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Short-term toxicity to aquatic invertebrates

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Description of key information

The acute toxicity of alphamethylstyrene was investigated in a study conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) and EU Method C.2 (Acute Toxicity for Daphnia) under static conditions. The 48 h NOEC, LOEC, and EC50 values were determined to be 0.64, 1.21, and 1.645 mg/L based on mean measured concentrations (geometric mean).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.645 mg/L

Additional information

Reliable results obtained in a guideline studies are available. The acute toxicity of alphamethylstyrene was investigated in a study conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) and EU Method C.2 (Acute Toxicity for Daphnia) under static conditions. Based on the results of a screening-test, the concentrations in the main test were fixed. 20 Daphnia per concentration step were exposed to alphamethylstyrene at nominal concentrations of 0 (control), 1, 2, 4, 8, and 16 mg/L (aqueous eluates, 'WAF') for 48 h in 100 mL carboys sealed with glass stoppers (no gas phase was present in the test vessels). The 48 h NOEC, LOEC, and EC50 values were determined to be 0.64, 1.21, and 1.645 mg/L effective. The measured concentrations deviated more than 20% from the nominal values. Therefore the reported effect concentrations refer to mean measured concentrations (geometric mean). The test substance proved to be stable during the test duration (recovery: 88.2 -97.1% of initial concentration). The validity criteria of the guideline were fulfilled.

The acute toxicity of alpha-methylstyrene to Daphnia magna was investigated in a study conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test). 20 Daphnia magna were exposed to alphamethylstyrene at nominal concentrations of 0 (control), solvent control, 1.0, 1.8, 3.2, 5.6 and 10.0 mg/L under semi-static conditions for 48 h. The test substance concentrations were determined by HPLC in freshly prepared solutions and in 24 h old test solutions. The geometric mean measured concentrations of freshly prepared test solutions and 24 h old solutions at concentrations of 1-10 mg/L nominal were in the range between 78 and 87% of the initial nominal concentration. A 48 h EC50=2.62 mg/L (geometric mean measured) was determined.