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Short-term toxicity to aquatic invertebrates

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Description of key information

The 48 hour EC50 was determined to be 0.15 mg/l and the NOEC was determined to be 0.056 mg/l

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.15 mg/L

Additional information

Method:

A 48 hour study was carried out under static conditions according to OECD guideline 202 to investigate the acute toxicity of the test material to Daphnia magna.

9 test concentrations (0.010, 0.018, 0.032, 0.056, 0.10, 0.18, 0.32, 0.56 and 1.0 mg/l) plus 1 control (including 100 µl/l auxiliary solvent) were tested, with 20 Daphnia per test concentration.

Results:

Analysis of the immobilisation data gave the following results:

Time (h)

LC50 (mg/l)

95% confidence limits (mg/l)

24

0.30

0.23 - 0. 38

48

0.15

0.12 - 0.19

 

No-effect level at 24 h = 0.10 mg/l

No-effect level at 48 h = 0.056 mg/l

Verification of test concentrations was not carried out as the test material was shown to decline markedly over a 24-hour period due to degradation in water and reaction with the surfactant Tween 80. Consequently, nominal test concentrations were used in the calculation of the EC50 values

The 48 hour LC50 was determined to be 0.15 mg/l and the NOEC was determined to be 0.056 mg/l.

A variety of approved dispersing agents, such as HC0 40 (hydrogenated castor oil), ethanol, acetone, DMF, DMSO etc., were used both prior to and after the definitive test but only the formula of 20% Tween 80 in tetrahydrofuran was found to give a satisfactory dispersion of the test substance in water. Although the test substance is now known to be unstable under these conditions all other preparations were unsuitable for testing. However, because of the instability/reactivity of the test substance, considerable caution should be exercised in the interpretation of these data.