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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1975
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
abstract
Qualifier:
no guideline available
Version / remarks:
In 1975 no guideline was available
Principles of method if other than guideline:
- Principle of test: In a static test with 6 concentrations the effect of the test item on the growth rate of Selenastrum capricornutum was tested.
GLP compliance:
no
Remarks:
Study was conducted in 1975
Analytical monitoring:
yes
Details on sampling:
not available
Vehicle:
yes
Remarks:
Acetone
Details on test solutions:
Primary and secondary stock Solutions of the toxicant were made up in acetone and water, respectively, and periodically renewed throughout the experiments. All test flasks received 7.8 mg acetone per 60 mL culture (0.130 mg/L) from the stock solutions. Preliminary tests with three times this acetone concentration produced no measurable effects on algal growth.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Selenastrum capricornutum Printz
- Source: National Eutrophication Research Program-EPA

Stock cultures were transferred to fresh media weekly to insure a continuous supply of cells in logarithmic growth phase to serve as inoculum for the toxicity tests.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
not specified
Test temperature:
23 ± 1 °C
pH:
7.5 ± 0.2
Nominal and measured concentrations:
Nominal concentrations: 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L and a control
Measured concentrations: Slight decreases in TFM concentration were observed at the termination of each test, presumably due to absorption and uptake of TFM by algal cells.
Details on test conditions:
TEST SYSTEM
- Test vessel: polyurethane-stoppered Erlenmeyer flasks
- Size: 60 mL og autoclaved medium
- Initial cells density: 1.0 x 10E4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Chamber: walk. in environmental chamber
- Shaking: reciprocating shaker operating at 80 oscillations per minute

GROWTH MEDIUM
- Standard medium used: yes, ASM-1 medium (Gorham et al, 1964; aIso in Eberly 1967)

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: as Growth medium

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the medium was adjusted to 7.5 ± 0.2 by the addition of 0.1N HCL or 0.1N NaOH.
- Photoperiod: continuous
- Light intensity and quality: cool-white fluorescent lighting of 400 (± 10%) foot-candles


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: The growth of the algae was determined spectrophotometrically at 680 nm on a Beckman DB spectrophotometer or a Bausch and Lomb Spectronic 20. The algae were counted directly under a microscope with a hemacytometer.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: max. 2
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes, LC50 between 5 and 10 mg/L
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
8.6 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence interval: 5.93 - 12.5 mg/L
Reported statistics and error estimates:
Statistical analysis of the data followed the basic recommendations of the National Eutrophication Research Program (EPA 1971). The optical density data were analyzed by the methods of Litchfield and Wilcoxon (1949) for the evaluation of median effective concentrations (EC50) and establishment of 95% confidence limits. The EC50 is the TFM concentration that causes a 50% inhibition of algal growth when compared with control cultures growing simultaneously in the absence of the lamprecide.
Validity criteria fulfilled:
yes
Conclusions:
In a static test with Pseudokirchneriella subcapitata (Selenastrum capricornutum) the EC50 value after 96 hours was determined to be 8.6 mg/L.
Executive summary:

In a static test the effect of the test item on the growth rate of Pseudokirchneriella subcapitata (Selenastrum capricornutum) was tested. The nominal concentrations were 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L. Slight decreases in the concentrations of the test item were oberved but not documented in detail. The EC50 value was determined to be 8.6 mg/L after 96 hours with a 95 % confidence interval of 5.93 - 12.5 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1975
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
abstract
Qualifier:
no guideline available
Version / remarks:
In 1975 no guideline was available
Principles of method if other than guideline:
- Principle of test: In a static test with 6 concentrations the effect of the test item on the growth rate of Anabaena cylindrica was tested.
GLP compliance:
no
Remarks:
Study was conducted in 1975
Analytical monitoring:
yes
Details on sampling:
not available
Vehicle:
yes
Remarks:
Acetone
Details on test solutions:
Primary and secondary stock Solutions of the toxicant were made up in acetone and water, respectively, and periodically renewed throughout the experiments. All test flasks received 7.8 mg acetone per 60 mL culture (0.130 mg/L) from the stock solutions. Preliminary tests with three times this acetone concentration produced no measurable effects on algal growth.
Test organisms (species):
Anabaena cylindrica
Details on test organisms:
TEST ORGANISM
- Common name: Anabaena cylincdrica Lemmerman
- Source: Michigan State University Culture Collection

Stock cultures were transferred to fresh media weekly to insure a continuous supply of cells in logarithmic growth phase to serve as inoculum for the toxicity tests.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
not specified
Test temperature:
23 ± 1 °C
pH:
7.5 ± 0.2
Nominal and measured concentrations:
Nominal concentrations: 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L and a control
Measured concentrations: Slight decreases in TFM concentration were observed at the termination of each test, presumably due to absorption and uptake of TFM by algal cells.
Details on test conditions:
TEST SYSTEM
- Test vessel: polyurethane-stoppered Erlenmeyer flasks
- Size: 60 mL og autoclaved medium
- Initial cells density: 1.0 x 10E4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Chamber: walk. in environmental chamber
- Shaking: reciprocating shaker operating at 80 oscillations per minute

GROWTH MEDIUM
- Standard medium used: yes, Allen and Amon medium (Allen and Amon 1955)

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: as Growth medium

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the medium was adjusted to 7.5 ± 0.2 by the addition of 0.1N HCL or 0.1N NaOH.
- Photoperiod: continuous
- Light intensity and quality: cool-white fluorescent lighting of 400 (± 10%) foot-candles


