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Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 03 to 17 September 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

23 March 2006

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Batch Sample Ref CRKL-719-09-12-VII-003-09

Analytical monitoring:

yes

Details on sampling:

the test solutions were measured at 0 and 72 hours

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution with a nominal concentration of nominal 32 mg/L was prepared by dissolving 0.064 g in 2000 mL of culture medium. The stock solution was ultrasonicated for 30 minutes after which it was observed to be a clear and colourless solution. The highest test concentration used this stock solution without any further alteration.

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: CCAP 278/4
- Source (laboratory, culture collection): from laboratory cultures maintained under axenic conditions
- Age of inoculum (at test initiation): 3 day old
- Method of cultivation:

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed:

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

20 oC

pH:

6.4 - 7.5

Nominal and measured concentrations:

Nominal concentrations: 0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 and 32 mg/L
Measured concentrations: 0.57, 1.0, 1.7, 3.2, 5.9, 10, 18 and 33 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass conical flasks of 250 mL
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 100 mL of test solution
- Aeration:
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): no
- Initial cells density: 5,320 cells/mL
- Control end cells density: 817,000 cells/mL
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates):

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: yes, adjusted where necessary with 0.1 M NaOH prior to being dispensed to the test vessels.
- Photoperiod:
- Light intensity and quality: 5613 lux (by cosine receptor)
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: After 24, 48 and 72 hours, samples were removed from each test and blank vessel. The appropriate blank particle count was subtracted from that of the test culture to obtain the cell density. Algal cell particle densities (cell particles per unit volume) were measured as a surrogate for biomass.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

9.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

6.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

The microscopic observations, made at test end, showed that for the control and all test concentrations the cells appeared normal.

Validity criteria fulfilled:

yes

Conclusions:

The 72 hours EC50 of the test item is 9.4 mg/L for algae growth rate, and 6.1 mg/L for yield; the NOEC value is 3.2 mg/L for growth rate and 1.8 mg/L for yield.

Executive summary:

The toxicity of the test item to the green alga Pseudokirchneriella subcapitata was determined, according to OECD Guideline 201 under GLP.

The 72 hours EC50 of the test item is 9.4 mg/L for algae growth rate, and 6.1 mg/L for yield; the NOEC value is 3.2 mg/L for growth rate and 1.8 mg/L for yield.

Description of key information

The toxicity of the test item to the green alga Pseudokirchneriella subcapitata was determined, according to OECD Guideline 201 under GLP.

The 72 hours EC50 of the test item is 9.4 mg/L for algae growth rate, and 6.1 mg/L for yield; the NOEC value is 3.2 mg/L for growth rate and 1.8 mg/L for yield.

Key value for chemical safety assessment

EC50 for freshwater algae:

9.4 mg/L

EC10 or NOEC for freshwater algae:

3.2 mg/L