Octanoic acid

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

12 Jan - 14 Jan 1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: DIN 38412/15

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

static test design instead of recommended semi-static or flow-through.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test substance was directly weighted into the test vessels and filled up to final volumes of 10 L with drinking water
- Controls: none

Test organisms (species):

Leuciscus idus

Details on test organisms:

TEST ORGANISM
- Common name: Golden orfe
- Length at study initiation: about 6 cm
- Feeding during test: none

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

16 dH (~93 mg Ca and 12 mg Mg/L)

Test temperature:

about 20 °C

pH:

4.5 - 7.1

Dissolved oxygen:

78 - 96%

Salinity:

n.a.

Nominal and measured concentrations:

nominal: 100, 300, 1000, 3000, 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: fish basin containing 10 L test water
- No. of organisms per vessel: 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: copper- and chlorine-free drinking water

OTHER TEST CONDITIONS
- Photoperiod: 16 h

EFFECT PARAMETERS MEASURED: mortality after 0, 6, 24 and 48 h

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

170 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC100

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: none

Sublethal observations / clinical signs:

Table 1: Mortality [%] of fish

Concentration	Incubation time [h]
[mg prod./L]	0	6	24	48
100	0	0	0	0
300	0	0	100	100
1000	0	80	100	100
3000	0	100	100	100
10000	0	100	100	100

.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

07 Jul - 20 Jul 1988

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Relevant methodological deficiencies

Qualifier:

according to guideline

Guideline:

other: Bewertung wassergefährdender Stoffe, Bestimmung der akuten Fischtoxizität

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution was formulated using Tween 80 as solvent combined with an ultrasound treatment. The solutions were prepared within 4 h before the test start
- Controls: water control and solvent control (Tween 80)
- Concentration of vehicle in test medium: Control with 0.1 mL Tween 80/L
- Evidence of undissolved material: During the main test, the test item could only be homogenously dispersed up to 180 mg/L with Tween 80. At higher concentrations a part of the test substance remained floating at the surface of the test media.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: Carp
- Length at study initiation: 2 -4 cm
- Feeding during test: none

ACCLIMATION
- Feeding frequency: no feeding 2 days prior to test
- Health during acclimation: mortality < 1% 7 days prior to test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20- 21.5 °C

pH:

pH values remained > 6 for concentrations higher than 180 mg/L.

Dissolved oxygen:

< 5 mg/L

Nominal and measured concentrations:

nominal: 32, 56, 100, 180, 320, 560 mg/L and 320 and 560 mg/L with pH adjustment

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume of test vessel: 10 L glass vessel containing 5 L test substance
- Aeration: continuous
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- No. of vessels per vehicle control: 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dutch standard water

OTHER TEST CONDITIONS
- Adjustment of pH: at 320 and 560 mg/L with with sodium hydroxide


EFFECT PARAMETERS MEASURED: mortality and behaviour at 2-5 h, 24 h and 48 h


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Range finding study
- Test concentrations: 0.01 - 1000 mg/L
- Results used to determine the conditions for the definitive study: 100 % mortality at 1000 mg/L, no mortality at 10 mg/L

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

134 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC100

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: fish showed decreased swimming ability at 560 mg a.s./L (pH adjusted)
- Mortality of control: 0%
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: The test substance was homogeneously dispersed
- Effect concentrations exceeding solubility of substance in test medium: During the main test, the test item could only be homogeneously dispersed up to 180 mg/L with Tween 80. At higher concentrations a part of the test substance remained floating at the surface of the test media.

Sublethal observations / clinical signs:

Table 1: Mortality [%] of fish

Concentration	Incubation time [h]
[mg prod./L]	2 - 5	24	48
control	0	0	0
solvent control (Tween 80)	0	0	0
32	0	0	0
56	0	0	0
100	0	0	0
180	100	100	100
320	100	100	100
560	100	100	100
320 (pH adjusted)	0	0	0
560 (pH adjusted)	10*	70*	70*

* Fish showed decreased swimming ability

The results indicate, that at least part of the toxicity of the test substance can be explained by its pH-lowering property.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 Jan- 08 Jan 1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented study report which meets basic scientific principles

Qualifier:

according to guideline

Guideline:

other: Methods for acute toxicity tests with fish, macroinvertebrates, and amphibians (U.S. EPA, 1975)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solution was prepared by adding 1.56 g test substance to distilled water and diluting to 1000 mL in a volumetric flask. Subsequently the solution was mixed on a magnetic stirrer for 30 min and then added to each test jar in the required amount. The test medium was also mixed for approximately 2 min.
- Controls: 1
- Evidence of undissolved material: At nominal concentrations of 14, 24 and 40 mg a.s./L the test material was not entirely dissolved.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: bluegill sunfish
- Source: Commercial fish supplier in Connecticut (USA)
- Length at study initiation: mean: 34 mm (range 25 - 44 mm, n = 30)
- Weight at study initiation: mean: 0.39 g (range: 0.16 - 0.99 g, n = 30)
- Feeding during test: none

