5H-Cyclopenta[h]quinazoline, 6,6a,7,8,9,9a-hexahydro-7,7,8,9,9-pentamethyl-

Endpoint summary

Description of key information

In the repeated dose toxicity study performed according to OECD TG 407 the following results were found:

The local NOAEL was determined to be 300 ppm corresponding to 22.1 mg/kg bw/day based on irritation effects in the stomach.

The systemic NOAEL was determined to be 300 ppm corresponding to 22.1 mg/kg bw/day based increased liver weight accompanied by changes in clinical chemistry parameters and histopathological abnormalities.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

22.1 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The one repeated dose toxicity study available is of sufficient quality for the present dossier.

System:

hepatobiliary

Organ:

liver

Additional information

In a subacute repeated dose toxicity study(OECD TG 407, GLP) the test substance was administered by continuous dietary admixture to three groups, each of five male and five female Han™:RccHan™:WIST strain rats at dietary concentrations of 300, 800 and 1200 ppm (equivalent to a mean achieved dosage of 22.1, 59.7, and 87.4 mg/kg bw/day respectively for males and 22.6, 59.1 and 81.4 mg/kg bw/day respectively for females). A control group of five males and five females were treated with basal laboratory diet. Two recovery groups, each of five males and five females, were treated with the high dose (1200 ppm) or basal laboratory diet for twenty-eight consecutive days and then maintained without treatment for a further fourteen days.

Clinical signs, body weight change, food and water consumption were monitored during the study. Haematology, blood chemistry and urinalysis were evaluated for all non-recovery group animals at the end of the treatment period and for all recovery group animals at the end of the treatment-free period. All animals were subjected to gross necropsy examination and histopathological examination of selected tissues was performed.

Results, clinical signs:There were no unscheduled deaths. There were no clinical signs apparent and no treatment-related changes in behaviour functional performance tests or sensory reactivity test.

Females treated with 1200 ppm showed a reduction in body weight gain during the first two weeks of treatment, with actual body weight losses evident during the first week. Females treated with 800 ppm also showed a reduction in body weight gain during Weeks 1 and 4. Although some recovery was evident in 1200 and 800 ppm females, overall body weight gains during the treatment period were lower than control females but did not show a clear dose-response. Terminal bodyweight was reduced by 10% in females treated with 1200 ppm accompanied by a decrease in the body weight gain of 70% and was considered adverse. No toxicologically significant effects on bodyweight, bodyweight gain and food consumption were detected in males treated with 1200 or 800 ppm, in animals of either sex treated with 300 ppm or in recovery animals during the treatment free period. The reduced bodyweight gain in females was accompanied by lower food consumption of up to -25% in high dose females. No such effects were detected in males or in recovery animals during the treatment free period. No adverse effect on water consumption was observed. Overall, the effect on body weight (gain) and food consumption at 1200 ppm in females was considered to represent an adverse effect of treatment although reluctance to eat the dietary formulation at this dose level may have contributed to this effect. The NOAEL for effects on body weight (gain) is 1200 ppm / 81.4 mg/kg bw/day.

Haematology:There were no toxicologically significant effects detected in the haematological parameters examined.

Clinical chemistry: At the end of the treatment period, males treated with 1200 ppm showed increases in total protein, albumin, calcium concentration and a reduction in glucose. Males treated with 1200 and 800 ppm showed an increase in gamma glutamyltranspeptidase (yGT). Females treated with 1200 ppm showed increases in chloride and calcium concentration and a reduction in aspartate aminotransferase. Females from all treatment groups showed increases in total protein, yGT and reductions in glucose and albumin/globulin ratio. Animals of either sex treated with 1200 or 800 ppm also showed an increase in cholesterol. No such effects were detected in males treated with 300 ppm or in recovery animals following fourteen days without treatment.

There were no treatment-related effects detected in the urinalytical parameters examined.

Organs:  No treatment-related macroscopic abnormalities were detected.

Organ-liver:At the end of the treatment period, animals of either sex treated with substance showed an increase in liver weight both absolute and relative to terminal body weight. The increase in rel. liver weight were 5%, 31% and 38% and 16%, 42% and 63% at 300 ppm, 800 ppm and 1200 ppm in males and females, respectively. Centrilobular hypertrophy was evident in animals of either sex from all treatment groups. Periportal vacuolation (fat-type) was evident in animals of either sex treated with 1200 or 800 ppm. Periportal cellular change (eosinophilic, homogenous cytoplasm) was also evident in males treated with 1200 or 800 ppm. All of these changes showed evidence of reversibility in the recovery period within the study.

