2,7-Naphthalenedisulfonic acid, 4-amino-3,6-bis[2-[4-(ethenylsulfonyl)phenyl]diazenyl]-5-hydroxy-, sodium salt (1:2)

Long-term toxicity to aquatic invertebrates

Description of key information

Result of study is not reliable due to surface active disturbances of the test substance

Additional information

The tested substance is a precursor of Reactive Black 5 Bis-Vinyl and hydrolyses in aqueous solution from the bis-ester to the bis-vinyl form. The study was performed by the MOE with test substance of unknown origin. The EC50 in this study was found to be 15.7 mg/L which is not in accordance with the data from studies with Reactive Black 5 performed with our own test compound. From comparative data for acute toxicity studies with Daphnia magna with Reactive Black 5 from Hoechst and from Aldrich, we know that the EC50 is strongly dependent on the supplier of the material. Whereas with the Hoechst substance the EC50 was > 800 mg/L, the EC50 was between 25 and 50 mg/L with the Aldrich substance, and the immobile daphnids were found on the surface of the test vessels. This is most likely due to the surface active properies of the test substance. In addition, in the MOE study, the control group showed a mortality rate of 20%, which raised doubts on the validity of the study. The NOEC of 1.25 mg/L is due to an effect on reproduction. The study was performed at concentrations of 20.0, 10.0, 5.00, 2.50 and 1.25 mg/L. At 5 and 2.5 mg/L, the reproduction rate was statistically significantly increased, therefore the NOEC was set to 1.25 mg/L. However, this effect could be caused by the same surface active effect as the higher mortality rate with the Aldrich substance.