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

Short-term toxicity in freshwater from each of the three trophic levels (on fish, aquatic invertebrate and aquatic plants) was evaluated considering data on Direct Black 22 (DBk22) and data on structural analogues.

No adverse effects were recorded at the limit concentrations tested in studies on short-term to fish and aquatic invertebrates, as well as in tests conducted in order to investigate the toxicity to microorganisms.

The IC50 recorded at 72 hours in the test on algae was 38.5 mg/L of active material (Riva, 2000), similar to results obtained in the study on the analogous Similar Substance 01 (Dolezavola, 1994). Nevertheless coloured substances are often assumed to behave differently in the algal growth inhibition test due to shading of the algae.

In order to clarify the (eco)toxicological properties related to toxicity for aquatic plants, it was considered a read across test with the analogue Similar Substance 01 using Lemna gibba as a test organism (Caduff, 2012), as the test substance is a dyestuff which could influence the photosynthesis capacity of algae cells in the test solution. The results reported on the Similar Substance 01 (Caduff, 2012) confirm the non-toxicity of the dye that is a structural analogue of DBk22.

The differences in outcomes of the two studies are most likely due to the shading effects of coloured water in the algae test.

From this point of view the results recorded in Lemna study are more reliable and, considering the structural analogy of the two dyes, DBK22 is expected to be non-toxic to aquatic plants.

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Long-term toxicity was not tested because direct and indirect exposure is unlikely due to the risk management measures that will be applied at industrial level. The risk management measures to avoid any release of the substance directly in the environment are discussed in detail within the exposure scenario; furthermore DBk22 has a low potential for bioaccumulation and aquatic toxicity is unlikely to occur as indicated by the short-term aquatic testing results. Therefore, long-term toxicity testing is not necessary, because the chemical safety assessment according to Annex I does not indicate the need to investigate further the effects on aquatic organisms.