2,2'-[oxybis(2,1-ethanediyloxy)]bisacetic 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:

from 2018-02-12 to 2018-05-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, section 3.1.2 Media preparation methods, Direct addition. OECD Series on Testing and Assessment No. 23, Paris September 2000

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot/batch No(s): 03/2016_R_JM

Analytical monitoring:

yes

Details on sampling:

Four parallel samples of 3 mL were taken from the 100 mg/L concentration level and from the control sample.

Vehicle:

no

Details on test solutions:

The test solution used in the test was prepared by mechanical dispersion. 0.0633 g of test item were dissolved in 633 mL ISO Medium in order to obtain the concentration of 100 mg/L. The pH value (4.9) of the test item solution was adjusted to the pH level of ISO Medium (according to OECD No. 23) with 1 N NaOH. The adjusted pH level of the stock solution was 7.95.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Waterflea
- Strain/clone: Straus
- Source: Laboratory of Hydrobiology (Central Agricultural Office, Directorate of Plant-, and Soil Protection) 2100 Gödöllő, Kotlán S. u. 3. Hungary
- Age at test start: Less than 24 hours old
- Feeding during test: no

ACCLIMATION
- Acclimation period: no, breeding conditions same as test conditions

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

249 mg/L (as CaCO3)

Test temperature:

20.4 – 20.8 °C

pH:

7.86 - 8.05

Dissolved oxygen:

8.30 - 8.64 mg/L

Nominal and measured concentrations:

nominal concentration: 100 mg/L
measured concentration: 99.8 - 106 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Material, fill volume: glass, 40 mL medium
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: ISO Medium, according to OECD 202

OTHER TEST CONDITIONS
- Adjustment of pH: yes, with 1N NaOH
- Photoperiod: 16 hours light (artificial illumination) and 8 hours darkness
- Light intensity: 679 lux

EFFECT PARAMETERS MEASURED
after 24 and 48 hours of exposure visual observation (immobility)

RANGE-FINDING STUDY
- Test concentrations: 0.1, 1, 10, 100 mg/L nominal concentration, with and without adjusted pH
- Results used to determine the conditions for the definitive study: No immobility or any sub-lethal effect were detected in the test concentrations and in the control group during the 48-h exposure period.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Results with reference substance (positive control):

- Results with reference substance valid - yes
- Relevant effect levels: 24h EC50: 1.41 mg/L, (95 % confidence limits: 1.19 – 1.68 mg/L)

Analytical results

The measured concentration of the test item in the test solution was 99.8 % of the nominal value at the start and 106 % of the nominal value at the end of the test. There is evidence that the concentration of the tested substance was maintained within ± 20 % of the nominal concentration throughout the test. Therefore, the analysis of the results was based on the nominal concentration value.

Biological results

There was no immobilisation observed in the twenty daphnids exposed to the test item treated group and to the twenty daphnids in the control group. In addition to immobility, no abnormal behaviour or appearance of the test animals was detected. Accordingly, the 48-h NOEC was determined as 100 mg/L nominal concentration and the LOEC, EC10, EC20 and EC50 values were determined to be higher than 100 mg/L (directly from the raw data).

Table 1: Immobilisation of the test animals

Nominal concentration [mg/L]	No. of Daphnia tested	No. of immobilised Daphnia after		% of immobilised Daphnia after
		24 h	48 h	24 h	48 h
Control	20	0	0	0	0
100	20	0	0	0	0

Table 2. Summary of biological endpoints

Endpoints	Concentration [mg/L] based on nominal concentration
48 h-EC10	>100
48 h-EC20	>100
48 h-EC50	>100
48 h-NOEC	100
48 h-LOEC	>100

 

Validity of the Study

- The immobilisation rate of the introduced Daphnia did not exceed 10 %. Immobility was not observed in the untreated control and no Daphnia were trapped at the water surface or showed any sign of disease or stress.

- The dissolved oxygen concentration at the end of the test was more than 3 mg/L in control and test vessels. The dissolved oxygen concentration was in the range of 8.30 – 8.64 mg/L during the test.

Validity criteria fulfilled:

yes

Conclusions:

In this 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item had no significant toxic effects on the mobility of the daphnids up to the concentration of 100 mg/L.

Executive summary:

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202, Regulation (EC) No. 440/2008 Method C.2 and EPA OPPTS 850.1010. The study was conducted in a static system over a period of 48 hours with a limit concentration of 100 mg/L. The pH of the test item stock solution was adjusted with 1N NaOH to the pH of the dilution water used for the test. 20 daphnids per test concentration and control were tested. The test item concentration was determined at the start and at the end of the test with HPLC-UV and it was in the range of 99.8 - 106 % of the nominal concentration. Therefore, the biological endpoints were based on the nominal concentration. The validity criteria of the test guideline were fulfilled. There was no immobilisation observed in twenty daphnids exposed to each test item treated and control group. Furthermore, no abnormal behaviour or appearance of test animals was noted. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is >100 mg/L. The 48-h NOEC was determined to be 100 mg/L.

Description of key information

In a 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item had no significant toxic effects on the mobility of the daphnids up to the concentration of 100 mg/L.

Additional information

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202, Regulation (EC) No. 440/2008 Method C.2 and EPA OPPTS 850.1010. The study was conducted in a static system over a period of 48 hours with a limit concentration of 100 mg/L. The pH of the test item stock solution was adjusted with 1N NaOH to the pH of the dilution water used for the test. 20 daphnids per test concentration and control were tested. The test item concentration was determined at the start and at the end of the test with HPLC-UV and it was in the range of 99.8 - 106 % of the nominal concentration. Therefore, the biological endpoints were based on the nominal concentration. The validity criteria of the test guideline were fulfilled. There was no immobilisation observed in twenty daphnids exposed to each test item treated and control group. Furthermore, no abnormal behaviour or appearance of test animals was noted. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is >100 mg/L. The 48-h NOEC was determined to be 100 mg/L.