2-[4-[[2-(cyanoimino)hexahydro-4,6-dioxo-5-pyrimidyl]azo]phenyl]-6-methylbenzothiazole-7-sulphonic acid, compound with 2,2',2''-nitrilotris[ethanol] (1:1)

Endpoint summary

Description of key information

The no observed adverse effect level (NOAEL) for general systemic toxicity for the read-across substance (Similar Substance 01) was determined to be 1000 mg/kg bw/d for male and female Wistar rats.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

GLP and guideline compliant study

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

Repeated dose toxicity

The test item (read-across substance Similar Substance 01) was assessed for repeated dose toxicity and reproduction/developmental toxicity according to OECD 422 and GLP.

The test item was administered daily as an aqueous preparation to groups of 10 male and 10 female Wistar rats (F0 animals) by gavage at doses of 100, 300 and 1000 mg/kg body weight/day (mg/kg bw/d). Control animals (10 male and 10 female Wistar rats) were dosed daily with the vehicle only (0.5 % Carboxymethylcellulose suspension in drinking water + 5 mg/100mL Tween 80). The duration of treatment covered a 2-week pre-mating and a mating period, approximately 7 days post-mating in males, and the entire gestation period as well as approximately 23 days of the lactation period and 31 days post-mating in females (for sperm negative female).

After 2 weeks of premating treatment the F0 animals were mated to produce F1 generation pups. Mating pairs were from the same test group. Mating was discontinued as soon as sperm were detected in the vaginal smear. F0 animals were examined for their reproductive performance including determination of the number of implantation sites and the calculation of postimplantation loss for all F0 females.

A detailed clinical observation (DCO) was performed in all animals before the start of the administration period and, as a rule, thereafter at weekly intervals.

Water consumption of the F0 parents was determined for premating days 0 - 3 and 7–10. In dams water consumption was determined for gestation days (GD) 0 - 1, 7 - 8, 14 - 15 and 20 - 21 and lactation days (PND) 1 - 2, 4 - 5, 7 - 8, 10 - 11 and 13 - 14.

Food consumption of the F0 parents was determined once weekly during premating. In dams food consumption was determined for GD 0 - 7, 7 - 14, 14 - 20 and PND 1 - 4, 4 - 7, 7 - 10 and 10 - 13.

Body weights of F0 parents were determined once a week, in males throughout the study and in females during premating. During gestation and lactation period, F0 females were weighed on GD 0, 7, 14 and 20, on the day of parturition (PND 0) and on PND 4, 7, 10 and 13.

Estrous cycle data were evaluated for F0 generation females over a two week period prior to mating until evidence of mating occurred. Moreover, the estrous stage of each female was determined on the day of scheduled sacrifice.

Clinico-chemical and hematological examinations were performed in 5 animals per sex and group towards the end of the administration period.

Blood samples from all dams at PND 14 and all males at termination were taken by puncturing the retrobulbar venous plexus under isoflurane anesthesia for hormone measurement.

At the end of the administration period a functional observational battery was performed and motor activity was measured in 5 parental males and females per group.

All F0 parental animals were sacrificed by decapitation, under isoflurane anesthesia, and were assessed by gross pathology. Weights of selected organs were recorded and a histopathological examination was performed.

No test substance-related clinical, reproductive or clinical pathology adverse findings were noted at 100, 300, 1000 mg/kg bw/d for the F0 parental animals.

In conclusion, under the conditions of the present OECD 422 combined repeated dose toxicity study with the reproductive/developmental screening test in Wistar rats the oral administration of the test item by gavage to male and female Wistar rats did not result in signs of systemic toxicity up to a dose level of 1000 mg/kg bw/d. Thus, the no observed adverse effect level (NOAEL) for general systemic toxicity was 1000 mg/kg bw/d for male and female Wistar rats.

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for classification purposes. In an OECD 422 study in rats with an analogous substance no effects on general systemic toxicity were observed, therefore the NOAEL for male and female rats was determined to be 1000 mg/kg bw. As a result the substance is not considered to be classified for repeated dose toxicity under Regulation (EC) No1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.