Methyl dodec-9-enoate

Short-term toxicity to aquatic invertebrates

Description of key information

The acute toxicity of the test item to the freshwater invertebrate Daphnia magna has been investigated according to OECD guideline 202 and, based on the time-weighted mean measured test concentrations, gave a 48-Hour EC50 value of 0.50 mg/L with 95% confidence limits of 0.308 – 0.819 mg/L. The Lowest Observed Effect Concentration was considered to be 0.819 mg/L. The No Observed Effect Concentration at 48 hours was 0.308 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.5 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 (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008 and the US EPA Draft Ecological Effects Test Guidelines OPPTS 850.1010 "Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids".

Methods

Twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 0.10, 0.18, 0.32, 0.56 and 1.0 mg/L for 48 hours at a temperature of 21 °C under semi-static test conditions. The number of immobilizedDaphniawas recorded after 24 and 48 hours. This study used a solvent spike method of preparation.

Results

In the highest test concentration, 100% immobilization was observed after 24 hours exposure. No treatment-related effects were observed in any other test concentrations at 24 or 48 hours.

Chemical analysis of the freshly prepared test media at 0 and 24 hours, and the old (or expired) test media at 24 and 48 hours gave the following results. At 24 hours the 1.0 mg/L test concentration was not renewed due to 100% immobilization after 24 hours exposure. Given the decline in measured test concentrations over each 24-Hour period it was considered justifiable to base the results on the time-weighted mean measured test concentrations. In cases where the measured concentration was less than the LOQ, a value of ½ the LOQ was used in the calculation of the time-weighted mean measured test concentration.

Nominal concentration (mg/L)	Measured concentration (mg/L)
	0 Hours (fresh media)	24 Hours (old media)	24 Hours (fresh media)	48 Hours (old media)	Time-weighted mean measured concentration (mg/L)
0.10	0.0831	<LOQ	0.105	<LOQ	0.0618
0.18	0.125	0.0918	0.150	<LOQ	0.0946
0.32	0.262	0.192	0.266	<LOQ	0.171
0.56	0.490	0.389	0.496	<LOQ	0.308
1.0	0.863	0.777	-	-	0.819

 

The decline in measured concentrations in the last 24 hours of the test was greater than that observed in the first 24-Hour period. This effect was observed in an initial test conducted but at that time it was attributed to a problem with the analysis and / or storage of the samples rather than a true effect. The above results in combination with those previously obtained would suggest that the increased losses of test item over the second half of the test are a true effect however the cause of this is currently unknown.

The 48-Hour EC50 for the test item to Daphnia magna based on the time-weighted mean measured test concentrations was 0.50 mg/L with 95% confidence limits of 0.308 – 0.819 mg/L. The Lowest Observed Effect Concentration was considered to be 0.819 mg/L. The No Observed Effect Concentration was 0.308 mg/L.

The decline in test item within relatively brief periods (24 hours) means that a stable concentration was not attained. Therefore the test should not be regarded reliable without restriction. The repeated observation of virtually complete disappearance suggests that this reflects an inherent property of the test item, although the cause of this is currently unknown.