3,5,5-trimethylhexanoic acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-04-06 to 2010-04-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

EU Commission Directive 92/69/EEC, Part C.2

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: duplicate samples were taken from each treatment before the test start and at the end of the test after 48 hours
- Sampling method:
- Sample storage conditions before analysis: All samples were stored protected from light and deep-frozen (at about -20 °C) immediately after sampling.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: stock solution: completely dissolving 60.02 mg of test item in 600 mL of test water stirring intensely for 15 minutes at room temperature. Adequate volumes of this test medium were diluted with test water to prepare the test media of the lower test item concentrations.
- Controls: negative (reconstituted water)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: waterflea
- Strain: Clone 5
- Source: University of Sheffield / UK (supplied in 1992); the clone has been bred at Harlan Laboratories since 1992
- Age at study initiation (mean and range, SD): 6 to 24 h
- Feeding during test: no

ACCLIMATION
- Acclimation period: none

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

20 °C

pH:

7.8 to 7.9

Dissolved oxygen:

8.5 to 8.7 mg/L

Nominal and measured concentrations:

nominal: 0 (control), 4.6, 10, 22, 46 and 100 mg/L
measured: 97 to 100% of nominal

Details on test conditions:

TEST SYSTEM
- Test vessel: 100-mL glass beakers
- Type (delete if not applicable): closed (covered wth glass plates)
- Material, size, headspace, fill volume: 100-mL glass beakers, 50-mL fill volume
- Aeration: test water aerated prior to start of the study until oxygen saturation was reached; no aeration during test
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 5
- No. of vessels per vehicle control (replicates): 4
- Biomass loading rate: 1 animal/10 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water according to ISO 6341
- Alkalinity: 0.8 mmol/L
- Ca/mg ratio: 4:1
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: 16 h light: 8 h dark, 30-minute transition period
- Light intensity: 520 to 680 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: approx. 2.2
- Justification for using less concentrations than requested by guideline: not applicable
- Range finding study
- Test concentrations: no data
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

68 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 46 to 100 mg/L

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

68 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 46 to 100 mg/L

Details on results:

- Behavioural abnormalities: no
- Other biological observations: no
- Mortality of control: 0%
- Other adverse effects control: no
- Abnormal responses: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not applicable
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50/LC50: 48-h EC50 : 0.43 mg/L (study C86933, March 2010)

Immobility

Nominal test item concentration	No. of daphnids tested	Immobilized daphnids after 24 hours		Immobilized daphnids after 48 hours
(mg/L)		No.	%	No.	%
Control	20	0	0	0	0
4.6	20	0	0	0	0
10	20	0	0	0	0
22	20	0	0	0	0
46	20	0	0	0	0
100	20	20	100	20	100

Dissolved Oxygen Concentrations, pH Values and Temperature in the Treatments

Nominal test item concentration	Start (0 hours)			End (48 hours)
(mg/L)	pH	Oxygen (mg/L)	Temperature (°C)	pH	Oxygen (mg/L)	Temperature (°C)
Control	7.8	8.7	20	7.8	8.7	20
4.6	7.9	8.6	20	7.8	8.7	20
10	7.9	8.7	20	7.8	8.7	20
22	7.9	8.5	20	7.8	8.7	20
46	7.9	8.5	20	7.8	8.7	20
100	7.9	8.5	20	7.8	8.7	20

Validity criteria fulfilled:

yes

Conclusions:

The 48-h EC50 was 68 mg/L (95% CL: 46 to 100 mg/L).

Executive summary:

3,5,5-trimethylhexanoic acid was tested on the waterfea Daphnia magna in a 48 -h acute toxicity test under static conditions. The study was performed according to OECD Guideline 202 and EU Commission Directive 92/69/EEC, Part C.2. Test concentrations were analytically verified by chemical analysis. pH values were in the neutral range for all test item concentrations tested. The recovery was between 97 and 100%. The 48 -h EC50 was 68 mg/L (95% CL: 46 to 100 mg/L. Based on this value, 3,5,5-trimethylhexanoic acid is acutely harmful to aquatic invertebrates.

Description of key information

Daphnia magna: 68 mg/L (OECD 202; OXEA, 2010)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

68 mg/L

Additional information

3,5,5-trimethylhexanoic acid was tested on the waterflea Daphnia magna in a 48 -h acute toxicity test under static conditions. The study was performed according to OECD Guideline 202 and EU Commission Directive 92/69/EEC, Part C.2. Test concentrations were analytically verified by chemical analysis. The recovery was between 97 and 100%. pH values were in the neutral range for all test item concentrations tested. The 48 -h EC50 was 68 mg/L (95% CL: 46 to 100 mg/L. Based on this value, 3,5,5-trimethylhexanoic acid is acutely harmful to aquatic invertebrates.