title: An alternative perspective: a critical evaluation of the Waddell threshold extrapolation model in chemical carcinogenesis.
abstract: In a recent Perspective article (Toxicologic Pathology 31: 260-262, 2003) Waddell asserts that he has developed a log linear extrapolation model that can demonstrate a threshold and resolve for once and for all the uncertainies associated with low dose cancer risk extrapolation. However, his method essentially forces, rather than demonstrates, a threshold, and has many serious flaws that result in significant under-estimation of low dose risk. It would be a serious mistake for the scientific community to adopt Waddell's log linear extrapolation model for chemical carcinogenesis risk assessment.
authors.affiliation: Biostatistics Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Haseman
mesh_terms: D000818:Animals; D000830:Animals, Laboratory; D015197:Carcinogenicity Tests / Q000662:veterinary*; D002273:Carcinogens / Q000633:toxicity*; D002277:Carcinoma / Q000139:chemically induced / Q000473:pathology / Q000662:veterinary*; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D016014:Linear Models; D008113:Liver Neoplasms / Q000139:chemically induced / Q000473:pathology / Q000662:veterinary*; D051379:Mice; D018570:Risk Assessment; D036401:Toxicity Tests, Chronic / Q000662:veterinary*
chemical_list: D002273:Carcinogens