1,8-bis[(4-methylphenyl)amino]anthraquinone

Endpoint summary

Description of key information

Several endpoints were covered by read-across with experimental studies of the source substance, Reinblau RLW (1,4-bis[(2-ethyl-6-methylphenyl)amino]anthraquinone; CAS n°41611-76-1), another member of the category.

Hydrolysis:

In accordance with REACH Annex VIII column 2, the study does not need to be conducted if the substance is highly insoluble in water.

Biodegradation in water:

From the degradability results determined over a period of 28 days based on the BOD (average 1% degradation) and the residual concentration of the source substance, Reinblau RLW (CAS n°41611-76-1), it is concluded that the source substance is not readily biodegradable. No transformation product was generated under the conditions of this test.

Based on category approach, Violet 36 (CAS n°82-16-6) is not readily biodegradable.

Biodegradation in water, sediment and soil:

According to the REACH Annex XIII Section 2.1, further biotic degradation testing in appropriate compartment shall be performed to investigate further the degradation of the substance and its degradation product to conclude on the persistency of the tested substance. Based on the profile of the substances of the category, an integrated testing strategy has been developped to assess the persistency of the tested substance. Simulation testing on ultimate degradation in surface water is not considered as scientifically relevant. It is proposed to start simulation testing in soil compartment with an OECD Test Guideline 307 on the source substance, Reinblau RLW (CAS n°41611-76-1) (OECD-TG 307 Testing Proposal, 2022). Depending on the outcome of the soil assessment, sediment simulation (OECD TG 308) testing would be considered at a later stage. Further simulation test would not be conducted if the substance is classified as persistent in soil.

Bioaccumulation:

The concentration of the Reinblau RLW (CAS n°41611-76-1) in fish ranged from 0.37 to 1.08 µg/g (w/w) and the bioconcentration (BCF) was 2 to 5 (Mitsubishi, 2011). On the basis of the BCF obtained and category approach, it is concluded that the bioaccumulation potential of Violet 36 (CAS n°82-16-6) in fish is low under the test condition.

This results is supported by the BCFBAF model (EPI-Suite Programm) on Solvent Violet 36 with a BCF estimated to be 798 L/kg wet-wt concluding that the substance is not considered bioaccumulative.

Adsorption/desorption:

As the adsorption coefficient (logKoc) of Violet 36 is 6.4 (Allmending, 2017), the result indicates that the substance is immobile in soils according to McCall et al. (1981).

McCall P.J., Laskowski D.A., Swann R.L., and Dishburger H.J., (1981), “Measurement of sorption coefficients of organic chemicals and their use, in environmental fate analysis”, in Test Protocols for Environmental Fate and Movement of Toxicants. Proceedings of AOAC Symposium, AOAC,Washington DC.

Additional information

Category approach:

LANXESS Deutschland GmbH has registered five mono-constituent anthraquinone dyes of similar chemical structure using a category approach: Solvent Violet 36 (CAS No 82-16-6), Solvent Green 28 (CAS No 4851-50-7), Reinblau RLW (CAS No 41611-76-1), Reinblau BLW (CAS No 32724-62-2) and Solvent Green 3 (CAS No 128-80-3). Additional data were taken from another registered anthraquinone dye, Solvent Blue 104 (CAS 116 -75 -6), leading to a category consisting of six members (see attached justification in IUCLID chapter 13). The category consists of substances all having the diamino-anthraquinone structure as a common moiety which is linked to phenyl groups via the amino groups. Differences within the category are described by various alkyl groups bound to the phenyl groups. All substances included in the category approach are poorly water soluble with high adsorption coefficient (log Koc>6),  high partition coefficient (logKow>8) and not readily biodegradable.