCs) in the environments in which people live and work. This research study was conducted to further evaluate and develop the potential of this exposure assessment methodology. Several people were exposed to the atmosphere in six microenvironments for several hours. Air concentrations of VOCs were measured during these exposures and breath samples were collected and analyzed at multiple time points after the exposure to evaluate elimination kinetics for 21 VOCs. A new alveolar breath collection technique was applied. Elimination half-lives were estimated using a mono- and bi-exponential model. The alveolar breath collection and analysis methodology proved to be very useful for collecting many samples in short time intervals and this capability was very important for more accurately describing the initial phase of the decay curves. Breath decay curves were generated from samples collected over a four hour period after exposure for 21 of 24 target VOCs. A biexponential function generally provided a better fit for the decay data than did the monoexponential function, supporting a multi-compartment uptake and elimination model for the human body.