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Toxicity to aquatic plants other than algae

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Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: ISO 20079
GLP compliance:
not specified
Specific details on test material used for the study:
HAsNa2O4.7H2O, Fluka, Germany
Analytical monitoring:
yes
Details on sampling:
The actual concentrations of the chemical compounds in all test solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7500ce, Japan), at the beginning and at the end of each single test, and presented as total concentrations of the corresponding element.
Vehicle:
no
Details on test solutions:
HAsNa2O4 diluted in laboratory water
test medium: modified Steinberg medium
Test organisms (species):
Lemna minor
Details on test organisms:
source: laboratory culture at LemnaTec GmbH (Wuerselen, Germany).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
20°C
Nominal and measured concentrations:
Between 10 and 80 mg As /L
Details on test conditions:
The tests were performed in climatic chambers.
Continuous light exposure at 127 ± 12 micro Einstein.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
45 245 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
82 000 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 using logistic model
Validity criteria fulfilled:
not specified
Conclusions:
The 7 days long chronic As toxicity test with sodium arsenate on Lemna minor resulted in the following values:
EC10: 45245 µg As/L
EC50: 82000 µg As/L
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: ISO 20079
GLP compliance:
not specified
Specific details on test material used for the study:
NaAsO2, Fluka, Germany
Analytical monitoring:
yes
Details on sampling:
The actual concentrations of the chemical compounds in all test solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7500ce, Japan), at the beginning and at the end of each single test, and presented as total concentrations of the corresponding element.
Vehicle:
no
Details on test solutions:
NaAsO2 diluted in laboratory water
test medium: modified Steinberg medium
Test organisms (species):
Lemna minor
Details on test organisms:
source: laboratory culture at LemnaTec GmbH (Wuerselen, Germany).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
20°C
Nominal and measured concentrations:
between 0.1 and 6 mg As/L
Details on test conditions:
The tests were performed in climatic chambers.
Continuous light exposure at 127 ± 12 micro Einstein.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
938 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
2 000 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 using logistic model
Validity criteria fulfilled:
not specified
Conclusions:
The 7 days long chronic As toxicity test with sodium arsenite on Lemna minor resulted in the following values:
EC10: 938 µg As/L
EC50: 2000 µg As/L
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
7-day toxicity test with the aquatic plant Wolffia arrhiza
GLP compliance:
not specified
Specific details on test material used for the study:
HAsNa2O4.7H2O, Fluka, Germany
Analytical monitoring:
yes
Details on sampling:
The actual concentrations of the chemical compounds in all test solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7500ce, Japan), at the beginning and at the end of each single test, and presented as total concentrations of the corresponding element.
Vehicle:
no
Details on test solutions:
HAsNa2O4 diluted in laboratory water
test medium: modified Steinberg medium
Test organisms (species):
other: Wolffia arrhiza
Details on test organisms:
W. arrhiza was obtained from a laboratory culture at Eurofins - GAB GmbH (Germany).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
20°C
Nominal and measured concentrations:
Between 0.01 and 60 mg As /L
Details on test conditions:
The tests were performed in climatic chambers.
Continuous light exposure at 127 ± 12 micro Einstein.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
776 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
17 000 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 using logistic model
Validity criteria fulfilled:
not specified
Conclusions:
The 7 days long chronic As toxicity test with sodium arsenate on Wolffia arrhiza resulted in the following values:
EC10: 7760 µg As/L
EC50: 17000 µg As/L
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
7-day toxicity test with the aquatic plant Wolffia arrhiza
GLP compliance:
not specified
Specific details on test material used for the study:
NaAsO2, Fluka, Germany
Analytical monitoring:
yes
Details on sampling:
The actual concentrations of the chemical compounds in all test solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7500ce, Japan), at the beginning and at the end of each single test, and presented as total concentrations of the corresponding element.
Vehicle:
no
Details on test solutions:
NaAsO2 diluted in laboratory water
test medium: modified Steinberg medium
Test organisms (species):
other: Wolffia arrhiza
Details on test organisms:
W. arrhiza was obtained from a laboratory culture at Eurofins - GAB GmbH (Germany)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
20°C
Nominal and measured concentrations:
Between 0.01 and 10 mg As /L
Details on test conditions:
