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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: read-across from a guideline study
Justification for type of information:
The read across justification is presented in the Endpoint summary Aquatic toxicity. The accompanying files are also attached there.
Reason / purpose:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.41 mg/L
Basis for effect:
mobility
Remarks on result:
other: read-across from Citronellyl butyrate
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 May 2016 - July 26, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
This information is used for read across to Geranyl Isobutyrate MCS.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
2008
Deviations:
no
Qualifier:
according to
Guideline:
other: OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures
Version / remarks:
2000
Deviations:
not specified
GLP compliance:
yes (incl. certificate)
Remarks:
Swiss Federal Office of Public Health. Consumer protection directorate. Notification authority of chemicals. CH-3003 Bern (d.d. 16 December 2015)
Specific details on test material used for the study:
Water solubility: 1.63 mg/L (at 20°C and pH 8.89)
Relative density: 0.8804
Log Pow: 6.20
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Control, undiluted filtrate of test item emulsion with a loading rate of 100 mg/L and dilutions 1:2.2, 1:4.6. The samples of the lower test concentrations (dilution 1:10, and 1:22) were not analyzed since these concentrations were below the 48-hour NOEC determined in this test and were therefore not relevant for the interpretation of the biological results.
- Sampling method: Duplicate samples were taken from each test concentration and the control at the start and at the end of the two 24-hour test medium renewal periods. For the 24-hour stability samples, the contents of the respective replicates were combined prior to sampling. Immediately after sampling, acetonitrile (6 mL acetonitrile per 9 mL sample volume) was added to each sample to stabilize the latter during the storage period. Thereafter, all samples were deep-frozen (at about -20 °C).
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION:
- Preparation method: At the start of the test (Day 0) and at the test medium renewal (Day 1) the highest test concentration (undiluted filtrate) was prepared by dosing 265 μL of the test item in 2320 mL test water. This volume is equivalent to a loading rate of 100 mg/L, considering the relative density of the test item of 0.88. The test item was mixed into test water by intensive stirring for three hours in the dark in a closed stirring vessel to dissolve a maximum of test item in test water. After stirring, the emulsion was filtered through a 0.45 μm membrane filter (Whatman, NC45). The filter was pre-conditioned with 200 mL filtrate to avoid losses of dissolved test item due to adsorption on the filter material. The undiluted filtrate was used as highest test concentration. It was further diluted with test water to prepare the test media with the lower test concentrations.
- Control: Test water without test item
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No remarkable observations were made concerning the appearance of the test media. All test media were clear solutions throughout the entire test duration.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain/clone: Dapnia magna Straus
- Source: Daphnia Collection of the University of Basel/Switzerland (2015); bred in the laboratory of Test Facility.
- Feeding during test: No
- Age of test organisms at start of test: <24 h old, not first brood progeny.

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.5 mmol/L; 250 mg/L as CaCO3
Test temperature:
21 °C
pH:
7.6-8.0
Dissolved oxygen:
7.9-8.5 mg/L
Nominal and measured concentrations:
Nominal: Control, Dilution 1:22, Dilution 1:10, Dilution 1:4.6, Dilution 1:2.2, Undiluted filtrate (loading rate of 100 mg/L)
Mean measured concentrations: Dilution 1:4.6 - 0.12 mg/L; Dilution 1:2.2 - 0.32 mg/L, Undiluted filtrate - 0.74 mg/L (See section "Any other information on materials and methods incl. tables" for details on calculation of mean measured concentrations and Table 1 for measured concentrations at each time point)
Details on test conditions:
TEST SYSTEM
- Test vessel: glass vessels completely filled with 60 mL test medium and tightly sealed with glass stoppers (closed system).
- Aeration: no
- Renewal rate of test solution: after 24 h with freshly prepared test medium.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO Standard 6341.
- Culture medium different from test medium: not specified
- Intervals of water quality measurement: pH, temperature, dissolved oxygen concentrations and water temperature were determined at the start and end of the test medium renewal periods.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: A 16-hour light to 8-hour dark cycle with a 30-minute transition period was used.
- Light intensity: Light intensity during the light period was between 15 and 18 μmol m^-2 s^-1.

