Developmental toxicity evaluation of sodium thioglycolate administered topically to Sprague-Dawley (CD) rats and New Zealand White rabbits.

Background: Sodium thioglycolate, which has widespread occupational and consumer exposure to women from cosmetics and hair-care products, was evaluated for developmental toxicity by topical exposure during the embryonic and fetal periods of pregnancy

Methods: Timed-mated Sprague-Dawley rats (25/group) and New Zealand White (NZW) rabbits (24/group) were exposed to sodium thioglycolate in vehicle (95% ethanol:distilled water, 1:1) by unoccluded topical application on gestational days (GD) 6-19 (rats) or 6-29 (rabbits) for 6 hr/day, at 0, 50, 100, or 200 mg/kg body weight/day (rats) and 0, 10, 15, 25, or 65 mg/kg/day (rabbits). At termination (GD 20 rats; GD 30 rabbits), fetuses were examined for external, visceral, and skeletal malformations and variations.

Results: In rats, maternal topical exposure to sodium thioglycolate, at 200 mg/kg/day (the highest dose tested) on GD 6-19, resulted in maternal toxicity, including reduced body weights and weight gain, increased relative water consumption and one death.

The genetic toxicity of 3,3',4,4'-tetrachloroazobenzene and 3,3',4, 4'-tetrachloroazoxybenzene: discordance between acute mouse bone marrow and subchronic mouse peripheral blood micronucleus test results.

3,3',4,4'-Tetrachloroazobenzene (TCAB) and 3,3',4, 4'-tetrachloroazoxybenzene (TCAOB) are dioxin-like chemicals that were investigated for toxicity in 13-week gavage studies in male and female B6C3F(1) mice and F344N rats by the National Toxicology Program. As part of the comprehensive toxicological investigation of these chemicals, peripheral blood smears from mice treated 5 days per week for 13 weeks with 0.1-30mg/kg/day TCAB or TCAOB were analyzed for the frequency of micronucleated (MN) normochromatic erythrocytes (NCE).

Toxicokinetics.

The toxicokinetic determinants of dioxin and related chemicals depend on three major properties: lipophilicity, metabolism, and binding to CYP1A2 in the liver. The induction of CYP1A2 is partially under the control of the aryl hydrocarbon receptor (AhR). Lipophilicity increases with more chlorination and controls absorption and tissue partitioning.

Statistical analysis of skin tumor data from Tg.AC mouse bioassays.

New strategies for identifying chemical carcinogens and assessing risk have been proposed based on the Tg.AC (zetaglobin promoted v-Ha-ras) transgenic mouse. Preliminary studies suggest that the Tg.

Effects of glutaraldehyde in a 2-year inhalation study in rats and mice.

Whole-body inhalation toxicology and carcinogenicity studies were performed with the widely used fixative and cold-sterilant glutaraldehyde. Groups of 50 male and female F344/N rats and B6C3F(1) mice were exposed to glutaraldehyde (rats: 0, 250, 500, or 750 ppb; mice: 0, 62.5, 125, or 250 ppb) 6 h/day, 5 days/week, for 104 weeks.