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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2005 february 3rd to 2005 february 11th
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study performed according to the OECD Guideline 201.

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:

Test material

Details on test material:
SRID: DEV75332
Physical State and Appearance: Tan powder
Aqueous Solubility: Determined to be <0.05 mg/L in algal growth medium.
Stability Determination: Stability of the test substance under test conditions was evaluated by
measuring the concentrations of the test substance in the exposure solutions and chemical
controls during the test.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test alga, Selenastrum capricorrzutunz, was obtained from the American Type Culture
Collection, Rockville, MD and was subsequently cultured in the testing facility. A 4-day culture
(passage 2) in liquid algal medium (Table l), was used as the source of test inoculum. Previous
passages were performed in order to confirm exponential growth under the conditions of the test.

Study design

Test type:
Water media type:
Total exposure duration:
72 h

Test conditions

Test Concentration (per 1.0 L)
NaNO3 (sodium nitrate) : 25.500 mg
MgCl2.6H20 (magnesium chloride) : 12.164 mg
CaCl2.2H20 (calcium chloride) : 4.410 mg
H3B03 (boric acid) : 185.520 µg
MnCl2.4H20 (manganese chloride) : 415.610 µg
ZnCl2 (zinc chloride) : 3.271 µg
FeCl3.6H20 (ferric chloride) : 160.000 µg
CoCl2.6H20 (cobalt chloride) : 1.428 µg
NaMo04.2H2O (sodium molybdate) : 7.260 µg
CuCl2.2H20 (cupric chloride) : 300.000 µg
Na2EDTA.2H20 (disodium EDTA) : 0.012 µg
MgS04-7H20 (magnesium sulfate) : 14.700 mg
K2HP04 (potassium phosphate) : 1.044 mg
NaHCO3 (sodium bicarbonate) : 15.000 mg
Test temperature:
A mean temperature of 24.8"C was maintained.
The pH values for the test and control solutions ranged from 7.45 at test start to 8.59 at test end.
By the end of the test, the pH values of the test solutions had not deviated by more than 1.5 units
as required by test guidelines.
Nominal and measured concentrations:
The concentrations of the test substance in the exposure solutions and in the chemical controls
(flasks without algae) were measured using HpLC/UV. The geometric mean concentration of the
nominally 0.1 mg/L exposure solution was determined to be 0.05 mg/L.
Reference substance (positive control):

Results and discussion

Effect concentrations
72 h
Dose descriptor:
Effect conc.:
ca. 0.05 mg/L
Basis for effect:
growth rate
Details on results:
Stability of the test substance under study conditions was evaluated by analyzing the exposure solutions as well as
chemical controls throughout the test. Loss of the test substance concentration from flasks
containing algae exposed to nominally 0.1 mg/L was determined to be 50.0%. Losses in test
substance concentrations from the chemical control flasks (without algae) were determined to be
50.0% in the light-exposed flasks, and 50.0% in the light-shielded flasks. The losses in
concentration are likely due to testing at a concentration exceeding the aqueous solubility of the
The cell count results indicate that algae in the solvent control flasks exhibited normal log
growth, increasing from lx10e4 cells/mL at time 0 to a mean of 1.25x10e6 at 72 hours.
There was no inhibition in biomass or growth rate measured in algae exposed to the test substance for 72 hours.
The EbC50(0-72hr)v alue was determined to be >0.05 mg/L. The EtC50(0-72hr) value was also
determined to be >0.05 mgL. The 72-hour NOEC value was estimated to be 0.05 mgL.

Applicant's summary and conclusion

The 72-hour EbC50 and EtC50 values for Selenastrunz capricormtum indicate, based on this study,
that the test substance would not be classified according to the European Union’s labeling
directive [2] and would be classified in a “low concern level” category according to U.S. EPA
assessment criteria [3]