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Description of key information

NOAEL in male rats 521 mg/kg bw/day (based on the chronic study on OB 3a-MSA)

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
521 mg/kg bw/day
Study duration:
chronic
Species:
rat

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 substance under registrationOB 3a-A(Na)belongs to the category of Stilbene Fluorescent Whitening Agents. The repeated dose toxicity of this category of substances was extensively explored and data on the toxic effects, after oral repeated exposure, are available on the substance as such and on similar substances belonging to the same category. Details on the Read Across approach for category are reported in a document attached in IUCLID section 13.

Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening, according to the OECD guideline 422 was performed on 3a-A(Na) and no effects have been reported up to the 750 mg/Kg bw/day.

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 was established as 750mg/kg body weight/day.

A Combined Repeated dose with Reproduction and Developmental toxicity study is furthermore availableOB 4-MSA(report n. 20-243, 2020). No toxic effects were observed in none of the two studies and theNOAEL values found were ≥ 750 mg/kg bw/day in both cases

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

The systemic toxicity endpoint has been firstly covered by the sub-chronic repeated dose study on1-MSAin rats, according to the OECD guideline 408, under GLP conditions (report n. 20-159, 2020).

The study was carried out following an oral administration by gavage at 120, 350 and 750 mg/kg bw/day.

The administration to rats for a period of 90 consecutive days at the highest dose level did not cause mortality related with the test item treatment.

No effect of the test item on the body weight, food consumption and water consumption were recorded during the study. Slight changes of these parameters were without toxicological importance.

No clinical findings or changes of urine parameters revealing influence of the test item were recorded.

Haematological examination showed no findings in males. Sporadic changes were measured in females: prolonged decreased total erythrocyte count, reversible increased value of platelets count (lowest and highest doses), increased mean corpuscular volume (lowest and middle doses) and reversible decreased prothrombin time (highest dose). Decreased percentual representation of reticulocytes was observed only at the lowest dose level. These differences were without dose response relationship and without correlation with other manifestations of toxicity.

Biochemical examination showed irreversible increased concentration of inorganic phosphorus in males (middle and highest doses). In females, inorganic phosphorus concentration was decreased only at the lowest dose level. Concentration of chloride ions was increased only in females (middle and highest dose levels). Value of sodium ions was decreased in both sexes of satellite animals. Other changes of measured biochemical parameters observed were without dose dependence, sex correlation and without association with related toxicologically significant endpoints.

Biometry of organs showed significantly decreased absolute and relative weight of spleen in females. These changes persisted in satellite females but without statistical significance. This effect is isolated. Changes in other related parametes usually associated with the effect of concern were not observed: no significant changes of red and white blood parameters and no histopathological findinds.

No toxicologically significant findings were detected during the histopathological examination of organs in animals at the highest dose level and satellite treated animals. Sporadic findings in epidydimis, testis and thymus were not related with test item treatment.

The NOAEL (No Observed Adverse Effect Level) value for male and female rats was established as 750 mg/kg body weight/day.

The value of NOAEL was established on the basis of no adverse effects found during haematological, biochemical and histopathological examination. Biometric changes of the spleen do not correlate with other toxicologically important endpoints.

 A test carried out on an analogue substance,OB 5-A,according to the OECD guideline 408 and under GLP (report n. 20-184, 2020), using conditions and doses similar to the ones used for target substance, supports these outcomes and was used in weight of evidence within a read-across approach.

The oral administration of the test item did not cause mortality.

No effects of the test item on the body weight, food consumption and water consumption were recorded during the study. Slight changes of these parameters were without toxicological importance.

No influence of the test item on clinical status of treated animals and satellite treated animals was recorded. No findings were detected during the histopathological examination of liver, spleen and kidneys of animals at the highest dose level and satellite treated animals.

All changes detected during the haematological and biochemical examinations were reversible (except decreased activity of ALP in males and delayed decreased activity of ALT and AST in males). All these changes observed in animals had probably an adaptive character - the organism's response to the test item treatment. A longer recovery time would probably be required to completely eliminate the altered hepatic enzyme activity in males.

All changed values of biochemical parameters in satellite treated animals have no biological or toxicological significance.

The value of NOAEL was established as 750 mg/kgbody weight/day for both males and females.

An additional 70d study is available forOB 3a-MSA(Kimmerle, 1967). Groups of 6 male and 6 female rats were given during 10 weeks (5 doses/week) 30, 60, 120, 250 or 500 mg of the test substance/kg as a solution in oil administered by gavage. A further group of 12 male and 12 female rats received daily 5.0 ml of oil/kg (control). During the experimental period, the condition of the animals was observed daily, body weights (all animals) were weekly recorded; blood and Harn status (3 males and 3 females per dose) were analysed at 14 -days, and at the end of the test, the prothrombin time (3 males and 3 female per group) and in all animals the SGPT and SGOT Transaminases and SDH were determined 24 hours after the last administration, the animals were sacrificed with ether and the internal organs (liver, kidneys, adrenals, thyroid, spleen, ovary, testis, lung) macroscopically examined and weighed.

No adverse effects were recorded: the animals of the experimental groups showed no apparent symptoms of poisoning and behaved similarly to the control animals.

