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The authors studied noncancer mortality among phenoxyacid herbicide and chlorophenol production workers and sprayers included in an international study comprising 36 cohorts from 12 countries followed from 1939 to 1992. Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin or higher chlorinated dioxins (TCDD/HCD) was discerned from job records and company questionnaires with validation by biologic and environmental measures. Standard mortality ratio analyses suggested a moderate healthy worker effect for all circulatory diseases, especially ischemic heart disease, among both those exposed and those not exposed to TCDD/HCD. In Poisson regression analyses, exposure to TCDD/HCD was not associated with increased mortality from cerebrovascular disease. However, an increased risk for circulatory disease, especially ischemic heart disease (rate ratio [RR] 1.67, 95% confidence interval [Cl] 1.23-2.26) and possibly diabetes (RR 2.25, 95% Cl 0.53-9.50), was present among TCDD/HCD-exposed workers. Risks tended to be higher 10 to 19 years after first exposure and for those exposed for a duration of 10 to 19 years. Mortality from suicide was comparable to that for the general population for all workers exposed to herbicides or chlorophenols and was associated with short latency and duration of exposure. More refined investigations of the ischemic heart disease and TCDD/HCD exposure association are warranted.

Objective: To investigate, in a population heavily exposed to 2,3,7,8-tetrachlorodibenzo-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 identified three exposure zones: (A) highest contamination, (B) substantial, and (R) low but higher than background contamination. Blood TCDD measurements, although limited in number, confirmed zone exposure ranking. The 15 year mortality in the exposed cohort was compared with that of a large population in the surrounding non-contaminated territory. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated with Poisson regression techniques., Results: The already noted increased occurrence of cardiovascular deaths was confirmed, in particular in zone A, among males for chronic ischaemic heart disease (five deaths, RR 3.0, 95% CI 1.2 to 7.3), and among females for hypertensive disease (three deaths, RR 3.6, 95% CI 1.2 to 11.4) and chronic rheumatic heart disease. Novel findings were the increase of chronic obstructive 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 increased 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), hypertension (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 these factors might have contributed to the noted increased risks (in particular, circulatory and respiratory). The cardiovascular and immune toxicity 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 suggesting cardiopulmonary and endocrine effects in humans highly exposed to TCDD.

The mortality experience of the population, aged 20-74 years, living in an area contaminated by TCDD after an industrial accident in 1976, was examined in the period 1976-1986 and compared with the mortality of the population of the surrounding noncontaminated territory. People who left the area during the study period were followed up, and vital status was successfully ascertained for over 99% of the cohort members. An increased mortality, from chronic ischemic heart disease (males) and hypertensive disease (females), which could not be explained in terms of chance, confounding, or bias, was noted in the exposed population. The stressful experience of the population in the aftermath of the disaster was deemed relevant to the interpretation of these findings. Overall, cancer mortality was not increased. Suggestive increases, however, were seen for melanoma, brain cancer, soft tissue sarcomas and certain hematologic neoplasms, whereas mortality from breast cancer and cancer of the liver was noticeably decreased. Further research is in progress in order to thoroughly investigate the association, if any, of cancer occurrence with TCDD contamination.

In 1976, an accidental explosion in a plant near Seveso, Italy, caused the contamination of a populated area by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The area was subdivided into three zones (A, B, and R) having decreasing mean levels of TCDD soil contamination. This study examines the mortality between 1976 and 1986 among the subjects, aged 20-74 years, who were resident in the area since the accident (n = 556 in zone A, n = 3,920 in zone B, n = 26,227 in zone R). Subjects' exposure was classified by residence. A referent cohort of 167,391 subjects who lived in the immediate surroundings was concurrently examined. Vital status ascertainment was successful for over 99% of the subjects. Increased mortality from cardiovascular causes was found; incident-related stressors were considered more relevant to increased mortality than was TCDD exposure. Mortality from several cancers was elevated. The increases in biliary cancer (females), brain cancer, and lymphatic and hemopoietic neoplasms (particularly leukemia in males) did not appear to result from chance, confounding, or information/comparison bias. However, no definite patterns related to exposure classification were apparent. Merely suggestive increases in soft tissue tumors and melanoma were also noted. Liver and breast cancer mortality tended to be below expectations. Interpretation is hampered by the short observation period, small number of deaths from certain causes, and poor exposure definition. Further research is in progress.

Andrea Baccarelli and colleagues show that maternal exposure to a dioxin following the industrial accident in Seveso, Italy in 1976 is associated with modified neonatal thyroid function even many years later. [ABSTRACT FROM AUTHOR]

Follow-up of the population exposed to dioxin after the 1976 accident in Seveso, Italy, was extended to 1996. During the entire observation period, all-cause and all-cancer mortality did not increase. Fifteen years after the accident, mortality among men in high-exposure zones A (804 inhabitants) and B (5,941 inhabitants) increased from all cancers (rate ratio (RR) = 1.3, 95% confidence interval (CI): 1.0, 1.7), rectal cancer (RR = 2.4, 95% CI: 1.2, 4.6), and lung cancer (RR = 1.3, 95% CI: 1.0, 1.7), with no latency-related pattern for rectal or lung cancer. An excess of lymphohemopoietic neoplasms was found in both genders (RR = 1.7, 95% CI: 1.2, 2.5). Hodgkin's disease risk was elevated in the first 10-year observation period (RR = 4.9, 95% CI: 1.5, 16.4), whereas the highest increase for non-Hodgkin's lymphoma (RR = 2.8, 95% CI: 1.1, 7.0) and myeloid leukemia (RR = 3.8, 95% CI: 1.2, 12.5) occurred after 15 years. No soft tissue sarcoma cases were found in these zones (0.8 expected). An overall increase in diabetes was reported, notably among women (RR = 2.4, 95% CI: 1.2, 4.6). Chronic circulatory and respiratory diseases were moderately increased, suggesting a link with accident-related stressors and chemical exposure. Results support evaluation of dioxin as carcinogenic to humans and corroborate the hypotheses of its association with other health outcomes, including cardiovascular- and endocrine-related effects. [ABSTRACT FROM PUBLISHER]