National Toxicology Program

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (TR-521)

The Subcommittee accepted unanimously (12 yes, 0 no) the conclusions as written, clear evidence of carcinogenic activity of 2,3,7,8-tetrachlorodibenzeno-p-dioxin in female rats. The Subcommittee recommended the addition of "mesenteric artery" to the list of sites of nonneoplastic lesions in the last line of the abstract.

3,3',4,4',5-Pentachlorobiphenyl (TR-520)

The Subcommittee accepted unanimously (12 yes, 0 no) the conclusions as written, clear evidence of carcinogenic activity of 3,3',4,4',5-pentachlorobiphenyl in female rats.

2,3,4,7,8-Pentachlorodibenzofuran (TR-525)

The Subcommittee accepted unanimously (12 yes, 0 no) the conclusions as written, some evidence of carcinogenic activity of 2,3,4,7,8-pentachlorodibenzofuran in female rats.

Dioxin mixture (PCB 126, TCDD, PeCDF) (TR-526)

The Subcommittee accepted unanimously (12 yes, 0 no) the conclusions as written, clear evidence of carcinogenic activity of the dioxin mixture (PCB 126, TCDD, PeCDF) in female rats.

Malachite Green and Leucomalachite Green (TR-527)

The Subcommittee accepted (10 yes, 2 no) the conclusions as written, equivocal evidence of carcinogenic activity of Malachite Green in female rats, and no evidence of carcinogenic activity in female mice exposed to 100, 225, or 450 ppm. The Subcommittee recommended that the finding of nonneoplastic lesions in the liver of female mice be deleted.

The Subcommittee accepted (11 yes, 1 no) the conclusions as written, equivocal evidence of carcinogenic activity of Leuocomalachite Green in male and female rats, and some evidence of carcinogenic activity in female mice. The Subcommittee recommended that the finding of marginally increased incidences of mammary gland adenoma or carcinoma (combined) in female rats be deleted.

Anthraquinone (TR-494)

The Subcommittee recommended that the title of the report be changed to "Anthracene-derived Anthraquinone" and that it be made clear throughout the report that the material used in the study was anthracene-derived anthraquinone. With these changes, the Subcommittee accepted (7 yes, 6 no) the technical report and the conclusions as written, some evidence of carcinogenic activity of anthraquinone in male rats and clear evidence of carcinogenic activity in female rats and male and female mice.

1,2,3-Trichloropropane 2,2-Bis(bromomethyl)-1,3-propanediol and Nitromethane in fish (TR-528)

The Subcommittee accepted (8 yes, 2 no and 2 absent) the conclusion as written, 2,2-bis(bromomethyl)-1,3-propanediol was carcinogenic in male guppies and male medaka and not carcinogenic in female medaka. The Subcommittee concluded that the study was inadequate to determine if 2,2-bis(bromomethyl)-1,3-propanediol was carcinogenic in female guppies.

The Subcommittee accepted (8 yes, 2 no and 2 absent) the conclusion as written, 1,2,3-trichloropropane was carcinogenic in male and female guppies and in male and female medaka.

The Subcommittee accepted (8 yes, 2 no and 2 absent) the conclusion that nitromethane was not carcinogenic in female guppies at concentrations up to 70 mg/L for 16 months and in female medaka at concentrations up to 40 mg/L for 13 months. The Subcommittee concluded that the study was inadequate to determine if nitromethane was carcinogenic in male guppies. The Subcommittee recommended that the call of equivocal evidence of carcinogenicity of nitromethane in male medaka at concentrations of up to 40 mg/L for 13 months be changed to not carcinogenic.