RETROSPECTIVE EVALUATION OF THE EXPOSURE TO POLYCYCLIC AROMATIC-HYDROCARBONS - COMPARATIVE ASSESSMENTS WITH A JOB EXPOSURE MATRIX AND BY EXPERTS IN INDUSTRIAL-HYGIENE

This work aimed at assessing the validity of job exposure matrix (JEM) for the retrospective evaluation of exposure to polycyclic aromatic h ydrocarbons (PAH) within the framework of population-based case-contro l studies, taking the evaluation of industrial hygiene experts as refe rence. For this purpose, we used a case-control study for which the di fferent levels of exposure were assessed by such experts after case by case evaluation of all job periods reported by the subjects. The JEM was applied to this set of data so that we had, according to job perio ds, the experts' evaluation on the one hand, and the JEM evaluation on the other. JEM sensitivity and specificity of the matrix vary widely from 0.13 to 0.96 and 0.58 to 0.99 respectively, depending on whether the experts chase a narrow or wide definition of exposure and on the c utoff point chosen to dichotomize the JEM. We also computed, according to the sensitivity and specificity of the JEM, the odds ratio (OR) an d relative efficiency IRE) given by the JEM for several hypothetical O R and frequencies of exposure among the controls. These calculations w ere made for different definitions of exposure by the experts and diff erent cutoff paints for the JEM. The results show a bias in the JEM's evaluation of the OR. In addition, the RE Varies widely from Very law values to high values (0.05-0.45) depending on the experts' definition of exposure and the cutoff point chosen for the matrix. Note, however , that all these calculations were made taking the experts' evaluation as the reference. This implies that the results could be different if we consider that experts' assessment might also be subject to bias, a lthough it is generally agreed so far that expert assessment constitut es the best way of evaluating exposure within the framework of a popul ation-based case-control study.