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Ecotoxicological information

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Sampling schedule:
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 20.8 mg of the test item were added to 1 litre of dilution water and treated for 1 hour in an ultrasonic-bath and afterwards stirred for 24 hours on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using a folded filter of pore size 7-12 µm.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Name: Desmodesmus subspicatus
- 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 Göttingen (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 & KÜHN (1977)) s 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 104 cells per millilitre in the test medium.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
21 - 25°C (+-2°)
pH:
7.9 - 9.9
Nominal and measured concentrations:
Nominal: 0.02, 0.04, 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L
Recovery rates ranged from 96.9 - 107.1% of nominal values at 0 hours, and from 27.7 - 92.2% of nominal values at 72 hours, respectively.
Details on test conditions:
- Test vessels: 300 ml Erlenrneyer flasks with cotton 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 uE. 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: 9 test concentrations plus 1 control, 3 replicates per concentration, 6 replicates per control, initial cell density in the test cultures approximately 10E4 cells per millilitre, additionally highest test concentration without algae
- Test concentration/s (nominal): 0.02, 0.04, 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L
- Method of administration: stock solution
- Duration of exposure: 72 h
- Criteria of effects: The criteria of adverse effects used in this study were the item-induced inhibition of growth [b] and growth rate [r], respectively, of the algal population.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.81 mg/L
Nominal / measured:
meas. (not specified)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1.48 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.27 mg/L
Nominal / measured:
meas. (not specified)
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.61 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
All results are expressed in terms of mean measured concentrations. Recovery rates ranged from 96.9 - 107.1% of nominal values at 0 hours, and from 27.7 - 92.2% of nominal values at 72 hours, respectively
Reported statistics and error estimates:
Analysis of the growth and growth rate of the algal population within the 72 h exposure period were determined by probit analysis and DUNNETT's test, respectively.
Conclusions:
After 72 h of exposure of algae to 2-chloro-5-chloromethylpyridine the following values were determined based on growth rate: EC50: 5.81 mg/L and NOEC: 1.48 mg/L.
Executive summary:

A study was performed to assess adverse effects of 2 -chloro-5 -chloromethylpyridine on the growth rate (rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with EEC 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 0.02, 0.04, 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L of 2-chloro-5-chloromethylpyridine dissolved in water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was

measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to DUNNETT (1955, 1964). The following values were determined: EC50: 5.81 mg/L, NOEC: 1.48 mg/L.

All results are expressed in terms of mean measured concentrations. Recovery rates ranged from 96.9 - 107.1% of nominal values at 0 hours, and from 27.7 - 92.2% of nominal values at 72 hours, respectively.

Description of key information

A study was performed to assess adverse effects of 2 -chloro-5 -chloromethylpyridine on the growth rate (rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted in accordance with EEC 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 0.02, 0.04, 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L of 2-chloro-5-chloromethylpyridine dissolved in water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was

measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to DUNNETT (1955, 1964). The following values were determined: EC50: 5.81 mg/L, NOEC: 1.48 mg/L.

All results are expressed in terms of mean measured concentrations. Recovery rates ranged from 96.9 - 107.1% of nominal values at 0 hours, and from 27.7 - 92.2% of nominal values at 72 hours, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:
5.81 mg/L
EC10 or NOEC for freshwater algae:
1.48 mg/L

Additional information