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Short-term toxicity to aquatic invertebrates

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Description of key information

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 (1984) No 202, "Daphnia sp, Acute Immobilisation Test and Reproduction Test" referenced as Method C.2 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).
Following a preliminary range-finding test, twenty daphnids (2 replicates of 10 animals) were exposed to an aqueous solution of the test material at concentrations of 0.011, 0.020, 0.035, 0.062, 0.11, 0.20, 0.35, 0.62 and 1.1 mg/l for 48 hours at a temperature of approximately 21°C under static test conditions. The number of immobilised Daphnia were recorded after 24 and 48 hours.
The 48-Hour EC50 for the test material to Daphnia magna based on nominal test concentrations was 0.037 mg/l with 95% confidence limits of 0.031 - 0.044 mg/l. The No Observed Effect Concentration was 0.011 mg/l.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.037 mg/L
EC50/LC50 for marine water invertebrates:
0.58 mg/L

Additional information

In the key study (Sewell & McKenzie, 2005; SPL project number: 1666/027) for the acute toxicity to Daphnia magna, the study was conducted according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test).

This study is presented as the key information as the reliability rating for this study is 1, according to the criteria of Klimisch, 1997, and this study was conducted most recently and therefore is considered the most reliable study.

The following supporting studies are also avaiable for this endpoint:

The Ward & Magazu, 1994 study is considered to have a reliability rating of 2, according to the criteria of Klimisch, 1997.

Restriction due to the lack of analytical confirmation of test concentrations.

The 48 hour median effective concentration (EC50) of the test material to daphnids (expressed as the nominal amount of test substance use to prepare the WAF) is 3.4 mg/L (95% confidence interval = 2.8 to 4.7 mg/L) and the 48 hour no observed effect concentration (NOEC) is 1.0 mg/L. Effect levels in this study were reported in terms of concentration, however as WAFs (water accommodation fraction) were used, the results should be reported in terms of loading levels (e.g. NOELR and EL50).

The Calvert & Adams, 1981 study is considered to have a reliability rating of 2, according to the criteria of Klimisch, 1997.

Restriction due to the lack of analytical confirmation of test concentrations.

The 24-hour EC50 was 0.074 mg/L. The 48-hour EC50 was 0.072 mg/L. The 48-hour no observed effect concentration was 0.031 mg/L.

The Scholz, 1992 study is considered to have a reliability rating of 4, according to the criteria of Klimisch, 1997 as the information was obtained from the 2006 SIDS dossier due to the original report being unavailable. Further restrictions due to the lack of analytical confirmation of exposure concentrations. In addition, acetone was used as a co-solvent at a level of 0.45 ml/L, which exceeds current guidance that recommends a limit of no more than 0.1 ml/L. This might possibly have affected the distribution of the different homologues in the actual test medium.

The 24 and 48 hour EC50 values were 106 and 92 µg/L.

The Simon, 1998 study is considered to have a reliability rating of 2, according to the criteria of Klimisch, 1997.

Restriction due to the lack of analytical confirmation of test concentrations. Tested on marine invertabrates.

Under the conditions of this study the 96-hour LC50 was 0.58 mg/L WAF. The associated 96-hour NOEC was 0.46 mg/L WAF. Effect levels in the reporting of the study were reported in terms of concentration, however as WAFs (water accommodation fraction) were used, the results should be reported in terms of loading levels.