RETROSPECTIVE ASSESSMENT OF EXPOSURE BY EXPERTS - THE EXAMPLE OF FORMALDEHYDE, SOLVENTS AND MINERAL-OILS AMONG TEXTILE AND METAL WORKERS

The validity of retrospective assessment of occupational exposure grea tly depends on the amount of detail in the available information, an t he knowledge of the specific industrial process by the experts, and on the criteria adopted to define relevant exposure. These criteria are difficult to standardize and are rarely made explicit in published rep orts, which makes it difficult to interpret inconsistencies among diff erent studies. In two ongoing case-control studies on kidney cancer an d, respectively. malignant lymphomas, a detailed occupational history was obtained and supplemented by 19 additional questionnaires, specifi cally addressing industrial activities where the knowledge of job titl e alone would have been insufficient for reliable exposure assessment. One further questionnaire was used to collect details of task and env ironment for all the other activities. These data are used to establis h probability, intensity and frequency of exposure to 30 substances kn own or suspected to be carcinogenic from previous studies. There are t wo basic steps in the exposure assessment procedure: firstly, general rules are defined for each job within each activity covered by specifi c questionnaires; secondly the judgement is modulated according to the detailed tasks, working conditions and environment. To illustrate the process and to facilitate comparison with other studies, examples are given for a few common exposures in the textile and metal industries- the two most frequent economic activities in the study area-namely exp osure to mineral oils, formaldehyde, aromatic solvents, chlorinated so lvents and other organic solvents.