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Long-term toxicity to aquatic invertebrates

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Description of key information

Exposure of Daphnia magna to the test item resulted in no significant mortalities at all the test concentrations employed during the test.
The 21-Day EL50 (immobilization) value, based on nominal loading rates for the parental Daphnia generation (P1) was estimated to be greater than 320 mg/L loading rate WAF.
No significant impairment of reproduction was observed at the test concentrations employed during the test.
The 21-Day EL50 (reproduction) based on nominal loading rates was greater than 320 mg/L loading rate WAF.
The "No Observed Effect Loading Rate" (NOEL) based on nominal loading rates was 320 mg/L loading rate WAF. The "Maximum Acceptable Toxicant Loading rate" (MATL) was calculated to be 320 mg/L loading rate WAF.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
320 mg/L

Additional information

Introduction

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2008) No 211, "Daphnia magna Reproduction Test" referenced as Method C.20 of Commission Regulation (EC) No. 440/2008 and the US EPA Draft Ecological Effects Test Guidelines OPPTS 850.1300 "Daphnid Chronic Toxicity Test".

 

 

Methods…….

Based on the results of an acute toxicity test, Daphnia magna were exposed (10 replicates of a single daphnid per group) to an aqueous solution of the test item over a range of test concentrations of 32, 100 and 320 mg/L loading rate WAF for a period of 21 days. The test solutions were renewed 3 times per week. The numbers of live and dead adult Daphnia and young daphnids (live and dead) were determined daily. The Daphnia were fed daily with a mixture of algal suspension and Tetramin flake food suspension.

 

 

Results….

The 21-Day EL50(immobilization) value, based on nominal loading rates, for the parental Daphnia generation (P1) was estimated to be greater than 320 mg/L loading rate WAF.

 

The 21-Day EL50(reproduction) value based on nominal loading rates was estimated to be greater than 320 mg/L loading rate WAF.

 

The "No Observed Effect Loading Rate" was considered to be 320 mg/L loading rate WAF on the basis that at this loading rate there were no significant mortalities (immobilization) observed in the parental generation (P1) and that there were no significant differences (P0.05) between the control and the 320 mg/L loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

 

The "Maximum Acceptable Toxicant Loading rate" was calculated to be 320 mg/L loading rate WAF.

 

Analysis of the 320 mg/L loading rate WAF on days 0, 5, 12 and 19 (fresh media) and days 3, 7, 14 and 21 (old media) showed that measured concentrations ranging from 0.000639 to 1.21 mg/L were obtained. The results of the analysis showed a decline in measured concentrations between the fresh and old test media samples on each preparation/exposure period.

 

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

 

 

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