Estimating serum polychlorinated biphenyl levels in highly exposed workers: An empirical model

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Abstract
A regression model estimating high‐homolog polychlorinated biphenyl (PCB) serum concentration on the basis of job exposure categorizations was developed. The model assumes first‐order kinetics with a half‐life determined empirically and uses variables that incorporate both intensity and duration of exposure over a 30‐yr period. In order to compare the efficiency of these regression‐based exposure estimates relative to often‐used epidemiological parameters, models with dichotomized, ordinal, and continuous exposure surrogates were also investigated. Among the alternative exposure categorizations the most straightforward measure, ever versus never direct, was a particularly poor predictor of serum PCB level (r2 = .01). Nearly all of the candidate exposure measures we tried predicted serum levels poorly. The best of these after the fact was with total months employed in direct‐exposure jobs (r2 = .43). None of the logical deductive models approached the predictability of the empirical model developed here (r2 = .69).