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Long-term toxicity to aquatic invertebrates

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Description of key information

Chronic toxicity studies with Daphnia magna provided NOEC values of ≥ 0.00415 and 0.025 mg a.i./L, respectively.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
0.025 mg/L

Additional information

A guideline study was conducted to assess the chronic toxicity of the read-across substance C12-16 ADBAC toDaphnia magnaunder daily renewal conditions.Daphnia magna(22 per group) were exposed to mean measured concentrations of 0, 0.41, 0.71, 1.33, 2.31 and 4.15 µg a.i./L of the test substance for 21 days. Analytical determination was performed for the test substance. Observations on daphnid behaviour, the number of immobilised organisms and the number of young produced were made at each renewal day and at test termination. No effects were observed on survival, reproduction and growth at measured concentration up to 4.15 µg a.i./L. However, reproduction was clearly affected at measured concentrations ≥ 5.02 µg/L in a range-finding study. Based on these results, the NOEC and LOEC for reproduction were considered to be at 4.15 and 5.02 µg a.i./L, respectively. The maximum acceptable toxicant concentration (MATC) derived from these results was 4.56 µg a.i./L. The NOEC and LOEC for survival and growth were ≥ 4.15 and > 4.15 µg a.i./L, respectively. Under the conditions of the study, the 21 day chronic NOEC for mortality, reproduction and growth was found to be ≥ 4.15 µg a.i./L (0.00415 mg a.i./L). The MATC was 4.56 µg/L (0.00456 mg/L) (Mclntyre DO and Pate HO, 1992).

In another guideline study, 20 daphnids per concentration were exposed to 0, 0.0031, 0.0063, 0.0125, 0.025, 0.05, 0.1 or 0.2 mg/L of the read-across substance C12-16 ADBAC for 21 days under semi-static conditions. There was no analytical method available to analyse the very low concentrations used in this test. All values given were therefore nominal. The number of living offspring per parent per day was assessed, as was the mortality of the parent animals. The NOEC and LOEC were determined for reproduction and mortality of the parent animals. In order to prove the stability of the test substance, a study was performed under test conditions at a concentration of 1 mg/L. Percentage recovery ranged between 98 and 107%. Under the conditions of the study, the NOEC (mortality parent animals) was 0.0125 mg a.i./L and the LOEC (mortality parent animals) was 0.025 mg a.i./L. At the next higher concentration, 0.05 mg a.i./L, all parent animals died within 48 hours. The NOEC and LOEC for reproduction were 0.025 and 0.05 mg a.i./L, respectively (Mark UE, 1995).