2-benzyl-4-methyl-4a,5,6,7,8,8a-hexahydro-4H-benzo[d][1,3]dioxine

Long-term toxicity to aquatic invertebrates

Description of key information

OECD Guideline 211, GLP, key study, validity 2:

21d-EC10 reproduction (Daphnia magna) : 1 mg/L based on measured (geom.mean)

21d-EC50 reproduction (Daphnia magna) : 2.3 mg/L based on measured (geom.mean)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC10

Effect concentration:

1 mg/L

Additional information

To assess the long-term toxicity of the registered substance to aquatic invertebrates, one experimental key study is available.

The chronic toxicity of the test item to Daphnia magna was conducted according to OECD 211 and EU Method C.20, "Daphnia magna Reproduction Test" and EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test).

 

A preliminary media preparation trial indicated that a dissolved test item concentration of approximately 27.4 mg/L was obtained from a saturated solution method of preparation indicating this to be the limit of water solubility of this test item under test conditions. Based on the results of a preliminary range-finding test and an initial experiment, Daphnia magna were exposed (10 replicates of a single daphnid per group) to solutions of the test item at nominal concentrations of 0.5, 1.0, 2.0, 4.0 and 8.0% v/v saturated solution for a period of 21 days. The test solutions were renewed 3 times per week throughout the test. The test item solutions were prepared by stirring an excess (100 mg/L) of test item in test water 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 um Sartorious Sartopore filter, first approximate 1 liter discarded in order to pre-condition the filter) to produce a 100% v/v saturated solution of the test item. This saturated solution was then further diluted as necessary, to provide the required test groups. 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.

 

Analysis of the fresh test preparations on days 0, 5, 9, 14 and 19 showed measured test concentrations to range from 0.20 to 3.4 mg/L. With the exception of the 0.50% v/v saturated solution on Day 14/16 where a recovery of 72% (old versus fresh) was observed, there was no significant change in the measured concentrations of the aged test preparations on days 2, 7, 12, 16 and 21 and so the results are based on mean measured test concentrations only. Exposure of Daphnia magna to the test item gave the following results based on the mean measured test concentrations:

Endpoint (Reproduction)
EC10(95% confidence limits)	1.0 (n.d)
EC50(95% confidence limits)	2.3 (n.d)

n.d - None determined due to the nature of the data.