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Ecotoxicological information

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:
2017-10-09 to 2017-10-19
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP study performed according to the OECD 202 guideline. All validity criteria were successful.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
14 January 2016
Specific details on test material used for the study:
None
Analytical monitoring:
yes
Details on sampling:
In order to verify the maintenance of the WAFs during the ecotoxicological testing, chemical analyses in daphnids test solutions were performed:
- In fresh solutions at the beginning of the test (T = 0h) and after renewal (T=24h)
- In old solutions (T = 24h and T= 48h)
The test tube were pooled randomly (2*10mL) for chemical analyses.

Schedule analysis at initial time:
- T0h Control Fresh
- T0h 100.0 mg/L Fresh
All the “Fresh” solutions were analysed taken directly from the starting solutions without daphnids.

Schedule analysis at 24h:
- T24h Control Old
- T24h 100.0 mg/L Old

- T24h Control Fresh
- T24h 100.0 mg/L Fresh

Schedule analysis at final time:
- T48h Control Old
- T48h 100.0 mg/L Old
Vehicle:
no
Details on test solutions:
TEST ITEM PREPARATION
The test item was not soluble in the test medium, a special solubilisation protocol was carried out before the experimentation, according to the OECD n°23 guidance document on aquatic toxicity testing of difficult substances and mixtures.
After having tried different methods for the preparation of the WAFs in the preliminary study, the following protocol was selected for the final test: this method consisted in stirring the test item nominal concentration 100 mg/L in test medium during 24 hours, in the dark and 20 ± 2°C. The test solution (100 mg/L) was then filtered (cellulose acetate with a mesh size of 0.45 µm) to remove suspended particles: solution obtained was named WAF (Water Accommodated Fraction).
The test was carried out under semi static conditions, which means that the WAF solutions were renewed at 24h.

TEST SOLUTIONS
According to the results of the preliminary test, this study was conducted at one concentration level: 100.0 mg/L: Limit test, WAF and semi static conditions
The test contained a minimum of 12 glass test tubes as follow:
- Control: 4 replicates with daphnids (and 2 test tubes without daphnids for chemical analysis at initial time)
- WAF 100.0 mg/L: 4 replicates with daphnids (and 2 test tubes without daphnids for chemical analysis at initial time)

Each glass test tube (sterilized by autoclave) contained 10 mL of test solution and 5 daphnids; they were covered in order to avoid evaporation and dust deposition. Some abiotic solutions (without daphnids) were stored in the same conditions (test conditions) for analyses, if needed.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Daphnia magna Straus, clone number 5, from at least the third generation (i.e. the third brood) obtained with a non-cyclic parthenogenesis reproduction.
The daphnids breeding was carried out in closed bottles placed in a climatic chamber free from any toxic vapour and in medium M4.
Daphnids used in this experimentation were previously filtered in order to obtain animals from a size between 560 µm and 800 µm (corresponding to daphnids less than 24 hours old.
- Feeding during test: None
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Remarks on exposure duration:
None
Post exposure observation period:
None
Hardness:
260 - 270 mg/L of CaCO3
Test temperature:
19.8 - 20.0°C
pH:
7.8 - 7.9
Dissolved oxygen:
9.3 mg/L
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
Nominal concentrations: limit test at WAF 100 mg/L (loading rate)
Details on test conditions:
TEST DETAILS
- Test vessel: glass test tube
- Type: closed
- Renewal rate of test solution: Renewal of test solutions at 24h
- No. of organisms per vessel: 5
- Test medium: The medium M4 ELENDT was prepared from concentrated stock solutions in ultrapure water as described in the guideline.
- Light intensity: Darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Observations of the daphnid’s immobility and behaviour were done after 24 and 48 hours in control and exposed groups.
- Any sign of stress observed on the daphnids after 48 hours of exposure to the test item were reported.
- pH and dissolved oxygen were measured before and after renewal of solutions (including the controls).

