Docosanoic acid

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adult fish: sub(lethal) effects

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

19 May 1998 - 02 June 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 204 (Fish, Prolonged Toxicity Test: 14-day Study)

Deviations:

no

GLP compliance:

yes

Remarks:

According to Japanes standard

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Test water was directly sampled by each vessel.
- Sample storage conditions before analysis: No strage before analysis.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test item was mixed with HCO-20 and diluted with dilution water (stock solution: 100 mg/L).
- Controls: Blank control and vehicle control
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): HCO-40
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 2000 mg/L in stock solution and 100 mg/L in final test solution

Test organisms (species):

Oryzias latipes

Details on test organisms:

TEST ORGANISM
- Common name: Medaka fish
- Source: Sankyo Suisan Company, Shinjuku, Japan
- Length at study initiation: 2.27 cm (2.01 - 2.49 cm)
- Weight at study initiation: 0.217 g (0.142 - 0.308 g)
- Feeding during test
- Food type: Tetramin
- Amount: 2% of body weight
- Frequency: Everyday


ACCLIMATION
- Acclimation period: 27 Feb - 19 May 1998
- Acclimation conditions (same as test or not): Same as test
- Type and amount of food: Tetramin
- Health during acclimation (any mortality observed): Mortality was < 5% during 7 days before exposure

Test type:

flow-through

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Hardness:

63 mg/L (as CaCO3)

Test temperature:

24.0 - 24.6 °C

pH:

7.4 - 7.8

Dissolved oxygen:

6.2 - 8.3 mg/L

Nominal and measured concentrations:

Nominal concentration: 4.99 mg/L
Measured concentration: 5.06 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Beaker
- Type (delete if not applicable): closed with teflon sheet
- Material, size, headspace, fill volume: Glass, 5 L
- Type of flow-through (e.g. peristaltic or proportional diluter): Proportional diluter
- Renewal rate of test solution (frequency/flow rate): 32 L/day
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: charcoal-treated, dechlorinated and aerated tap water in Yokohama, Japan
- Alkalinity: 44 mg/L
- Ca/mg ratio: 17/4.9
- Culture medium different from test medium: Same medium

OTHER TEST CONDITIONS
- Photoperiod: 16 hours in the light, 8 hours in the dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
General condition and mortality were observed everyday.

TEST CONCENTRATIONS
- Range finding study: Acute toxicity test was perfomed.
- Test concentrations: 4.99 mg/L
- Results used to determine the conditions for the definitive study: Mortality for 96 hours was 0%.

Reference substance (positive control):

yes

Remarks:

copper sulfate pentahydrate (analytical grade)

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 4.99 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks on result:

other: no effect on mortality, toxicological behaviour, food consumption, body weight and body length was detected

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 4.99 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Observed effects at each concentration for each observation time: No toxicological symptom was observed during 14 days in all groups.
- Cumulative mortality at each concentration and for each recommended observation time if possible: Mortality was 0% during 14 days in all groups.
- Mortality in the controls: 0% both in blank control and vehicle control.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: LC 60 for 96 hours: 0.73 mg/L

Reported statistics and error estimates:

Dunnet test

Table 1. Measured concentration

Nominal Concentration (mg/L)	Measured Concentration (mg/L)
	0 day	7 day	14 day	Geometric mean
Control	< 0.06	< 0.06	< 0.06	-
Solvent Control	< 0.06	< 0.06	< 0.06	-
4.99	4.91 (98)	5.22 (104)	5.04 (100)	5.06 (101)

Validity criteria fulfilled:

yes

Reference 2

Endpoint:

fish, juvenile growth test

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles.

Qualifier:

equivalent or similar to guideline

Guideline:

other: Crossland (1985): A method to evaluate effects of toxic chemicals on fish growth. Chemosphere 18: 1621-1631

Principles of method if other than guideline:

Fish were exposed in 5 L vessels to different concentrations of the test material. The test was conducted in a flow-through system over a period of 28 days.

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Sampling intervals/frequency for test medium samples: Concentrations of laurate in all the test media were determined frequently throughout the test (n = 21; one sample per test concentration on each sampling occasion) using liquid scintillation counting method (LSC).

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stocks of sodium laurate were prepared daily by warming (above the Kraft point of 35–40°C) equimolar quantities of sodium hydroxide and lauric acid in distilled water in a water bath to keep the soap in solution (stock solutions of 5.7, 3.2, 1.82, 1.03 and 0.57 g/L). Radiolabeled lauric acid in dimethyl sulfoxide (DMSO) was added to each stock (final concentration, 0.5 ml DMSO/L) to give specific activities of 0.57, 1.02, 1.79, 3.16, and 5.71 mCi/g, respectively.
- Controls: yes, only vehicle control
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): dimethyl sulfoxide (DMSO)
- Concentration of vehicle in test medium(final test solution(s): final concentration 0.5 mL/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc): No undissolved material observed in the stocks

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebrafish
- Age at study initiation (mean and range, SD): approx. 2 months old
- Weight at study initiation (mean and range, SD): 68.9 mg ± 9.8 mg
- Weight at termination (mean and range, SD): 111.3±7.8 mg
- Method of breeding: feeding based on body weight, before feeding, surface scum (precipitated calcium laurate) was removed to minimize uptake of laurate via dietary sources
- Health status: healthy
- Feeding during test: yes, Fish were fed during the week and on weekends. Feeding levels were adjusted for mortalities that occurred during the test. To recalculate the food ratio for each exposure vessel, fish were not fed on day 13, as well not on day 27 (a day before the test termination).
- Food type: Tetramint and Artemia
- Amount: 2% of wet weight during the week, 4% of wet weight in weekends
- Frequency: during the week the fish was feed once daily with each type of food, respectively, at weekend once only with Tetramint.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Post exposure observation period:

no

Hardness:

