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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The test substance 4,4’-Difluorbenzophenon was tested in the Alga, Growth Inhibition Test according to the OECD Guideline for the Testing of Chemicals No. 201 (23 March 2006) using the single cell green algae Desmodesmus subspicatus as test organism. The test was performed with test substance preparations of nominal 0.1; 0.32; 1.02; 3.28 and 10.49 mg/L culture medium. The results of this study show that the test substance 4,4’-Difluorbenzophenon induced inhibition of algal growth from 1.02 mg/L upwards after 72 hours of exposure, based on nominal concentrations and analytically determined from 0.89 mg/L upwards after 72 hours of exposure. The EC50 for growth rate based on measured concentrations is 1.92 mg/L and the corresponding NOEC is 0.23 mg/L.

In a second study Desmodesmus subspicatus was exposed to the test substance at nominal concentrations ranging from 0.37 to 6.1 mg/L  according to OECD TGD 201. The EC50 for growth rate resulting from this study is 2.4 mg/L (based on the geometric mean measured test concentrations) and the NOEC is 1.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
2.147 mg/L
EC10 or NOEC for freshwater algae:
0.55 mg/L

Additional information

As both studies are reliable without restrictions and as the EC50 values are in the same order of magnitude the geometric mean of both ErC50 values was considered as key value (2.147 mg/L). In the same manner an overall NOEC of 0.55 mg/L was calculated.

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