title: Significant shortcomings of the U.S. Environmental Protection Agency's latest draft risk characterization for dioxin-like compounds.
abstract: 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 solely 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 epidemiology studies of TCDD-exposed chemical workers. Herein it is shown that the U.S. EPA model fails to provide an adequate fit to that data, whereas an intercept-only model, having no slope whatsoever, is entirely adequate. Although the epidemiology data used by U.S. EPA are consistent with a significant elevation in all-cancer mortality, by about 32%, among TCDD-exposed workers, this elevation should not be attributed to the workers' TCDD exposure.
authors.affiliation: TBS Associates, 7500 Rainwater Road, Raleigh, North Carolina 27615, USA. tbstarr@mindspring.com
authors.forename: T B
authors.initials: TB
authors.lastname: Starr
mesh_terms: D000818:Animals; D001822:Body Burden; D002273:Carcinogens; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000009:adverse effects*; D006801:Humans; D015201:Meta-Analysis as Topic; D009369:Neoplasms / Q000453:epidemiology* / Q000401:mortality; D000072317:Polychlorinated Dibenzodioxins / Q000009:adverse effects*; D018570:Risk Assessment; D014481:United States; D014484:United States Environmental Protection Agency / Q000331:legislation & jurisprudence / Q000592:standards*
chemical_list: D002273:Carcinogens; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins