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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Well performed study (clear from Materials & Methods section). However, some information is missing (e.g., control performance, measurements of pH and Se concentrations). Se concentrations were measured but not reported and clearly not used for calculation of effect concentrations. Most likely Se concentrations did not deviate much from nominal concentrations.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
- Frequency: no data
Vehicle:
no
Details on test solutions:
see test conditions
Test organisms (species):
Lemna minor
Details on test organisms:
TEST ORGANISM
- Common name: Duckweed
- Source (laboratory, culture collection): Department of Plant Physiology of the Wageningen Agricultural University, the Netherlands
- Age of inoculum (at test initiation): no data
- Treatment of inoculum: duckweed was disinfected by immersing the fronds in 70% ethanol, followed by 1% NaOCl and rinsing with sterilised water
- Method of cultivation: The stock culture was kept in glass petri dishes, which were sterilized at 150°C for 2 h. The stock culture was kept sterile and transferred to fresh medium every 2 weeks. All incubations were performed in a laminar flow chamber.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
2 wk
Hardness:
Can be calculated (0.5 g Ca(NO3)2.4H2O and 0.25 g MgSO4.7H2O per L)
Test temperature:
23 ± 1°C
pH:
5.0 ± 0.1
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
No data
Details on test conditions:
TEST SYSTEM
- Incubation chamber used: yes
- Test vessels: disposable high petri dishes (diameter 9.5 cm, height 5 cm), cleaned in 0.1 N HNO3 for 24 h and rinsed with Milli-Q water
- No. of fronds per vessel: 10
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: medium modified by Rombach according to Gorham (see Table 1 "other information")
- The growth medium was sterilized (120°C, 20 min) before use

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test medium composed using Milli-Q water as dilution water
- Composition see Table 1

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 16:8 (light:dark)
- Light intensity and quality: 80 µmol/m²/s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The number of fronds was enumerated twice a week, viz., on days 4, 7, 11 and 14. A distinction was made between fully grown (1), near-fully grown (3/4), half-grown (1/2), and newly formed (1/4) fronds.
- Multiplication rate (MR): The MR is a measure for the rate of increase in the number of fronds (MR= 1000(log n1 - log n0)/t; t= t1-t0 (days); n1= number of fronds on day t1 and n0 is number of fronds on day t0).
- Percentage of surface coverage: Determined by image processing (PC Vision Plus framegrabber) and software package TIM (Difa Measuring Systems BV, Breda, the Netherlands)
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
80 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
800 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
1 700 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
3 500 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Reported statistics and error estimates:
No data
Conclusions:
Reliable (Klimisch 2) study on the toxicity of Se (IV) to duckweed (Lemma minor). The toxicity was evaluated based on the effect on multiplication rate and percentage of surface coverage. Using the results for multiplication rate the 2-week NOEC and EC50 were 800 and 3500 µg Se/L, respectively. The NOEC and EC50 based on % surface coverage were 80 and 1700 µg Se/L, respectively.
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Well performed study (clear from Materials & Methods section). However, some information is missing (e.g., control performance, measurements of pH and Se concentrations). Se concentrations were measured but not reported and clearly not used for calculation of effect concentrations. Most likely Se concentrations did not deviate much from nominal concentrations.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
- Frequency: no data
Vehicle:
no
Details on test solutions:
see test conditions
Test organisms (species):
Lemna minor
Details on test organisms:
TEST ORGANISM
- Common name: Duckweed
- Source (laboratory, culture collection): Department of Plant Physiology of the Wageningen Agricultural University, the Netherlands
- Age of inoculum (at test initiation): no data
- Treatment of inoculum: duckweed was disinfected by immersing the fronds in 70% ethanol, followed by 1% NaOCl and rinsing with sterilised water
- Method of cultivation: The stock culture was kept in glass petri dishes, which were sterilized at 150°C for 2 h. The stock culture was kept sterile and transferred to fresh medium every 2 weeks. All incubations were performed in a laminar flow chamber.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
2 wk
Hardness:
Can be calculated (0.5 g Ca(NO3)2.4H2O and 0.25 g MgSO4.7H2O per L)
Test temperature:
23 ± 1°C
pH:
5.0 ± 0.1
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
No data
Details on test conditions:
TEST SYSTEM
- Incubation chamber used: yes
- Test vessels: disposable high petri dishes (diameter 9.5 cm, height 5 cm), cleaned in 0.1 N HNO3 for 24 h and rinsed with Milli-Q water
- No. of fronds per vessel: 10
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: medium modified by Rombach according to Gorham (see Table 1 "other information")
- The growth medium was sterilized (120°C, 20 min) before use

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test medium composed using Milli-Q water as dilution water
- Composition see Table 1

