Registration Dossier
Registration Dossier
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EC number: 266-273-5 | CAS number: 66241-11-0 This substance is identified in the Colour Index by Colour Index Constitution Number, C.I. 53185.
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
The sulfur dye Leuco Sulfur Black 1 is a black pasty UVCB substance with a mean molecular weight > 8000 Da. It is very poorly or even not soluble in common polar and non-polar solvents such as water (solubility of 62.4 mg/L), DMSO, methanol, DMF, THF, chloroform and not soluble in acids like sulfuric acid and trifluoroacetic acid. The vapour pressure of the pure substance, calculated from the boiling point of > 400 °C, is 1.8 x 10E-5 hPa at 25 °C.
Based on these properties it is very unlikely that Leuco Sulfur Black 1 can cross any biological membrane. Thus, absorption of toxicologically significant amounts of Leuco Sulfur Black 1 following oral, dermal or inhalation exposure can be excluded. This is substantiated by the results obtained in toxicity and ecotoxicity studies, where no substance related local and/or systemic effects indicative of toxicity were seen in all tests, including acute animal and acute ecotoxicity studies, sensitization, repeated dose toxicity and mutagenicity tests.
In the acute oral toxicity study black stained faeces was observed for maximally four days starting the day after administration of the substance at 2000 mg/kg bw. Dark discoloured faeces were also seen in the repeated dose toxicity study (OECD 422) at 1000 mg/kg bw/d, starting on day 3 of the study and lasting throughout the administration period until termination. The discolouration of faeces was the only effect observed in both studies and can be attributed to the strong staining properties of the substance. This indicates that Leuco Sulfur Black 1 is directly excreted and that absorption in the gastrointestinal tract does not occur following oral administration, especially since organs or urine were not discoloured and signs of substance deposits were not found in histopathological analysis of the organs.
Based on the substance properties and as absorption via any route is negligible, metabolism and distribution in the body is also negligible. After oral administration Leuco Sulphur Black 1 is excreted via faeces as demonstrated in the acute oral as well as repeated dose toxicity study (OECD 422).
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