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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The respiration rates of the sludge-associated microbes exposed to the five nominal concentrations of the test material were 37.2, 49.2, 36.0, 42.0 and 17.2 mg O2/L*hr respectively. The EC50 is 4550 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
4 550 mg/L

Additional information

The potential impact of the test material on microbial metabolism, as represented by the consumption of oxygen, was investigated using the "Activated Sludge, Respiration Inhibition Test" as prescribed by OECD Guideline 209. The test duration was a three-hour exposure period to the test material followed by up to ten minutes for the measurement of oxygen consumption. The study design was comprised of five nominal exposure concentrations: 1, 10, 100, 1,000 and 10,000 ppm; a duplicate control group; and an assessment of the sensitivity of the inoculum used in the test to a reference toxicant (3,5- dichlorophenol).

The EC50 calculated for the reference toxicant was 11.2 mg/L, within the acceptable range of 5 to 30 mg/L. The two control replicates produced oxygen consumption rates within the required 95% of each other, 51.8 and 60.7 mg O2/L*hr. The respiration rates of the sludge-associated microbes exposed to the five nominal concentrations of the test material were 37.2, 49.2, 36.0, 42.0 and 17.2 mg O2/L*hr respectively. The EC50 is 4550 mg/L.