2-ethylhexanoic acid, compound with 2-aminoethanol (1:1)

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28/10/2009 - 01/02/2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO 5667-16 (1998) Water quality sampling – guidance on biotesting on samples.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Solubility and stability of the test substance in the solvent/vehicle: Characterised as soluble. Diluted in seawater.Stability not specified.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test substance added to seawater and stirred for 1 hour to dissolve.
- Final dilution of a dissolved solid, stock liquid or gel: A series of dilutions was made (3.2, 10, 32, 100, 320, 1002 mg/L nominal concentration) from a prepared 1000 mg/L (Nominal concentration) stock solution.
- Final preparation of a solid: Dissovled in seawater.

FORM AS APPLIED IN THE TEST- Aqueous, in solution

Analytical monitoring:

no

Details on sampling:

- Concentrations: 3.2, 10, 32, 100, 320, 1000 mg/L test substance (nominal concentrations)
- Sampling method: Population or biomass growth observations over time using a microscope with a haemocytometer.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Growth rate measured over time
Test substance was added directly to filtered and sterilised seawater, stirred for 1 hour.
- Controls: 4 growth rate controls and 3 positive (reference substance) controls.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No, substance stated as soluable

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Common name: Skeletonema costatum
- Age of parental stock (mean and range, SD): Not specified, test organisms were pre-cultured for 3 (+-1) days.
- Feeding during test: Same for definitive test as for the pre-culture conditions. Sea water was inoculated with microorganisms in a nutirent culture.
- Food type: Nutrient medium
- Amount: Cell density for pre-culutre and for testing was approximately 2 x 10(to the power of 3) to 10 (to the power of 4) cells/ ml

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

Results recorded at 24, 48 and 72 hours

Test temperature:

20.1 - 21.5 °C

pH:

pH 8.01 - 8.06 at 0 hours and pH 8.15 - 9.15 at 1 hours

Salinity:

35‰ salinity

Nominal and measured concentrations:

For the definitive test the test substance nominal concentrations were 3.2, 10, 32, 100, 320 and 1000 mg/L and the actual nominal concentrations were 3.2, 10, 32, 100, 320 and 1002 mg/L, respectively.

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flasks
- Type: closed
- Material, size, headspace, fill volume: 100 ml
- Aeration: Partial, aluminium cap is loosely mounted
- No. of organisms per vessel: Estimated at 9993 cells/ml
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 4 growth rate controls and 3 positive controls (1.0, 1.8, 3.2 mg/L reference substance) with 2 replicates each

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Natural seawater supplied by Scapa Flow (Orkney).
- Alkalinity: pH 8.01 - 8.06
- Salinity: 36‰ ± 4‰ salinity
- Culture medium different from test medium: No
- Intervals of water quality measurement: At 0 hours and partial observations at 1 hour after test initiation.

OTHER TEST CONDITIONS
- Photoperiod: continual
- Light intensity: cool white illuminestion as specified in the ISO guidelines.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Population growth over 24, 48 and 72 hours

RANGE-FINDING STUDY
- Test concentrations: 1, 10, 100 and 1000 mg/L
- Results used to determine the conditions for the definitive study: yes, same concentrations used

Reference substance (positive control):

yes

Remarks:

3,5 Dichlorophenol

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

584.53 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

625.26 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

427.14 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

885.43 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes, guideline criterion met
- Any stimulation of growth found in any treatment: No, none above control
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 2.56 mg / Lfor 72 hours

Validity criteria fulfilled:

yes

Remarks:

Guideline criteria met

Conclusions:

This study concludes that the EC50 for the test substance was 584.53 mg/L for 24 hours, 625.26 mg/L for 48 hours, 427.14 mg/L for 72 hours. The study also concluded that at 72 hours there is a EC90 of 885.43 mg/L and a NOEC of 32 mg/L.

Executive summary:

The study assesses the toxicity of 2 -Butyl butanoic acid compounds with aminoethanol to algae. This study is performed in compliance with GLP and uses the testing standards ISO 10253 (2006) Water quality – marine algal growth inhibition toxicity test and ISO 5567 - 16 (1998) Water quality sampling- guidance on biotesting of samples. All validity criteria was complied with. The test organism was Skeletonema costatum and the test was performed using saltwater (seawater) . A rangefinding test was initially performed to show that the EC50 at 72 hours was 427.14 mg/ L. The definitive test used a range of nominal concentrations of 3.2, 10, 32, 100, 320 and 1000 mg/L. This range was produced by dissolving the test material in seawater at 1000 mg/L and subsequent lower concentrations were produced by serial dilution. The definitive test examined 5 concentrations with 2 replicates each. 4 negative controls were included with 1 replicate each to show a calculated growth rate of 0.99 - 1.04 at 72 hours. 4 positive controls (reference product: 3,5 Dichlorophenol) were included at difference concentrations (1, 10, 100, 1000 mg/ L of reference substance) with 1 replicate each to show that the EC50 value for 72 hours was 2.56 mg/L. The results of the definitive test shows that the test substance has an EC50 value of 584.53 mg/L for 24 hours, 625.26 mg/L for 48 hours, 427.14 mg/L for 72 hours. Other results from the study were at 72 hours the EC90 is 885.43 mg/L and the NOEC is 32 mg/L.

Description of key information

The study assesses the toxicity of 2 -Butyl butanoic acid compounds with aminoethanol to algae. This study is performed in compliance with GLP and uses the testing standards ISO 10253 (2006) Water quality – marine algal growth inhibition toxicity test and ISO 5567 - 16 (1998) Water quality sampling- guidance on biotesting of samples. All validity criteria was complied with. The test organism was Skeletonema costatum and the test was performed using saltwater (seawater) . A rangefinding test was initially performed to show that the EC50 at 72 hours was 427.14 mg/ L. The definitive test used a range of nominal concentrations of 3.2, 10, 32, 100, 320 and 1000 mg/L. This range was produced by dissolving the test material in seawater at 1000 mg/L and subsequent lower concentrations were produced by serial dilution. The definitive test examined 5 concentrations with 2 replicates each. 4 negative controls were included with 1 replicate each to show a calculated growth rate of 0.99 - 1.04 at 72 hours. 4 positive controls (reference product: 3,5 Dichlorophenol) were included at difference concentrations (1, 10, 100, 1000 mg/ L of reference substance) with 1 replicate each to show that the EC50 value for 72 hours was 2.56 mg/L. The results of the definitive test shows that the test substance has an EC50 value of 584.53 mg/L for 24 hours, 625.26 mg/L for 48 hours, 427.14 mg/L for 72 hours. Other results from the study were at 72 hours the EC90 is 885.43 mg/L and the NOEC is 32 mg/L.

Key value for chemical safety assessment

EC50 for marine water algae:

427.14 mg/L