VOC Exposures among a Nationally Representative Sample of US Workers: Analysis of the NHANES 1988 through 2004 Data Sets

Research Trainee: Feng-Chiao Su, MS, PhD Student in Environmental Health Sciences at the University of Michigan

Faculty Researcher: Stuart Batterman, PhD, Professor of Environmental Health Sciences and Civil & Environmental Engineering at the University of Michigan

The overall objective of the proposed Pilot Project Research Training grant is to investigate exposures to volatile organic compounds (VOCs) among occupationally-exposed individuals as sampled across cohorts in the several National Health and Nutrition Examination Surveys (NHANES). The work has the following specific aims: (1) Evaluate and compare exposures to VOCs among a nationally representative sample of workers and non-occupationally exposed populations; (2) Characterize and compare distributions of VOC exposures in air and blood among a nationally representative sample of workers and the general population; (3) Examine trends (changes over time) in VOC exposures among a national representative sample of workers and the general population; and (4) Provide background and training to a doctoral student in the field of occupational health.

These aims are to be accomplished using a statistical investigation that combines data from the VOC Projects in the data sets from the NHANES 1988-1994, 1999-2000, and 2001-2004 studies. The analysis will include the following: verification and descriptive analysis of archived data, including detection frequency and parametric and non-parametric measures; parametrization of distributions using maximum likelihood estimates and multiple measures of goodness-of-fit, e.g., Anderson-Darling (A-D), Kolmogorov-Smirnov (K-S), and Chi-square (χ2); Student’s t-tests to examine group differences of VOC concentrations between workers and the general population; ANOVA analyses to test for differences among different occupational groups, and changes in mean exposures over the three study periods; and simple and multiple linear regression models to analyze associations between VOC exposures in air and blood. The analyses will culminate in a manuscript submitted to a peer review journal.

The NHANES data provides an outstanding opportunity to contrast blood and personal air samples and to evaluate occupational exposures (Specific Aim 1). These analyses, which have not been undertaken
previously, will provide a better understanding of the magnitude of exposures, the significance of occupational exposures versus other exposure sources, and the utility of and correlation between airborne and blood measurements of VOCs. The investigation of VOC distributions is important to understand the range of exposures, especially the most exposed individuals, and to facilitate uncertainty analysis (Specific Aim 2). There is surprising little quantitative and representative information on long term trends of VOC exposures in workplace (and most other) settings, although it is expected that overall exposures are declining due product substitution (e.g., use of low VOC materials), better controls, the changing nature of the workplace, decreasing smoking exposures, etc. (Specific Aim 3). Many of these factors may tend to increase the relative contribution of workplace exposure. The NHANES study provides an excellent opportunity to examine VOC exposure trends, an analysis that also has not been performed using a nationally representative sample.


Publications resulting from this project:
Su F-C, Mukherjee B, Batterman S. Trends of VOC exposures among a nationally representative sample: Analysis of the NHANES 1988 through 2004 data sets. Atmospheric Environment. 2011;45(28):4858-4867. doi:10.1016/j.atmosenv.2011.06.016. PMCID: 4335682.


Research trainee’s current position:
Feng-Chiao Su completed her PhD in 2013 and is now a Research Industrial Hygienist at the National Institute for Occupational Safety and Health, CDC.