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Ecotoxicological information

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study, to GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Test material form:
liquid
Details on test material:
Identification: Linalyl isobutyrate
Chemical name: 3,7-dimethyl-1,6-octadien-3-yl 2-methylpropanoate
Empirical Formula: C14H24O2
Molecular Weight: 224.35 g/mol
EC No.: 201-108-2
CAS No.: 78-35-3
Physical state/Appearance: Clear colorless liquid

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At 0 and 24 hours for fresh media and at 24 and 48 hours for old media.

Test solutions

Details on test solutions:
In the range-finding test Daphnia magna were exposed to a series of nominal test concentrations of 0.10, 1.0, 10 and 100% v/v saturated solution.
Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 10, 18, 32, 56 and 100% v/v saturated solution.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
The test was carried out using 1st instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium (see Appendix 2) in a temperature controlled room at approximately 20 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Study design

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
none

Test conditions

Test temperature:
Temperature was maintained at 19 to 20 °C throughout the test. The water temperature was recorded daily throughout the test using a Hanna Instruments HI 93510 digital thermometer.
pH:
The pH of the prepared media was 7.9 ± 0.3. The pH was measured daily using a Hach Flexi handheld meter
Dissolved oxygen:
The dissolved oxygen concentration at the end of the test is ≥3 mg/L in the control and test vessels. The dissolved oxygen concentration was measured daily using a Hach Flexi handheld meter
Salinity:
No (freshwater)
Nominal and measured concentrations:
Range finding test: Nominal test concentrations of 0.10, 1.0, 10 and 100% v/v saturated solution

Definitive test: Nominal test concentrations of 10, 18, 32, 56 and 100% v/v saturated solution; 0-Hour measured test concentrations: 0.35, 0.66, 1.3, 2.2, 4.3 mg/L
-
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
1.4 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 1.2 - 1.7
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.66 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
1.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
In accordance with the tiered approach for selecting an appropriate exposure regime for unstable and volatile substances (OECD 2000), a closed semi-static system was used with no headspace. Under such conditions it is considered appropriate to base the effect results on the mean measured concentrations of fresh solutions. This gave a 48-hour EC50 of 1.4mg/L for linalyl isobutyrate. In order to give a “worse case” analysis of the data, the results were also calculated using the time-weighted mean measured test concentrations, which gave a slightly lower 48-hour EC50 value of 1.1 mg/L. Both results are within the same environmental classification band of > 1 and <= 10 mg/L.
Results with reference substance (positive control):
A positive control used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L.
Exposure conditions for the positive control were similar to those in the definitive test.
Analysis of the immobilization data by probit analysis using linear maximum likelihood regression at 24 and 48 hours. All analysis was carried out using the ToxRat Professional computer software package (ToxRat):

The 24 h EC50 was 1.1 mg/L .
The 48 h EC50 was 0.75 with 95 % confidence limits of 0.69 - 0.82 mg/L.
The NOEC was 0.56 mg/L and the LOEC was 1.0 mg/L.

The No Observed Effect Concentration is based upon less than 10% immobilization at this concentration.
The results from the positive control with potassium dichromate were within the normal range for this reference item.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In a guideline study, conducted according to GLP, Linalyl Isobutyrate was found to have an EC50 (48 hr) (average initial measured test concentrations) of 1.4 mg/L.