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

Key value for chemical safety assessment

Effects on fertility

Description of key information

The NOAEL for reproductive performance and fertility for the read-across substance (Similar Substance 01) was determined to be 1000 mg/kg bw/d for male and female Wistar rats.

Effect on fertility: via oral route

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

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

The test item (read-across source 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.

The pups were sexed and examined for macroscopically evident changes on PND 0. They were weighed on PND 1, 4, 7 and 13. Their viability was recorded. At necropsy on PND 13, all pups were sacrificed with CO2, under isoflurane anesthesia, and examined macroscopically for external and visceral findings.

Anogenital distance (defined as the distance from the anus [center of the anal opening] to the base of the genital tubercle) measurements were conducted in a blind randomized fashion, using a measuring ocular on all live male and female pups on PND 1.

All surviving pups were examined for the presence or absence of nipple/areola anlagen on PND 13. The number of nipple/areola anlagen were counted.

Blood samples were taken from all surplus pups or 2 preferably female pups per litter at PND 4 as well as one male and one female pup per litter at PND 13 by decapitation under isoflurane anesthesia for hormone measurement.

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 and F1 pups.

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 reproductive toxicity up to a dose level of 1000 mg/kg bw/d.

The NOAEL for reproductive performance and fertility was determined to be 1000 mg/kg bw/d for male and female Wistar rats.

Effects on developmental toxicity

Description of key information

The NOAEL for developmental toxicity for the read-across source substance (Similar Substance 01) was 1000 mg/kg bw/d as determined in the OECD 422 study.

Effect on developmental toxicity: via oral route

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

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

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 with an analogous substance in rats, no effects on fertility or developmental toxicity were observed. As a result the substance is not considered to be classified for reproduction and developmental toxicity under Regulation (EC) No 1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.