The effects observed at the mid and the high dose, increases in liver weight accompanied by changes in liver-related clinical chemistry parameters, such as yGT, total protein and cholesterol and histopathological abnormalities, were considered adverse. Effects observed at the low dose level (rel. weight < 16% and hypertrophy in females in 3/5 animals) are considered adaptive. Therefore the NOAEL for liver effects is set at 300 ppm / 22.1 mg/kg bw/day.

Organ-kidney effects: At the end of the treatment period, males and females treated with 1200 ppm showed an increase in kidney weight both absolute and relative to terminal body weight (not statistically significant in females). Increased hyaline droplets and multifocal basophilic tubules were evident in males from all treatment groups. These findings are linked to the accumulation of alpha 2u-globulin, which is unique to the male rat and considered to be of no relevance to man and therefore not considered relevant for NOAEL derivation.

Organ-Thyroid:Follicular epithelial hypertrophy was evident in animals of either sex from all treatment groups. This finding persisted in one recovery male only following the recovery period. These effects can be the result of hepatocellular induction and enhanced hepatic metabolism. Thyroid hormone levels were unaffected by treatment.

Organ-Stomach:Irritation effects of the substance such as erosion or ulceration were present in the glandular region the stomach of females treated with 1200 ppm. Inflammatory change, and/or non-glandular hyperplasia was also present in females treated with 800 and 1200 ppm. Complete regression was evident in recovery females following fourteen days without treatment.

Conclusion:Oral administration of the substance to rats for a period of twenty-eight consecutive days at dietary concentrations of 300, 800 and 1200 ppm resulted in treatment-related effects detected in animals of either sex from all treatment groups. The effect on body weight (gain) and food consumption at 1200 ppm was considered to represent an adverse effect of treatment. Local irritation effects were observed in the stomach at the mid and high dose levels with a NOAEL at 300 ppm / 22.1 mg/kg bw/day. The liver is considered a target organ and relative increases in liver weight and effects including clinical chemistry and histopathological changes were observed from the low dose onwards. The liver shows a dose related increase in processing the substance resulting in hypertrophy (at the low dose), periportal vacuolation and eosinophilic cytoplasm at the mid and high dose levels. It seems that from the mid dose onwards the liver becomes overloaded. The function of the liver was not impaired but the effects are considered adverse. Therefore the NOAEL is 300 ppm / 22.1 mg/kg bw/day. The NOAEL for local effects is 300 ppm equivalent to 22.1 mg/kg bw/day based on irritation effects in the stomach and the NOAEL for systemic effects is 300 ppm equivalent to 22.1 mg/kg bw/day based on the liver effects at higher doses.

Dose range finder - 14 days

In a fourteen day repeated dose oral range finding toxicity/palatability study the test substance was administered by continuous dietary admixture to three groups, each of three male and three female Han™:RccHan™:WIST strain rats at dietary concentrations of 500, 1000 and 2000 ppm (equivalent to a mean achieved dosage of 39.4, 75.7, and 125.3 mg/kg bw/day respectively for males and 42.0, 85.5 and 122.2 mg/kg bw/day respectively for females). A control group of three males and three females were treated with basal laboratory diet. No analysis was conducted to determine the concentration of the dietary admixtures.

Clinical signs, body weight change, dietary intake and water consumption were monitored during the study. All animals were subjected to gross necropsy examination.

There were no unscheduled death during the study and no apparent clinical signs. Terminal body weight and bodyweight gain were decreased in the animals treated with 2000 and 1000 ppm and two of three female animals in the 2000 ppm group had a terminal weight below their starting weight. Animals of either sex treated with 2000 ppm showed a notable reduction in food consumption throughout the treatment period. Food conversion efficiencies were lower than controls transiently during the study in males and throughout the treatment period in females. At 1000 ppm, food consumption was transiently reduced in females while food consumption was transiently reduced in animals of either sex.

There was no effect on water consumption in treated animals. No macroscopic abnormalities were apparent at terminal necropsy.

Dietary exposure to the test substance was associated with adverse effects on bodyweight and food consumption at 2000 ppm and this dietary level was considered too high for use in a future toxicity study. The effects observed at 1000 ppm were insufficient to exclude this dietary level from further investigation. Dietary levels of 0 (control), 500, 800 and a high dose level between 1200 and 1500 ppm are recommended for further repeated dose toxicity studies.

 

Justification for classification or non-classification

Based on the results of the 28-day repeated diet toxicity study the substance does not have to be classified for repeated dose toxicity according to EU CLP (EC 1272/2008 and its amendments).