1-bromo-3,4,5-trifluorobenzene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

1988

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

In the first experiment the test substance was added quantitatively to the test vessels at a concentration of 100 mg/L.
In the second experiment a stock solution of 5 g/L was prepared in Milli-Q water and stirred, in a closed vessel, for 24,5-26 hours. Samples for the preparation of the test vessels were taken from the stirring stock solution. Six concentrations were tested: 125, 250, 500, 100, 2000 and 2840 mg/L, corresponding to 12.5, 25, 50, 100, 200 and 284 mL of the prepared stock solution in 500 mL final volume.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Municipal sewage treatment plant "Waterschap de Maaskant", s-Hertogenbosch, The Netherlands
- Preparation of the sludge:
Experiment 1:
The sludge was coarsely sieved and washed with tap-water. A small amount of the sludge was weighed and dried at ca. 105 °C to determine the amount of suspended solids (4 g/L of sludge). The batch of sludge was used on subsequent days (maximum four days), therefore 50 mL of synthetic sewage feed was added to each litre of activated sludge at the end of each working day. The sludge was kept aerated at test temperature until use. Before use the pH was checked (measured value: 7.2).
Experiment 2:
The sludge was coarsely sieved, washed with tap-water and concentrated. A small amount of the sludge was weighed and dried at ca. 105 °C to determine the amount of suspended solids (3.7 g/L of sludge). The sludge was kept aerated at test temperature until use. Before use the pH was checked. Since the measured value of the sludge was 8.4, the pH was adjusted with 1 N HCl to 7.6.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test temperature:

20-21 °C

Nominal and measured concentrations:

Nominal concentrations: 125, 250, 500, 1000, 2000, 2840 mg/L
No measured concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: All glass, 500 mL beakers and 300 mL oxygen bottles.
- Aeration: yes
- No. of vessels per concentration (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-Q water

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3.2, 10 and 32 mg/L)

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

ca. 3 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

In the first experiment no significant inhibition in respiration rate of the sludge was recorded at approximately 100 mg test item/L. The duplicate measurement confirmed the result of the first measurement.
In the second experiment no significant inhibition in respiration rate of the sludge was recorded up to and including 1000 mg test item/L. At 2000 mg/L the inhibitory effect of the test item on aerobic waste-water bacteria was 22% and at 2840 mg/L the inhibitory effect was 47%. Hence, the EC50-value was not reached in the range tested, but was estimated to be approximately 3000 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 of 11 mg/L

Acceptability of the test

Experiment 1:

- The mean respiration rate of control 1 and 2 was 38 mg O2/L/hr. The difference between the controls was 0%.

- The mean respiration rate of control 3 and 4 was 34 mg O2/L/hr. The difference between the controls was 0%.

- The EC50 of 3,5-dichlorophenol was 11 mg/L (95% fiducial limits: 1-80 mg/L, regression line: Y =   64.0312 X -15.9113).

Experiment 2:

- The mean respiration rate of control 1 and 2 was 38 mg O2/L/hr. The difference between the controls was 0%.

- The mean respiration rate of control 2 and 3 was 36 mg O2/L/hr. The difference between the controls was 11%.

- The EC50 of 3,5-dichlorophenol was 11 mg/L (95% fiducial limits: 5-21 mg/L, regression line: Y =   66.0111 X -17.8978).

Since all criteria for acceptability of the test were met, these studies were considered to be valid.

Validity criteria fulfilled:

yes

Conclusions:

A test on respiration inhibition using acivated sludge of a predominantly domestic sewage treatment plant was conducted according to OECD 209. After 30 min of exposure the EC50 was determined to be ca. 3 g/L.

Executive summary:

The influence of the test item on the respiration rate of activated sludge was investigated after a contact time of 30 minutes according to OECD guideline 209. Two experiments were performed.

In the first experiment the test substance was added quantitatively to the test vessels at a concentration of 100 mg/L. The concentration was tested in duplicate. No significant inhibition in respiration rate of the sludge was recorded at approximately 100 mg test item/L. The duplicate measurement confirmed the result of the first measurement.

In a second experiment a stock solution of 5 g/L was prepared in Milli-Q water and stirred, in a closed vessel, for 24,5-26 hours. Samples for the preparation of the test vessels were taken from the stirring stock solution. Six concentrations were tested: 125, 250, 500, 100, 2000 and 2840 mg/L, corresponding to 12.5, 25, 50, 100, 200 and 284 mL of the prepared stock solution in 500 mL final volume. No significant inhibition in respiration rate of the sludge was recorded up to and including 1000 mg test item/L. At 2000 mg/L the inhibitory effect of the test item on aerobic waste-water bacteria was 22% and at 2840 mg/L the inhibitory effect was 47%. Hence, the EC50-value was not reached in the range tested, but was estimated to be approximately 3000 mg/L.

In both experiments the respiration rates of the controls were within 15% of each other and the EC50 of the reference substance, 3,5-dichlorophenol, was 11 mg/L. Therefore, both experiments were considered to be valid.

Description of key information

A test on respiration inhibition using acivated sludge of a predominantly domestic sewage treatment plant  was conducted according to OECD 209. After 30 min of exposure the EC50 was determined to be ca. 3 g/L (reference 6.1.7-1).

Key value for chemical safety assessment

EC50 for microorganisms:

3 000 mg/L

Additional information

The influence of the test item on the respiration rate of activated sludge was investigated after a contact time of 30 minutes according to OECD guideline 209. Two experiments were performed.

In the first experiment the test substance was added quantitatively to the test vessels at a concentration of 100 mg/L. The concentration was tested in duplicate. No significant inhibition in respiration rate of the sludge was recorded at approximately 100 mg test item/L. The duplicate measurement confirmed the result of the first measurement.

In a second experiment a stock solution of 5 g/L was prepared in Milli-Q water and stirred, in a closed vessel, for 24,5-26 hours. Samples for the preparation of the test vessels were taken from the stirring stock solution. Six concentrations were tested: 125, 250, 500, 100, 2000 and 2840 mg/L, corresponding to 12.5, 25, 50, 100, 200 and 284 mL of the prepared stock solution in 500 mL final volume. No significant inhibition in respiration rate of the sludge was recorded up to and including 1000 mg test item/L. At 2000 mg/L the inhibitory effect of the test item on aerobic waste-water bacteria was 22% and at 2840 mg/L the inhibitory effect was 47%. Hence, the EC50-value was not reached in the range tested, but was estimated to be approximately 3000 mg/L.

In both experiments the respiration rates of the controls were within 15% of each other and the EC50 of the reference substance, 3,5-dichlorophenol, was 11 mg/L. Therefore, both experiments were considered to be valid (reference 6.1.7-1).