Docosanoic 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:

13 May - 15 May 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Water hardness was not above 140 mg/L.

GLP compliance:

yes

Remarks:

According to Japanese standard

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Test water was directly sampled by each vessel.
- Sample storage conditions before analysis: No storage 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 (concentration of stock solution: 1000 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)): 20000 mg/L in stock solution and 100 mg/L in final test solution

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Source: Incorporated Administrative Agency, National Institute for Environmental Studies, Tsukuba, Japan
- Age at study initiation: within 24 hours
- Feeding during test: No food

ACCLIMATION
- Acclimation period: 2 weeks for parental animals
- Acclimation conditions (same as test or not): Same as test
- Type and amount of food: Chlorella vulgaris, 0.15 mgC/day
- Health during acclimation (any mortality observed): Only healthy stock was used for exposure.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

63 mg/L

Test temperature:

20.4 - 20.7 °C

pH:

7.8 - 7.9

Dissolved oxygen:

8.3 - 8.6 mg/L

Nominal and measured concentrations:

Nominal concentration: 5 mg/L
Measured concentration: 5.02 mg/L (geometric mean during 48 hours)

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL Beaker
- Material, size, headspace, fill volume: Glass, 100 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: charcoal-treated, dechlorinated and aerated tap water in Yokohama, Japan
- Alkalinity: 45 mg/L
- Ca/mg ratio: 18/4.9
- Culture medium different from test medium: Same medium

OTHER TEST CONDITIONS
- Photoperiod: 16 hours in the light, 8 hours in the dark
- Light intensity: < 1200 lux

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

TEST CONCENTRATIONS
- Range finding study: Performed twice.
- Test concentrations: (1) 0.3, 1 and 3.3 mg/L, (2) 0.5, 1 and 5 mg/L
- Results used to determine the conditions for the definitive study:
(1) Immobilization was 0% in 0.3 and 1 mg/L during 48 hours. 10% immobilization was observed in 3.3 mg/L during 24 hours and 48 hours.
(2) Immobilization was 0% in all groups in 48 hours.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

- Behavioural abnormalities: No abnormality was detected.
- Mortality of control: 0%
- Other adverse effects control: No adverse effects were detected in control.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.23 mg/L

Table 1. Measured concentration

Nominal Concentration (mg/L)	Measured Concentration ,mg/L (Percent of nominal)
	0 Hour new	48 Hour old	Geometric mean
Control	< 0.3	< 0.3	-
Solvent control	< 0.3	< 0.3
5.0	5.16 (103)	4.88 (98)	5.02

new: freshly prepared test solutions

old: test solutions after 48 hours exposure

Table 2. The number of immobile Daphnia magna

Nominal Concentration (mg/L)	Measured Concentration (mg/L)	Cumulative Number of Immobilized Daphnia (Percent Immobility)
		24 Hours	48 Hours
Control	Control	0 (0)	0 (0)
Solvent Control	Solvent Control	0 (0)	0 (0)
5	5.02	0 (0)	2 (10)

Validity criteria fulfilled:

yes

Description of key information

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

Additional information

One study is available on the toxicity of docosanoic acid (CAS 112-85-6) on invertebrates.

The 48 h test provided by the Ministry of the Environment, Government of Japan (1998) was conducted according to OECD 202 and in accordance with GLP requirements. Daphnids (Daphnia magna) were exposed to 96.5% pure docosanoic acid under static conditions in a limit test by using a solvent. The EC50 (48 h) was determined to be > 5.0 mg/L based on nominal concentrations (geom.mean measured concentration: 5.02 mg/L). Thus no effects could be observed within the range of water solubility, which is determined to be 0.016 mg/L.

Based on the results of that study it can be concluded that no acute toxic effects of docosanoic acid on invertebrates are expected up to the limit of water solubility.