The tests were performed in climatic chambers.
Continuous light exposure at 127 ± 12 micro Einstein.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
192 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
1 000 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
frond number
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 using logistic model
Validity criteria fulfilled:
not specified
Conclusions:
The 7 days long chronic As toxicity test with sodium arsenite on Wolffia arrhiza resulted in the following values:
EC10: 192 µg As/L
EC50: 1000 µg As/L
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
7 days long chronic As toxicity test on Lemna disperma.
GLP compliance:
not specified
Specific details on test material used for the study:
Na2HAsO4 · 7H2O, purity 98–102 %, Sigma-Aldrich, USA
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
OECD medium
Test organisms (species):
Lemna sp.
Details on test organisms:
Lemna disperma
source: University of Technology, Sydney
cultured axenically in the laboratory
life stage: One colony with 3 fronds
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
24°C
pH:
7.5
Nominal and measured concentrations:
nominal: 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 mg As/L
Details on test conditions:
Cultures were grown in sterile 500 mL Erlenmeyer flasks containing approximately 200 mL of standard, filtered (0.45 mm pore size cellulose acetatemembrane, Millipore) OECD media. The cultures were maintained in a dedicated, at constant room temperature (on a 12:12 light:d ark cycle and 70–80 μmol photons /m2/ s under daylight-type fluorescent lights.
Each treatment contained four replicates. The test vessels used were 25 mL plastic vials (polypropylene plastic, Sarstedt, Australia) to avoid As adsorption. Ten mL of test solution were added to each vial along with 50 μg/L antibiotic (oxytetracycline hydrochloride, 95%, HPLC grade, Sigma-Aldrich, USA) to preclude the effects of any residual bacteria that may be present in the medium. This antibiotic concentration did not affect L. disperma growth rate in OECD medium.
A single healthy L. disperma colony consisting of three fronds was added to each vial. The vials were then incubated in a constant temperature room for 7 days. At the end of the exposure period, digital photographs of the frond surface area of the plants were taken with a Canon SLR (350 d,3456 x 2304 pixels, scaled). The plants were then separated from their media by filtration through a 0.5 mm mesh size stainless steel sieve. The media were collected, frozen and stored for chemical analysis. The plants were rinsed with deionised water to remove any residual As or nutrients and touch-dried with paper towel. Fresh weights of the plants were then measured. The surface areas of healthy fronds (with no signs of chlorosis, discoloration, death, or decomposition) of the plants in each vial were determined from the digital photographs by counting pixel numbers using the histogram tool in Photoshop CS7 (Adobe software). These pixels were then converted to mm2 with the aid of the scale.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
1 223 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
other:
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
2 300 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
other:
Details on results:
To demonstrate that EC50 values are dependent on the endpoint chosen, the EC50 values for As species were calculated based on a range of different endpoints related to the growth of the organisms. For L. disperma, EC50 values for AsIII and AsV were calculated from total surface area, healthy surface area, number of colonies, number of fronds, healthy surface area per frond and fresh weight. Results showed that for both As species, endpoints of total surface area, healthy surface area and number of colonies provide statistically similar EC50 values (p>0.05). From these results, and those of other As species, it was decided that healthy surface area, which is related to growth, provided the best estimate of the EC50 value. This endpoint was chosen for the determination of the toxicities of As species to L. disperma because of its low standard errors across all As species, and because it allowed differentiation between healthy and unhealthy fronds, as well as living and dead material, which was not possible from other endpoints.
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 have beevn calculated using 4-parameter log-logistic curve fitting
Validity criteria fulfilled:
not specified
Remarks:
Composition test medium is reported; control performnace is not reported
Conclusions:
The 7 days long chronic As toxicity test with sodium arsenate on Lemna disperma was resulted in the following values:
EC10: 1223 µg As/L
EC50: 2300 µg As/L
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
7 days long As toxicity test on Lemna disperma.
GLP compliance:
not specified
Specific details on test material used for the study:
NaAsO2, purity 90 %, Sigma-Aldrich, USA
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
OECD medium
Test organisms (species):
Lemna sp.
Details on test organisms:
Lemna disperma
source: University of Technology, Sydney
cultured axenically in the laboratory
life stage: One colony with 3 fronds

