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EC number: 455-560-2 | CAS number: -
The OECD TG 407 study of good quality (GLP, OECD guideline). The following treatment related microscopic findings were observed: (1) Bile duct proliferation of minimal or slight degree (2/5 males and 2/5 females at 150 mg/kg/day, 4/5 males and 4/5 females at 450 mg/kg/day); (2) Diffuse midzonal/centrilobular hypertrophy of the liver at minimal or slight degree (4/5 males at 450 mg/kg/day); (3) Increased severity of cortical hyaline droplets in the kidneys to slight or moderate degree (4/5 males at 150 mg/kg/day and 5/5/ males at 450 mg/kg/day); (4) Very slight increase in the severity of splenic hemopoiesis (primarily erythropoiesis) to a moderate degree (1/5 males at 450 mg/kg/day).
The bile duct effects observed at 150 mg/kg/day were not indicative of clear organ dysfunction and were not regarded to be adverse in toxicological terms. Reduced red blood cell counts, hemoglobin level, and hematocrit level in females at 150 and 450 mg/kg/day were seen, but reticulocytosis was seen only at the high dose. Liver weight of males and females at 450 mg/kg/day were increased, while liver to body weight ratios were increased in males and females at 150 and 450mg/kg/day. There were no increases in the enzymes indicative of liver pathology. The liver changes were considered as typical adaptive changes to xenobiotics.
A slightly increased kidney to body weight ratio was measured for males at 450 mg/kg/day. The kidney microscopic observation (hyaline droplets formation) is a well-known species (rat) and gender (male) specific finding with certain chemicals. This finding, although adverse in the rats, is irrelevant for human hazard assessment.
Deaths at 450 mg/kg/day were considered treatment-related, and as such considered to be clear evidence for an adverse effect of the test substance at this dose level. Therefore, from the results presented in this report, a definitive systemic No Observed Adverse Effect Level (NOAEL) for Pentamethyl-trioxepane of 150 mg/kg/day was established.
In conclusion, the effects observed at 150 mg/kg/day were not indicative of clear organ dysfunction and were not regarded to be adverse in toxicological terms. Deaths at 450 mg/kg/day were considered treatment-related, and as such considered to be clear evidence for an adverse effect of the test substance at this dose level. Therefore, from the results presented in this report, a definitive No Observed Adverse Effect Level (NOAEL) for Pentamethyl-trioxepane of 150 mg/kg/day was established.
The kidney effects observed are irrelevant to human health hazard assessment. The liver weight effects are adaptive changes to xenobiotics.
In a OECD 421 repeated dose reproductive screening study, a NOAEL of 150 mg/kg/d was determined. Except for an increased liver weight, no significant systemic toxicity was noted.
Based on the reapted dose study information, the data are complete and not sufficient for classification.
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