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Short-term toxicity to aquatic invertebrates

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Description of key information

Based on the time-weighted mean measured test concentrations the 48-Hour EC50 was 1.4 mg/L; 95% confidence limits 0.63 – 7.6 mg/L. The No Observed Effect Concentration was 0.046 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.4 mg/L

Additional information

Two studies are available on the short-term toxicity of cyclamen aldehyde to aquatic invertebrates. The determined 48 hour EC50 values are 1.4 mg/L (key study, Harlan 2012) and 4.19 mg/L (supporting study, Noack 2000). The Harlan (2012) study was considered more reliable since it was performed under semi-static conditions with the concentration and stability of the test item in the test preparations verified by chemical analysis at 0 and 24 hours (fresh media), and at 24 and 48 hours (old media). In contrast, the Noack (2000) study was performed under static conditions and the concentration of the test item was only analytically verified at the start of the test. The details of the key study are summarised below.

The method followed was designed to be compatible with the US EPA Draft Ecological Effects Test Guidelines OPPTS 850.1010 and the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

The test item was known to be volatile (EPIWIN V3.20 predicted Henry’s law constant greater than 100 Pa.m3/mol) and hence it was likely that losses of test item would occur during the time taken to prepare the required test concentrations. As such, samples were taken for immediate chemical analysis to minimize losses as far as practically possible. Analysis of the freshly prepared test preparations showed measured test concentrations to range from 0.018 to 1.4 mg/L at 0 hours and from 0.013 to 1.6 mg/L at 24 hours. A decline in measured test concentration was observed in the old or expired test media in the range of less than the limit of quantitation (LOQ) of the analytical method employed which was determined to be 0.013 mg/L to 1.1 mg/L at 24 hours and from less than the LOQ to 0.99 mg/L at 48 hours.

Given this decline in measured test concentrations it was considered justifiable to base the results on the time-weighted mean measured test concentrations in order to give a "worst case" analysis of the data.

The 48-Hour EC50 based on the time-weighted mean measured test concentrations was 1.4 mg/L; 95% confidence limits 0.63 – 7.6 mg/L. The No Observed Effect Concentration was 0.046 mg/L.