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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The 3 hour EC50 > 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

The potential of the test material to cause toxic effects to microorganisms was investigated in accordance with the standardised guideline OECD 209. The study was conducted in line with GLP and was well reported. It was therefore assigned a reliability score of 1 in accordance with the criteria defined in Klimisch (1997).

In a 3 hour toxicity study, activated sewage sludge from a plant treating predominantly domestic sewage was exposed to the test material. In a range-finding study, the sludge was exposed to an aqueous dispersion of the test material at concentrations of 10, 100 and 1000 mg/L (3 replicates at the highest concentration) with the addition of a synthetic sewage as a respiratory substrate.

The rate of respiration was determined after 3 hours contact time and compared to a blank control and reference material.

The effect of the test material on the respiration of activated sewage sludge microorganisms gave a 3 hour EC50 > 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L.

It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/L; no toxic effects were seen at any of the test concentrations employed and it was therefore considered justifiable not to perform a definitive test.