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: The growth of the algae was determined spectrophotometrically at 680 nm on a Beckman DB spectrophotometer or a Bausch and Lomb Spectronic 20.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: max. 2
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes, LC50 between 5 and 10 mg/L
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.8 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence interval: 0.82 - 3.96 mg/L
Reported statistics and error estimates:
Statistical analysis of the data followed the basic recommendations of the National Eutrophication Research Program (EPA 1971). The optical density data were analyzed by the methods of Litchfield and Wilcoxon (1949) for the evaluation of median effective concentrations (EC50) and establishment of 95% confidence limits. The EC50 is the TFM concentration that causes a 50% inhibition of algal growth when compared with control cultures growing simultaneously in the absence of the lamprecide.
Validity criteria fulfilled:
yes
Conclusions:
In a static test with Anabaena cylincdrica the EC50 value after 96 hours was determined to be 1.8 mg/L.
Executive summary:

In a static test the effect of the test item on the growth rate of Anabaena cylincdrica was tested. The nominal concentrations were 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L. Slight decreases in the concentrations of the test item were oberved but not documented in detail. The EC50 value was determined to be 1.8 mg/L after 96 hours with a 95 % confidence interval of 0.82 - 3.96 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1975
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
abstract
Qualifier:
no guideline available
Version / remarks:
In 1975 no guideline was available
Principles of method if other than guideline:
- Principle of test: In a static test with 6 concentrations the effect of the test item on the growth rate of Nitzschia sp. was tested.
GLP compliance:
no
Remarks:
Study was conducted in 1975
Analytical monitoring:
yes
Details on sampling:
not available
Vehicle:
yes
Remarks:
Acetone
Details on test solutions:
Primary and secondary stock Solutions of the toxicant were made up in acetone and water, respectively, and periodically renewed throughout the experiments. All test flasks received 7.8 mg acetone per 60 mL culture (0.130 mg/L) from the stock solutions. Preliminary tests with three times this acetone concentration produced no measurable effects on algal growth.
Test organisms (species):
Nitzschia sp.
Details on test organisms:
TEST ORGANISM
- Common name: Nitzschia sp.
- Source: Indiana Culture Collection, Indiana University

Stock cultures were transferred to fresh media weekly to insure a continuous supply of cells in logarithmic growth phase to serve as inoculum for the toxicity tests.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
not specified
Test temperature:
23 ± 1 °C
pH:
7.5 ± 0.2
Nominal and measured concentrations:
Nominal concentrations: 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L and a control
Measured concentrations: Slight decreases in TFM concentration were observed at the termination of each test, presumably due to absorption and uptake of TFM by algal cells.
Details on test conditions:
TEST SYSTEM
- Test vessel: polyurethane-stoppered Erlenmeyer flasks
- Size: 60 mL og autoclaved medium
- Initial cells density: 1.0 x 10E4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Chamber: walk. in environmental chamber
- Shaking: reciprocating shaker operating at 80 oscillations per minute

GROWTH MEDIUM
- Standard medium used: yes, National Eutrophication Research Program medium (Environmental protection Agency [EPA] 1971) with the addition of silica (10 mg/L)

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: as Growth medium

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the medium was adjusted to 7.5 ± 0.2 by the addition of 0.1N HCL or 0.1N NaOH.
- Photoperiod: continuous
- Light intensity and quality: cool-white fluorescent lighting of 400 (± 10%) foot-candles


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: The growth of the algae was determined spectrophotometrically at 680 nm on a Beckman DB spectrophotometer or a Bausch and Lomb Spectronic 20.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: max. 2
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes, LC50 between 5 and 10 mg/L
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
3.6 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence interval: 2.57 - 5.04 mg/L
Reported statistics and error estimates:
Statistical analysis of the data followed the basic recommendations of the National Eutrophication Research Program (EPA 1971). The optical density data were analyzed by the methods of Litchfield and Wilcoxon (1949) for the evaluation of median effective concentrations (EC50) and establishment of 95% confidence limits. The EC50 is the TFM concentration that causes a 50% inhibition of algal growth when compared with control cultures growing simultaneously in the absence of the lamprecide.
Validity criteria fulfilled:
yes
Conclusions:
In a static test with Nitzschia sp. the EC50 value after 96 hours was determined to be 3.6 mg/L.
Executive summary:

In a static test the effect of the test item on the growth rate of Nitzschia sp. was tested. The nominal concentrations were 2.5, 5.0, 7.0, 8.0, 10.0, and 15.0 mg/L. Slight decreases in the concentrations of the test item were oberved but not documented in detail. The EC50 value was determined to be 3.6 mg/L after 96 hours with a 95 % confidence interval of 2.57 - 5.04 mg/L.

Description of key information

Pseudokirchneriella subcapitata (Selenastrum capricornutum): EC50 (96 h) = 8.6 mg/L

Anabaena cylincdrica: EC50 (96 h) = 1.8 mg/L

Nitzschia sp.: EC50 (96 h) = 1.2 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
1.2 mg/L

Additional information

As the test item is registered since 1964 for limited use in tributaries of the Great Lakes in the US for control of the parasitic sea lamprey, numerous studies on aquatic algae are available. Only the most important study presented here: The test with the lowest EC50 (Nitzschia sp.) and two additional species for the endpoint (Pseudokirchneriella subcapitata and Anabaena cylindrica). No guidelines were available in 1975 and in the publications the description of the methods are insufficient. For all three species the field grade test item (35.7 %) showed lower EC50 values based on the active ingredient. As all results are in the same range (EC50: 1.2 – 8.6 mg/L) they are considered valid. Additionally they match with the data given in the RED document of the test item of EPA (Reregistration Eligibility Decision, United States Environmental Protection Agency, November 1999, 7508C) where an EC50 of less than 10 mg/L is given.