Ethanone, 1-(3-methyl-2-benzofuranyl)-

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:

2000-01-18 to 2000-01-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Analytical method: TOC-analysis

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Remarks:

TOC-analysis

Vehicle:

no

Test organisms (species):

other: Scenedesmus subspicatus

Details on test organisms:

TEST ORGANISM
- Common name: green algal
- Strain: Scenedesmus subspicatus CHODAT
- Source: Institute of Plant Physiology, University of Göttingen
- Method of cultivation: in a light chamber at 23 ± 2 'C and with a quantum flux which equals 120 µE/m2•s.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

n.a.

Test temperature:

23 ± 2 °C

pH:

7.8-10.2

Dissolved oxygen:

n.a.

Salinity:

n.a.

Conductivity:

n.a.

Nominal and measured concentrations:

Nominal concentrations: 0 (contro), 2.5, 5 and 5 (without algae), 10, 20, 40 and 40 (without algae) mg/L (TOC concentration)
Measured concentrations at 0 h: < 2 (control), - (not measured), 6 and 6 (without algae), 10, 17, 32, 32 (without algae) mg/L (TOC concentration)
Measured concentrations at 72 h: 3 (control), - (not measured), 8 and 5 (without algae), 9, 17, 32, 32 (without algae) mg/L (TOC concentration)

Details on test conditions:

TEST SYSTEM
- Test vessel:300 mL Erlenmeyer flasks with stoppers
- Fill volume: 100 mL
- Initial cells density: 10000 cells/mL
- Control end cells density: 364000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: BRINGMANN-KÜHN-Medium

EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations: counting chamber (microcellcounter sysmex F-300 Digitana)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.0
- Results used to determine the conditions for the definitive study: yes

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

15.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 12.4 - < 22.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

9.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

12.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Results with reference substance (positive control):

n.a.

Reported statistics and error estimates:

statistic method: Dunnett-t

Validity criteria fulfilled:

yes

Conclusions:

The value of 72h-ErC50 (growth rate) was determined to be between 12.4 and 22.1 mg/L and the value of 72h-NOEC (growth rate) was determined to be 9.1 mg/L based on measured concentration, respectively.

Executive summary:

The toxicity of test item to aquatic algae was assessed according to council directive 92/69/EEC C.3 (1992) and GLP. In a static test, green algae (Scenedesmus subspicatus CHODAT) were exposed to five concentration levels with parallel controls for 48 h. The test media were prepared by diluting a stock solution of 125 mg/L into 0 mg/L (control), 2.5 mg/L, 5 mg/L, 10 mg/L, 20 mg/L, and 40 mg/L based on TOC (1 mg/L TOC equals to 1.3 mg/L test substance) with a separating factor of 2. Additionally, two concentrations, 5 and 40 mg/L were added without algae. The initial cell density was adjusted to be 10000 cells/mL. Test item concentrations were analytically verified by TOC-analysis in fresh media at the start of exposure (0 h) and the end of exposure (72 h) in all concentration levels except 2.5 mg/L which was expected blow the detection limit of TOC determination method (2 mg/L) and the control. The cell density was daily measured by microcellcounter and the growth rate as well as biomass were calculated accordingly. The value of 72h-ErC50 (growth rate) was determined to be between 12.4 and 22.1 mg/L and the value of 72h-NOEC (growth rate) was determined to be 9.1 mg/L based on measured concentration, respectively.

Description of key information

The value of 72h-ErC50 (growth rate) was determined to be between 12.4 and 22.1 mg/L. A value of 12.4 mg/L was as the worst case given for EC50 of freshwater algae (a range values are not acceptable in the field of key value for chemical safety assessment).

Key value for chemical safety assessment

EC50 for freshwater algae:

12.4 mg/L

EC10 or NOEC for freshwater algae:

9.1 mg/L

Additional information

There is one study, in which the toxicity of test item to aquatic algae was assessed according to council directive 92/69/EEC C.3 (1992) and GLP. In a static test, green algae (Scenedesmus subspicatusCHODAT) were exposed to five concentration levels with parallel controls for 48 h. The test media were prepared by diluting a stock solution of 125 mg/L into 0 mg/L (control), 2.5 mg/L, 5 mg/L, 10 mg/L, 20 mg/L, and 40 mg/L based on TOC (1 mg/L TOC equals to 1.3 mg/L test substance) with a separating factor of 2. Additionally, two concentrations, 5 and 40 mg/L were added without algae. The initial cell density was adjusted to be 10000 cells/mL. Test item concentrations were analytically verified by TOC-analysis in fresh media at the start of exposure (0 h) and the end of exposure (72 h) in all concentration levels except 2.5 mg/L which was expected blow the detection limit of TOC determination method (2 mg/L) and the control. The cell density was daily measured by microcellcounter and the growth rate as well as biomass were calculated accordingly. The value of 72h-ErC50 (growth rate) was determined to be between 12.4 and 22.1 mg/L and the value of 72h-NOEC (growth rate) was determined to be 9.1 mg/L based on measured concentration, respectively.