Tetrasodium 4-amino-6-[[2,5-dimethoxy-4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]-5-hydroxy-3-[[4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonate

Endpoint summary

Description of key information

No adverse effects observed after repeated administration.

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

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

A 21-day study with 14 applications of Reactive Black 5 was performed with a single dose of 500 mg/kg bw/day was performed without revealing any adverse effects. The only effects seen were substance stained urine and faeces.

Structural Analogue 01: A 28 d oral (gavage) repeated dose toxicity study was conducted in rats according to OECD Guideline 407, EPA: OPPTS 870.3050, MITI guideline and EU Method B.7 in compliance with GLP. Groups of male and female rats received the test item at dose levels of 0, 62.5, 250 or 1000 mg/kg bw/day by oral gavage for a period of 28 days. 14-day recovery groups (controls and high dose animals) were also included in the study.

There were no unscheduled deaths throughout the study. Behaviour, state of health, body weight gains and food consumption were not influenced by the administration of the test substance. High dose animals showed discoloured faeces from Day 5 onwards, which was caused by the colour of the test item. Neurotoxicology measurements and haematological evaluation did not reveal any test substance-related changes.

In clinical chemistry, slightly increased triglycerides, bilirubin, AP activity [males], albumin values were observed, which lie still within the historical control values. This increase could either be a sign of a mild metabolic overload for the high dose group (1000 mg/kg bw/day) as shown by slightly higher liver weights or due to interference of the photometric method (esp. bilibubin) by the discoloration of serum and urine resulting from the test substance absorption/excretion. Additionally, slightly higher kidney weights were observed in this dose group in both sexes at the end of the treatment period. Macroscopic evaluation at final necroscopy revealed that kidneys in the high dose group were discoloured by the test substance, as well as stomachs in two high dose males. These changes at 1000 mg/kg bw/day were fully reversible in females and showed tendency to recovery in the males, after the 14-day recovery period. No test substance-related histopathological findings were detected.

Based on alteration in clinical chemistry parameters and organ weight as well as pigment storage in the kidneys at 1000 mg/kg bw/day, the NOEL were established at the next lower dose of 250 mg/kg bw/day. As these were mild, did not show any histopathological correlate and were reversible within the 14-day recovery period, they were not considered to be adverse effects, hence the NOAEL was considered to be 1000 mg/kg bw/day.

Structural Analogue 02: The test substance was administered orally by gavage to SPF-Wistar rats over a period of 29 days (a total of 28 applications, 7 days a week) at dose levels of 0.62.5.250 or 1000 mg kg body weight. Behaviour and general state of health were examined in all study groups. Body weights and food consumption were recorded twice a week, water consumption once weekly. Haematology, clinical chemistry and urinalysis were performed at study end. During necropsy the animals were examined for macroscopically visible abnormalities, the main organs were weighed and the organ to body weight ratios calculated. Relevant organs of the animals were processed for histopathological examination and checked for microscopically visible changes. Body weights, haematological and clinical chemistry data, albumin and globulin values, urine data (pH-value and specific weight) as well as the absolute and relative organ weights were analysed with the aid of a statistical program to show differences compared to control groups.

Behaviour, general state of health, body weight development as well as food and water consumption remained unaffected by the administration of the test compound. Faeces of animals of the 1000 mg/kg test group were red discoloured, beginning with day 6.There was no evidence for compound-related toxicity in haematology and clinical chemistry. Urine was red-brown discoloured in all animals of the 1000 mg/kg test group. Evaluation of absolute and relative organ weights showed no compound-related effects.

Necropsy revealed red discoloration of the kidneys in all animals of the 1000 mg/kg test group. Additionally, the testes of the male animals were red discoloured. Vacuolization of the epithelial cells of the renal cortex was microscopically observed in two female animals of this test group which are considered to be a result of an increased re-absorption and subsequent deposition of the test compound. However, no adverse tissue reaction resulted from these deposits and no correlating changes in clinical pathology was observed, hence these deposits were of no toxicological relevance.

Summarizing, the 29-day oral administration of the test substance at a dose of 1000 mg/kg body weight/day resulted in two female animals in microscopic renal findings as described above. There was no evidence in clinical chemistry and histopathology of an adverse effect on the renal function. The administration of the test compound in a dose of 1000 mg/kg body weight/day did not induce any evident relevant compound-related changes in male animals. The NOAEL was therefore considered to be 1000 mg/kg bw/day.

Based on this data from structural analogues, it can be concluded that the NOAEL for Reactive Blue 203 is also 1000 mg/kg bw/day.

Justification for classification or non-classification

No classification necessary