RANGE-FINDING STUDY (non GLP)
- Test concentrations: control, 1, 10 and 100 mg/L with the same method of WAF preparation than the definitive test.
- Another non-GLP preliminary test with solvent conditions was also performed. Acetone has been determined as the most suitable solvent to be used. For stock solution at 100 g test item /L acetone, 4 loading rates 1; 10; 50 and 100 mg/L were prepared before acute immobilisation test with daphnids. During this study, it has not been possible to solubilize the test item at the maximal solvent concentration recommended in the OECD 23 guideline (100 mg/L or 0.1 mL/L). The solvent concentrations used were above this limit. Therefore, this method cannot be selected for the final test.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
24 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
loading rate of WAF
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
loading rate of WAF
Basis for effect:
mobility
Details on results:
No sign of stress was observed on the mobile daphnids after 48 hours of exposure to the highest loading rate.
Results with reference substance (positive control):
The last toxic response obtained on the reference item K2Cr2O7 (September 21, 2017) indicates an EC50-24h of 1.34 mg/L (1.22 – 1.47), indicating that the daphnids sensitivity is correct (within the accepted interval of 0.6–2.1 mg/L fixed by the International Standard ISO 6341 December 2012 as mentioned in the OECD 202 Guideline) and in accordance with historical data obtained by the laboratory.
Reported statistics and error estimates:
N/A

Table 6.1.3/1: Daphnids immobilisation

Raw data (daphnids immobilisation in cumulative number for each observation time 24 and 48 hours) are presented hereafter:

Nominal test item loading rate
 in mg/L

Number of daphnids exposed
at the start

Immobilised daphnids (%)

at 24h

at 48h

WAF Control

20

0 (0%)

0 (0%)

WAF 100.0

20

0 (0%)

0 (0%)

Table 6.1.3/2: Chemical analysis of daphnids solutions

The table below summarizes the results achieved and the variation between initial measurement and after 24 hours and after renewal at 24 hours and 48 hours of exposure.

Nominal test item loading rate

Renewal

Results of the determination of TOC analysis (mg/L)

At initial time

(Fresh solutions)

After 24 hours of exposure(Old solutions)

Variation(%)

WAF 100 mg/L

T0h to T24h

(0.40)* < 2

(0.61)* < 2

NA

T24h to T48h

(0.53)*< 2

(0.76)* < 2

NA

*(for information)

NA: Not Applicable

All measured values were lower than 2 mg/L (=LOQ) and are notified for information (in brackets). The slight increase after 24 hours of exposition was mainly due to the gaseous exchange.

TOC analyses indicated that organic compounds were found below the LOQ in the control and in the WAFs at 100 mg/L. Therefore, the maintenance of the WAFs throughout the test, cannot be accurately evaluated. Nevertheless, since WAFs are by definition a complex mixture and since the test item is an UVCB substance, the results are based on the nominal test loading rates.

Table 6.1.3/3: Validity criteria conformity

  Values for OECD 202   Validity criteria for the test
 Immobilised daphnids in the control  =< 10 %  Ok (0%)
 Dissolved Oxygen concentration at the end of the test  >= 3 mg/L  Ok (8.8 mg/L)

All the validity criteria were successful.

Validity criteria fulfilled:
yes
Conclusions:
Under test conditions, the results obtained for the test item “TREE MOSS CONCRETE” on the toxicological endpoint “immobilisation” give an EL50-24h and an EL50-48h higher than the highest tested loading rate, i.e. 100 mg/L, based on nominal test item loading rate.
Executive summary:

The aim of this study was to determine the acute toxicity of the test item “TREE MOSS CONCRETE” on the daphnids Daphnia magna, according to the OECD guideline202. The daphnidswere exposed toWater Accommodated Fractions (WAFs) of the test item, following the “Guidance document on aquatic toxicity testing of difficult substances and mixtures” (OECD No.23).

 

Following the results of a preliminary study, a limit test at a nominal loading rate of 100 mg test item/L was performed, in order to demonstrate that the test item has no significant effect on the test organism at this test loading rate or that EL50 at 24h and 48h is higher than 100 mg/L. The immobility of the daphnids was determined in a closed semi-static 48-hour test by visual observation after 24 and 48 hours.

 

In order to check the stability of the WAFs in the test solutions, concentration of dissolved organic material in the control and the WAFs was checked by TOC analysis at start (t=0h), at t=24h (new and old solutions) and at the end of the test (t=48h). These non-specific chemical analyses were performed by Carbon Analyzer.

