Tb. Starr, Significant shortcomings of the US Environmental Protection Agency's latest draft risk characterization for dioxin-like compounds, TOXICOL SCI, 64(1), 2001, pp. 7-13
The United States Environmental Protection Agency (U.S. EPA) has concluded
that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a human carcinogen, and
it has stated that the lifetime all-cancer mortality risk attributable sole
ly to the current background body burden of dioxin-like compounds could be
as high as 1.3 per 100. U.S. EPA's most current human cancer risk estimate
was obtained from a linear dose-response model fit to the data from three e
pidemiology studies of TCDD-exposed chemical workers. Herein it is shown th
at the U.S. EPA model fails to provide an adequate fit to that data, wherea
s an intercept-only model, having no slope whatsoever, is entirely adequate
. Although the epidemiology data used by U.S. EPA are consistent with a sig
nificant elevation in all-cancer mortality, by about 32%, among TCDD-expose
d workers, this elevation should not be attributed to the workers' TCDD exp
osure.