Association between personal exposure to volatile organic compounds and asthma among US adult population.

Objectives: There is growing concern about adverse respiratory health effects from exposure to indoor air pollution. The purpose of this study was to analyze association between exposure to volatile organic compounds (VOC) and asthma in adults.

Methods: This study utilized passive personal exposure data on ten VOC collected as part of the National Health and Nutrition Examination Survey (NHANES) 1999-2000. A total of 550 subjects who were of non-Hispanic whites, Mexican-Americans, or non-Hispanic Blacks race/ethnicity were included in this analysis. The primary outcome variable was physician-diagnosed asthma and the secondary outcome variable was presence of wheezing in the previous 12 months among those without physician-diagnosed asthma. Exploratory factor analysis was used to generate factor scores to group VOCs, which were included as indicator variables in the analyses. Associations between exposure to VOCs, physician-diagnosed asthma, and wheezing in the previous 12 months were evaluated using multiple logistic regression analyses. Odds ratios are for 1-U increase in level of exposure.

Results: Seven of the ten VOC variables loaded on two factors, "aromatic compounds" and "chlorinated hydrocarbons." The geometric mean concentration of VOCs varied from as low as 0.03 microg/m3 for trichloroethene to as high as 14.33 microg/m3 for toluene. Mexican-Americans had the highest personal exposures to benzene (geometric mean=2.38 microg/m3) as compared to non-Hispanic whites (geometric mean=1.15 microg/m3) and non-Hispanic Blacks (geometric mean=1.07 microg/m3). The odds of physician-diagnosed asthma were significantly higher among those exposed to aromatic compounds (Adjusted OR=1.63, 95% CI: 1.17-2.27). Among those subjects never diagnosed by a physician to have asthma, a significantly increased odds of one to two wheezing attacks were observed for aromatic compounds (Adjusted OR=1.68, 95% CI: 1.08-2.61) and chlorinated hydrocarbons (Adjusted OR=1.50, 95% CI: 1.01-2.23) as compared to no wheezing. No association with three wheezing attacks or more was observed in the study.

Conclusion: In this cross-sectional study of a representative sample of the US population, environmental exposures to VOCs, especially aromatic compounds, were associated with adverse respiratory effects.