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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2012-05-07 to 2012-05-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
, 2006.
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
, 2009
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II)
Version / remarks:
, 1996.
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Batch No.: 10191-AKm
- Purity: 100.5 % (aldimine titration)
- Expiry date: 2013-06-16
Analytical monitoring:
yes
Details on sampling:
For determination of the test item concentration, samples were taken from each testing concentration and from the control at the start and at the end of the experiment.
Vehicle:
no
Details on test solutions:
A stock solution of 100 mg/L (nominal) was first prepared by dissolving an amount of 0.1 g test item in 1000 mL dilution water (OECD medium) using intensive shaking (until all of the test item dissolved). The test solutions of the chosen test concentrations were prepared by appropriate dilution of this stock solution.
The test solutions were prepared immediately before introduction of algae (start of the experiment).
Concentrations of the test item were analytically determined at the start and at the end of the experiment.
The measured concentrations deviated more than 20 % from the nominal during the experiment therefore the exposure concentrations were calculated as geometric mean of the concentrations measured at the start and at the end of the test.
The measured concentrations of Sika Hardener MH varied between 36 and 81 % of the nominal during the experiment.

Based on the results of pre-experiments the following six test concentrations in a geometric series (with a separation factor of 2.9) were tested: 1.1, 3.2, 9.3, 26.8 and 77.8 mg/L (nominal).
The measured concentrations deviated more than 20 % from the nominal during the experiment therefore the geometric mean of the measured concentrations were calculated in order to determine exposure concentrations.
The calculated geometric mean concentrations were the followings: 0.6, 2.2, 7.4, 20.6 and 59.8 mg/L.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Species: Pseudokirchneriella subcapitata (formerly: Selenastrum capricornutum) (Printz-Starr).
- Strain number: 61.81 SAG (identical strains: CCAP 278/4; UTEX 1648; ATCC 22662)
- Origin: The algae were supplied by the SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Nikolausberger Weg 18, D-37073 Göttingen, Germany
- Breeding Conditions: The stock cultures are small algal cultures that are planted on agar regularly. These are transferred to fresh medium at least once every two months under standardised conditions according to the test guidelines.
- The pre-culture is intended to give an amount of algae suitable for the inoculation of test cultures. The pre-culture was prepared with Algal Mineral Salts Culture Medium, incubated under the conditions of the test and used when still exponentially growing, normally after an incubation period of about three days. (The pre-culture was incubated for three days at this test.)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
21.3 – 22.1 °C
pH:
The pH was 8.01 – 9.54 during the study.
Nominal and measured concentrations:
The following nominal concentrations of test item were tested: 1.1, 3.2, 9.3, 26.8 and 77.8 mg/L.
The corresponding calculated geometric mean test item concentrations (based on the analytical measurements) were: 0.5, 2.2, 7.4, 20.6 and 59.8 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks of 250 mL volume with 100 mL test medium. The test flasks were covered with air-permeable stoppers.
- Initial cells density: Approximately 10.000 algal cells per mL test medium
- Replicates: 3 replicates per test concentration and six replicates in the control group. Volumes of 100 mL algal suspension per replicate were continuously shaken by a laboratory orbital shaker.

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: 7966 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: Manual cell counting using a microscope with a counting chamber
- Other: The cell morphology was examined in parallel

TEST CONCENTRATIONS
- Range finding study: A non GLP preliminary range-finding tests were performed. In the first range-finding test the examined nominal concentrations were: 0.1, 1, 10 and 100 mg test item/L.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
52.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% conf. limits (42.1 - 65.2)
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
14.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% conf. limits (11.2 - 18.3)
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
20.6 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
6.2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% conf. limits (4.8 - 7.9)
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
22.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% conf. limits (19.0 - 26.2)
Results with reference substance (positive control):
The results for the reference item Potassium dichromate are as follows:
The 72h ErC50: 1.19 mg/L, (95 % confidence limits: 1.09 – 1.30 mg/L)
The 72h EyC50: 0.80 mg/L, (95 % confidence limits: 0.73 – 0.87 mg/L)
Validity criteria fulfilled:
yes
Conclusions:
In this 72-h algal growth inhibition test with Pseudokirchneriella subcapitata, the 72-h EC50 value based on growth rate was determined as 52.4 mg/L and based on yield was determined as 22.3 mg/L.
The 72-h EC10 value based on growth rate was determined as 14.3 mg/L and based on yield was determined as 6.2 mg/L.
The 72-h NOEC related to growth rate was determined to be 20.6 mg/L and related to yield was determined to be 2.2 mg/L.
The results are based on the measured geometric mean concentrations.
Executive summary:

An acute growth inhibition test with Sika Hardener MH on Algae (Pseudokirchneriella subcapitata) over an exposure period of 72 hours in a static system was assessed according to OECD Guideline 201 and EU method C.3. Five different concentrations arranged in a geometric series and an untreated control group were tested in the main study. The following nominal concentrations of test item were tested: 1.1, 3.2, 9.3, 26.8 and 77.8 mg/L. The corresponding calculated geometric mean test item concentrations (based on the analytical measurements) were: 0.5, 2.2, 7.4, 20.6 and 59.8 mg/L.

Under the conditions of this acute algal growth inhibition test on Pseudokirchneriella subcapitata the observed endpoints on the growth rate were the followings: 72h EC50 value: 52.4 mg/L test, 72h NOEC value: 20.6 mg/L and the 72h EC10 14.3 mg/L. The results are based on the measured geometric mean test item concentrations.

Description of key information

In a 72-h algal growth inhibition test with Pseudokirchneriella subcapitata, the 72-h EC50 value based on growth rate was determined as 52.4 mg/L and based on yield was determined as 22.3 mg/L.

The 72-h EC10 value based on growth rate was determined as 14.3 mg/L and based on yield was determined as 6.2 mg/L.

The 72-h NOEC related to growth rate was determined to be 20.6 mg/L and related to yield was determined to be 2.2 mg/L.

The results are based on the measured geometric mean concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:
52.4 mg/L
EC10 or NOEC for freshwater algae:
14.3 mg/L

Additional information

An acute growth inhibition test with Sika Hardener MH on algae (Pseudokirchneriella subcapitata) over an exposure period of 72 hours in a static system was assessed according to OECD Guideline 201 and EU method C.3. Five different concentrations arranged in a geometric series and an untreated control group were tested in the main study. The following nominal concentrations of test item were tested: 1.1, 3.2, 9.3, 26.8 and 77.8 mg/L. The corresponding calculated geometric mean test item concentrations (based on the analytical measurements) were: 0.5, 2.2, 7.4, 20.6 and 59.8 mg/L.

Under the conditions of this acute algal growth inhibition test on Pseudokirchneriella subcapitata the observed endpoints on the growth rate were the followings: 72h EC50 value: 52.4 mg/L test, 72h NOEC value: 20.6 mg/L and the 72h EC10 14.3 mg/L. The results are based on the measured geometric mean test item concentrations.