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E-M:/ New evidence supports IARC classification of dioxin as Class Icarcinogen



Title: New evidence supports IARC classification of dioxin as
Given the controversy surrounding dioxin in mid-Michigan, and some legislators' confusion about its toxicity, this new evidence supporting dioxin as a confirmed human carcinogen is a crucial piece of information in the public debate.


New evidence supports IARC classification of dioxin as Class I carcinogen

Steenland, K., Bertazzi, P., Baccarelli, A., Kogevinas, M., 2004.  Dioxin revisited: developments since the 1997 IARC classification of dioxin as a human carcinogen.  Environ. Health Perspect. In Press.  doi:10.1289/ehp.7219 (available at http://dx.doi.org/)
Online 10 June 2004


In 1997 the International Agency for Research on Cancer (IARC) classified 2,3,7,8-TCDD
(tetrachlorodibenzo-para-dioxin, the most potent dioxin congener, hereafter referred to as simply TCDD) as a Group 1 carcinogen based on limited evidence in humans, sufficient evidence in experimental animals, and extensive mechanistic information indicating that TCDD acts through a mechanism involving the Ah receptor which is present in both humans and animals. The judgment of limited evidence in humans was based primarily on an elevation of all cancers combined in four industrial cohorts. The Class 1 classification has been somewhat controversial, and has been challenged in the literature in recent years. Here we review the epidemiologic and mechanistic evidence which has emerged since 1997. New epidemiologic evidence consists primarily of positive exposure-response analyses is several of the industrial cohorts, as well as evidence of excesses from several specific cancers in the Seveso accident cohort. There are also new data regarding how the Ah receptor functions in mediating the carcinogenic response to TCDD. We conclude that the new evidence generally supports the 1997 IARC classification.