Sensitivity survival data

In a 2-year oral chronic-duration feeding study, no tumors or precancerous lesions were noted in rats administered mercuric acetate in the diet at doses of 0.2-66 mg Hg/kg/day (Fitzhugh et al. 1950) no conclusions could be derived on the carcinogenicity of mercuric acetate. The study was limited because the group sizes were small (10-12 rats per group) survival data were not reported a considerable but unspecified number of rats reportedly died from pneumonia, which reduced the sensitivity of the study to detect a carcinogenic response and only limited histopathological analyses were performed. 

Fisher, M., Gore, M., (2013). Cost-effectiveness of trabectedin plus pegylated liposomal doxorubicin for the treatment of women with relapsed platinum -sensitive ovarian cancer in the UK analysis based on the final survival data of the OVA-301 trial. Value Health 16(4), 507-516. 

No acute oral MRL was derived for methyl parathion because data regarding the most sensitive effect that was observed after acute oral exposure are conflicting. Increased pup mortality and altered behavior occurred in offspring of rats exposed to 1 mg/kg/day methyl parathion during, but no effects on pup survival or on sensitive electrophysiological indices of neurotoxicity were seen at virtually the same dose, 0.88 mg/kg/day, in a similar developmental toxicity study. 

Data on nickel toxicity to terrestrial invertebrates are scarce. A soil concentration of 757 mg/kg DW soil is lethal to 50% of earthworms (Eisenia foetida) in 14 days, and higher concentrations of 1200 to 12,000 mg/kg DW soil for shorter periods produced reduced growth and survival in the same species (WHO 1991). Earthworms are less sensitive to nickel if the medium is rich in microorganisms and organic matter, thus, making the nickel less bioavailable (WHO 1991). 

In rats, inhalation exposure to 330-1,000 ppm during gestation caused maternal weight loss and clear maternal hepatotoxicity, but no effect on conception, number of implants, or number of resorptions (Schwetz et al. 1974). There were no gross anomalies, although fetal size was somewhat decreased. These data suggest that the fetus is not preferentially sensitive to carbon tetrachloride, and effects of carbon tetrachloride on fetal development and post-natal survival are likely secondary to maternal toxicity. 

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