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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The acute toxicity of 4 -Hydroxydiphenylamine the main hydrolysis product of IPPD to alga (Desmodesmus subspicatus former name: Scenedesmus subspicatus) was tested according to OECD guideline 201 ' Alga, Growth Inhibition Test' (2006). During 72 hours exposure an ErC50 of 2.6 mg/L and ErC10 of 0.58 mg/L was measured (Currenta, 2010). Another key study performed with the parent substance IPPD (Duslo 2007) resulted in an ErC50 of 26.5 mg/L and a NOEC of 4 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
2.6 mg/L
EC10 or NOEC for marine water algae:
0.58 mg/L

Additional information

Justification for performing the read across approach with 4 -Hydroxydiphenylamine:

IPPD hydrolysis rapidly with a half-life of 3.9 hours under conditions relevant for the environment. In this case the REACH guidance document R7 allows the choice of performing the ecotox study either with the parent compound or with the hydrolysis product. It was therefore decided to use the hydrolysis product as it is more stable and allows a significant result by the outcome of the analytical monitoring.