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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Under the conditions of the present study with Selenastrum capricornutum, butyl methoxydibenzoylmethane did not reduce growth rate of this fresh water algae species significantly at a 5 µm filtered test solution prepared at a nominal loading of 100 mg/L. The EC50 for both algal growth inhibition and growth rate reduction exceeded the maximum solubility of butyl methoxydibenzoylmethane in test medium at a 5 µm filtered test solution prepared at a nominal loading of 100 mg/L, the regulatory limit concentration.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

Selenastrum capricornutum, Fresh Water Algal Growth inhibition Test with butyl methoxydibenzoylmethane. The study procedures described in this report were based on OECD guideline No. 201. Under the conditions of the present study with Selenastrum capricornutum, butyl methoxydibenzoylmethane did not reduce growth rate of this fresh water algae species significantly at a 5 µm filtered test solution prepared at a nominal loading of 100 mg/L.

The test item was not soluble in test medium at 100 mg/L. The water solubility determined in the water solubility study was 0.03 mg/L. Analysis of the samples taken during the limit test showed that the measured concentration decreased from 0.145 mg/L at the start of the test to 0.053 mg/L after 24 hours and to 0.037 mg/L after 96 hours of exposure. The time weighted average concentration was determined to be 0.055 mg/L being the geometric mean of the concentrations measured during the test period.

Under the conditions of the present study with Selenastrum capricornutum, butyl methoxydibenzoylmethane did not reduce growth rate of this fresh water algae species significantly at a 5 µm filtered test solution prepared at a nominal loading of 100 mg/L. The EC50 for both algal growth inhibition and growth rate reduction exceeded the maximum solubility of butyl methoxydibenzoylmethane in test medium at a 5 µm filtered test solution prepared at a nominal loading of 100 mg/L, the regulatory limit concentration.