 

 

Nominal test item loading rate

Renewal

Results of the determination of TOC analysis (mg/L)

At initial time

(Fresh solutions)

After 24 hours of exposure(Old solutions)

Variation(%)

WAF 100 mg/L

T0h to T24h

(0.40)* < 2

(0.61)* < 2

NA

T24h to T48h

(0.53)*< 2

(0.76)* < 2

NA

*(for information)

NA: Not Applicable

 

TOC analyses indicated that organic compounds were found below the LOQ in the control and in the WAFs at 100 mg/L. Therefore, the maintenance of the WAFs throughout the test, cannot be accurately evaluated. Nevertheless, since WAFs are by definition a complex mixture and since the test item is an UVCB substance, the results are based on the nominal test loading rates.

 

Validity criteria conformity:

 

Values for OECD 202

Validity criteria for the test

Immobilised daphnids in control

<10%

Ok (0%)

Dissolved Oxygen concentration

>3 mg/L

Ok (8.8 mg/L)

 

 

Daphnids immobilisation

Nominal test item loading rate
 in mg/L

Number of daphnids exposed
at the start

Immobilised daphnids (%)

at 24h

at 48h

WAF Control

20

0 (0%)

0 (0%)

WAF 100.0

20

0 (0%)

0 (0%)

 

Conclusion

Despite the discussions on the stability of the test item, all the validity criteria were successful. The results are as follows:

- EL50-24h is higher than 100 mg/L

- EL50-48h is higher than 100 mg/L

These values are based on nominal test item “TREE MOSS CONCRETE” loading rate.

Under test conditions, no ecotoxicity was observed after 24 hours and 48 hours of exposure during the testing at 100 mg/L of the test item (loading).

 

Therefore, the results obtained for the test item “TREE MOSS CONCRETE” on the toxicological endpoint “immobilisation” give an EL50-24h and an EL50-48h higher than the highest tested loading rate, i.e. 100 mg/L, based on nominal test item loading rate.

Description of key information

Under test conditions, the results obtained for the test item “TREE MOSS CONCRETE” on the toxicological endpoint “immobilisation” give an EL50-24h and an EL50-48h higher than the highest tested loading rate, i.e. 100 mg/L, based on nominal test item loading rate.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

An experimental study performed on the registered substance was available for that endpoint.

The aim of this study was to determine the acute toxicity of the test item “TREE MOSS CONCRETE” on the daphnids Daphnia magna, according to the OECD guideline 202. The daphnids were exposed to Water Accommodated Fractions (WAFs) of the test item, following the “Guidance document on aquatic toxicity testing of difficult substances and mixtures” (OECD No.23).

 

Following the results of a preliminary study, a limit test at a nominal loading rate of 100 mg test item/L was performed, in order to demonstrate that the test item has no significant effect on the test organism at this test loading rate or that EL50 at 24h and 48h is higher than 100 mg/L. The immobility of the daphnids was determined in a closed semi-static 48-hour test by visual observation after 24 and 48 hours.

 

In order to check the stability of the WAFs in the test solutions, concentration of dissolved organic material in the control and the WAFs was checked by TOC analysis at start (t=0h), at t=24h (new and old solutions) and at the end of the test (t=48h). These non-specific chemical analyses were performed by Carbon Analyzer. TOC analyses indicated that organic compounds were found below the LOQ in the control and in the WAFs at 100 mg/L. Therefore, the maintenance of the WAFs throughout the test, cannot be accurately evaluated. Nevertheless, since WAFs are by definition a complex mixture and since the test item is an UVCB substance, it is considered acceptable to base the results on the nominal test loading rates.

Under test conditions, no ecotoxicity was observed after 24 hours and 48 hours of exposure during the testing at 100 mg/L of the test item (loading). Therefore, the results are as follows:

- EL50-24h is higher than 100 mg/L

- EL50-48h is higher than 100 mg/L

Despite the discussions on the stability of the test item, all the validity criteria were successful. This study complied with the guideline requirement and can therefore be considered acceptable for that endpoint.