Annals of Occupational Hygiene Advance Access originally published online on August 9, 2007
Annals of Occupational Hygiene 2007 51(6):533-541; doi:10.1093/annhyg/mem033
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Analysis of Exposure–Biomarker Relationships with the Johnson SBB Distribution
Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, NC 27599-7431, USA
* Author to whom correspondence should be addressed. Tel: +919-966-3473; fax: +919-966-7911; e-mail: mike_flynn{at}unc.edu
Application of the Johnson bivariate SB distribution, or alternatively the SBB distribution, is presented here as a tool for the analysis of concentration data and in particular for characterizing the relationship between exposures and biomarkers. Methods for fitting the marginal SB distributions are enhanced by maximizing the Shapiro–Wilk W statistic. The subsequent goodness of fit for the SBB distribution is evaluated with a multivariate Z statistic. Median regression results are extended here with methods for calculating the mean and standard deviation of the conditional array distributions. Application of these methods to the evaluation of the relationship between exposure to airborne bromopropane and the biomarker of serum bromide concentration suggests that the SBB distribution may be useful in stratifying workers by exposure based on using a biomarker. A comparison with the usual two-parameter log-normal approach shows that in some cases the SBB distribution may offer advantages.
Keywords: biomarkers exposure Johnson SB distribution; SBB distribution
Received March 2, 2007; in final form May 31, 2007