Cancer incidence in the population exposed to dioxin after the "Seveso accident": twenty years of follow-up

Abstract

BackgroundThe Seveso, Italy accident in 1976 caused the contamination of a large population by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Possible long-term effects have been examined through mortality and cancer incidence studies. We have updated the cancer incidence study which now covers the period 1977-96.MethodsThe study population includes subjects resident at the time of the accident in three contaminated zones with decreasing TCDD soil levels (zone A, very high; zone B, high; zone R, low) and in a surrounding non-contaminated reference territory. Gender-, age-, and period-adjusted rate ratios (RR) and 95% confidence intervals (95% CI) were calculated by using Poisson regression for subjects aged 0-74 years.ResultsAll cancer incidence did not differ from expectations in any of the contaminated zones. An excess of lymphatic and hematopoietic tissue neoplasms was observed in zones A (four cases; RR, 1.39; 95% CI, 0.52-3.71) and B (29 cases; RR, 1.56; 95% CI, 1.07-2.27) consistent with the findings of the concurrent mortality study. An increased risk of breast cancer was detected in zone A females after 15 years since the accident (five cases, RR, 2.57; 95% CI, 1.07-6.20). No cases of soft tissue sarcomas occurred in the most exposed zones (A and B, 1.17 expected). No cancer cases were observed among subjects diagnosed with chloracne early after the accident.ConclusionThe extension of the Seveso cancer incidence study confirmed an excess risk of lymphatic and hematopoietic tissue neoplasms in the most exposed zones. No clear pattern by time since the accident and zones was evident partly because of the low number of cases. The elevated risk of breast cancer in zone A females after 15 years since the accident deserves further and thorough investigation. The follow-up is continuing in order to cover the long time period (even decades) usually elapsing from exposure to carcinogenic chemicals and disease occurrence.

The role of environmental estrogens and autoimmunity

“…However, very high doses may, in addition, cause cancer indirectly; one of the proposed mechanisms is oxidative stress and the subsequent oxygen damage to DNA [72]. TCDD has also been shown to exert an antiestrogenic activity in the presence of estrogens, and estrogenic property in the absence of estrogen [73].…”

“…In the immediate aftermath, typical effects of exposure to polychlorinated hydrocarbons such as chloracne were observed mainly in children [74], an excess risk of lymphatic and hematopoietic tissue neoplasms in the most exposed zones was reported [73].…”

Impact of Environmental Contaminants on Breast Cancer / Wpływ Zanieczyszczenia Środowiska Na Raka Piersi

“…Breast cancer among females was found to be below expectations in the most contaminated zones [63] and a 15-year mortality study after the ''Seveso accident'' showed no increase for breast cancer among females exposed to TCDD in comparison with the population of a surrounding non contaminated area [64]. On the other hand, Pesatori et al [65] mentioned an increased risk of breast cancer of females in the most contaminated zone 15 years since the accident (five cases, risk ratio 2.57; 95% CI, 1.07-6.20). Dioxin levels in the archived area that were collected soon after the explosion showed that the hazard ratio for breast cancer associated with the 10-fold increase of TCDD levels in serum was significantly increased to 2.1 (95% confidence interval, 1.0-4.6) [66].…”

The Benefits of Contaminated Site Cleanup Revisited: The Case of Naples and Caserta, Italy

“…These very same VPF figures could also be used to estimate the monetized benefits of regulations that reduce the risk of industrial accidents where carcinogens are released into the environment (Pesatori et al, 2009) or that impose higher emission standards on hazardous or solid waste incinerators (Zambon et al, 2007).…”