Reaction products of diazotised 4,4-diaminodiphenylamine-2-sulfonic acid, subsequently coupled with 6-amino-4-hydroxynaphthalene-2-sulfonic acid, further diazotised and coupled with metaphenylendiamine, sodium salts

Endpoint summary

Additional information

The primary source, if releases would occur of environmental pollution of Direct Black 22 (DBk22) is represented by industrial waste water and secondary by release during washing of dyed textile, thus the fate and pathways of DBk22 in surface water is of primary concern.

 

In the aquatic environment hydrolysis is not expected to be an important removal process for DBk22. Read across proposed with a similar substance reported that less than 10% of the test substance was hydrolysed within a 5 days period, concluding that the hydrolysis half-life time can therefore be expected to be greater than 1 year at 25°C and that the test substance is relatively stable in the medium term (Netusilova, 2010).

Phototransformation in air/water/soil has not been investigated

If released to soil, DBk22 is expected to have very high mobility based upon a measured Koc of 1 determined for a similar substance.

Given the intended use in aqueous-based treatments, DBk22 is not expected to be released to air and is not expected to partition to this compartment.

 

Under standard test conditions no readily biodegradation was observed; in a study (Riva, 2000) DBk22 was tested to determine the biodegradation in 28 days, at 80% active material and results showed that the test substance is not ready biodegradable. Further studies on a structural analogue supported this conclusion: the substance resulted as not inherently biodegradable in an experimental study (Haner, 2007) nor in any of the further tests reported in literature (Pagga et al, 1986).

There are no empirical bioaccumulation data available for DBk22, therefore available results on water solubility, molecular weight and cross-sectional diameter have also been considered in order to determine the bioaccumulation potential of DBk22, as well as the physical and chemical properties of relevant analogues (disulfonated dyes): DBk22 is a relatively large molecule and it is expected to have a low potential for bioaccumulation and/or a low potential to cross biological membranes.

Based on CSR and reported risk management measures, direct and indirect exposure of sediment and soil to DBk22 is unlikely; since no exposure of the aquatic compartment is foreseen and thus subsequent sediment and/or soil exposure can be excluded.