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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:
other: Guideline OECD 201, GLP, analytical monitoring.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(1984)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II)
Version / remarks:
(1996)
Qualifier:
equivalent or similar to
Guideline:
other: JMAFF No. 700, 1039 and 1014 (1986)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Source: cultured at CIT, origin: Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, Far Sawrey, Ambleside, Cumbria,
LA22 OLP, UK
- Age of inoculum (at test initiation):
- Method of cultivation: the algae were cultured under sterile conditions and maintained at exponential growth rate by adding weekly aliquots of
algal culture to fresh reconstituted water samples.

ACCLIMATION
- Acclimation period: no data, alga were cultured at CIT
- Any deformed or abnormal cells observed: no data
Test type:
static
Limit test:
no
Total exposure duration:
96 h
Remarks on exposure duration:
closed bottle
Hardness:
34 mg/L as CaCO3
Test temperature:
20.5 to 22.6 °C
pH:
7.79 to 10.87 (7.79 to 10.28 for the control)
Nominal and measured concentrations:
Nominal concentrations: 0, 0.001, 0.01, 0.1, 1.00, 10.00 and 100 mg/L corresponding to
Measured concentrations: The limit of detection (1 mg/L) was not sufficient to determine the concentrations of Ethylene Glycol Dimethacrylate in the test solutions at 0.001, 0.01 and 0.1 mg/L . The other measured concentrations in the test solutions were 0.909, 8.62 and 98.0 mg/L (the concentrations were within ± 20% of the corresponding nominal value)
Details on test conditions:
TEST SYSTEM
- Test vessel: glass test vessels (250 mL Erlenmeyer flasks)
- Type: closed system
- Aeration: was not used during the test but the cultures were constantly agitated
- Initial cells density: The number of cells in solutions was calculated for each replicate at time 0 as 1 x 10E+4 cells/mL.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: LC reconstituted water
- Hardness: 34 mg/L ± 17 mg/L as CaCO3
- pH: 7.5 ± 0.3

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no adjustment of pH before addition of the algae
- Photoperiod: illumination was continuous
- Light intensity and quality: 6950 lux to 7660 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: with a Malassez cell counter

TEST CONCENTRATIONS
- Limit test
- Test concentrations: 0, 100 mg/L
- Range finding study
- Test concentrations: 0.01, 0.1, 1.0 and 10 mg/L
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
19 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: static, closed bottle test
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
10.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: static, closed bottle test
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
0.804 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
(< LOQ) based on both the growth rate and biomass
Remarks on result:
other: static, closed bottle test
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
17.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: static, closed bottle test
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.1
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: static, closed bottle test.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
6.93 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: static, close bottle test
Reported statistics and error estimates:
The EC50 values were calculated, using geometric mean measured concentrations, according to Probit analysis The confidence interval limits were not presented because the ratio between the tested concentrations was too high to determine these limits with enough accuracy.

pH values:
Concentration (mg/l)
    pH Start    pH End
          0              7.79        10.28
          0.001          8.05        10.70
          0.01           8.04        10.87
          0.1            8.05        10.84
          1.0            8.04        10.78
          10             8.02        10.13
          100            8.01         8.68


Definitive (EC50) test 96 -hour % inhibition

 Nominal concentration

[mg/L]

 Measured concentration

[mg/L]

 Percentage inhibition growth rate    Percentage inhibition bio mass
 0  0    
 0.001 below the limit of detection (1.0 mg/L) or below the LOQ    
 0.01 below the limit of detection (1.0 mg/L) or below the LOQ    
 0.1 below the limit of detection (1.0 mg/L) or below the LOQ    
 1  0.804 (< LOQ)  1  5
 10  7.34  3  28
 100  76.2  100  100

Variation coefficient of the control cell density at 96 -hours: 10.19%

At 72 hours:
ErC 10 =
 6.93 mg/l
EbC 10 = 2.65 mg/l
ErC 50 = 17.3 mg/l
 (95% Confidence Limits)
EbC 50 = 9.10 mg/l (95% Confidence Limits)
NOEC = 0.906 mg/l (< LOQ) based on both the growth rate and biomass

At 96-hours:
ErC 10 = 8.10 mg/l
EbC 10 = 2.30 mg/l
ErC 50 = 19.0 mg/l (95% Confidence Limits)
EbC 50 = 10.1 mg/l (95% Confidence Limits)
NOEC = 0.804 mg/l (< LOQ) based on both the growth rate and biomass

Validity criteria fulfilled:
yes
Conclusions:
Under the experimental conditions of this study, the 72-hour ErC50 and the 72-hour EbC50 of Ethylene Glycol Dimethacrylate (EGDMA; CAS: 97-90-5 were 17.3 and 9.10 mg/L, respectively, and the 96-hour ErC50 and the 96-hour EbC50 were 19.0 and 10.1 mg/L, respectively, in a static test
system for Pseudokirchneriella subcapitata according to guideline OECD 201.
The NOEC's were 0.906 mg/L (< LOQ) at 72 hours and 0.804 mg/L (< LOQ) at 96 hours based on both the specific growth rate data and biomass
data.
Executive summary:

In a 96 hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata strain no. CCAP 278/4 were exposed to Ethylene Glycol Dimethacrylate at nominal concentrations of 0, 0.001, 0.01, 0.1, 1.0, 10.0, and 100 mg/L under static conditions in accordance with the guideline OECD 201. The validated limit of quantification of the analytical method (1 mg/L) was not sufficient to determine the concentrations of Ethylene Glycol Dimethacrylate in the nominal test solutions at 0.001, 0.01 and 0.1 mg/L. Therefore, analysis was only performed in the test solutions at 1, 10 and 100 mg/L. The control sample of time 0 confirmed that the test item concentration was below the limit of detection.

The ErC50value based on growth rate was 19.0 mg/L and

EbC50value based on biomass was 10.1 mg/L after 96 hours, respectively.

This toxicity study is classified as acceptable and satisfies the guideline requirements for this acute algal toxicity study with Pseudokirchneriella subcapitata.

 

Results Synopsis

 

Test Organism: Pseudokirchneriella subcapitata

Test Type: Static, closed bottle test

 

96-hr ErC50: 19.0 mg a.i./L                  

96-hr EbC50: 10.1 mg a.i./L               

96-hr NOEC: 0.804 mg a.i./L (<LOQ)     

Endpoint(s) Effected:  based on growth rate and biomass

Description of key information

The toxicity of the substance to the freshwater alga Pseudokirchneriella subcapitata has been evalutaed in a 72h/96-h exposure growth inhibition test according to OECD guideline 201 (Klimisch score 1). The 72-h EC50 was found to be 17.3 mg/l and the 72-h EC10 6.93 mg/l, based on growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:
17.3 mg/L
EC10 or NOEC for freshwater algae:
6.93 mg/L

Additional information