2-ethoxybenzoic 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:

31-05-2017 to 2-05-2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Principles of method if other than guideline:

Short term toxicity of test chemical to aquatic invertebrates was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

The stock solution 200.0 mg/l was prepared by dissolving colourless liquid in reconstituted water. The test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Straus
- Source: Own breeding at University of Chemistry and Technology, Prague
- Age at study initiation (mean and range, SD): The animals used for the test shall be less than 24 h old and should not be first brood progeny
- Feeding during test: No feeding
ACCLIMATION - No data available

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Remarks on exposure duration:

± 1 hr

Test temperature:

20±1°C

pH:

pH value: without adjustment
Start of the test 7.5 7.2 6.4 at 160 mg/l
The end of the test 7.8 7.8 7.7 7.6 5.1
control: pH = 8.0 changed to pH = 7.8 during the test

Dissolved oxygen:

higher than 7.7 mg/L at the end of test

Nominal and measured concentrations:

10.0 , 20.0, 40.0, 60.0, 180.0 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 ml glass vessel
- fill volume: 25 ml
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Natural water (surface or ground water), reconstituted water or dechlorinated tap water are acceptable as culturing and dilution water if D. magna survives in it for the duration of the culturing, acclimation and testing without showing signs of stress. Waters in the range pH 6 to pH 9, with hardness between 140 mg/l and 275 mg/l (as CaCO3) are recommended.
As an example, the preparation of dilution water meeting the requirements is described below.
Dissolve known quantities of reagents in water. The dilution water prepared shall have a pH of 7.8 ± 0.5, a hardness of (225 ± 50) mg/l (expressed as CaCO3), a molar Ca + Mg ratio close to 4 + 1 and a dissolved oxygen concentration above 7 mg/l.

Prepare the solutions specified below:
- Calcium chloride solution: Dissolve 117.6 g of calcium chloride dihydrate (CaCl2.2H2O) in water (4.2) and make up to 1 l with water (4.2).
- Magnesium sulfate solution: Dissolve 49.3 g of magnesium sulfate heptahydrate (MgSO4.7H2O) in water (4.2) and make up to 1 l with water (4.2).
- Sodium bicarbonate solution: Dissolve 25.9 g of sodium bicarbonate (NaHCO3) in water (4.2) and make up to 1 l with water (4.2).
- Potassium chloride solution: Dissolve 2.3 g of potassium chloride (KCI) in water (4.2) and make up to 1 l with water (4.2).

Mixing
Mix 2.5 ml of each of the four solutions and make up to 1 l with water.
The dilution water shall be aerated until the dissolved oxygen concentration has reached saturation and the pH has stabilized. If necessary, adjust the pH to 7.8 ± 0.5 by adding sodium hydroxide (NaOH) solution or hydrochloric acid (HCI). The dilution water prepared in this way shall not be further aerated before use.

- Sodium hydroxide solution, e.g. [NaOH] : 1 mol/l.
- Hydrochloric acid, e.g. [HCl] : 1 mol/l.

Reference substance:
Dissolve 600 mg of potassium dichromate (K2Cr2O7) in water and make up to 1 l with water (4.2).

OTHER TEST CONDITIONS
- Adjustment of pH: no adjustment done
- Photoperiod: No - Darkness
- Light intensity:

CALCULATION:
EC50 was calculated using non linear regression by the software Prism 4.0

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

30.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % CI 11.1- 86.2 mg/l

Remarks:

Tested substance is an acid and that is why the higher concentration the lower pH. The optimum pH for daphnids is 6.0 - 9.0. The inhibition of the mobility of daphnids could be influenced by pH at the concentration 160 mg/l

Results with reference substance (positive control):

- Results with reference substance valid
- EC50: 0.73mg/L (24 hours)

Reported statistics and error estimates:

EC50 was calculated using non linear regression by the software Prism 4.0

Sample concentration (mg/l)	10.0	20.0	40.0	80.0	160.0
Start of the test	7.5	7.2	6.9	6.4	5.0
The end of the test	7.8	78	7.7	7.6	5.1

Validity criteria fulfilled:

yes

Conclusions:

The median effective concentration (EC50) for the test substance, in Daphnia magna was determined to be 30.9 mg/L on the basis of mobility inhibition effects in a 48 hour study.

Executive summary:

Aim of this study was to assess the short term toxicity of test material to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs. The stock solution 200.0 mg/l was prepared by dissolving colourless liquid in reconstituted water. The test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water. 10.0 , 20.0, 40.0, 60.0, 180.0 mg/l concentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance, in Daphnia magna was determined to be 30.9 mg/L on the basis of mobility inhibition effects in a 48 hour study. Tested substance is an acid and that is why the higher concentration the lower pH. The optimum pH for daphnids is 6.0 - 9.0. The inhibition of the mobility of daphnids could be influenced by pH at the concentration 160 mg/l and that is why EC50 was calculated also for results without the concentration 160.0 mg/l with low pH.The test material can not be classified based on the above effect concentration as the inhibition of the mobility of daphnids could be influenced by pH.

Description of key information

Short term toxicity to aquatic invertebrate:

Aim of this study was to assess the short term toxicity of test material to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs.The stock solution 200.0 mg/l was prepared by dissolving colourless liquid in reconstituted water. The test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water.10.0 , 20.0, 40.0, 60.0, 180.0 mg/lconcentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance, in Daphnia magna was determined to be 30.9 mg/L on the basis of mobility inhibition effects in a 48 hour study.Tested substance is an acid and that is why the higher concentration the lower pH. The optimum pH for daphnids is 6.0 - 9.0. The inhibition of the mobility of daphnids could be influenced by pH at the concentration 160 mg/l and that is why EC50 was calculated also for results without the concentration 160.0 mg/l with low pH.The test material can not be classified based on the above effect concentration as the inhibition of the mobility of daphnids could be influenced by pH.

Additional information

Short term toxicity to aquatic invertebrate:

Aim of this study was to assess the short term toxicity of test material to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs.The stock solution 200.0 mg/l was prepared by dissolving colourless liquid in reconstituted water. The test solutions of required concentrations were prepared by mixing the stock solution of the test sample in reconstituted water.10.0 , 20.0, 40.0, 60.0, 180.0 mg/lconcentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance, in Daphnia magna was determined to be 30.9 mg/L on the basis of mobility inhibition effects in a 48 hour study.Tested substance is an acid and that is why the higher concentration the lower pH. The optimum pH for daphnids is 6.0 - 9.0. The inhibition of the mobility of daphnids could be influenced by pH at the concentration 160 mg/l and that is why EC50 was calculated also for results without the concentration 160.0 mg/l with low pH.The test material can not be classified based on the above effect concentration as the inhibition of the mobility of daphnids could be influenced by pH.