ACCLIMATION
- Acclimation period: 14 d
- Acclimation conditions: same as during test
- Type and amount of food: dry pelleted food, ad libitum
- Feeding frequency: daily except during 48 h prior to test
- Health during acclimation: mortality during the 48 h prior to test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

49 mg/L

Test temperature:

22 ± 1 °C

pH:

6.4 - 7.3

Dissolved oxygen:

0.3 - 9.4 mg/L (= 3.4 - 100%)

Nominal and measured concentrations:

nominal: 3.1, 5.2, 8.6, 14, 24 and 40 mg a.s./L

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume of test vessel: 19.6 L glass jar containing 15 L test medium
- Aeration: no aeration provided
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/ 8 h dark

EFFECT PARAMETERS MEASURED: mortality and sublethal effects every 24 h

Reference substance (positive control):

yes

Remarks:

sodium lauryl sulfate

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% conficdence interval: 17 .- 31 mg a.s./L

Details on results:

- Behavioural abnormalities: fish were lethargic, respiring repidly and/or at water surface
- Mortality of control: no fish died in the control
- Effect concentrations exceeding solubility of substance in test medium: At nominal concentrations of 14, 24 and 40 mg a.s./L the test material was not entirely dissolved.

Results with reference substance (positive control):

- LC50: 12 mg sodium lauryl sulfate/L, confidence interval: 10 - 15 mg/L

Sublethal observations / clinical signs:

Table 1: Mortality and sublethal effects of the test substance to fish

Time after test start [h]	Effects	Nominal test concentrations [mg a.s./L]
		0	3.1	5.2	8.6	14	24	40
24	m	0	0	0	0	0	0	0
	r		×	×	×	×	×	×
	l							×*
	s
	f
	c
48	m	0	0	0	0	0	0	0
	r		×	×	×	×	×	×
	l				×	×	×	×
	s							×
	f
	c		×	×	×	×	×	×
72	m	0	0	0	0	30	10	20
	r		×	×	×	×	×	×
	l			×	×	×	×	×
	s					×	×	×
	f
	c		×	×	×	×	×	×
96	m	0	0	0	0	30	50	80
	r		×	×	×	×	×	×
	l				×	×	×	×
	s					×	×	×
	f					×	×	×
	c		×	×	×	×	×	×

m = mortality [%]

r = all fish were respiring rapidly

l = all fish were lethargic

s = all fish were at the test solutions surface

f = fine white flocculent was observed in the test solution

c = test solution was cloudy

* not all, but 2 fish were lethargic

Reference 4

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

12 Oct - 16 Oct 1977

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Test methodology followed recommended bioassay practices (U.S. environmental Protection Agency, 1975)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: test substance was directly weighted into test vessels with dilution water and thoroughly mixed
- Controls: 1

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: bluegill sunfish
- Source: from a commercial hatchery in Nebraska (USA)
- Age at study initiation: approximetaly 2 month
- Length at study initiation: mean (n = 10): 30 mm (range 26 - 35 mm)
- Weight at study initiation: mean (n = 10): 0.23 g
- Feeding during test: none (feeding was stopped 48 h before test start)

ACCLIMATION
- Acclimation period: 24 h prior to test
- Acclimation conditions: same as during test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

42 mg CaCO3/L

Test temperature:

22.5 ± 1 °C at test start and test end in the control, high, medium and low toxicant concentration

pH:

test start: 5.49 - 7.50
test end: 6.02 - 7.23

Dissolved oxygen:

0.7 - 9.0

Nominal and measured concentrations:

nominal: 10, 18, 32, 56 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume of test vessel: 5-gallon, chemically clean glass jars containing 15 L test medium
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 3
- Biomass loading rate: 0.15 g fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dilution water deionised and treated by referse osmosis, reconstituted to desired pH and hardness

EFFECT PARAMETERS MEASURED: lethal and sublethal effects after 24, 48 and 96 h.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

39.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% confidence interval: 35.6 - 44.8 mg/L

Details on results:

- Behavioural abnormalities: none
- Other biological observations: at concentrations of 32 mg prod./L and higher, the fish became darkly discoloured
- Mortality of control: no mortality in control

