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Long-term toxicity to aquatic invertebrates

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Description of key information

Under the conditions of the present study according to OECD 211 acetyl acetone did not affect survival, reproduction or growth of Daphnia magna at 18 mg/l after 21 days of exposure (NOEC).

Key value for chemical safety assessment

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

Additional information

Daphnia magna, 21-day reproduction study with Acetyl acetone:

The study procedures described in this report were based on the OECD guidelines for Testing of Chemicals: Guideline No. 211, 2012. In addition, the procedures were designed to meet the test methods and validity criteria of the ISO International Standard 10706, 2000 and the Commission Regulation (EC) No 440/2008 Part C.20, 2008.

The batch of Acetyl acetone tested was a clear colourless liquid with a purity of 99.8% and completely soluble in test medium at the concentrations tested.

The reproduction test was performed in a semi-static system, included 10 vessels per test concentration and 20 vessels for an untreated control group. Each of the vessels contained one neonate (<24h old) Daphnia magna in 50 ml test medium. The nominal concentrations of Acetyl acetone tested were 1.0, 2.6, 6.8, 18 and 46 mg/l. The study duration was 21 days and the test solutions were renewed three times a week. The daphnids were fed on a daily basis with a Chlorella pyrenoidosa suspension. Every workday the condition of the parental daphnids was recorded, during the reproduction phase the number of living offspring, immobile young and appearance of unhatched (aborted) eggs was recorded. At the end of the test the lengths of the surviving parental daphnids were measured.

During the study samples for Total Organic Carbon (TOC) analyses were taken at the beginning and the end of four intervals of 48 hours. The concentrations measured in the freshly prepared solutions were generally in agreement with nominal and thus confirmed the correct preparation and repeatability of the preparation of the test concentrations. Concentrations decreased only slightly during the periods of renewal. The mean measured concentrations were calculated to correspond with 0.48, 1.23, 3.2, 8.8 and 22.3 mg C/l. When corrected for the carbon content of 60% as present in Acetyl acetone, the range corresponded with 0.80, 2.1, 5.3, 15 and 37 mg Acetyl acetone per litre. This was 78 to 83% relative to nominal. As TOC-analyses generally confirmed correct preparation and showed no significant loss of Carbon in test medium it was decided to base all test results on the nominal concentrations.

Two out of the twenty parental daphnids exposed to the control died during the test period. On day 6 all parental daphnids had died at 46 mg/l. No significant mortality was observed at any of the lower test concentrations (10-20%) except for the intermediate concentration of 6.8 mg/l which unexpectedly showed 70% mortality. It was unknown what caused the mortality in this group.

Reproduction in the control group at the end of the test period averaged 118 young. The reproduction in the treatment groups up to and including 18 mg/l was comparable to the control group with average offspring numbers between 96 and 130. Reproduction at 46 mg/l was absent due to complete mortality of the parents before onset of the reproduction.

There were only insignificant recordings of a few immobile young in the various groups (one or two, including the control). There was one parent that released 8 unhatched (aborted) eggs in the test group of 2.6 mg/l.

The average body length in the test groups was 3 to 8% reduced in comparison to the control body length. The difference was considered biologically irrelevant as it was below 10%.

Test conditions were maintained within the limits prescribed by the protocol and the test was considered valid.

Acetyl acetone did not affect survival, reproduction or growth of Daphnia magna at 18 mg/l after 21 days of exposure (NOEC).