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Toxicity to microorganisms

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Description of key information

The magnesium sulfonate target substance (CAS 231297-75-9)_OECD209: EC50(3h) > 10000 mg/L, NOAEC(3h): 10000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L
EC10 or NOEC for microorganisms:
10 000 mg/L

Additional information

The potential of the magnesium sulfonate target substance (CAS 231297-75-9) to impact microbial metabolism based on oxygen consumption was evaluated using the Respiratory Inhibition Test with activated sludge, OECD Guideline 209 (Goodrich, 2005). Nominal test concentrations were 1, 10, 100, 1000 and 10000 mg/L and the exposure time was 3 hours. Activated sludge of a predominantly domestic sewage was used as inoculum. The sludge solution was diluted to a concentration of 4 g/L using dechlorinated water. The first test vessel was used as the first control in the testing series of dechlorinated tap water, and 200 mL of the sludge inoculum were added to this vessel. The vessel was immediately placed in the temperature-controlled incubator (20 °C) in darkness and aerated. Under the conditions of this test no significant adverse effect on oxygen consumption was observed when the microbes associated with the activated sludge were exposed to the test material. Respiratory inhibitions at 1, 10, 100, 1000, and 10000 mg/L were determined to be 7.47, 22.15, 13.50, 24.51, and 5.64 %. Because no test concentration produced an inhibition greater than 50 %, an EC50 was not calculated. No toxicity was observed, hence EC50 amounts to >10000 mg/L. The corresponding NOAEC (No Observed Adverse Effect Concentration) is 10000 mg/L. The response of the reference toxicant, 3,5-dichlorophenol, indicated that the test is valid (EC50: 5.2 mg/L).