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RELATIONSHIPS BETWEEN LEVELS OF VOLATILE ORGANIC COMPOUNDS IN AIR AND BLOOD FROM THE GENERAL POPULATION
Citation:
LIN, Y. S., P. P. EGEGHY, AND S. M. RAPPAPORT. RELATIONSHIPS BETWEEN LEVELS OF VOLATILE ORGANIC COMPOUNDS IN AIR AND BLOOD FROM THE GENERAL POPULATION. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(4):421-429, (2007).
Impact/Purpose:
The objectives for this task are to
Compile results and important findings from NERL-sponsored children's exposure studies;
Determine which pathways produce the greatest contribution to aggregate exposure among children for specific classes of pesticides;
Identify and quantify the factors that influence pesticide exposures among children;
Develop input parameters (e.g. multimedia pesticide distributions, exposure factor data) for exposure and dose models for assessing aggregate exposures and cumulative risks;
Evaluate exposure and dose models, including algorithms for estimating route-specific exposures, against real world data; and
Identify additional data gaps for modeling aggregate exposure and dose.
Description:
Background: The relationships between levels of volatile organic compounds (VOCs) in blood and air have not been well characterized in the general population where exposure concentrations are generally at ppb levels. Objectives: This study investigates relationships between the levels of 9 VOCs, namely, benzene, chloroform, 1,4-dichlorobenzene (1,4-DCB), ethylbenzene, methyl tert-butyl ether (MTBE), tetrachloroethene, toluene, and m-/p- and o-xylene, in blood and air from a stratified random sample of the general U.S. population. Methods: We used data collected from 354 participants, including 89 smokers and 265 nonsmokers, aged 20-59 years, who provided samples of blood and air in the National Health and Nutrition Examination Survey (NHANES) 1999-2000. Demographic and physiological characteristics were obtained from self-reported information; smoking status was determined from levels of serum cotinine. Multiple linear regression models were used to investigate the relationships between VOC levels in air and blood, while adjusting for effects of smoking and demographic factors. Results: Although levels of VOCs in blood were positively correlated with the corresponding air levels, the strength of association (R 2) varied from 0.02 (ethylbenzene) to 0.68 (1,4-DCB). Also, the blood-air relationships of benzene, toluene, ethylbenzene, and the xylenes (BTEX) were influenced by smoking, exposure-smoking interactions, and by gender, age, and BMI, whereas those of the other VOCs were not. Interestingly, the particular exposure-smoking interaction for benzene was different from those for toluene, ethylbenzene, and the xylenes. Whereas smokers retained more benzene in their blood at increasing exposure levels, they retained less toluene, ethylbenzene, and xylenes at increasing exposure levels. Conclusions: Investigators should consider interaction effects of exposure levels and smoking when exploring the blood-air relationships of the BTEX compounds in the general population.