home edit2 whole TSD November 2002 PDF format - OEHHA

feeding studies on by NCI (1979) using male and female B6C3F 1 mice and Fischer 344 rats and by
Weisburger et al. (1978) using male and female CD-1 HaM/ICR mice and male Charles River CD rats
are reported in Gold et al. (1984). In contrast to rats, mice are sensitive to p-chloro-o-toluidine
hydrochloride-induced carcinogenicity. Vascular tumors (hemangiomas and hemangiosarcomas) were
induced in treated mice of both strains and sexes tested.
Methodology
Expedited Proposition 65 methodology (with cross-route extrapolation) was used to derive a cancer
potency factor. The cancer potency for p-chloro-o-toluidine is based on the bioassay results for the
hydrochloride, adjusted for differences in molecular weight. An overall cancer potency was estimated
by taking the geometric mean of the 4 values derived from dose-response data for vascular tumors from
each of the mouse sex and strains tested (male and female CD-1 and B6C3F 1 mice) (Weisburger et al.,
1978; NCI, 1979; see Table 1). Male B6C3F 1 mouse survival in the NCI (1979) study was poor; a
cancer potency for that sex and strain was therefore derived using a time-to-tumor analysis (Crump et
al., 1991; Cal/EPA, 1992). A unit risk factor was then calculated by OEHHA/ATES from the cancer
potency factor using a reference human body weight of 70 kg and an inspiration rate of 20 m 3 /day.
V. REFERENCES
Anderson EL and the Carcinogen Assessment Group of the U.S. Environmental Protection Agency
1983. Quantitative approaches in use to assess cancer risk. Risk Anal 3:277-295.
California Environmental Protection Agency (Cal/EPA) 1992. Expedited Cancer Potency Values and
Proposed Regulatory Levels for Certain Proposition 65 Carcinogens. Office of Environmental Health
Hazard Assessment, Reproductive and Cancer Hazard Assessment Section, Berkeley, CA.
Crump KS, Howe RB, Van Landingham C and Fuller WG. 1991. TOXRISK Version 3. TOXicology
RISK Assessment Program. KS Crump Division, Clement International Division, 1201 Gaines Street,
Ruston LA 71270.
Currie AN. 1933. Chemical haematuria from handling 5-chloro-ortho-toluidine. J Ind Hyg 15:203-213.
Gold L, Sawyer C, Magaw R, Backman G, de Veciana M, Levinson R, Hooper N, Havender W,
Bernstein L, Peto R, Pike M and Ames B. 1984. A Carcinogenic Potency Database of the
standardized results of animal bioassays. Environ Health Perspect 58:9-319.
Hazardous Substance Data Bank (HSDB) 1994. National Library of Medicine, Bethesda MD (CD-
ROM Version). Micromedix, Inc., Denver CO, Edition 22.
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