(3Z)-hex-3-en-1-yl 2-methylprop-2-en-1-yl ether

Toxicity to aquatic algae and cyanobacteria

Description of key information

A study was performed according to OECD 201 to assess the effect of the test item on the growth of the green algae Pseudokirchneriella subcapitata. Following a preliminary range-finding test,Pseudokirchneriella subcapitata was exposed to solutions of the test item at 0-Hour measured concentrations of 2.9, 7.4, 14, 31 and 61 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1°C. Analysis of the test preparations at 72 hours showed measured test concentrations in the range of 81% to 89% of the 0-Hour measured test concentrations were obtained.

Key value for chemical safety assessment

EC50 for freshwater algae:

12 mg/L

EC10 or NOEC for freshwater algae:

2.9 mg/L

Additional information

Pre-study solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication. A pre-study media preparation trial indicated that the use of a saturated solution method of preparation was most appropriate for this test item.

 The test item solutions were prepared by stirring an excess (100 mg/L) of test item in culture medium using a propeller stirrer at approximately 1500 rpm for 24 hours. After the stirring period any undissolved test item was removed by filtration (0.2 µm Sartorius Sartopore filter, first approximate 2 liters discarded in order to pre-condition the filter) to produce a saturated solution of the test item with a 0-Hour measured concentration of 61 mg/L. This saturated solution was then further diluted as necessary, to provide the remaining test groups.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter^®Multisizer Particle Counter.

The test material was known to be volatile and hence testing was conducted in completely filled, stoppered test vessels in order to minimize possible losses due to volatilization. Following the recommendations of published data (Hermanet al1990) in order to prevent inhibition of growth due to the restriction of gaseous exchange, additional sodium bicarbonate was added to the culture medium to provide a source of carbon dioxide for algal growth.

Chemical analysis of the test preparations at 0 hours showed measured test concentrations of 2.9, 7.4, 14, 31 and 61 mg/L were obtained. Analysis of the test preparations at 72 hours showed measured test concentrations in the range of 81% to 89% of the 0-Hour measured test concentrations were obtained. Due to the volatile nature of the test item, additional test replicates prepared at 0 hours were incubated alongside the test to provide samples for unopened vessel analysis at 72 hours. Analysis of these additional samples showed measured test concentrations in the range of 93% to 102% of the 0-Hour measured test concentrations were obtained indicating that the slight decline in measured concentration observed in the test samples from vessels which had been opened on a daily basis was due to volatility rather than instability and/or adsorption to the algal cells present. Given this it was considered appropriate to base the results on the 0-Hour measured test concentrations.