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Toxic effect type:
dose-dependent

Effects on fertility

Description of key information

NOAEL for fertility ≥ 750 mg/kg bw/day (based on the sub-acute studies on OB 4 -MSA and OB 3a-A(Na))

NOEL for parental toxicity = 300 mg/kg/day (based on the chronic study on OB 3a-MSA)

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
300 mg/kg bw/day
Study duration:
subchronic
Species:
rat
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 substance under registration OB 2-DSA belongs to the category of Stilbene Fluorescent Whitening Agents.Currently, a study on 2-DSA assessing reproductive toxicity is still in progress and will support the possibility to use the studies on the analogue 2-A to adapt the information requirement of developmental toxicity.

The preliminary results of dose range finding at 100, 300, 1000 mg/Kg bw/day indicates very little effects only at the highest tested dose of 1000 mg/Kg bw/day.

Following oral exposure by gavage, the similar substances show no toxicological effects on the reproduction parameters, therefore, considering the high structural similarity and the comparable physicochemical/toxicokinetic profile between this category of substances, their studies are used to cover the endpoint of OB 2-DSA.Details on the Read Across approach for category are reported in a document attached in IUCLID section 13.

Recently, a Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening (OECD 422), following GLP’s principles, was performed on OB 4-MSA at doses of 80, 250 and 750 mg/kg/bw.

No toxicologically adverse effects of the test item on growth of animals, food consumption and health condition of animals were detected in both sexes.

During the biometry of organs, statistically significantly increased relative weight of testes and statistically insignificantly increased absolute and relative weight of pituitary gland in males were found out. Examination of sperm motility and morphology did not show any significant changes. During pathological inspection of reproductive organs, no changes were detected in animals of both sexes. During histopathological examination, only spontaneous change in prostate gland (chronic inflammation) was found out. The findings, which related to previous gravidity in uterus (presence of hemosiderin and focal accumulation of lipophages and siderophages in the mesometrium) were found out in females. These findings were not related to the treatment of the test item.

In females the number of implantation sites was increased. One female with abort was detected. The fertility parameters were not changed compared to control group.

All changes in reproductive parameters observed in parental males and females at all dose levels were considered to be of no toxicological significance. The NOAEL for reproduction was therefore established as 750mg/kg body weight/day.

A further Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening is available and was carried out on OB 3a-A(Na), with the same conditions and doses as the one performed for OB 4-MSA.

Repeated oral administration of the test item, to rats by gavage did not cause any mortality (except one male from the dose level 250 mg/kg/day). This death was accidental and not treatment-related.

The body weight of parental males and females was not affected by the test item administration.

Evaluation of the absolute and relative weight of reproductive organs of male and female, as well as the weight of pituitary and thyroid gland, did not reveal any statistically significant differences in organ weight.

Test item treatment did not affect male ability to produce sperm that can fertilise eggs and ability of females to become pregnant. 

No adverse effect of the test item treatment was observed during examination of thyroxine and rat thyroid stimulating hormone blood concentration in males. 

Histological examination did not reveal negative effect of the test item on collected organs of reproductive organs (pituitary and thyroid gland). Spermatogenesis in the testes of the high dose administered males was without any pathological findings. Epididymides of both control and high dose males were without any pathological findings. Sporadic findings were of spontaneous origin. The administration of test item did not cause pathological changes in the organs. Examination of sperm motility and morphology in treated parental males did not show any differences in comparison with the control males. The administration of test item did not cause damage of sperms.

The number of implantations was comparable between treated and control groups. The test item did not affect the number of pups and their development.

Under test condition, the NOAEL (No Observed Adverse Effect Level) value for REPRODUCTION was established as 750mg/kg body weight/day.

An additional study on OB 3b-A, according to the OECD guideline 422, is still in progress and data will be updated as soon as results will be available.

A two-generation reproductive toxicity study was conducted on the analogue substance OB 3a-MSA, according to the EPA OPPTS 870.3800 (Reproduction and Fertility Effects) guideline, under GLP conditions.

A dose range-finding experiment in Sprague-Dawley rats was firstly conducted. 10 rats/sex/dose were dosed at 30, 100, 300 or 1000 mg/kg bw/day by oral gavage during premating, mating, gestation and lactation. Males were killed after mating and females and pups were killed on day 4 of lactation. No substance-related finding was noted in any of the parental animals or pups at any dose level.

Based on the results of the DRFE, the final doses selected for the main study were 0, 100, 300 and 1000 mg/kg bw, at a constant volume of 10 ml/kg.

