Much to the chagrin of EPA and the International Agency for Research on Cancer (IARC), updated results from the dioxin-exposed Seveso population are in.
In 1976, a chemical facility explosion in Seveso, Italy exposed a large population to relatively high levels of dioxin. Tironi et al. examined cancer mortality in the Seveso population during the period 1976 to 1991.
The study population was classified by estimated exposure: Zone A soil had the highest levels of dioxin; Zone B soil was next; and Zone R soils had the least dioxin. Although the follow-up period is only 15 years (and some cancers take 20 or more years to appear following exposure), the results are interesting.
1. When all types of cancers were grouped into one category, no statistically significant excess of cancer was observed.
2. Of the 78 efforts to find an association with different types of cancer in females,only one association was statistically significant (a relative risk of 6.6 for myeloma). With this type of data dredging, you might expect 3 to 4 statistically significant associations just by chance.
3. Of the 81 efforts to find an association with different types of cancer in males, only three associations were statistically significant (relative risks of 2.9 for rectal cancer, 2.4 for lymphohemopoietic cancer and 3.1 for leukemia). Again, data dredging could easily account for these observed excesses in cancer.
Ironically, IARC has just classified dioxin as a "known human carcinogen?" And EPA could very well follow suit.
But inquiring minds want to know: WHY?
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