The carcinogenic potencies of 2,3,7,8-tetrachlorodibenzo-p-dioxin: Letting the data speak for themselves

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:495335

Green, L C; Crouch, E A.C.; Lester, R R ^[1]

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1. Cambridge Environmental Inc., MA (United States)

The authors analyze here the dose-response data generated from the seminal bioassay of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in Sprague-Dawley rats, reported by Kociba and coworkers. That chronic toxicity and oncogenicity study showed 2,3,7,8-TCDD to increase the incidence of certain tumors, while decreasing the incidence of others. Further, results in female rats were markedly different from those in male rats--a result ascribed to the dependence of dioxin on estrogen for some of its toxic effects. For each sex, the authors analyze each tumor type on which 2,3,7,8-TCDD has, or might have, an effect, whether positive, negative, or neutral. After generating dose-response relationships for each tumor type, the authors combine them. The combination involves simply adding the slopes of each tumor-specific dose-response relationship. They perform separate analyses for each set of dose-ranges. They also calculate upper (and lower) bounds on the maximum likelihood estimates, using the upper 95th percentile estimates for the slopes of the net dose-response relationships as conservative estimates of carcinogenic potency.

• OSTI ID: 495335
• Report Number(s): CONF-9504119--
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOASSAY
CARCINOGENESIS
DIOXIN
DOSE-RESPONSE RELATIONSHIPS
EXPERIMENTAL DATA
NEOPLASMS