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

Short-term toxicity to aquatic invertebrates

Description of key information

The test substance showed a low acute toxicity to Daphnia magna with an EC50 of 748 mg/L calculated as the geometric mean of the test concentration with and without effect.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

748 mg/L

Additional information

Reactive Black 5-OH was tested for acute toxic effects on Daphnia magna according to OECD 202 at concentrations of 2 to 128 mg/L over an exposure time of 48 hours. No adverse effects were observed during this study. The EC0 and EC50 values are above the highest test concentration of 128 mg/L, tested.

Reactive Black 5 in its bis-ester form, was tested for acute toxic effects on Daphnia magna according to OECD 202 at concentrations of 320, 560 and 1000 mg/L over an exposure time of 48 hours in a semi-static test under slightly acidic test conditions (pH 6) to avoid abiotic degradation of the test substance. No adverse effects were observed during this study at 320 and 560 mg/L. At 1000 mg/L all daphnids were immobile after 48 hours.

The EC0 was 560 mg/L, the EC50 was calculated (as the geometric mean between 560 and 1000 mg/) to be 748 mg/L, the EC100 was 1000 mg/L.

A comparative study between test material (Reactive Black 5) from Hoechst and Aldrich showed that the batch from Aldrich prevented the Daphnias from diving due to surface active effects and thus led to the death of the daphnia starting at a very low concentration. The batch from Hoechst did not show these effects and led to EC50 of above 800 mg/L at different pH levels (6.5 to 8.5).

A futher Daphnia sp. Acute Immobilisation Test (OECD Guideline 202) from MOE, Japan, with Reactive Black 5 led to and EC50 of higher than 1000 mg/L.