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Description of key information

In a reliable 48 -h acute toxicity study with Daphnia magna performed with a structural analogue of Norethylac, Norethyl, the 48 -h EC50 was above the solubility limit of the substance (>0.064 mg/L). This result can be read across to Norethylac.

In a reliable 72 -hr toxicity study with freshwater algae conducted with a structural analogue of Norethylac, Norethyl, the 72 -h ERC50 was > 0.0014 mg/L based on TWA concentrations. This result can be read across to Norethylac.

Additional information

In a 48h acute toxicity study with a structural analogue of Norethylac, Norethyl, conducted according to OECD guideline 202, Daphnia magna were exposed to Norethyl under static conditions at the following nominal concentrations: 0 (Control), 10, 18, 32, 56, and 100% of the Saturated Solution prepared at a loading rate of 100 mg/L. The geometric mean measured concentration in the SS was calculated to be 0.064 mg/L, which was considered the solubility limit in test medium. No immobility was observed at any of the test concentrations and the control during the exposure period. Therefore, the 48h-EC50 was above the solubility limit, i.e. >0.064 mg/L. The study is considered to be reliable without restrictions. This result can be read across to Norethylac.

In a 72 h toxicity study conducted according to OECD guideline 201 and GLP principles with a structural analogue of Norethylac, Norethyl, freshwater algae (Pseudokirchneriella subcapitata) were exposed to Norethyl at a nominal loading rate of 100 mg/L (saturated solution) and an untreated control. Exposure concentration was verified by a validated analytical method to be 0.0014 mg/L (TWA). No inhibition of growth rate was recorded at the concentration of Norethyl tested. The 72h-ERC50 was >0.0014 mg/L and the 72h-NOEC was 0.0014 mg/L, based on TWA concentrations. The study is considered to be reliable without restrictions. This result can be read across to Norethylac.