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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. 
Following a preliminary range finding study, twenty daphnids (2 replicates of 10 animals) were exposed to Water Accommodated Fractions of the test material over a range of nominal loading rates of 10, 18, 32, 56, and 100 mg/L for 48 hours at a temperature of 21 degrees C under static test conditions. The number of immobilized Daphnia were recorded after 24 and 48 hours.
The 48 hour EL50 for the test material to Daphnia magna based on nominal loading rates was 75 mg/L WAF with 95% confidence limits of 56 to 100 mg/L. The 48 hour No Observed Effect loading rate was 56 mg/L loading rate WAF.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
75 mg/L

Additional information

- In the key study (Goodband, 2004; SPL project number: 1666/058) 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 2, according to the criteria of Klimisch, 1997

as analytical measurements on the test material were not conducted. This is the most recent and robust study available and has been used for classification purposes.

- The Ward & Magazu, 1994 study was conducted to recognised OECD guidelines and GLP, however a WAF method was used to disperse the test material in solution. It was noted in the study that undissolved insoluble test material was seen at some of the higher concentrations and no attempt was made to removed the undissolved test material and surface slick, hence trapping or fouling of test organisms may occur which are physical affects rather than toxic effects. A reliability rating of 3 was assigned according to the criteria of Klimisch, 1997.

Results: The test vessels containing the 2.5 mg/L WAF had a surface slick at the end of the test and test vessels containing 4.0 and 6.0 mg/L WAFs had a surface slick at the beginning and end of the test. No other insoluble material was noted in test vessels containing the WAF of the test material.

All of the surviving daphnids exposed to 6.0 mg/L were immobilized at 24 hours, all of the surviving daphnids exposed to 1.5 mg/L were immobilized at 48 hours, and all of the surviving daphnids exposed to 2.5, and 4.0 were immobilized at 24 and 48 hours. No other sublethal effects were noted during the test.

The 24 hour EC50 for daphnids exposed to the test material is 1.9 mg/L (95% confidence interval = 1.5 to 2.5 mg/L) and the 48 hour EC50 (reported as EL50) is 1.2 mg/L (95% confidence interval = 1.0 to 1.5 mg/L). The 48 hour NOEC (reported as NOELR) is <1.0 mg/L.