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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:
11. Dec. 2018 - 20. Dec. 2018
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)
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
Nominal concentrations [mg/L]: 0 (blank control), 4.6, 10, 22, 46, 100
Test organisms (species):
Daphnia magna
Details on test organisms:
Species Daphnia magna
Authority STRAUS
Strain Berlin
Sex female
Age between 0 and 24 hours
Origin Umweltbundesamt Berlin
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
Resulting hardness in mmol/L: 2.502
Resulting hardness in mg CaCO3/L: 250
Test temperature:
19.6 - 23.3 °C
pH:
7.8 - 8.2
Dissolved oxygen:
8.5 - 9.3 mg/L
Details on test conditions:
Medium renewal: twice a week
Photo period: 16/8 hours, using neon tubes
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality

Immobility

1stExperiment

In the blank control, one of the Daphnia was immobilised (see table below).

Table7.1‑a      Immobility

Nominal Concentration in mg/L

Immobility 24 hours

Immobility 48 hours

absolute

in %

absolute

in %

Blank control

0

0

0

0

0

1

0

0

0

5

100

0

0

0

0

0

0

2

1

1

20

 

2ndExperiment

In the blank control, none of the Daphnia was immobilised (see table below).

Table7.1‑b     Immobility

Nominal Concentration in mg/L

Immobility 24 hours

Immobility 48 hours

absolute

in %

absolute

in %

Blank control

0

0

0

0

0

0

0

0

0

0

4.6 *

0

0

0

0

0

0

0

1

0

5

10 *

0

0

0

0

0

0

0

0

0

0

22

0

0

0

0

0

0

0

0

0

0

46

0

0

0

0

0

0

0

1

0

5

100

0

0

0

0

0

0

0

1

2

15

* The two lowest concentrations (4.6 mg/L and 10 mg/L) were excluded from the evaluation of the biological results, because they showed no significant toxicity compared to the control.

Validity criteria fulfilled:
yes
Conclusions:
Based on the test results the EC50, 48h for Daphnie magna can be stated to be > 100 mg/L.
Executive summary:

Two valid experiments were performed.

The 1stexperiment was performed using one concentration of 100 mg/L (limit test). For the test concentration and the blank control, 20 Daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised Daphnia were counted.

In this experiment more than 10 % of the Daphnia in the test concentration were immobilised and therefore a 2ndexperiment was performed using 5 concentrations ranging from 4.6 to 100 mg/L (full test). The test was carried out under the same conditions like the 1stexperiment.

The biological results base on the results of the second experiment.

The two lowest concentrations (4.6 mg/L and 10 mg/L) were excluded from the evaluation of the biological results, because they showed no significant toxicity compared to the control.

The two highest concentrations (46 mg/L and 100 mg/L) showed toxicity between 5 and 15 % immobilisation. None of the animals was immobilised in the blank control.

At the beginning and at the end of the test, the content of the test item in the test solutions was determined usingHPLC-UV-determination. The measured concentrations in the 3 highest concentrations were between 98 % and 104 % of the nominal concentration at the beginning and between 108 % and 115 % of the nominal concentrations at the end of the test. Therefore, the determination of the biological results was based on the nominal concentrations of the second experiment.

Potassium dichromate K2Cr2O7(CAS No. 7778-50-9) was used as positive controlin a current reference study to assure that the test conditions are reliable.


The following results were determined for the test itemN-(2-hydroxypropyl)imidazole, purified by distillation
(species:Daphnia magna).

 

48h-NOEC100 mg/L
48h-LOEC
> 100mg/L
48h-EC50> 100 mg/L

 

The immobilisation of 15 % at the concentration of 100 mg/L lay in the same range as in the limit test (20 %), but the evaluation program does not recognize this as a significant difference in comparison to the control. Therefore, the NOEC was determined as≥the highest tested concentration.

Description of key information

A study according to OECD 202 was conducted.

Based on the test results the EC50, 48h for Daphnie magna can be stated to be > 100 mg/L.

Thus the test material is not toxic towards aquatic invertebrates according to the criteria of CPL.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information