Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not applicable
GLP compliance:
yes
Analytical monitoring:
yes
Remarks:
Gas Chromatography (GC)
Details on sampling:
Sampling schedule of chemical analysis:
- Stock solution: at 0 hours
- Control: at 0 and 72 hours
- Test concentration/s: at 0 and 72 hours
Vehicle:
no
Details on test solutions:
A stock solution was prepared to give the desired series of test concentrations. To achieve this 1.2 mg of the test substance were added to 2 litres of dilution water and treated for 60 seconds at 8000 rpm with an ultra turrax and afterwards sti1Ted for 24 h on a magnetic stirrer.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Source: Non-axenic strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Gottingen (Germany)
- Maintenance of stock cultures: Exponentially-growing stock cultures are maintained in the test facility under constant temperature conditions (23 +/- 2°C) at a light intensity in the range 60 - 120 μE. x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The nutrient medium (according to BRINGMANN & KUHN (1977) is renewed once a week. Cell density measurements are made using a microcell counter.
- Preparation of pre-cultures: Pre-cultures are set up three days before the start of a test. They are grown under identical exposure conditions as the stock cultures, except from the use of a different nutrient medium
- Test cultures: The algal inocula for a test are taken from an exponentially-growing pre-culture and are mixed with the nutrient medium to make up to a final
cell density of about 10E+4 cells per millilitre in the test medium.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
No data
Test temperature:
21-25 °C
pH:
9.4 (concerning the highest test concentration)
Salinity:
n.a.
Conductivity:
No data
Nominal and measured concentrations:
- Test concentration (nominally): 0.007, 0.0125, 0.025 0.05 and 0.1 mg/L
- Test concentration after 72 hours (measured): <0.0025 mg/L concerning 0.007 (n), 0.0125 (n) and 0.025 mg/L (n) and 0.0080 concerning 0.1 mg/L (n)
- Measured concentrations ranged from 64 - 94% of nominal values at O hours, and from 2.5 - 25% of nominal values at 72 hours, respectively
Details on test conditions:
EXPOSURE CONDITIONS:
- Test vessels: 300 mL Erlenmeyer flasks with stoppers
- Culturing apparatus: Light chamber in which a temperature in the range 21 °C to 25°C can be maintained at +/- 2°C, and continuous uniform illumination is provided in the spectral range 400 to 700 nm
- Light intensity: At the average of the test solutions, a light intensity in the range 60 to 120 μE. x m-2 x s-1, or an equivalent range of 4000 to 8000 Ix, is recommended to use
- Cell density measurements: Cell densities are measured in a microcell counter or, alternatively, are determined by means of a microscopic counting chamber
- Experimental design: 5 test concentrations plus 1 control; 3 replicates per concentration, 6 replicates per control; initial cell density in the test cultures approximately 10E+4 cells per millilitre; additionally highest test concentration without algae
- Method of administration: stock solution
- Criteria of effects: substance-induced inhibition of growth and growth rate, respectively, of the algal population
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
< 0.021 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.006 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.004 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.011 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.004 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.006 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
%Concentration loss over test: 75 ... 97.5
Validity criteria fulfilled:
yes
Conclusions:
After 72 hours of exposure to the test substance an EC50 value concerning the growth rate of higher as 0.021 mg/L and lower as 0.044 mg/L was determined. The NOECr and the LOECr were 0.005 and 0.0086 mg/L, respectively. All results are expressed in terms mean measured concentrations. Measured concentrations ranged from 64 - 94% of nominal values at 0 hour, and from 2.5 - 25% of nominal values at 72 hours, respectively.
Executive summary:

A study was performed to assess adverse effects on the growth and the growth rate of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 'Algal inhibition test' which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test'. Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 0.007, 0.0125, 0.025 0.05 and 0.1 mg/1 of test item dissolved in water. Auxiliaries used to prepare the test media were an ultra turrax and a magnetic stirrer. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. Growth and growth rates were used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to DUNNETT (1955, 1964). After 72 hours of exposure an EC50 value concerning the growth rate of higher as 0.021 mg/L and lower as 0.044 mg/L was determined. The NOECr and the LOECr were 0.005 and 0.0086 mg/L, respectively. All results are expressed in terms mean measured concentrations. Measured concentrations ranged from 64 - 94% of nominal values at 0 hour, and from 2.5 - 25% of nominal values at 72 hours, respectively. This toxicity study is classified as acceptable and satisfies the guideline requirements for the algae study.

Description of key information

A study was performed to assess adverse effects on the growth and the growth rate of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC (O.J. No. L383A, 29.12.92) Part C, Method 3 'Algal inhibition test' which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test'. Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 0.007, 0.0125, 0.025 0.05 and 0.1 mg/1 of test item dissolved in water. Auxiliaries used to prepare the test media were an ultra turrax and a magnetic stirrer. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. Growth and growth rates were used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to DUNNETT (1955, 1964).After 72 hours of exposure an EC50 value concerning the growth rate of higher as 0.021 mg/L and lower as 0.044 mg/L was determined. The NOECr and the LOECr were 0.005 and 0.0086 mg/L, respectively. All results are expressed in terms mean measured concentrations. Measured concentrations ranged from 64 - 94% of nominal values at 0 hour, and from 2.5 - 25% of nominal values at 72 hours, respectively.This toxicity study is classified as acceptable and satisfies the guideline requirements for the algaestudy.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.021 mg/L
EC10 or NOEC for freshwater algae:
0.006 mg/L

Additional information

"Should read: EC 50r (72 h): > 0.021 < 0.044 mg/L"