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 16:8 (light:dark)
- Light intensity and quality: 80 µmol/m²/s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The number of fronds was enumerated twice a week, viz., on days 4, 7, 11 and 14. A distinction was made between fully grown (1), near-fully grown (3/4), half-grown (1/2), and newly formed (1/4) fronds.
- Multiplication rate (MR): The MR is a measure for the rate of increase in the number of fronds (MR= 1000(log n1 - log n0)/t; t= t1-t0 (days); n1= number of fronds on day t1 and n0 is number of fronds on day t0).
- Percentage of surface coverage: Determined by image processing (PC Vision Plus framegrabber) and software package TIM (Difa Measuring Systems BV, Breda, the Netherlands)
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
800 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 2 400 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
5 300 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
11 500 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Reported statistics and error estimates:
No data
Conclusions:
Reliable (Klimisch 2) study on the toxicity of selenium (VI) to duckweed (Lemma minor). The toxicity was evaluated based on the effect on multiplication rate and percentage of surface coverage. Using the results for multiplication rate the 2-week NOEC and EC50 were > 2400 and 11500 µg Se/L, respectively. The NOEC and EC50 based on % surface coverage were 800 and 5300 µg Se/L, respectively.
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Well performed study (clear from Materials & Methods section). However, some information is missing (e.g., control performance, measurements of pH and Se concentrations). Se concentrations were measured but not reported and clearly not used for calculation of effect concentrations. Most likely Se concentrations did not deviate much from nominal concentrations.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
- Frequency: no data
Vehicle:
no
Details on test solutions:
see test conditions
Test organisms (species):
Lemna minor
Details on test organisms:
TEST ORGANISM
- Common name: Duckweed
- Source (laboratory, culture collection): Department of Plant Physiology of the Wageningen Agricultural University, the Netherlands
- Age of inoculum (at test initiation): no data
- Treatment of inoculum: duckweed was disinfected by immersing the fronds in 70% ethanol, followed by 1% NaOCl and rinsing with sterilised water
- Method of cultivation: The stock culture was kept in glass petri dishes, which were sterilized at 150°C for 2 h. The stock culture was kept sterile and transferred to fresh medium every 2 weeks. All incubations were performed in a laminar flow chamber.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
2 wk
Hardness:
Can be calculated (0.5 g Ca(NO3)2.4H2O and 0.25 g MgSO4.7H2O per L)
Test temperature:
23 ± 1°C
pH:
5.0 ± 0.1
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
No data
Details on test conditions:
TEST SYSTEM
- Incubation chamber used: yes
- Test vessels: disposable high petri dishes (diameter 9.5 cm, height 5 cm), cleaned in 0.1 N HNO3 for 24 h and rinsed with Milli-Q water
- No. of fronds per vessel: 10
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: medium modified by Rombach according to Gorham (see Table 1 "other information")
- The growth medium was sterilized (120°C, 20 min) before use

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test medium composed using Milli-Q water as dilution water
- Composition see Table 1

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 16:8 (light:dark)
- Light intensity and quality: 80 µmol/m²/s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The number of fronds was enumerated twice a week, viz., on days 4, 7, 11 and 14. A distinction was made between fully grown (1), near-fully grown (3/4), half-grown (1/2), and newly formed (1/4) fronds.
- Multiplication rate (MR): The MR is a measure for the rate of increase in the number of fronds (MR= 1000(log n1 - log n0)/t; t= t1-t0 (days); n1= number of fronds on day t1 and n0 is number of fronds on day t0).
- Percentage of surface coverage: Determined by image processing (PC Vision Plus framegrabber) and software package TIM (Difa Measuring Systems BV, Breda, the Netherlands)
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
800 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
800 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
2 900 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: % surface coverage
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
8 600 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: multiplication rate
Reported statistics and error estimates:
No data
Conclusions:
Reliable (Klimisch 2) study on the toxicity of selenium dioxide to duckweed (Lemma minor). The toxicity was evaluated based on the effect on multiplication rate and percentage of surface coverage. Using the results for multiplication rate the 2-week NOEC and EC50 were 800 and 8600 µg Se/L, respectively. The NOEC and EC50 based on % surface coverage were 800 and 2900 µg Se/L, respectively.

Description of key information

The most critical NOEC and EC50 for higher aquatic plants were 80 and 1700 µg Se/L, respectively, obtained from a 14-d growth inhibition study with duckweed (Lemna minor) for the endpoint % surface coverage.

These effect concentrations were obtained from the experiment with disodium selenite and will be used in the statistical extrapolation approach for determination of a waterborne PNEC.

Key value for chemical safety assessment

EC50 for freshwater plants:
1 700 µg/L
EC10 or NOEC for freshwater plants:
80 µg/L

Additional information

Jenner and Janssen-Mommen (1993) investigated the toxicity of SeO2, Na2SeO3, and Na2SeO4 to duckweed (Lemna minor) in a 14-d growth inhibition study according to the OECD 221 guideline. Percentage surface coverage was identified as the most sensitive endpoint, yielding NOEC values of 800, 80, and 800 µg Se/L for SeO2, Na2SeO3, and Na2SeO4, respectively, whereas EC50 values of 2900, 1700, and 5300 µg Se/L were obtained for SeO2, Na2SeO3, and Na2SeO4, respectively.