The main study consisted of 3 treatment groups and 1 vehicle (0.5% aqueous carboxymethylcellulose) control group (26 rats per sex per group). The animals were exposed to the test article daily via oral gavage throughout 2 consecutive generations. The test article was administered at dose levels of 0, 100, 300, and 1000 mg/kg/day at a constant volume of 10 mL/kg.

The duration of the entire study was approximately 9 months. Adult rats were paired after a growth (premating) period of at least 10 weeks for P and F, parental rats. Observations for clinical signs, body weights, and food consumption were measured pretest (P generation only) and during the premating, gestation, and lactation periods in adult animals from both generations.

Estrous cyclicity in P and F1 females was evaluated beginning 3 weeks before and continuing throughout mating. Fertility of adults was evaluated. Sperm count, motility, and morphology were determined for all adult males. Selected organs from adult animals were collected, weighed, preserved, and microscopically examined. Gross lesions from selected control and 1000 mg/kg/day P and F1 parental animals were microscopically examined. Parameters recorded for offspring included survival at birth and during lactation, litter size, individual pup weights and sex at birth and during lactation, gross abnormalities, and clinical observations. Sexual maturation (vaginal opening and preputial separation) was measured in F1 pups selected as parents for the second generation. Selected F1 and F2 weanlings were subjected to a necropsy, and specified organs were weighed and preserved.

A total of 3 animals from the P generation and 8 animals from the F1 generation died or were euthanized in extremis during the study. None of these deaths, however, were considered to be test article related.

No effects on parental body weight, food consumption, or macroscopic and microscopic observations were noted during the premating, gestation, or lactation periods in either parental generation.

A test article-related increase in kidney weight (absolute and relative) was evident in P females and F1 males and females at 1000 mg/kg/day.

No test article-related effects on reproductive performance were noted for either parental generation. Mating, fertility, and fecundity indices, copulatory interval, gestation length, sperm analysis and primordial follicle count (in F1 animals only) parameters were considered to be comparable between concurrent control and treatment groups or within historical control range for this laboratori.

No adverse, test article-related changes in growth or development of offspring were noted in either the F1 or F2 generations. Body weight was higher in F1 pups from all treatment groups when compared with controls, but although this was considered to be test article-related, the effect was not considered to be adverse or biologically significant. Other measured parameters that included litter size at birth (total, live and stillborn), survival during lactation, sexual maturation in the F1 animals, clinical observations, and macroscopic and microscopic observations and organ weights were considered to be comparable between control and treatment groups.

Based on the results of this study, the No Observed Adverse Effect Level (NOAEL) for parental toxicity was 300 mg/kg/day and for parental reproductive performance, the NOAEL was 1000 mg/kg/day.

For offspring growth and development, the NOAEL was also 1000 mg/kg/day.

Overall, the results obtained in the performed studies are consistent. Following oral exposure by gavage, the similar substances show no toxicological effects on the reproduction parameters, therefore, considering the high structural similarity and the comparable physicochemical/toxicokinetic profile between this category of substances, OB 2-DSA can be considered safe for fertility and reproduction and theNOAEL value for fertility and reproduction for the all category is assumed to be≥750 mg/kg bw/day.

Since some effect was instead observed in parental animals at the highest dose level in the two-generation study, theNOAEL value for parental toxicity was considered to be≥300 mg/kg bw/day.

 

Effects on developmental toxicity

Description of key information

NOAEL for developmental toxicity ≥ 750 mg/kg bw/day (based on the sub-acute studies on OB 4 -MSA and OB 3a-A(Na))

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
750 mg/kg bw/day
Study duration:
subacute
Species:
rat
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

The substance under registration OB 2 -DSA belongs to the category of Stilbene Fluorescent Whitening Agents. The investigation on developmental toxicity potential is not a standard requirement for the tonnage band registration of this substance. However, with regard to this endpoint the category was extensively explored and no significant adverse treatment-related maternal or developmental effects were observedDetails on the Read Across approach for category are reported in a document attached in IUCLID section 13.

Currently, a study on 2-DSA assessing reproductive toxicity is still in progress and will support the possibility to use the studies on the analogue 2-A to adapt the information requirement of developmental toxicity.

The preliminary results of dose range finding at 100, 300, 1000 mg/Kg bw/day indicates very little effects only at the highest tested dose of 1000 mg/Kg bw/day.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), 3.7 Reproductive toxicity section, reproductive toxicity includes adverse effects on sexual function and fertility in adult males and females, as well as developmental toxicity in the offspring.

The available experimental data are adequate for classification and labelling and the substance is not classified for reproductive and developmental toxicity according to the CLP Regulation (EC 1272/2008).

Additional information