T e t r a c h l o r o d i b e n z o d i o x i n -Chloracne.
An epidemiokogical study, aiming to assess the extent of the exposure to tetrachloro.dibenzodioxin (TCDD) of the population involved in the Seveso accident, needs an effective information system, able to answer the questions usually asked --such as: why? what? who? ~vhere? when? how long? --and therefore concerning the wide range of the expected events, from the early cases till the ones ,expected in the long term. The p a p e r is concerned with evaluation .of possible use of chloracne as indicator of h u m a n exposure to TCDD, taking into account from one hand chloracne itself (i.e. its latency period, sensitivity, specificity, predictive value of diagnosis, etc) and, from the other, the development of the observational process. Moreover, the paper points out the role of the dermatological findings as representative --more than and before the other clinical findings --of the exposure conditions in the polluted area. The group of subjects classified as ~ chloracne ,, by the end of the second screening (May, 1977) included 187 cases, 164 of which were .children 0-14 yrs old by the 10th of July 1976; 34 out of 164 were diagnosed in September-December 1976, the other 13'0 were diagnosed w~thin the screening program. The results of a survey concerning their exposure data, clinical and laboratory findings are detailed. Finally, some remarks are made related to the quality of data. The Authors emphasize that the reliability of assessment of health status of the exposed population depends not only upon a comprehensive a posteriori analysis of the different sets of clinical findings, but .also upon the degree of integration of the professional staffs involved at operational levels. This statement has the obvious consequence that the assessment of httman exposure to TCDD, using chloracne as a reliable marker, needs a multidimensional approach.