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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-09-20 - 2010-11-23
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was performed in compliance with the Good Laboratory Practice (GLP) regulations (revised in 1997, ENV/MC/CHEM(98)17). The method followed that described in the OECD Guidelines for Testing of Chemicals (Adopted: 4 April 1984) No 201 "Alga, Growth Inhibition Test", adopted March 23, 2006.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
The stability of the test material in the test medium under the conditions of the study was shown in a separate analytical study prior to start of this study. Due to the absence of any adverse effects no analytical sampling was performed during the study.

Test solutions

Vehicle:
no
Details on test solutions:
The test medium (reconstituted water and test material) was freshly prepared. The calibrated flask with test material and vehicle, reconstituted water, was treated in an ultrasound bath for 1 hour. Subsequently, the preparation was stirred with a magnetic stirrer for further 23 hours.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test system used for this study was a green unicellular algae species, Desmodesmus subspicatus, strain No. SAG 86.81, supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universitat Gottingen". This strain is recommended by international guidelines.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
none

Test conditions

Hardness:
250 mg CaCO3
Test temperature:
22-23°C
pH:
6.97-8.99
Salinity:
for details see composition of reconstituted water "details on test conditions"
Nominal and measured concentrations:
Nominal concentration of 100 mg/L (limit test)
Details on test conditions:
The test medium (reconstituted water and test material) was freshly prepared. The light intensity was approximately 7500 to 9500 Lux. The experimental part was started by inoculation of algae to the different groups so that the flasks contained about 10,000 cells/mL. The algae were taken from an exponentially growing pre-culture which was set up 3 days prior to the experimental part under the same conditions as in the final study.

Details on composition of the reconstituted water:

Macro-nutrients:
50.00 mg/L NaHCO3
18.00 mg/L CaCl2 x 2 H2O
15.00 mg/L NH4Cl
15.00 mg/L MgSO4 x 7 H2O
12.00 mg/L MgCl2 x 6 H2O
1.60 mg/L KH2PO4

Trace elements:
100.00 µg/L Na2EDTA x 2 H2O
80.00 µg/L FeCl3 x 6 H2O
415.00 µg/L MnCl2 x 4 H2O
185.00 µg/L H3BO3
7.00 µg/L Na2MoO4 x 2 H2O
3.00 µg/L ZnCl2
1.50 µg/L CoCl2 x 6 H2O
0.01 µg/L CuCl2 x 2 H2O

The pH of the reconstituted water after aeration is approximately 8.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
In a pre-test under static conditions, inhibition of growth rate of the algae, Desmodesmus subspicatus, was not observed at a concentration of normally 100 mg/L.
In the main study, in the control group the biomass increased by a factor of 93.3; the mean coefficient of variation of the daily growth rates (section-by-section growth rate) was 4.7% during 72 hours, the coefficient of variation of the average specific growth rates in the replicates of the control group was 1.2%
Results with reference substance (positive control):
no data

Any other information on results incl. tables

The test material concentration in the aqueous medium was not quantified at the start and at the end of this study because the test material was shown to be stable under the test conditions in a separate analytical study. Due to the absence of any adverse effects at the limit concentration, the study was performed without analytical concentration verification.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
An aqueous preparation of nominal 100 mg/L of the test material revealed no toxic effect in the test system. Therefore, the 72 hours EC50 could not be determined.
Executive summary:

Purpose

The purpose of this assay was to identify the aquatic toxicity potential of the test material in algea to provide a rational basis for hazard estimation for the test item in aquatic environments.

Study design

The influence of the test material on the growth and growth rate of the green algae species Desmodesmus subspicatus was tested. The study design included one control and one test material group with six replicates, each containing about 100 rnL reconstituted water or test medium and 10,000 cells/mL at the start of the experimental phase. The algae were exposed to a concentration of 100 mg/L and the study was performed as a limit test in an open static test system. The growth was calculated after 24, 48, and 72 hours exposure in the test medium.

Results

The concentration of 100 mg/L revealed no biological effects (NOEC),

Due to the absence of toxic effects at the limit concentration, EC50 values cannot be calculated.

72 h EbC50 > 100 mg/L

72 h ErC50 > 100 mg/L

NOEC: 100 mg/L

Conclusions

An aqueous preparation of 100 mg/L of the test material revealed no toxic effect in the test system. The 72 hours EC50 to Desmodesmus subspicatus exceeded the limit concentration (100 mg/L) and could thus not be determined.