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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Non-toxic to microorganisms.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
2 000 mg/L

Additional information

The inhibitory effect of Direct Red 23 (DR23) on the oxygen consumption of activated sludge microorganisms of a municipal sewage treatment plant was investigated under aerobic static conditions (Clariant 2002); at 3h EC20 is > 2000 mg/L, EC50 is > 2000 mg/L and EC80 is >2000 mg/L.

The other studies reported on structural analogues/surrogates Direct Red 239 (Clariant 1989 and Kemira 1989) confirm the conclusion that DR23 could be considered as non-toxic to microorganisms.