3,3'-[(2-chloro-5-methyl-p-phenylene)bis[imino(1-acetyl-2-oxoethylene)azo]]bis[4-chloro-N-(3-chloro-o-tolyl)benzamide]

Endpoint summary

Description of key information

Short description of key information on bioaccumulation potential result:  Based on the physico-chemical properties and the absence of systemic toxicity in acute and repeated-dose studies, absorption of the substance is unlikely.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

There were no studies available in which the toxicokinetic properties of the ‘yellow disazo condensation pigments’ were investigated. 

The ‘yellow disazo condensation pigments’ (molecular weight between about 716 g/mol and 1229 g/mol) are yellow powders at room temperature with an extremely low water solubility (highest measured water solubility of the pigments: < 50 µg/L at 20 °C (CAS 5280-80-8, see chapter "water solubility")). The substances are not prone to hydrolysis and contain the same type of linkages.

 

ABSORPTION

In acute oral toxicity studies done with the ‘yellow disazo condensation pigments’common clinical signs as dyspnea, exophthalmos, ruffled fur, curved body position, diarrhea and sedation were seen when the substances were applied in high concentrations. These systemic toxic effects were all transient. No indication of a substance specific systemic toxicity can be found in acute toxicity study in rats with dermal or inhalative administration (see chapter „acute toxicity“) as well as in a subacute toxicity study and a reproductive toxicity screening study in rats with oral application (see chapter „repeated dose toxicity“ and “reproductive toxcity”). Therefore, absorption and bioavailability of the test substance after oral administration is not expected (see chapter “acute oral toxicity” and chapter “repeated dose toxicity”).

Furthermore, calculation of the dermal absorption potential based on the criteria of the Danish EPA resulted in a very low absorption potential of 10%. Therefore, systemic absorption through the skin is expected to be low.

The test substance is a non-volatile powder at room temperature (the melting point is above 300 °C, see chapter “vapour pressure”). Furthermore, the substances decompose before boiling so that inhalation of test substances vapour is not relevant. In conclusion, based on the physical-chemical properties and the absence of systemic toxicity in acute inhalation studies, absorption of the test substances through the lung are unlikely.

 

DISTRIBUTION

There is no experimental evidence of distribution.

 

METABOLISM

There is no experimental evidence of metabolism. In theory the chemical structure indicates that the most likely route of biotransformation is by reductive cleavage of the azo bond either by bacterial enzymes in the gut or by microsomal azo reductase in the liver. In that theoretical case, uptake and metabolism of these substances should result in the release of aromatic amines. Such compounds have a characteristic toxicity profile as shown in the overview table on amine toxicity above. As no toxicity was observed, the substances are not considered to have been taken up by the body. As a consequence, metabolism is not expected due to lack of absorption after oral administration of the test substance. Studies on genetic toxicity (bacterial reverse mutation assay (Ames-Test), in vitro mammalian cell gene mutation and chromosome aberration test, see chapter “genetic toxicity”) were negative and gave no indications of a reactivity of the test substances or its metabolites under the test conditions (i.e. no increased mutagenicity in treatments with and without metabolic activation).

 

EXCRETION

The observation of yellowish faeces in the repeated oral study is assessed as indication of intestinal passage of the pigment. The extremely low water solubility of the test substance makes absorption from the gastro-intestinal tract unlikely and the substance is expected to be eliminated unchanged (ECHA guidance document R.7c, 2017).