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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

OECD Guideline 202, GLP, key study, validity 2:
No acute effects were observed on Daphnia magna up to the solubility limit of the test substance.

Key value for chemical safety assessment

Additional information

To assess the short-term toxicity of the registered substance to aquatic invertebrates, one valid study is available.

This GLP study, assessed as a key study, was performed on the registered substance according to OECD Guideline 202. Twenty Daphnia magna were exposed to each concentration level of the test substance (nominal concentrations: 31.3, 62.5, 125, 250, 500 and 1000 µg/L) and the control, in closed system (sealed glass flasks) under semi-static conditions, over a period of 48 hours. The concentrations of the test substance were analytically verified via GC-MS at the start of the exposure intervals (0 and 24h) and at the end of the exposure intervals (24 and 48h) in all concentration levels and the control. The measured concentrations of the test substance at the start of the exposure intervals were in the range of 81 to 98 % of the nominal values. At the end of the exposure intervals, the measured concentrations of the test substance were in the range of 56 to 88 % of the nominal values. Therefore, the geometric mean measured concentrations of the test substance were calculated to be: 24.1, 45.9, 94.4, 212, 378 and 863 µg/L. According to the water solubility study, performed in compliance with the OECD Guideline 105 with a slow-stirring method, the solubility limit measured in Daphnia medium was 376 µg/L. Therefore, semi-stable emulsions may have been formed in the test solutions. These emulsions, particularly at concentrations lower than 1 mg/L, are generally invisible, that is why no any undissolved particles were observed. Immobilization of daphnids for the definitive test was 0, 0, 0, 0, 0, 15 and 50 % (24 h); 0, 0, 0, 0, 0, 25 and 85 % (48 h) at geometric mean measured concentrations of 24.1, 45.9, 94.4, 212, 378 and 863 µg/L, respectively. According to this result, toxic effects were observed only at concentrations greater than the solubility limit. The first effects (25% immobilisation at 48 h) were observed at a geometric mean concentration of 378 µg/L, just above the solubility limit. The 48h-EC50 value was determined to be 522 µg/L (Cl: 457 – 607 µg/L), which is significantly greater than the solubility limit.

In conclusion, no acute effects were observed on Daphnia magna up to the solubility limit of the test substance.