Benzene-induced hematopoietic neoplasms including myeloid leukemia in Trp53-deficient C57BL/6 and C3H/He mice.

This research focused on three major questions regarding benzene-induced hematopoietic neoplasms (HPNs). First, why are HPNs induced equivocally and at only threshold level with low-dose benzene exposure despite the significant genotoxicity of benzene even at low doses both in experiments and in epidemiology? Second, why is there no linear increase in incidence at high-dose exposure despite a lower acute toxicity (LD(50) > 1000 mg/kg body weight; WHO, 2003, Benzene in drinking-water. Background document for development of WHO Guidelines for Drinking-Water Quality)? Third, why are particular acute myeloid leukemias (AMLs) not commonly observed in mice, although AMLs are frequently observed in human cases of occupational exposure to benzene? In this study, we hypothesized that the threshold-like equivocal induction of HPNs at low-dose benzene exposure is based on DNA repair potential in wild-type mice and that the limited increase in HPNs at a high-dose exposure is due to excessive apoptosis in wild-type mice.

[Gymnema sylvestre leaf extract: a 52-week dietary toxicity study in Wistar rats].

A 52-week study of oral-repeated-dose toxicity for the extraction powder of Gymnema sylvestre (GS), Indian-native genus, Metaplexis japonica, was conducted in both genders of Wistar rats. The rats were administered a graded dose of GS at 0.01, 0.

[Twenty-eight day repeated dose oral toxicity test of synergist of a pyrethroid insecticide, 2,3,3,3,2',3',3',3'-Octachlorodipropyl ether (S-421) in rats].

2,3,3,3,2',3',3',3'-Octachlorodipropyl ether (Abbreviation; S-421) is originally developed as synergist of a pyrethroid insecticide. In recent years, S-421 is used widely at home, for a mosquito-repellent incense, electric mosquito-repellent, an insect-killing spray, a vacuum cleaner paper pack, etc. as well.

[Kooroo color: 90-day dietary toxicity study in F344 rats].

A subchronic toxicity study on kooroo color was conducted using F344 rats of both genders. Kooroo color is an extract of yam root, Dioscorea matudai Hayata, of which the major components are known to be flavonoid pigments. Use of kooroo as a food color is permitted by the Food Sanitation Law in Japan, but the chronic toxicity has not been evaluated in the literature.