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Short-term toxicity to aquatic invertebrates

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Description of key information

The acute toxicity of the test material to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EL*50 value of greater than 100 mg/l loading rate WAF.  Correspondingly the No Observed Effect Loading rate was 100 mg/l loading rate WAF.
EL = Effective Loading Rate

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

Introduction:

A study was performed to assess the acute toxicity of the test material to Daphnia magna. The method followed that described in the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp, Acute Immobilisation Test" referenced as Method C.2 of Commission Directive 92/69/(which constitutes Annex V of Council Directive 67/548/).

Methods:

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to a Water Accommodated Fraction (WAF) of the test material, at a single nominal loading rate of 100 mg/l for 48 hours at a temperature of 20 ± 1°C under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours.

A positive control conducted approximately every six months used potassium dichromate as the reference material. Daphnia magna was exposed to an aqueous solution of the reference material at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/l for 48 hours at a temperature of approximately 20°C under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 3, 24 and 48 hours.

Results:

The 48-Hour EL*50for the test material to Daphnia magna based on nominal loading rates was greater than 100 mg/l loading rate

WAF and correspondingly the No Observed Effect Loading rate was 100 mg/l loading rate WAF. It was considered unnecessary and unrealistic to test at loading rates in excess of 100 mg/l.

Analysis of the fresh media at 0 hours showed measured concentrations of 0.0435 and 0.0667 mg/l. Analysis of the old media at 48 hours showed measured concentrations of 0.0411 and 0.0527 mg/l.

Given that toxicity cannot be attributed to a single component or a mixture of components but to the test material as a whole the results were based on nominal loading rates only.

The 48-Hour EC50 for the reference material to Daphnia magna based on nominal concentrations was 0.47 mg/l with 95% confidence limits of 0.43 – 0.53 mg/l. The No Observed Effect Concentration was 0.32 mg/l.


*EL = Effective Loading rate