Sublethal observations / clinical signs:

Table 3: Mortality of fish at different test substance concentrations [%]

Time after test start [h]	0 mg/L (control)	10 mg/L	18 mg/L	32 mg/L	56 mg/L	100 mg/L
24	0	0	0	0	60	100
48	0	0	0	0	100	100
96	0	0	10	0	100	100

Reference 5

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Oryzias latipes was studied under static freshwater and marine water conditions for 48 h.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: octanoic acid was dissolved in artifical sea water by adding 10 g/L and mixing in an Erlenmeyer flask for 24 h with a magnetic bar at room temperature (25 ± 2 °C). The mixture was left still for a few hours and the upper layer was remoced with a capillary pipette. The lower layer was used for testing.
For the freshwater test octanoic acid was disolved with Tween 80 (a dispersant).

Test organisms (species):

Oryzias latipes

Details on test organisms:

TEST ORGANISM
- Common name: Red killifish
- Source: commercial source
- Length at study initiation: approximately 2.5 cm
- Weight at study initiation: approximately 0.2 g
- Feeding during test: feeding was stopped one day prior to the test
- Food type: commercial fish food

ACCLIMATION
- Acclimation period: Although Oryzias latipes is a freshwater fish, it was used in a marine test. First the fish were kept under laboratory conditions in freshwater for more than 2 weeks. Then fish were acclimated to sea water by changing salt concentrations from 0 to 10 per mille (kept at 10 per mille for more than 4 days), to 20 per mille (kept at 20 per mille for more than 4 days) and to the final salinity of 30 per mille (kept for more than 7 days before test start)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

51 mg CaCO3/L

Test temperature:

25 ± 2°C

pH:

freshwater: 7.2
saltwater: 8.2

Dissolved oxygen:

If dissolved oxygen was < 60 % of air saturation, aeration was provided once for 5 min at 24 h intervals.

Salinity:

30 per mille

Nominal and measured concentrations:

Animals were exposed to a geometric series of concentrations of the test chemical (max. 1000 mg/L), but when LC50 values of the test chemicals were close to or higher than the saturated concentrations, animals were exposed only to the saturated solutions and the half-dilution of the saturated solutions.

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 2 L test water
- Aeration: if oxygen saturation was < 60% of air saturation aeration for 5 min, 24 h interval
- Renewal rate of test solution: no, static test
- No. of organisms per vessel: 10

OTHER TEST CONDITIONS
- Photoperiod: 12 h light/12 h dark

EFFECT PARAMETERS MEASURED: lethal effects

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

150 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

mortality (fish)

Remarks on result:

other: in sea water

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

57 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

mortality (fish)

Remarks on result:

other: in freshwater

Description of key information

LC50 (96 h) = 22 mg/L (nominal), based on mortality of Lepomis macrochirus

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

22 mg/L

Additional information

In the key study (1982) the toxicity to Lepomis macrochirus was tested under static conditions according to an EPA-method (1975, Methods for acute toxicity tests with fish macroinvertebrates, and amphibians). Nominal test concentrations were 3.1, 5.2, 8.6, 14, 24 and 40 mg/ L. No analytical monitoring was performed. At all concentrations all fish respired rapidly and the test solution was cloudy. In addition at the three highest concentrations, all fish were lethargic. After incubation time of 96 h, an LC50 of 22 mg/L (nominal) was determined.

The observation of toxic effects in the range of water solubility was corroborated by further test results.

In a supporting study (1977) according to a bioassay practice from U.S. EPA (1975), Lepomis macrochirus as the test organism was exposed to 10, 18, 32, 56 and 100 mg/L test substance. The study resulted in an LC50 (96 h) of 39.9 mg/L.

In a further supporting study (2002) conducted according to DIN 38412/15, Leuciscus idus was exposed to 100, 300, 1000, 3000, 10000 mg/L test item. The study showed effects towards the fish species, resulting in an LC50 (48 h) of 170 mg/L.

In a static study conducted for 48 h (Onitsuka 1989, no guideline followed) in freshwater and in saltwater medium with Oryzias latipes as the test organism, an LC50 of 57 mg/L for freshwater and an LC50 of 150 mg/L for saltwater was determined. Allthough the publication gives valuable information the documentation is inadequate for assessment purposes and the study was rated as RL4.

The last available study (1988), reported an LC50 of 134 mg/L. However, due to significant methodological deficiencies this study was considered not reliable and rated RL 3.

In conclusion, octanoic acid shows toxicity to fish within the range of water solubility, with an LC50 of 22 mg/L being the most sensitive value. This value was therefore used for further assessment.