2-butyloctanoic 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:

1999-11-17 to 1999-11-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study without GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

no

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

STOCK AND TEST SOLUTION AND THEIR PREPARATION
- Dispersion: no
- Vehicle, solvent: no
- Concentration of vehicle/ solvent: not applicable
- Other procedures: A stock solution was prepared by mixing of 1 g/l test substance with synthetic freshwater, stirring for 18 hours and subsequently filtering.
STABILITY OF THE TEST CHEMICAL SOLUTIONS: No stability test was performed.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Strain: Daphnia magna straus; clone 5
- Source/supplier: laboratory bred
- Breeding method: The females were maintained in M4 medium in 1 l beakers. At two to three day intervals, the exuviae were siphoned off and the water was changed. In the course of this, the offspring was removed from the breeding vessels. At regular intervals of approx. 4 weeks, offspring was isolated from the vessels and served as a basis for further breeding.
- Age: not older than 24 hours
- Feeding: Scenedesmus subspicatus
- Pretreatment: Females were separated from the offspring 24 hours before the start of the test. The offspring produced overnight are transferred into the test water.
- Feeding during test: no
- Control group: 4 replicates with 5 animals each in synthetic freshwater

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Hardness:

14°dH = 250 mg CaCO3/l

Test temperature:

20 +- 1 ° C

pH:

7.2 - 7.9

Dissolved oxygen:

90 - 104 %

Nominal and measured concentrations:

The measured analytical value was 76.9 mg TOC/l corresponding to 107 mg of test substance/l. This result was used for the calculatiion of test test substance.

Details on test conditions:

DILUTION WATER
- Source: synthetic freshwater
- Aeration: no
- Alkalinity: not mentioned
- Hardness: 14 °dH (2.5 mmol Ca2+/Mg2+)
- Salinity: CaCl2 x 2 H2O: 294 mg/l; MgSO4 x 7 H2O: 114 mg/l; NaHCO3: 65 mg/l; KCl: 6 mg/l
- TOC: not mentioned
- Ca/Mg ratio: 4:1
- Na/K ratio: 10:1
- TSS: not mentioned
- pH: 7.8
- Oxygen content: 98 %
- Conductance: not mentioned
- Holding water: synthetic freshwater
TEST SYSTEM
- Test type: static
- Concentrations: 0 (control), 2.68, 5.35, 10.7, 21.4, 42.8, 85.6 mg/l (based on TOC measurement of stock solution)
- Renewal of test solution: no
- Exposure vessel type: Round-bottom test tubes calibrated to 10 ml
- Number of replicates, individuals per replicate: 4 replicates, 5 animals per replicate
- Test temperature: 20 +/- 1 °C
- Dissolved oxygen: 90-104 %
- pH: 7.2 – 7.9
- Adjustment of pH: no
- Photoperiod: test was performed in the dark
- Intensity of irradiation: not applicable
DURATION OF THE TEST: 48 hours
TEST PARAMETER: immobilisation, pH value, dissolved oxygen
SAMPLING: after 24 and 48 hours
MONITORING OF TEST SUBSTANCE CONCENTRATION: The measured analytical value of the stock solution was 76.9 mg TOC/l corresponding

Reference substance (positive control):

yes

Remarks:

potassium dichromate, 1.0 and 2.0 mg/l (historical control), 24 hours exposure

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL 22-42 mg/L

Details on results:

- concentration / effect data (Immobilisation)
(mg/l) 24h 48h
0 0% 0%
2.68 0% 0%
5.35 0% 5%
10.7 5% 10%
21.4 5% 20%
42.8 30% 65%
85.6 100% 100%

Results with reference substance (positive control):

Immobilsation after 24 h: 1 mg/l: 45%; 2 mg/l: 100 %

Validity criteria fulfilled:

yes

Remarks:

not more tha 10% daphnids immobilised or trapped at the surface, dissolved oxygen at the end of the test >= 60% of air saturation, test with reference substance

Conclusions:

The 48h-EC50 was 31 mg/l (95% confidence interval between 22 and 42 mg/l).

Executive summary:

In an OECD 202 -study the 48h-EC50 of 2 -butyl octanoic acid was 31 mg/l (95% confidence interval between 22 and 42 mg/l).

Description of key information

In the key study (Daphnia magna, OECD 202, GLP compliant) with 2-butyloctanoic acid the 48h-EC50 was 31 mg/l (95% confidence interval between 22 and 42 mg/l). In the ECOSAR calculation a value of 48 h-EC50 of  9.363 mg/L is predicted. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

31 mg/L

Additional information

In the key study (Daphnia magna, OECD 202, GLP compliant) with 2-butyloctanoic acid the 48h-EC50 was 31 mg/l (95% confidence interval between 22 and 42 mg/l). In the ECOSAR calculation a value of 48 h-EC50 of 3.585 mg/L is predicted.

Acute toxicity in Daphnia magna with the similar substance Reaction mass of n-undecanoic-acid and 2-methyl-decanoic-acid and 2-ethyl-nonanoic-acid and 2-propyl-octanoic-acid and 2-butyl-heptanoic-acid was tested according to OECD guideline No. 202. The study met the acceptability criteria and was conducted GLP compliant, therefore considered reliable without restrictions. The 48h-EC50 was 16 mg/L based on average exposure concentrations (95% confidence interval between 13 and 19 mg/L) and thus confirming the range of toxicity to invertebrates.