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Toxicity to microorganisms

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Description of key information

EC50 (3 h) > 1000 mg/l (nominal, act. ingr.)

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

The determination of the inhibition of oxygen consumption in the activated sludge was performed in a 3-hours test with 3b-A, according to the OECD guideline 209. The concentration tested were 1000, 500, 250, 125, 62.5 mg/l based on active ingredient of the test substance, which equate to a nominal test concentration of 1333, 667, 333, 167 and 83.3 mg/l. The EC50 at 3 hours was stated as greater than 1000 mg/l (nominal, act. ingr.) (BASF SE, 2015).

Three further studies on the analogue substance 3a-A(Na) are available in order to assess the toxicity of the substance to microorganisms, but each of them presents some lacking: in two of them a water solution with 20 % of the substance was tested and for the third one just the summary is available. The RCC - Umweltchemie GmbH & Co. study (1993) can be considered as the most reliable, since even if the tested substance concentration is low, the test was performed at 1000 mg/l, with no inhibitory effect. This set the result at > 200 mg/l, calculated on the substance effective concentration. Justification for Read Across is given in Section 13 of IUCLID.