Methyl benzoate

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:

1992-07-14 to 1992-07-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution was prepared by dissolving 1 g test substance per litre dilution water

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: CHODAT (86.81 SAG)
- Source (laboratory, culture collection): initially obtained from the Institut für Wasser-, Boden- und Lufthygiene, Berlin, Germany and cultures then maintained in testing laboratory
- Method of cultivation: in sterile Erlenmeyer flasks under light (ca. 8000 lux, white)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 2 °C

pH:

study start: 8.1
study end: 7.8 to 9.5

Nominal and measured concentrations:

Nominal concentrations: control, 30, 60, 100, 170, 300, 500 and 900 mg/L

Details on test conditions:

TEST SYSTEM
- Type: not reported
- Material, size, headspace, fill volume: Erlenmeyer flasks
- Aeration: with sterile air
- Initial cells density: 20000/mL
- Control end cells density: 1150000/mL
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 5

GROWTH MEDIUM
- Standard medium used: not reported

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water; information of composition not available

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no, but significant increase in pH was observed in some test flasks
- Photoperiod: test performed under continuous light
- Light intensity and quality: ca. 8000 lux

EFFECT PARAMETERS MEASURED: growth rate
- Determination of cell concentrations: photometric cell number determination

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

111.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

62.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Complete growth inhibition was observed with test concentrations equal to or greater than 300 mg/L. The pH values of some test and control vessels was significantly increased at the end of the study period. However, this change had no influence on the cell growth and was considered to not affect the validity of the test.

Reported statistics and error estimates:

The effect concentrations were calculated after Probit transformation of percentages of inhibition by regression analysis followed by a Probit analysis according to Cavalli-Sforza (1972).
The validity of the study was evaluated with ToxRat v.3.3.

Validity criteria fulfilled:

yes

Conclusions:

The substance inhibited the growth of the green alga Desmodesmus subspicatus and the observed EC50 value (based on growth rate) was 111.9 mg/L after 72 hours.

Executive summary:

The toxicity of the test substance methyl benzoate to the green alga Desmodesmus subspicatus was tested under GLP in a static test over a period of 72 hours in accordance with OECD TG 201. The test substance was directly added to dilution water at 1 g/L and test solutions were prepared from this stock solution. The study was performed with five controls using dilution water and eight replicates of nominal test concentrations of methyl benzoate in dilution water of 30, 60, 100, 170, 300, 500 and 900 mg/L. Tests were conducted at 24 ± 2 °C in Erlenmeyer flasks with sterile aeration with an initial cell density of 20000 cells/mL under constant white light at ca. 8000 lux. The cell number was counted photometrically. The cell growth was completely inhibited at concentrations equal to or greater than 300 mg/L. The EC50 value based on growth rate was 111.9 mg/L and the EC10 value was 62.4 mg/L. A significant increase in the pH value was seen in some of the test and control flasks, which had no influence on cell growth.

Description of key information

The substance exhibited low acute toxicity to freshwater algae. In a 72-hour study with Desmodesmus subspicatus the ErC50 for inhibition of the growth rate was 111.9 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

111.9 mg/L

EC10 or NOEC for freshwater algae:

62.4 mg/L

Additional information

The algal toxicity of the registration item methyl benzoate to the freshwater green alga Desmodesmus subspicatus was studied in a valid test in accordance with EU Method C.3. The substance inhibited the cell growth and the ErC50 value was 111.9 mg/L. Complete growth inhibition was seen at 300 mg/L or greater.