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
24°C
pH:
7.5
Nominal and measured concentrations:
nominal: 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4 mg As /L
Details on test conditions:
Cultures were grown in sterile 500 mL Erlenmeyer flasks containing approximately 200 mL of standard, filtered (0.45 mm pore size cellulose acetatemembrane, Millipore) OECD media. The cultures were maintained in a dedicated, at constant room temperature (on a 12:12 light:d ark cycle and 70–80 μmol photons /m2/ s under daylight-type fluorescent lights.
Each treatment contained four replicates. The test vessels used were 25 mL plastic vials (polypropylene plastic, Sarstedt, Australia) to avoid As adsorption. Ten mL of test solution were added to each vial along with 50 μg/L antibiotic (oxytetracycline hydrochloride, 95%, HPLC grade, Sigma-Aldrich, USA) to preclude the effects of any residual bacteria that may be present in the medium. This antibiotic concentration did not affect L. disperma growth rate in OECD medium.
A single healthy L. disperma colony consisting of three fronds was added to each vial. The vials were then incubated in a constant temperature room for 7 days. At the end of the exposure period, digital photographs of the frond surface area of the plants were taken with a Canon SLR (350 d,3456 x 2304 pixels, scaled). The plants were then separated from their media by filtration through a 0.5 mm mesh size stainless steel sieve. The media were collected, frozen and stored for chemical analysis. The plants were rinsed with deionised water to remove any residual As or nutrients and touch-dried with paper towel. Fresh weights of the plants were then measured. The surface areas of healthy fronds (with no signs of chlorosis, discoloration, death, or decomposition) of the plants in each vial were determined from the digital photographs by counting pixel numbers using the histogram tool in Photoshop CS7 (Adobe software). These pixels were then converted to mm2 with the aid of the scale.
Key result
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
292 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
other:
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
570 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
As
Basis for effect:
other:
Details on results:
To demonstrate that EC50 values are dependent on the endpoint chosen, the EC50 values for As species were calculated based on a range of different endpoints related to the growth of the organisms. For L. disperma, EC50 values for AsIII and AsV were calculated from total surface area, healthy surface area, number of colonies, number of fronds, healthy surface area per frond and fresh weight. Results showed that for both As species, endpoints of total surface area, healthy surface area and number of colonies provide statistically similar EC50 values (p>0.05). From these results, and those of other As species, it was decided that healthy surface area, which is related to growth, provided the best estimate of the EC50 value. This endpoint was chosen for the determination of the toxicities of As species to L. disperma because of its low standard errors across all As species, and because it allowed differentiation between healthy and unhealthy fronds, as well as living and dead material, which was not possible from other endpoints.
Reported statistics and error estimates:
EC10 have been re-calculated using Trap software (log-logistic curve fitting)
EC50 have been calculated using 4-parameter log-logistic curve fitting
Validity criteria fulfilled:
not specified
Remarks:
Composition test medium is reported; control performnace is not reported
Conclusions:
The 7 days long As toxicity test with sodium arsenite on Lemna disperma was resulted in the following values:
EC10: 292 µg As/L
EC50: 570 µg As/L

Description of key information

Chronic toxicity data were retrieved for 3 different freshwater plant species. 

For Lemna minor, chronic toxicity values as EC10 for the endpoint growth rate (number of fronds) varied between 938 µg As/L (tested with AsIII) and 45245 µg As/L (tested with AsV). For the similar species Lemna disperma, chronic EC10 for the endpoint growth rate (surface area) varied between 292 µg As/L (tested with AsIII) and 1223 µg As/L (tested with AsV). Chronic toxicity (EC10) values for Wolffia arrhiza varied between 192 µg As/L (tested with AsIII) and 7760 µg As/L (tested with AsV). All tests with the higher plants were performed for 7 d.

Key value for chemical safety assessment

Additional information