Butanone

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998

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:

reliability based in 2006 guideline

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling method: samples of test medium were collected from the negative control and each treatment group at exposure initiation and termination to measure concentrations of the test substance. The samples were placed in glass scintillation vials and were analyzed immediately.

Vehicle:

no

Details on test solutions:

Primary stock solutions were prepared by dissolving the test substance directly in culture medium at a concentration of 50 mg MEK/mL. The primary stock was inverted to aid solubilization of the test substance. Five test solutions were prepared by proportional dilution of the primary stock with culture medium. All test solutions appeared clear and colourless.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: freshwater alga
- Strain: Selenastrum capricornutum
- Source (laboratory, culture collection): UTEX - The culture collection of algae at the University of Texas at Austin



ACCLIMATION
- Acclimation period: at least 2 weeks
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

One flask per treatment for observations of growth recovery for 9 days.

Hardness:

132 mg/L as CaCO3

Test temperature:

23.9 to 25.8 degrees celcius

pH:

7.3-7.8

Dissolved oxygen:

Not reported

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal - 313, 625, 1250, 2500, and 5000 mg/L
Measured - Samples collected at the begining of the test has measured concentrations that ranged from 94 to 104% of nominal. Samples collected on day 4 had recoveries that ranged from less than the limit of quantification to 25% of nominal.
Geometric mean 0-96h: All values are based on these geometric mean concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: sterile, 250-mL Erlenmeyer flasks plugged with foam stoppers and contained 100 mL of test or control algal medium.
- Initial cells density: 1.0 X 10^6 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


GROWTH MEDIUM
-The algal cells were cultured and tested in freshwater algal medium. Stock nutrient solutions were prepared by adding reagent-grade chemicals to well water by reverse osmosis.


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: primary stock solutions were prepared by dissolving the test substance directly in culture medium at a concentration of 50 mg MEK/mL. The primary stock was inverted to aid in solubilization of the test substance.
- All test solutions appeared clear and colourless.


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: using 10% HCL
- Light: continuous cool-white fluorescent lighting with a target 4300 lux



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter at 24, 48, 72 and 96 hour

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 220 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI 560 - 2660

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1 050 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 230 - 4760

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

566 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1 240 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 130 - 12200

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

1 010 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI 260 - 4710

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

566 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): None were observed
- Volatility of test substance: As test concentrations could not be maintained within 80% of nominal in the experiment, results are based on the geometric mean concentrations.
- Coefficient of variation section by section was below 35% (12-19% for individual replicates).
- Coefficient of variation of average specific growth rate was below 7% (2%).

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Values were determined based on growth rate with a log-logistic model.

Validity criteria fulfilled:

yes

Description of key information

The substance was not toxic to algae when tested according to OECD TG 201 (Alga, Growth Inhibition Test), with a 72-hour EC₅₀ value of 1220 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 220 mg/L

EC10 or NOEC for freshwater algae:

566 mg/L

Additional information

Five studies addressing toxicity to aquatic algae and cyanobacteria are presented in the dossier. Please refer to the document attached to Section 13 for further discussion of the studies.

Toxicity to aquatic algae and cyanobacteria. 001 – Selenastrum – 1998 – Key: Acute toxicity to Pseudokirchneriella subcapitata (previously known as Selenastrum capricornutum) was assessed according to OECD guideline 201 (Alga, Growth Inhibition Test) method C.3 of European Directive 92/69/EEC, and in compliance with GLP. Algae were exposed to the substance at nominal concentrations of 313, 625, 1250, 2500, and 5000 mg/L in the culture medium. The study was performed using 250 mL glass Erlenmeyer flasks, stoppered with foam, containing 1000 mL of test solution inoculated with an algal suspension such that the initial cell concentration was 1x10^6 cells/mL. Test flasks were incubated at 23.9-25.8°C and constantly exposed to a light intensity of 4178-4370 lux. Analytical chemistry and physico-chemical measurements were carried out at the beginning and the end of the test. An electronic particle counter was used to determine the cell concentrations. During the test, the control pH ranged between 7.3 and 7.8. The following validity criteria were met: exponential growth in the control was observed. The concentrations of the test substance at the beginning of the test were approximately 94 to 104% of nominal. All test concentrations dropped below 70% of nominal at exposure termination, the test results were calculated based on the 0 -96d geometrical mean concentration. No abnormalities of algae were observed during the test and the 72 and 96 hour No Observed Effect Concentration (NOEC), was determined to be 566 mg/L based on growth rate. The 72 hour EC₅₀ was determined to be 1220 mg/L which also was based on growth rate.

Toxicity to aquatic algae and cyanobacteria.002-Scenedesmus – 1980: Acute toxicity to Scenedesmus quadricauda was assessed; however, no guideline was followed. The algae were exposed to the substance under static conditions for 7 days. The toxicity threshold was determined to be 4300 mg/L based on mean extinction value. This toxicity threshold, approximately equivalent to the LC₃, over a longer exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.003-Scenedesmus – 1977: Acute toxicity to Scenedesmus quadricauda was assessed; however, no guideline was followed. The algae were exposed to the substance under static conditions for 8 days. The toxicity threshold was determined to be 4300 mg/L based on growth inhibition. This toxicity threshold, approximately equivalent to the LC₃, over a longer exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.004-Microcystis – 1978: Acute toxicity to Mycrocystis aeruginosa was assessed; however, no guideline was followed. The algae were exposed to the substance under static conditions for 8 days. The toxicity threshold was determined to be 120 mg/L based on growth inhibition. This toxicity threshold, approximately equivalent to the LC₃, over a longer exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.005-Scenedesmus – 1978: Acute toxicity to Scenedesmus quadricauda was assessed; however, no guideline was followed. The algae were exposed to the substance under static conditions for 8 days. The toxicity threshold was determined to be 4300 mg/L based on growth inhibition. This toxicity threshold, approximately equivalent to the LC₃, over a longer exposure period is in keeping with the result of the key study.