Relationships between concentrations in environmental and alveolar air: Benzene and naphthalene

Biological levels that reflect actual body burden are more closely related to potential adverse health effects than external concentrations. Exhaled breath analysis has been Iona advocated as a noninvasive means of measuring biological levels. The relationship between levels in air and in breath is influenced by factors related to both the environment and the human body and is often characterized by tremendous variability. The relative influences of environment- and subject-specific factors were investigated through self-monitoring of benzene in breath and in air among gasoline customers refueling automobiles and mechanics performing vehicle maintenance. Self-collection of alveolar air samples was evaluated and found to be reliable. A longitudinal sampling design with measurements repeated over time for each subject was used to investigate the importance of covariates obtained by questionnaire. Results of mixed-effects statistical models indicated that differences among individuals had much less of an effect on benzene uptake than environmental differences. The methods were then extended to compare benzene and naphthalene uptake as a consequence of exposure to jet fuel. Concentrations of naphthalene in breath were much lower than concentrations of benzene in breath. Multiple regression analysis was used to identify significant predictors of both naphthalene and benzene in breath. Overall, this research presents evidence that exhaled air monitoring, when accompanied by environmental monitoring, is an efficient and effective tool for evaluating factors that influence risk of disease.