2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-, coupled with 3-aminophenol, diazotized 5-amino-2-[(4-aminophenyl)amino]benzenesulfonic acid and diazotized benzenamine, sodium salts

Endpoint summary

Description of key information

No evidence of bioaccumulative potential.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Direct Black 168 is a dark organic powder.

Direct Black 168 is not toxic/harmful for short-term exposures and it is not skin irritating; however, it is able to cause eye irritation.

Direct Black 168 is not a skin sensitizer agent. No CMR activity has never been reported and has been observed in specific experiments performed.

No adverse effects were observed during the experiments run, thus, mechanisms of bioactivation leading to adverse effects are not expected to occur at moderate dosages.

Specific studies or specific literature data on toxicokinetics and metabolism are not available, thus information about the substance has been taken into account, avoiding further tests.

Because of the molecular structure and the hydrophilic of Direct Black 168, dermal absorption is expected to be negligible. Based on the available information, potential dermal toxicity is not suspected. Furthermore, the substance gave negative results in skin sensitisation assay, thus it is considered as not able to cause an allergic response in susceptible individuals, after exposure via the skin.

Because of the physical state and the characteristic particle size distribution, inhalation is not an appropriate route of exposure.

During the oral toxicity experiments, both acute and subacute, the treatment did not produce severe changes detected in health condition. The main finding, attributable to the test item treatment, was dark stool in the bedding material recorded in the groups tested at the medium and high dose levels; dark colour of the faeces was due to the elimination of test item or its metabolite by the gastrointestinal tract.

Clinical signs of systemic toxicity related to the test item and significantly impacting the tested animals were not detected at moderate dose levels. Haematological evaluation did not reveal adverse test item related changes, as well as changes in the serum thyroid hormone were not detected.

Minimal centrilobular vacuolation in the hepatocytes – sign of hepatic lipidosis – was found during the repeated dose toxicity test (lasting 42 – 56 days). Hepatic lipidosis is considered as a slight reversible liver injury in connection with a disturbance of energy metabolism of affected hepatocytes.

The finding of coloured faeces after single dose, as well as after repeated administrations, and the almost complete absence of any other effects let to expect that the substance can be significantly excreted.

The presence of coloured stool and coloured content of stomach and intestines let to expect that the scaffold was not significantly modified by transformation; colour proves that the conjugation is not completely interrupted. However, the extension of the elimination rate of the substance as such cannot be estimated.