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Toxicity to microorganisms

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Description of key information

No toxicity towards STP microorganisms was observed in reliable Activated Sludge Respiration Inhibition tests up to tested concentrations far above 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
1 144 mg/L

Additional information

Reliable Activated Sludge Respiration Inhibition Tests according to OECD Guideline No. 209 and compliant to GLP are available for 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol (key study) and 6-(isononanoylamino)hexanoic acid (key study, RA from supporting substance).


For 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol, no respiration inhibition was observed up to the highest tested concentration of 10000 mg/L (reliability category 1).


In the test on 6-(isononanoylamino)hexanoic acid Tween 80 was used to enhance solubility of the otherwise poorly soluble test item far above the level of water solubility, which renders the study reliable with restrictions (RL 2). In spite of artificially high concentration levels due to the solubilizer, observed respiration inhibition was comparably low with an observed EC20 (3h) of 386 mg/L and an EC50 (3h) of 1144 mg/L (key value for safety assessment). Thus, under natural conditions taking the poor solubility of 6-(isononanoylamino)hexanoic acid into account, no toxicity towards sewage treatment plant microorganisms is expected also for this compound.