96.5 ± 4.5 mg/L CaCO3

Test temperature:

21.5 ± 0.5 ℃

pH:

7.6 ± 0.2

Dissolved oxygen:

8 ± 0.7

Salinity:

no data

Nominal and measured concentrations:

nominal laurate concentrations: 0, 2.0, 3.6, 6.4, 11.2 and 20.0 mg/L
measured laurate concentrations: 0, 2.2, 3.7, 6.6, 12.9 and 20.1 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 5 Liter
- Type (delete if not applicable): open
- Type of flow-through (e.g. peristaltic or proportional diluter): proportional diluter
- Renewal rate of test solution (frequency/flow rate): 170 -180 mL/min.
- No. of organisms per vessel: 16
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


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

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light/8 h dark
- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

6.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

9.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Fish weights (individual and mean values) on day 0, 14 (if measured) and 28: see Table [1]
- Pseudo-specific growth rates for periods 0-28 or 0-14 and 0-28: see Table [1]
- Type of and number with morphological abnormalities: not observed
- Type of and number with behavioural abnormalities: not observed
- Other biological observations: not observed
- Effect concentrations exceeding solubility of substance in test medium: no
- Incidents in the course of the test which might have influenced the results:

1) Exposure concentrations and the estimated water solubility of laurate in the test media

 

Recovery of laurate concentration in media: 100 to 115% of nominal concentrations. At concentrations of 2, 3.6, and 6.4 mg/L, there was little difference between total and soluble laurate, but approximate 8.6 mg/L and 8.0 mg/L of soluble laurate were measured in the 11.2 and 20 mg/L test media, corresponding to 80 and 40% of the total laurate, respectively. Therefore, an approximate solubility limit for laurate in the test medium was 8 to 9 mg/L.

During the test, precipitates were visible, particularly at the higher concentrations (11.2 and 20.0 mg/L).

 

No shorter-chain carboxylic acids (<12 carbons) were observed by GC–FID, indicating that the test substance in aqueous media was present as intact sodium laurate throughout the exposure period.

2) Effects on survival and growth

Exposure to sodium laurate caused mortalities at total concentrations of 3.6 (6%), 6.4 (14%), 11 (75%), and 20 mg/L

(75%). The estimated 4-, 8-, 15-, and 28-d median lethal concentrations (LC50s) were 20, 12, 9.9, and 9.8 mg/L, respectively. Based on soluble concentrations of laurate, LC50 values for the above time intervals were 10, 7.6, 7.6, and 7.6 mg/L. The 28-d NOEC for mortality was 2 mg/L.

 

Control fish increased in weight by 18 and 47% after 14 and 28 d, respectively. Fish exposed to the lower concentrations (2–6.4 mg/L) all increased in weight, and this increase was greater than that seen in control animals. It is known that fattyacids formed de novo and those originating from dietary lipids are easily esterified into neutral lipids and phospholipids.Once absorbed, laurate could perhaps be used as an additional food source by these fish, resulting in slightly enhanced growth compared to that of the control fish. The 28-d NOEC for growth was 6.4 mg/L.

Table1. Pseudospecific growth rates for zebrafish exposed to increasing concentrations of sodium laurate

Time period of exposure	Pseudospecific growth rate ± SD
	control	2 mg/L	3.6 mg/L	6.4 mg/L
0 - 14	1.14 ± 1.10	1.75 ± 1.31	2.04 ± 0.89	1.50 ± 1.26
0 - 28	1.36 ± 0.54	1.72 ± 0.79	1.99 ± 0.46	1.70 ± 0.50
14 - 28	1.57 ± 1.08	1.69 ± 1.58	1.94 ± 0.92	1.90 ± 0.99

Description of key information

No long-term toxicity effects up to the limit of water solubility

Additional information

One study is available on the chronic toxicity of docosanoic acid (CAS 112-85-6) to fish. The 14 d test was conducted according to OECD 204 and in accordance with GLP requirements. Medaka (Oryzias latipes) were exposed to docosanoic acid under flow-through conditions in a limit test by using a solvent. The NOEC (14 d) was determined to be ≥ 4.99 mg/L based on nominal concentrations (measured concentration: 5.06 mg/L). Thus no effects could be observed within the range of water solubility, which is determined to be 0.016 mg/L.

Nevertheless, as the test duration of this study is not long enough and will not show results on sensitive life-stages based on Guidance on – chapter r.7b: Endpoint specific guidance (ECHA, 2017) , further read across data with sodium laurate (CAS 629-25-4) were taken into account. Therefore, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across was done to the structurally related source substance sodium laurate. This Read-across is described and justified in the Fatty Acids category justification (see IUCLID data set, section 13). The source substance is characterized by similar chemical structure and is therefore considered as suitable representative for the assessment of the long-term toxicity of the target substance to fish. Furthermore, this read-across is a worst case approach as for sodium laurate a higher water solubility and thus a higher bioavailability is expected than for docosanoic acid.

The study with sodium laurate is summarized by Egmond et al. (1999) and was conducted according to OECD 305E (flow-through fish test). For an exposure period of 28 days NOEC values were determined based on growth rate and mortality and were 6.4 mg/L and 2 mg/L, respectively. In addition an LC50 (28 d) of 9.8 mg/L based on mortality is reported. All values were given as nominal values, since the measured values were in the range of 100 - 115% of nominal concentrations.

Therefore, long-term effects of docosanoic acid to fish are not expected. Due to animal welfare further chronic tests with fish are thus considered as not appropriate.