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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 2019 - August 2019
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
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: The concentration of the test item was measured at each test concentration at the beginning and end of the test in double determination. Additionally two test solutions and one blank without daphnids were prepared for the analytical determination.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A 100 mg/l stock solution of the test sample was prepared in dilution water. The sample was weighed using a weighing dish. The solution was then stirred overnight at room temperature. The test solutions were prepared by adding dilution water (ISO Test water) to the stock solution of the test item.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna Straus
- Age at study initiation: <24 hours old
- Source: own in-house culture of the test laboratory
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
207 mg/l CaCO3
Test temperature:
19.5 to 20.5 °C
pH:
7.6 - 8.5
Dissolved oxygen:
8.4 - 8.8 mg/L
Nominal and measured concentrations:
Five concentrations in a geometric series with four replicates and one control with 4 replicates were tested. The test concentrations were 6.25, 12.5, 25, 50 and 100 mg/L (nominal concentrations). The factor between concentrations was 2.
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml glass beakers
- Type: closed (covered with watch glass dishes)
- Fill volume: 20 mL
- 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
- Source/preparation of dilution water: ISO Test water
- Intervals of water quality measurement: The dissolved oxygen and the pH were measured at the beginning and end of the test in the control and in each test concentration. The temperature was continuously measured in the ambient air in the thermostat cabinet during the test.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light, 8 hours dark

EFFECT PARAMETERS MEASURED: All test vessels were checked for immobilised daphnids after 24 and 48 hours. Any abnormal behaviour or appearance was reported.

RANGE-FINDING STUDY
- Test concentrations: 100 mg/L, 10 mg/L, 1.0 mg/L, 0.1 mg/L and 0.01 mg/L
- Results used to determine the conditions for the definitive study: The expected EC50-value (48 hours) will be > 100 mg/L
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 28.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 28.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Results with reference substance (positive control):
The determined EC50-24h of 1.9 mg/l lies within the range from the inter laboratory test to ISO 6341.
Reported statistics and error estimates:
From the determined effects the EC50-, EC20- and EC10-values of the test item after 24 and 48 hours were calculated by non-linear regression. The calculation was carried out with the software SigmaPlot 13.

Results of analysis

The recovery of the nominal concentration at 0 hours was between 18 and 42 %. The low recovery may be due to the use of a weighing dish in the preparation of the stock solution. It is also possible that other ad- or absorption effects or the lifetime of the sample until processing may have played a role.

The recovery of the initial concentration at the end of the test was between 18 and 64 %. Thus, the substance was not stable over the test period or further ad- or absorption effects occurred. This cannot be conclusively clarified.

The test organism had no influence on the recovery, since the solutions without daphnia were comparable in its range regarding recovery with the solutions with daphnia. The start value of the test solution 100 mg/l without Daphnia can be regarded as an outlier.

Therefore, a mean test concentration was calculated over the test period to determine the dose-response relationship. The mean of the initial and final concentrations for each test solution was used.

 

Nominal and measured concentrations of the test item in the control and each test concentration:

Nominal
concentration ofEpeg

Determined concentration of
Epeg

Mean concentration of Epeg determined over the test period

 

at 0 hours1)

at 48 hours

 

[mg/l]

[mg/l]

[mg/l]

[mg/l]

 

 

 

 

0

0.0

0.0

0.0

6.25

2.6

0.5

1.5

12.5

3.5

1.5

2.5

25

4.7

2.6

3.6

50

18.1

6.1

12.1

100

35.2

22.4

28.8

02)

0.0

0.0

0.0

12.52)

3.1

1.1

2.1

1002)

15.8

16.3

16.1

1)samples at 0 hours were taken before daphnids were placed into the test vessels
2)test solutions without daphnids

 

 

Results of the test:

Test concentration1)

Number

Number of

Percentage

Percentage

of
daphnids

immobilised
daphnids

immobilised
daphnids

immobilised
daphnids. total

[mg/l]

 

24 h

48 h

24 h

48 h

24 h

48 h

0
(0)

5

0

0

0

0

0

0

5

0

0

0

0

5

0

0

0

0

5

0

0

0

0

1.5
(6.25)

5

0

0

0

0

0

0

5

0

0

0

0

5

0

0

0

0

5

0

0

0

0

2.5
(12.5)

5

0

0

0

0

0

0

5

0

0

0

0

5

0

0

0

0

5

0

0

0

0

3.6
(25)

5

0

0

0

0

0

0

5

0

0

0

0

5

0

0

0

0

5

0

0

0

0

12.1
(50)

5

0

0

0

0

0

0

5

0

0

0

0

5

0

0

0

0

5

0

0

0

0

28.8
(100)

5

1

1

20

20

5

10

5

0

0

0

0

5

0

0

0

0

5

0

1

0

20

1)determined (nominal) concentration

 

Calculated effect concentrations after 24 and 48 hours:

 

Results after 24 hours

Results after 48 hours

 

Concentra-tion

95% Confidence Limits

Concentration

95% Confidence Limits

 

[mg/l]

lower

upper

[mg/l]

lower

upper

EC10

>28.8

13.3

-

28.8

13.0

-

EC20

>28.8

14.5

-

>28.8

14.1

-

EC50

>28.8

16.2

-

>28.8

15.6

-

 

Validity criteria fulfilled:
yes
Conclusions:
The test item caused an inhibition of the mobility of Daphnia magna of 10 % in the highest test concentration of 28.8 mg/L after 48 hours. The EC50-value was therefore > 28.8 mg/L. After 24 hours an inhibition of 5 % was observed in the highest test concentration of 28.8 mg/L.
Executive summary:

The acute toxicity of Ethylphthalyl ethyl glycolate to Daphnia magna was tested according to the OECD Guideline 202.

The test item caused an inhibition of the mobility of Daphnia magna of 10 % in the highest test concentration of 28.8 mg/L after 48 hours. The EC50-value was therefore > 28.8 mg/L. After 24 hours an inhibition of 5 % was observed in the highest test concentration of 28.8 mg/L.

Description of key information

The acute toxicity of Ethylphthalyl ethyl glycolate to Daphnia magna was tested according to the OECD Guideline 202.

The test item caused an inhibition of the mobility of Daphnia magna of 10 % in the highest test concentration of 28.8 mg/L after 48 hours. The EC50-value was therefore > 28.8 mg/L. After 24 hours an inhibition of 5 % was observed in the highest test concentration of 28.8 mg/L.

Key value for chemical safety assessment

Additional information