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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
April 2013
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP study performed according to the current guideline, but quoted with reliability 2 due to the read across

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Description: orange colored powder
Purity: 99.7%
Expiry date: 24 December 2013
Storage conditions: room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The concentration and stability of the test item in the test solutions were verified by chemical analysis at 0 and 72 hours.
The test samples were thawed with the aid of sonication. Nitric acid (2 mL) was added to a volume (100 mL) of sample and the samples were ultrasonicated for 15 minutes.

Test solutions

Vehicle:
no
Details on test solutions:
An amount of test item (1100 mg) was dispersed in 11 liters of culture medium with the aid of propeller stirring at approximately 1500 rpm for 48 hours. After 48 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 µm Sartorius Sartopore filter (first approximate 2 liters discarded in order to pre-condition the filter) to give a 100% v/v saturated solution.

Test organisms

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 (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland.
- Method of cultivation: maintained in the laboratory by the periodic replenishment of culture medium
- Culturing media and conditions: same as test

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
24 ± 1°C
pH:
6.9 to 7.8
Nominal and measured concentrations:
0.68, 2.0, 6.8, 21 and 67 mg/L measured concentrations at 0 hours
99% to 102% of the 0-Hour measured test concentrations were obtained at 72 hours
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass conical flasks were used, constantly shaken at approximately 150 rpm for 72 hours
- cells density: Pre-culture conditions gave an algal suspension in log phase growth characterised by a cell density of 3.74 x 10^ 5 cells per mL. Inoculation of 900 mL of test medium with 12.1 mL of this algal suspension gave an initial nominal cell density of 5 x 10^ 3 cells per mL and had no significant dilution effect on the final test concentration.
- No. of vessels per concentration (replicates): Six flasks each containing 100 mL of solution were used for the control and three flasks each containing 100 mL were used for each treatment group.

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination (intensity approximately 7000 lux)

TEST CONCENTRATIONS
- Range finding study: The results showed no effect on growth at the test concentrations of 0.10 and 1.0% v/v saturated solution. However, growth was observed to be reduced at 10 and 100% v/v saturated solution.
- Test concentrations: 1.0, 3.2, 10, 32 and 100% v/v saturated solution were selected for the definitive test
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
14 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
7.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Remarks:
vanadium
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
6.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
17 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Inhibition of growth rate:
ErC10 (0- 72 h): 14 mg/L
ErC20 (0- 72 h): 15 mg/L
ErC50 (0- 72 h): 17 mg/L

Inhibition of yield:
EyC10 (0- 72 h): 15 mg/L
EyC20 (0- 72 h): 15 mg/L
EyC50 (0- 72 h): 17 mg/L
Reported statistics and error estimates:
Statistical analysis of the growth rate data was carried out for the control, 0.68, 2.0, 6.8 and 21 mg/L test groups using one way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett 1955). There were no statistically significant differences between the control, 0.68, 2.0 and 6.8 mg/L test concentrations (P≥0.05), however the 21 mg/L test concentration was significantly different (P<0.05) and, therefore the "No Observed Effect Concentration" (NOEC) based on growth rate was 6.8 mg/L.
Correspondingly the "Lowest Observed Effect Concentration" (LOEC) based on growth rate was 21 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
see below in the conclusion field
Conclusions:
The following data show that the cell concentration of the control cultures increased by a factor of 96 after 72 hours. This increase was in line with the OECD Guideline that states the enhancement must be at least by a factor of 16 after 72 hours.
Mean cell density of control at 0 hours: 4.54 x 103 cells per mL
Mean cell density of control at 72 hours: 4.35 x 105 cells per mL
The mean coefficient of variation for section by section specific growth rate for the control cultures was 28% and hence satisfied the validation criterion given in the OECD Guideline which states the mean must not exceed 35%.
The coefficient of variation for average specific growth rate for the control cultures over the test period (0 – 72 h) was 2% and hence satisfied the validation criterion given in the OECD Guideline which states that this must not exceed 7%.
Executive summary:

A study was performed to assess the effect of V2O5 on the growth of the green alga Pseudokirchneriella subcapitata.  The method followed that described in the OECD Guidelines for Testing of Chemicals (2006) No 201, and the test was performed under GLP procedures.

Chemical analysis of the 1.0, 3.2, 10, 32 and 100% v/v saturated solution test preparations at 0 hours showed measured test concentrations of 0.68, 2.0, 6.8, 21 and 67 mg/L respectively were obtained. Measured concentrations in the range of 99% to 102% of the 0-Hour measured test concentrations were obtained at 72 hours and hence it was considered appropriate to calculate the results based on the 0-Hour measured test concentrations only.

Exposure of Pseudokirchneriella subcapitata to V2O5 gave the following results for inhibition of growth rate:

ErC10 (0 - 72 h): 14 mg/L

ErC50 = 17 mg/L

No Observed Effect Concentration (NOEC) = 6.8 mg/L