EFFECT PARAMETERS MEASURED
- Immobility, visually determined after 24 and 48 h of exposure

RANGE-FINDING STUDY
- Test concentrations: Control, Dilution 1:20, Dilution 1:5, Undiluted filtrate with a loading rate of 100 mg/L.
- Results used to determine the conditions for the definitive study: yes.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate, performed March 2016
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.41 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limits: 0.32-0.53
Details on results:
- Behavioural abnormalities: in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water)
- Mortality of control: none observed
- After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 0.12 mg/L. At the next higher test concentrations of 0.32 and 0.74 mg/L, 35 and 85% of the daphnids were immobile. For details on immobility, see Table in 'Any other information on results incl. tables'.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Relevant effect levels: 24-hour EC50: 1.6 mg/L; the sensitivity of the test organisms was within the range given by the guideline (24-hour EC50: 0.60-2.1 mg/L)
Reported statistics and error estimates:
The 48-hour EC50 was calculated by Probit Analysis using linear maximum likelihood regression. Statistical analysis was performed using ToxRat Professional®

Effect of CITRONELLYL BUTYRATE on the Mobility of Daphnia magna

 

Treatment/dilution

Mean measured concentration [mg/L]

No. of daphnids tested

Immobilized daphnids after 24 hours

Immobilized daphnids after 48 hours

No.

[%]

No.

[%]

Control

---

20

0

0

0

0

Dilution 1:22

n.a.

20

0

0

0

0

Dilution 1:10

n.a.

20

0

0

0

0

Dilution 1:4.6

0.12

20

0

0

0

0

Dilution 1:2.2

0.32

20

0

0

7

35

Undiluted filtrate*

0.74

20

5

25

17

85

 

N.a.: not analyzed since below the NOEC determined in this test

*: Undiluted filtrate with a loading rate of 100 mg/L

Validity criteria fulfilled:
yes
Remarks:
See 'Overall remarks' section for details on validity criteria
Conclusions:
The 48-hour EC50 was calculated to be 0.41 mg/L based on mean measured concentrations.
Executive summary:

The acute toxicity to Daphnia was examined in a study according to OECD TG 202 and in compliance with GLP criteria. In a 48 h semi-static test daphnids were exposed to Citronellyl butyrate as an undiluted filtrate with a loading rate of 100 mg/L and to dilutions of this filtrate at 1:22, 1:10, 1:4.6 and 1:2.2. Test substance analysis was performed on the dilutions 1:4.6 and 1:2.2 and on the undiluted filtrate. The respective measured concentrations were determined to be 0.12, 0.32 and 0.74 mg/L. These measured concentrations were calculated as the arithmetic mean of the two geometric means which were determined from the test item concentrations measured at the start and end of each of the two test medium renewal periods. After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 0.12 mg/L. At the next higher test concentrations of 0.32 and 0.74 mg/L, 35% and 85% of the daphnids were immobile. The 48-hour EC50 was calculated to be 0.41 mg/L (95%-C.L: 0.32 - 0.53 mg/L) based on mean measured concentrations. The validity criteria are met and the study considered to be reliable without restrictions.

Description of key information

The short-term toxicity to aquatic invertebrates is assessed based on read-across from the close structural analogue Citronellyl butyrate (CAS# 141 -16 -2).

For Citronellyl butyrate, the acute toxicity to Daphnia was examined in a study according to OECD TG 202 and in compliance with GLP criteria (Symrise, 2016). In a 48 h semi-static test daphnids were exposed to Citronellyl butyrate as an undiluted filtrate with a loading rate of 100 mg/L and to dilutions of this filtrate at 1:22, 1:10, 1:4.6 and 1:2.2. Test substance analysis was performed on the dilutions 1:4.6 and 1:2.2 and on the undiluted filtrate. The respective measured concentrations were determined to be 0.12, 0.32 and 0.74 mg/L. These measured concentrations were calculated as the arithmetic mean of the two geometric means which were determined from the test item concentrations measured at the start and end of each of the two test medium renewal periods. After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 0.12 mg/L. At the next higher test concentrations of 0.32 and 0.74 mg/L, 35% and 85% of the daphnids were immobile. The 48-hour EC50 was calculated to be 0.41 mg/L (95%-C.L: 0.32 - 0.53 mg/L) based on mean measured concentrations. The validity criteria are met and the study considered to be reliable without restrictions.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.41 mg/L

Additional information

See CSR section 7.1.