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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Using a read across approach, the EC50 for Dowfax 2A1 was estimated to be 100 mg/L in an activated sludge respiration inhibition test.

Key value for chemical safety assessment

EC50 for microorganisms:
100 mg/L

Additional information

The key study for this endpoint was selected using a read across approach from two analogous compounds, Dowfax Dry Hydrotrope Powder (disodium di- and monohexyl (linear C6) diphenyloxide disulfonate) and Dowfax 8390 (disodium di- and monohexyl (linear C16) diphenyloxide disulfonate). In activated sludge respiration inhibition tests, the effects of the test materials were assessed on respiration rate of activated sludge from municipal waste water treatment plants. Dowfax Dry Hydrotrope Powder at a concentration of 100 mg/L showed no significant inhibitory effect on aerobic waste water bacteria. Dowfax 8390 showed a slight inhibitory effect on aerobic waste water bacteria, the inhibition ranging from 11 to 25% at 25 and 200 mg/L, respectively. At the highest concentration of 284 mg/L Dowfax 8390 that was tested, there was 26% inhibition of respiration. Thus, the EC50 value for Dowfax 8390 was determined to be greater than 284 mg/L. Based on the results of these two studies, both of which were determined to be reliable (Klimish scores =2), the EC50 for Dowfax 2A1 in the activated sludge respiration inhibition test was conservatively estimated to be 100 mg/L.