Tumorigenic effect of an organomanganese compound on F344 rats and Swiss albino mice

Trioctanoin suspensions of manganese dioxide and manganese powder were injected im into inbred F344 rats and Swiss albino mice. The manganese powder was also administered orally to the rats. No difference in tumor incidence was noted between treated and control animals. In contrast, manganese (manganous) acetylacetonate administered im to rats produced a statistically significant number of fibrosarcomas at the sites of injection.

Toxicity of styrene and styrene oxide on chick embryos

Styrene and styrene oxide were injected into the air space of fertilized chicken eggs at different times during an incubation period of 14 days. The toxicity of styrene and styrene oxide when injected on the fourth day of incubation revealed an LD50 of 40 mumol/egg and 1.5 mumol/egg, respectively. Malformations were found in 0-20% of the embryos, but never in the controls. The results obtained point to a need for further experimental, and possibly epidemiologic, studies on the consequences of styrene exposure.

Comparison of the tumor-initiating activities of benzo(a)pyrene arene oxides and diol-epoxides

The ability of arene oxides, and diol epoxides of benzo(a)pyrene to initiate skin tumors in mice was determined by using a two-stage system of tumorigenesis. (+/-)-7beta,8alpha-Dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene was a more effective tumor initiator than was (+/-)-7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene when applied topically to CD-1 mice and then followed by twice-weekly applications of the promotor 12-O-tetradecanoylphorbol-13-acetate. (+/-)-7beta,8alpha-Dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene was approximately 20 to 30% as active as benzo(a)pyrene was as a tumor initiator. (+/-)-7beta,8alpha-Dihydroxy-7beta,8beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, benzo(a)pyrene, 9,10-oxide, and benzo(a)pyrene 11, 12-oxide, possessed about 1, 2, and 10%, respectively, of the tumor-initiating activity of benzo(a)pyrene.

Mesothelial reaction of asbestos and other irritants after intraperitoneal injection

Ten groups of rats were injected intraperitoneally with one of the following suspensions; (i) standard reference crocidolite; (ii) acid-treated crocidolite (iii) crocidolite plus iron oxide; (iv) crocidolite plus silica; (v) iron oxide; (vi) silica; (vii) long fibre crocidolite; (viii) short fibre crocidolite; (ix) long fibre glass and (x) short fibre glass. Two rats from each group were killed at 45, 90, 150, 240 and 330 days respectively, and the pathology induced by the different suspensions was studied histologically at each time interval. No evidence in support of the chemical induction theory or mechanical irritation theory in the pathogenesis of peritoneal mesotheliomas could be found, although all the suspensions except iron oxide caused a reactive mesothelium.

Factors affecting the toxicity of the element indium

Hydrated indium oxide is 40 times more toxic than ionic indium, when expressed as lethality per quantity of metal injected.

Ionic indium is nephrotoxic, causing damage in the proximal portion of the proximal convoluted tubule. In this respect, it resembles the element mercury. At extremely high doses, ionic indium causes focal necrosis in the liver.

Hydrated indium oxide causes damage to those organs which contain phagocytic cells which clear the insoluble particles from the blood after i.v. injection. Actual focal necrosis was found in the liver, spleen and bone marrow. Damage was also found in the thymus and lymph nodes. At extremely high doses, damage was observed in the proximal convoluted tubules of the kidney.

Hydrated indium oxide caused extensive haemorrhage and marked thrombocytopenia. Fibrin thrombi were observed in the liver.

The increase in toxicity of indium resulting from phagocytosis of insoluble oxides by the reticuloendothelial system may represent a general mechanism by which the toxicity of certain heavy metals is increased.