Comparison of chronic toxicity and carcinogenicity of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) in 2‐year bioassays in female Sprague‐Dawley rats
- 28 September 2006
- journal article
- research article
- Published by Wiley in Molecular Nutrition & Food Research
- Vol. 50 (10), 934-944
- https://doi.org/10.1002/mnfr.200600031
Abstract
The cancer bioassay for 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) conducted by the Dow Chemical company in the mid 70s has been used extensively for conducting quantitative cancer risk assessments for human exposure to TCDD. More recently the National Toxicology Program (NTP) conducted a cancer bioassay of similar design as part of its evaluation of the dioxin toxic equivalency factor methodology. This report compares the design and the results of these two cancer bioassays. This comparison confirms, in most cases, previously published and widely used carcinogenic response characteristics with respect to dose, time course, organ selectivity, tumor type and maximum intensity of TCDD‐induced carcinogenicity and toxicity in the Sprague‐Dawley rat. Specifically, increases in the incidences of neoplasms were seen in both studies in the liver, lung and oral mucosa. The most notable difference was the significant increase in the incidence of cholangiocarcinoma of the liver seen in the NTP study but not in the Dow study. The experimental designs for the two studies are similar but some protocol parameters differed, such as vehicle, dosing schedule, diet and rat sub‐strain utilized. Differences in the shapes of the dose response curves for several neoplasms were noted between the studies, with the NTP study showing non‐linearity for all neoplasms. This may result from differences in the experimental protocols as well as divergence in the biological behavior of the different stocks of Sprague‐Dawley rat strains used.Keywords
This publication has 28 references indexed in Scilit:
- Mechanisms of Exocrine Pancreatic Toxicity Induced by Oral Treatment with 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Female Harlan Sprague-Dawley RatsToxicological Sciences, 2005
- Dose-Additive Carcinogenicity of a Defined Mixture of “Dioxin-like Compounds”Environmental Health Perspectives, 2005
- Classification of Proliferative Hepatocellular Lesions in Harlan Sprague–Dawley Rats Chronically Exposed to Dioxin-Like CompoundsToxicologic Pathology, 2005
- Gingival Carcinogenicity in Female Harlan Sprague-Dawley Rats following Two-Year Oral Treatment with 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Dioxin-Like CompoundsToxicological Sciences, 2004
- Exocrine pancreatic pathology in female Harlan Sprague-Dawley rats after chronic treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin and dioxin-like compounds.Environmental Health Perspectives, 2004
- Characterization of Bronchiolar Metaplasia of the Alveolar Epithelium in Female Sprague—Dawley Rats Exposed to 3,3',4,4',5-Pentachlorobiphenyl (PCB126)Toxicologic Pathology, 2004
- Follicular Epithelial Cell Hypertrophy Induced by Chronic Oral Administration of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Female Harlan Sprague—Dawley RatsToxicologic Pathology, 2004
- Hepatic stem cells: a reviewPathology, 2001
- 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD): Results of a 13-week oral toxicity study in ratsToxicology and Applied Pharmacology, 1976
- Nonparametric Estimation from Incomplete ObservationsJournal of the American Statistical Association, 1958