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Description of key information

NOAEL (OECD 422) = 400 mg/kg bw/day (RTC, 2013)

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The toxic effects on rats after repeated oral dosing with (Z)-4-[C11-13 (branched) alkylamino]-4-oxo-2-butenoic acid, as well as any effects of the test item on male and female reproductive performance, such as gonadal function, conception, parturition and early lactation of the offspring were investigated. The study was conducted according to OECD 422 guideline and GLP (RTC, 2013).

The vehicle was corn oil. All doses were administered at a constant volume of 4 mL/kg body weight. The dose levels were 0, 40, 125 and 400 mg/kg bw/day.

Males were treated for 2 weeks prior to pairing and during pairing with females until the day before necropsy, for a total of 31 or 32 days.

Females were treated for 2 weeks prior to pairing, during pairing and throughout the gestation and lactation periods until Day 3 post partum.

The following investigations were performed: body weight, clinical signs (including neurotoxicity assessment, motor activity and sensory reaction to stimuli), food consumption, oestrous cycle, mating performance, clinical pathology investigations (haematology and clinical chemistry), litter data, macroscopic observations, organ weights and histopathological examination.

Mortality and fate of females

 

Two cases of premature death occurred during the study. One male of the control group was found dead on Day 2 of treatment but the cause of death could not be determined. One female of the high dose group was found dead on Day 3 of treatment and the cause of death was considered as a consequence of mis-dosing.

Two females were found not pregnant: one in the control and one in the mid-dose group.

In addition, one high dose female was sacrificed for total litter loss on Day 2 post partum.

The number of females with live pups on Day 4 post partum was: 9 in each of the control and mid-dose groups, 10 in the low dose group and 8 in the high dose group.

 

Clinical signsand clinical observations (Functional Observation Battery Tests)

 

Salivation and decreased muscle tone were the main clinical sign observed in all high dose males throughout the study and in all high dose females during post coitum and post partum periods.Decreased muscle tone was considered not to be of toxicological relevance, since no effects were seen in the functional observation battery tests, especially in the grip strength and foot splay tests.

Neurotoxicity assessment (removal of animals from the home cage and open arena)

Observation of animals at removal from the cage and in an open arena (neurotoxicity assessment) did not reveal changes attributable to the test item.

 

Body weight and body weight gain

 

Males of the high dose showed a slight body weight loss during the first week of the study, and body weights remained slightly decreased compared to the other groups throughout the study. However, these changes were mainly attributable to one male, which was probably mis-dosed. No differences of toxicological significance in body weights were recorded in animals of both sexes compared to the control group, throughout the study.


Food consumption

No effects on food consumption were observed in either males or females.

 

Motor activity and sensory reactivity to stimuli

No relevant differences were noted in all parameters investigated between control and treated groups.

 

Haematology

 

No changes of toxicological significance were observed in haematology parameters and coagulation tests.

 

Clinical chemistry

Due to the absence of related histopathological changes, the recorded alterations were considered of no toxicological relevance.

 

Oestrous cycle, reproductive parameters, pairing combination and mating performance

 

No relevant differences were observed for these parameters between treated and control groups.

All females mated both in the control and treated groups.

Oestrous cycle, copulatory index and fertility index did not show intergroup differences.

 

Implantation, pre-implantation loss data, pre-birth loss data and gestation length of females

 

No relevant differences were observed for these parameters between treated and control groups.

 

Litter data at birth, on Day 1 and on Day 4 post partum of females and sex ratio of pups

 

No significant differences were observed on litter data parameters and sex ratios at birth, on Day 1 and Day 4 post partum.

 

Clinical signs of pups

Clinical signs noted in pups throughout the study were considered unrelated to treatment.

 

Necropsy findings in decedent pups and in pups sacrificed on Day 4 post partum

 

Necropsy findings in decedent pups and in pups sacrificed on Day 4 post partum did not reveal any treatment-related effect.

 

Terminal body weight and organ weights

 

Terminal body weight was slightly decreased in high dose males, while no differences were observed in females.

Differences noted in absolute and relative organ weights between treated and control animals were not accompanied by histological findings. Therefore, they were considered of no toxicological importance.

 

Macroscopic observations

Unscheduled death

Two cases of premature death occurred during the study. One control male for which the cause of death could not be determined and one high dose female for which the cause of death is considered as related to mis-dosing of the test item.

 

Terminal kill

No treatment-related changes were noted.

Microscopic observations

 

No treatment-related findings were noted.

In a single male rat from the high dose, the bronchi and the alveoli in the centriacinar areas contained mucus-like fluid. This change was associated with goblet-cell metaplasia of the epithelium lining the bronchi, peribronchial fibrosis, presence of polymorphonuclear cells and histiocytes within the mucus.

The lung changes are suggested to be related to mis-dosing of the test item.

 

Seminiferous tubules were evaluated with respect to their stage in the spermatogenic cycle and no alterations were noted.

 

Conclusions

 

On the basis of the results obtained in the study, the NOAEL (No Observed Adverse Effect Level) for both systemic toxicity and reproduction/developmental toxicity was considered 400 mg/kg/day for males and females.

Justification for classification or non-classification

Based on the available data, the test substance is not classified with regard to repeated dose toxicity according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP), respectively.