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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:
2018-11-27 to 2018-12-14
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Remarks:
TOC measurements
Details on sampling:
- Concentrations: all test item concentrations and control
- Sampling method: at test start from fresh solutions and after 24 hours and 48 hours from aged solutions
- Sample storage conditions before analysis: All samples were stored refrigerated until they were transferred to the analytical laboratory.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test item has a low water solubility and is hydrologically unstable, therefore a degraded solution of the test item was prepared before application based on OECD Series on Testing and Assessment No. 23.
- Method:
Degraded solutions were prepared by directly weighing appropriate test item amounts in test medium. The stock solutions were stirred in the dark at room temperature for 24 h. At the highest concentration (100 mg/L) up to 12.5 mg/L particles were observed floating at the surface of the solution,side walls and at the bottom of the glass vessel. Subsequently the undissolved test item was allowed to sediment and/or float for a period until the phases had separated. After the settling of 30 minutes the necessary volumes for the test were withdrawn via a Teflon tube from the medium level of the degraded stock solutions. Approximately 50 mL of the prepared solutions were transferred to each test vessel.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna Straus
- Clone: Clone V
- Age at study initiation (mean and range, SD): 24h old
- Method of breeding: Daphnia magna was bred as single culture (1 daphnid per 100 mL) in Elendt M4 medium. The animals were fed with single cell green algae (Desmodesmus subspicatus, formerly Scenedesmus subspicatus) at least three times a week.
- Source: Federal Environment Agency in Berlin/Germany
- Feeding during test: no


ACCLIMATION
- Acclimation period: no

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
13°dH
Test temperature:
18.9-20.6°C
pH:
6.55-7.81
Dissolved oxygen:
≥ 7.3 mg/L
Salinity:
/
Conductivity:
/
Nominal and measured concentrations:
- Nominal concentrations: 100, 50.0, 25.0, 12.5, 6.25 mg/L and control.
- Measured concentrations (TOC): 47, 25.5, 16.8, 6.75, 1.81 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beakers, 100 mL
- Type: open
- Fill volume: 50mL
- Volume of solution: 50 mL
- Aeration: none
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 test medium


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours photoperiod /8 hours darkness daily


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
After 24 h and 48 h the immobilised daphnids were counted. All daphnids not able to swim within 15 seconds after gentle agitation of the test vessel were considered to be immobilised. If present, behavioural changes of daphnids were recorded at 24 and 48 hours after starting the test.

VEHICLE CONTROL PERFORMED: no, not needed as no vehicle was used

RANGE-FINDING STUDY
- Test concentrations: 0, 0.1, 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: 0% immobilisation in control, 0.1 and 1 mg/L. 5% and 25% immobilisation in respectively 10 and 100 mg/L test solutions.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 47 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
other: TOC measurement
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
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
47 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
other: TOC measurement
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: no
- Observations on body length and weight: not relevant
- Other biological observations: At a test item concentration of 6.25 mg/L 90 % of the daphnids swam on the medium surface after 24 and 48 hours. At test item concentration of 25.0 mg/L all daphnids swam on the medium surface after 24 and 48 hours.
- Other adverse effects control: none
- Immobilisation of control: none
- Abnormal responses: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: At test start at test item concentrations 12.5 to 100 mg/L an increasing part of substance could be observed at the surface, on the bottom and the sidewalls.
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: EC50
- Limit test: no
- Dose-response test: Test concentrations 1 and 2 mg/L
- ECx: EC50=1 mg/L
Reported statistics and error estimates:
The values for EC50 were not determined statistically due to a lack of immobilisation.

Biological test results

  Nominal test concentration (mg/L)
control 6.25 12.5 25 50 100
replicate 1 0 1 0 0 0 0
replicate 2 0 0 0 0 1 0
replicate 3 0 1 0 0 0 1
replicate 4 0 0 0 1 0 0
sum 0 2 0 1 1 1
% 0 10 0 5 5 5

TOC measurements

Test item nominal TOC content nominal sampling TOC found Actual test item conc 
mg/L mg/L mg/L mg/L blank corrected % of nominal mg/L
control 0 0h fresh 1.18 - - -
48h aged 0.58 - -
6.25 3.21 0h fresh 2.85 1.67 26 1.81
48h aged 2.6 2.02 32
12.5 6.41 0h fresh 4.23 3.05 48 6.75
48h aged 4.47 3.89 61
25 12.8 0h fresh 9.31 8.13 64 16.8
48h aged 9.5 8.92 70
50 25.7 0h fresh 13.7 12.5 49 25.5
48h aged 14.2 13.6 53
100 51.3 0h fresh 25.1 23.9 47 47
48h aged 24.6 24.0 47
Validity criteria fulfilled:
yes
Conclusions:
The toxicity of ODPA to Daphnia was assessed in a OECD 202 study. No toxicity (as reduced mobility) has been observed. The NOEC and EC50 values are 100 and > 100 mg/L (nominal concentration). This relates to a NOEC and EC50 value of 47 and > 47 mg/L as measured by TOC.
Executive summary:

The toxicity of ODPA to Daphnia was assessed in a OECD 202 study. Daphnia were exposed for 48h to following ODPA nominal concentrations: 100, 50, 25, 12.5, 6.25 and 0 mg/L.

Since the substance is hydrolytically unstable, aged solutions were used for the tests, i.e. substance dissolved and stirred for 24h in the dark. Verification of test concentrations was done by TOC measurement. The substance was found to be between 32 and 70 % of the nominal test concentration.

No toxicity (as reduced mobility) has been observed. The NOEC and EC50 values are 100 and > 100 mg/L (nominal concentration). This relates to a NOEC and EC50 value of 47 and > 47 mg/L as measured by TOC.

Description of key information

For this endpoint, two experimental studies are available. The most recent study performed in 2019 has been used as key study. In this study the toxicity of ODPA to Daphnia was assessed in a OECD 202 study. Daphnia were exposed for 48h to following ODPA nominal concentrations: 100, 50, 25, 12.5, 6.25 and 0 mg/L.

Since the substance is hydrolytically unstable, aged solutions were used for the tests, i.e. substance dissolved and stirred for 24h in the dark. Verification of test concentrations was done by TOC measurement. The substance was found to be between 32 and 70 % of the nominal test concentration.

No toxicity (as reduced mobility) has been observed. The NOEC and EC50 values are 100 and > 100 mg/L (nominal concentration). This relates to a NOEC and EC50 value of 47 and > 47 mg/L as measured by TOC.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
47 mg/L

Additional information

The supporting study is an experimental study conducted in 1992 according to EU Method C.2. The effect levels based on measured concentrations were found to be EC50 = 91 mg/L (24h), EC50 = 17 mg/L (48h) and NOEC = 9.7 mg/L (48h). The results are in the same order of magnituted as test results obtained in 2019.