The body weight is not significantly altered in the experimental groups compared with the control groups. The complete blood count, the checks of liver function tests and the urine tests did reveal no pathological findings.

After killing the rats, the internal organs in the experimental groups compared with the control groups did not appear changed and a significant dose-dependent change in the absolute and relative organ weights could not be determined (P > 0.1) in the experimental groups compared with the control group.

The NOAEL value established in this study was therefore ≥ 500 mg/kg bw/day.

Moreover, experiments investigating the effects of chronic feeding administration of the substance under registration as such along withOB 2-A, OB3a-A(free acid) andOB 3a-MSAare available.

As forOB3a-A(Na),three groups of 60 male and 60 female rats received the compound thoroughly mixed in the feed along with a fourth group of as control, for two years (1974). After death or sacrifice, all animals were examined grossly and almost all microscopically. Histopatological examination of all twenty rats sacrificed at six months was negative.

Of the twenty animals sacrificed at mid-term (12 months), there was one male rat at 10000 PPM rat with chronic mild nephritis (chronic cystitis) and two female control rats with adenocarcinoma of the mammary glands.

As the experiment progressed more and more pathology became evident; the most striking clinical finding was the observation of adenocarcinomas of the mammary glands.

The incidence was high among the four groups, excluding a correlation to the compound administration. Other effects observed were nephritis, pituitary adenomas and some pathologies/lesions, known to occur spontaneously in the albino rat and frequently in old rats, thus, no treatment related.The NOAEL value found under this test conditions was established to be ≥ 542 mg/kg bw/day for males and ≥ 779 mg/kg bw/day for females.

The study onOB3a-A(free acid)was conducted following a procedure similar to the OECD TG 453 and the substance was administered via the diet to rats (report n. 7396, 1978). The kidney weights of female animals at mid- and high-dose groups increased with respect to the control group. No evidence of a carcinogenic effect was identified and no other relevant toxicological effects were reported, a NOAEL equivalent to 779 mg/kg bw/day for females and 542 mg/kg bw/day for males, which were the highest doses tested, was set.

In the study carried out onOB 2-A, male and female rats received test for 2 years with the feed (report n. 7234, 1978).

The treated animals showed no treatment-related symptoms during the entire experimental period in any dose group. At all the doses tested the clinical chemistry analysis, sections and histopathological studies revealed no evidence of treatment-related damage to the liver. Urinalysis, urea and creatinine concentrations in serum as well as macroscopic, gravimetric and histopathological findings did not indicate kidney injuries. Histopathological examinations showed the usual age-related, spontaneous alterations. Doses up to 10000 ppm (included) were thus tolerated without any damage, therefore theNOAEL value found under this test conditions was established to be ≥ 523.9 mg/kg bw/day for males and ≥ 790.6 mg/kg bw/day for females.

As perOB 3a-MSA, the 50 male and 50 female rats (100 animals in the control group) received test substance administered for 2 years (report n. 7214, 1978).

The animals in the highest dose groups did not show during the entire experimental period any treatment-related symptoms. The growth of the rats was not affected. The haematological investigations performed during and at the end of the test showed no dose of injuries. The studies of male animals to the remaining time points and all investigations in the female animals showed no evidence for a corresponding finding. The clinical chemical analysis, sections and histopathological examinations revealed no evidence for treatment-related damage to the liver. Urinalysis, urea and creatinine concentrations in serum as well as macroscopic and histopathological organ findings did not indicate any influence on the kidneys because the incidence is low (<10%) and the significantly increased kidney weights in male and female rats in the highest dose group was not regarded as an expression of injury. Blood sugar and cholesterol levels were not substance-related alterated.

The sections of dead and killed rats did not show reference to a specific ending damage that could be caused by the substance. Histopathological examination showed the usual age-related spontaneous alterations.The NOAEL value found under this test conditions was established to be ≥ 521 mg/kg bw/day for males and ≥ 709 mg/kg bw/day for females.

 

In conclusion, the NOAEL values found in all the studies above mentioned are in line with the one obtained for the target substance, confirming an analogous behaviour of this category of substances after prolonged repeated oral exposure.For the all category a conservative value was however selected from the study carried out on OB 3a-MSA, according to a procedure similar to the OECD TG 453, were the NOAEL for male rats was established to be 521 mg/kg bw/day.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), 3.9 Specific target organ toxicity - repeated exposure section, substances are classified as specific target organ toxicants following repeated exposure by the use of expert judgement, on the basis of the weight of all evidence available, including the use of recommended guidance values which take into account the duration of exposure and the dose/concentration which produced the effect(s), and are placed in one of two categories, depending upon the nature and severity of the effect(s) observed.

Classification in Category 2 is applicable, when significant toxic effects observed in a 90-day repeated-dose study conducted in experimental animals are seen to occur within the guidance value ranges as:

- oral (rat): 10 < C ≤ 100 mg/kg bw/day

The guidance values refer to effects seen in a standard 90-day toxicity study conducted in rats.

The No Observed Adverse Effect Level was established at 521 mg/kg bw/day, on the basis of the results from a chronic study on rats.

In conclusion, the available experimental data are adequate for classification and labelling and the substance is not classified for repeated dose toxicity according to the CLP Regulation (EC 1272/2008).