[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 12, 2019 to October 29, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

EC Number:

231-324-2

EC Name:

[(3,7-dimethyl-6-octenyl)oxy]acetaldehyde

Cas Number:

7492-67-3

Molecular formula:

C12H22O2

IUPAC Name:

2-[(3,7-dimethyloct-6-en-1-yl)oxy]acetaldehyde

Test material form:

liquid

Specific details on test material used for the study:

Batch: VE00601569
Appearance: Colorless to pale yellow liquid
Expiration Date: January 12, 2020
Purity: 92.9% (sum of the two peaks)

Sampling and analysis

Analytical monitoring:

yes

Remarks:

GC-FID

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

The study was performed with young daphnias of the species Daphnia magna Straus. A clone of this species (originally from the Daphnia Collection of the University of Basel/Switzerland in 2015) is successfully bred in IES Ltd Laboratories.

Study design

Test type:

semi-static

Water media type:

other: Reconstituted test water (ISO Test water) according to OECD Guideline No. 202 was used in the study.

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

The immobility of the daphnias was determined by visual inspection after 24 and 48 hours of exposure. Those daphnids not able to swim within 15 seconds after gentle agitation of the test vessel were considered to be immobilized.

Test conditions

Test temperature:

Determined

pH:

Determined

Dissolved oxygen:

Determined

Nominal and measured concentrations:

Dilutions tested: 1:2.2, 1:4.6, 1:10 and 1:22. Additionally, a control (test water without test item) was tested in parallel.

Details on test conditions:

At the start and end of each test medium renewal period, the pH values, dissolved oxygen concentrations and water temperature were determined in each treatment. In addition, the appearance of the test media was visually controlled and documented at the same time.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

14 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Effect concentrations 2

Key result

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

5.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Effect concentrations 3

Key result

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

47 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Effect concentrations 4

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

8.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Effect concentrations 5

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

5.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Effect concentrations 6

Key result

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

21 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Results with reference substance (positive control):

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in April 2019 (24-hour EC50: 1.5 mg/L, IES Study 20190095) showed that the sensitivity of the test organisms was within the internal historical range (24-hour EC50 from 2015 to 2019: 0.78-1.60 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

A clear dose-response effect was observed after the exposure period of 48 hours. Up to and including the mean measured concentration of 5.2 mg/L no toxic effect was observed until test end. At the three highest test concentrations of 11, 21 and 47 mg/L, 90%, 100% and 100% of the daphnids were found to be immobile after 48 hours, respectively.

Executive summary:

The acute toxicity of the test item CITRONELLYL OXYACETALDEHYDE to Daphnia magna was determined in a 48-hour semi-static test according to the OECD Guideline for Testing of Chemicals, No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2.

As the test item is a volatile substance, the test was performed using glass tubes completely filled (without headspace) with test medium that were tightly sealed with glass stoppers to avoid losses of test item by evaporation (closed system). A semi-static test design was used.

As the test item is a liquid with low water solubility, the slow-stirring method (to avoid formation of micro-droplets) was applied for preparation of a saturated test item solution. For preparation of the highest concentration of test medium, the test item was carefully applied (pipetted) onto the surface of the test water at a loading rate of 100 mg/L. Thereafter slow-stirring was applied for 24 hours in a closed vessel.

After this treatment the lower part of the equilibrated test medium was carefully harvested from the stirring vessel through a tap at the bottom of the vessel. This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest concentration and was diluted with test water to obtain the dilutions 1:2.2, 1:4.6, 1:10 and 1:22. Additionally, a control (test water without test item) was tested in parallel.

The preparation of the test media was based on the OECD Guidance Document No. 23 on Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals, 2019.

The measured concentrations of the test item CITRONELLYL OXYACETALDEHYDE in the undiluted test medium and the dilutions 1:2.2, 1:4.6 and 1:10 are shown in the table below. The results demonstrate the correct preparation of the test media, i.e. the spacing factor of 2.2 between the different test concentrations was met. At the end of the test or at the end of the respective exposure period when all daphnia were immobile, 78 to 102% of the initially measured values were found. The samples from the dilution 1:22 were not analyzed, since this concentration was below the NOEC determined in this test and thus not relevant for the interpretation of the biological results.

The biological results were based on the mean measured concentrations. These were calculated as follows: For each test medium renewal period (i.e. Day 0-Day 1, Day 1-Day 2), the mean concentration was calculated as the geometric mean of the test item concentrations measured at the start and the end of the test medium renewal period. From the two geometric mean values obtained, the mean measured test item concentration during the test period of 48 hours was calculated as an arithmetic mean:

Treatment / Dilution#	Measured Test Item Concentrations at the Start of the Renewal Periods (Day 0 and Day 1) [mg/L]	Measured Test Item Concentrations at the End of the Renewal Periods (Day 1 and Day 2) [mg/L]	Mean Measured Concentration of the Test Item during the 48 Hour Test Period [mg/L]
1:22	Not analyzed	Not analyzed	--
1:10	5.51/5.04	5.19/5.12	5.2
1:4.6	10.6/12.2	10.7/9.53	11
1:2.2	23.3/20.9	20.8/19.4	21
Undiluted Test Medium*	47.5/46.8	45.7/ n.d.	47°

*: Equilibrated test medium with a loading rate of 100 mg/L.

#: Dilutions of the equilibrated test medium with a loading rate of 100 mg/L.

n.d.: Not determined since all daphnids were already dead after 24 hours exposure time.

°: Mean measured (geometric mean) calculation only based on the first renewal period.

A clear dose-response effect was observed after the exposure period of 48 hours. Up to and including the mean measured concentration of 5.2 mg/L no toxic effect was observed until test end. At the three highest test concentrations of 11, 21 and 47 mg/L, 90%, 100% and 100% of the daphnids were found to be immobile after 48 hours, respectively.

ECx Values Immobility	Based on Mean Measured Concentration of the Test Item [mg/L]
24-hour EC50 (95% Confidence Limits)	14 (12-17)
24-hour EC0 and 24-hour NOEC	5.2
24-hour EC100	47
48-hour EC50 (95% Confidence Limits)	8.9 (8.1-9.9)
48-hour EC0 and 48-hour NOEC	5.2
48-hour EC100	21