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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
Study period:
October 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: N/A, lot no. 3777937
- Purity, including information on contaminants, isomers, etc.: N/A
- Composition: 5-ethyl-5-hydroxymethyl-1,3-dioaxane (CAS no. 5187-23-5) (25-60 %), 1,3-Propandiol, 2-ethyl (CAS no. 2612-29-5) (20-50 %), 2-ethyl-2-hydroxymethyl-1,3-propanediol (CAS no. 77-99-6) (15-25 %)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: sealed containers, room temperature, dark
- Stability and homogeneity of the test material in the vehicle/solvent under test conditions (e.g. in the exposure medium) and during storage: stable for at least 6 months
- Stability in the medium, i.e. sensitivity of the test material to hydrolysis and/or photolysis: N/A
- Solubility and stability of the test material in the solvent/vehicle and the exposure medium: soluble
- Reactivity of the test material with the incubation material used (e.g. plastic ware): N/A

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing (e.g. warming, grinding): N/A
- Final concentration of a dissolved solid, stock liquid or gel: 2000 mg/L
- Final preparation of a solid: 2000.1 g of Polyol TD was dissolved per 1 l of growth medium by magnetic stirring
Analytical monitoring:
yes
Details on sampling:
Samples of the stock solution and the highest tested concentration at 0 h and 72 h were collected and stored in the freezer until analysed by the Sponsor.
Vehicle:
no
Details on test solutions:
2000.1 mg of the test item was solved in 1000 mL of growth medium by magnetic stirring on the day of the test start. The test solutions were made by dilution of the stock solution (2000 mg/L) with growth medium.
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): Toxicon's culture, originating from NIVA, Oslo, Norway.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
21 - 24ºC - nominal values
pH:
8.1±0.2 - nominal values
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
nominal: 31.2, 62.5, 125, 250, 500, 1000, 2000 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): E-bottles
- Material, size, headspace, fill volume: glass, 250 mL, 100 mL fill volume
- Aeration: not applicable
- Control end cells density: Yield (end density - starting density) = 556667 cells/mL (C.V. = 16.1%).
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6



GROWTH MEDIUM
- Standard medium used: yes (as specified in OECD TG 201)


OTHER TEST CONDITIONS
- Sterile test conditions: yes (components of growth medium were autoclaved or sterile filtered before use.
- Adjustment of pH: No.
- Photoperiod: Continuous illumination
- Light intensity and quality: 100 µEm-2s-1


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The number of cells/mL was counted by microscope at 0, 24, 48, and 72 hours.


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2-fold ( 31.2, 32.5, 125, 250, 500, 1000, and 2000 mg/L)
Reference substance (positive control):
yes
Remarks:
Test substance not identified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
743 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
62 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
144 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
62 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: No
Results with reference substance (positive control):
Report states the following:

A qualification test on the alga culture was made on 5 June 2008 to assure the quality of the test animals. ErC50 was 1.5 mg/L which confirmed theculture was suitable as a test organism according to OECD TG no 201.
Reported statistics and error estimates:
The EC50 values were calculated by means of graphic interpolation. The NOEC was defined as the highest tested concentration not statistically different from the controls according to the Mann-Whitney U-test (p>0.05)

Calculated specific growth and biomass results (72 hours)

Nominal concentration (mg/L)

72 hours Specific growth rate (μ) Mean ± CV (%)

% inhibition

Control

1.34 ± 4.0

-

31.2

1.27 ± 5.8

5

62.5

1.19 ± 13.0

11

125

1.11 ± 16.0

17

250

1.03 ± 5.8

23

500

0.97 ± 6.2

28

1000

0.35 ± 26.8

74

2000

0.0

100

 

72 h Yield (cells/ml)

Mean ± CV (%)

% inhibition

Control

556667 ± 16.1

-

31.2

450000 ± 21.2

19

62.5

373333 ± 40.2

33

125

290000 ± 45.6

48

250

213333 ± 17.8

62

500

176667 ± 18.2

68

1000

2000 ± 50.0

100

2000

0.0

100

Validity criteria fulfilled:
yes
Conclusions:
A 72 hour algal growth inhibition study, test species Pseudokirchneriella subcapitata, was performed to determine the toxic effects of the test substance Polyol TD. The test was conducted according to OECD test guideline 201, and performed to GLP. Based on nominal exposure concentrations the 72 hour ErC50 was calculated to be 743 mg/L and the corresponding no-observed effect concentration (NOEC) was 62 mg/L. The 72 hour EyC50 was calculated to be 144 mg/L and the corresponding NOEC was 62 mg/L.
Executive summary:

In 72 hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata were exposed to Polyol TD at nominal concentrations of 31.2, 62.5, 125, 250, 500, 1000, 2000 mg Polyol TD/L under static conditions in accordance with the OECD test guideline 201.  The EC50 values based on biomass and growth rate were 144 mg/L and 743 mg/L respectively. The corresponding NOEC values based on both, biomass and growth rate, are 62 mg/L.

There were no compound related phytotoxic effects.

 

Results Synopsis

 

Test Organism: Pseudokirchneriella subcapitata

Test Type (Flowthrough, Static, Static Renewal): Static

 

72 hr ErC50743 mg Polyol TD/L                 95% C.I.:  N/A

72 hr EyC50:  144 mg Polyol TD/L         95% C.I.:  N/A

72 hr NOEC:  62 mg Polyol TD/L                  Probit Slope:  N/A

Endpoint(s) Effected:  Algae growth

Description of key information

One growth inhibition study on Pseudokirchneriella subcaptitata was conducted. In 72 hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata were exposed to Polyol TD at nominal concentrations of 31.2, 62.5, 125, 250, 500, 1000, 2000 mg Polyol TD/L under static conditions in accordance with the OECD test guideline 201.  The EC50values based on biomass and growth rate were 144 mg/L and 743 mg/L respectively. The corresponding NOEC values based on both, biomass and growth rate, are 62 mg/L.

There were no compound related phytotoxic effects.

Key value for chemical safety assessment

EC50 for freshwater algae:
743 mg/L
EC10 or NOEC for freshwater algae:
62 mg/L

Additional information

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