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Short-term toxicity to aquatic invertebrates

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Description of key information

Reading across the result that methyl ethyl ketone was not acutely toxic to Daphnia magna when tested according OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test); the substance is predicted to possess a 48-hour EC50 in Daphnia magnia that is equal to 308 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
308 mg/L

Additional information

Three studies addressing short-term toxicity to aquatic invertebrates are presented in the dossier. The study selected as key was carried out on the read-across substance, methyl ethyl ketone (CAS No. 78-93-3). Metabolic data demonstrate that s-butanol is rapidly and extensively converted to methyl ethyl ketone via oxidation of the alcohol functional group by alcohol dehydrogenase in the liver. Thus, methyl ethyl ketone may be used as an appropriate surrogate for s-butanol and vice versa considering that exposure to either substance would essentially result in exposure to methyl ethyl ketone.

RA Short-term toxicity to aquatic invertebrates.001 – Daphnia – 1998 – key: Acute toxicity of the read-across substance, methyl ethyl ketone (CAS No. 78-93-3), to Daphnia magna was assessed according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test), and in compliance with GLP. Daphnia were exposed under static conditions to the substance at concentrations of 52, 86, 144, 240, and 400 mg/L in freshwater. The test was performed with 10 daphnia per vessel and 20 daphnia per concentration. For each concentration, the percentage of immobilisation at 24 hours and 48 hours was recorded, and test concentrations were confirmed by GC analysis. The following validity criteria were met: immobilisation in the control did not exceed 10% at the end of the test; dissolved oxygen concentrations remained above 60% of the air saturation value at the end of the test; pH did not vary by more than one unit throughout the test; and the concentrations of the test substance remained within 80% of the initial concentration throughout the test. The measured concentrations at the end of the test were 48, 68, 136, 234, and 345 mg/L which were used to express the results of the test. After 48 hours immobility in the 136, 234 and 345 mg /L treatment groups was 0, 5 and 75% respectively.   Under the conditions of the test, the 48-hour EC50 was determined to be 308 mg/L.

Short-term toxicity to aquatic invertebrates.002 - Daphnia - 1982: Acute toxicity to Daphnia magna was not assessed according to a specific guideline, however; it appears to follow OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) but was not conducted according to GLP (pre-dates GLP). The Daphnia were exposed to the substance under static conditions for 24 hours and the 24-hour EC50 for immobility was determined to be 2300 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Short-term toxicity to aquatic invertebrates.003 - Daphnia - 1977: Acute toxicity to Daphnia magna was not assessed according to a specific guideline, however; it appears to follow OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) but was not conducted according to GLP (pre-dates GLP). The Daphnia were exposed to the substance under static conditions for 24 hours and the 24-hour EC50 for immobility was determined to be 3750 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.