DIOXIN EXPOSURE AND NONMALIGNANT HEALTH-EFFECTS - A MORTALITY STUDY

Objective-To investigate, in a population heavily exposed to 2,3,7,8-t etrachlorodibenzo-p-dioxin (TCDD), the possible unusual occurrence of diseases other than cancer. Methods-Five year extension of the follow up of the cohort involved in the Seveso accident. Soil measurements id entified three exposure zones: (A) highest contamination, (B) substant ial, and (R) low but higher than background contamination. Blood TCDD measurements, although limited in number, confirmed zone exposure rank ing. The 15 year mortality in the exposed cohort was compared with tha t of a large population in the surrounding non-contaminated territory. Relative risks (RRs) and 95% confidence intervals (95% CIs) were esti mated with Poisson regression techniques. Results-The already noted in creased occurrence of cardiovascular deaths was confirmed, in particul ar in zone A, among males for chronic ischaemic heart disease (five de aths, RR 3.0, 95% CI 1.2 to 7.3), and among females for hypertensive d isease (three deaths, RR 3.6, 95% CI 1.2 to 11.4) and chronic rheumati c heart disease. Novel findings were the increase of chronic obstructi ve pulmonary disease, most notably among males in zone A (four deaths, RR 3.7, 95% CI 1.4 to 9.9) and females in zone B (seven deaths, RR 2. 4, 95% CI 1.1 to 5.1); and from diabetes, which was significantly incr eased in females in zone B (13 deaths, RR 1.9, 95% CI 1.1 to 3.2). In zone R, chronic ischaemic heart disease (males and females), hypertens ion (females), and diabetes (females) showed less pronounced, although significant excesses. Conclusions-As well as high TCDD exposure, the accident caused a severe burden of strain in the population. Both thes e factors might have contributed to the noted increased risks (in part icular, circulatory and respiratory). The cardiovascular and immune to xicity of TCDD, as well as its complex interaction with the endocrine system, might be relevant to the explanations of these findings. These results, although not conclusive, concur with previous data in sugges ting cardiopulmonary and endocrine effects in humans highly exposed to TCDD.