Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

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:
October 1989
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed according to the guideline.
Qualifier:
according to guideline
Guideline:
other: EEC L 133, p. 118-122
Deviations:
yes
Remarks:
Instead a centrifuged sludge a settled sludge was used.
Principles of method if other than guideline:
The inhibitions were calculated on the basis of the measured time depend oxygen consumption of a Blank and Test solution.
GLP compliance:
yes
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
activated sludge
Details on inoculum:
Test system : Activated sludge collected from the sewage treatment plant of CH-4106 Therwil on 16/10/89. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation.
Test type:
static
Water media type:
freshwater
Total exposure duration:
3 h
Test temperature:
20 ± 2°C
Nominal and measured concentrations:
TEST CONCENTRATIONS
- Test concentrations:
Reference substance : 32, 10 and 3.2 mg/l
Test substance : 100.58, 32.19, 10.1, 3.22 and 1.01 mg/L
The sludge concentration in the test bottles was 1.5 g/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml BOD flasks with gas inlet

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated drinking water

Measurements : Oxygen consumption per hour in mg/liter with a ORION - Electrode Type 97-08, ORION Microprocessor lonalizer 901 and plotted on a recorder.
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
15 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: Graphically determined
Duration:
3 h
Dose descriptor:
other: IC20
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: Graphically determined
Duration:
3 h
Dose descriptor:
other: IC80
Effect conc.:
78 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: Graphically determined
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
12 mg/L
Nominal / measured:
nominal
Conc. based on:
other: reference substance
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: Graphically determined
Details on results:
The inhibitions were calculated on the basis of the measured time depend oxygen consumption of a Blank and Test solution.

Table: Test result

Sample

Concentration (mg/l)

Consumption rate (mg/l/h)

Inhibition percentage (%)

Blank 1

Blank 2

Reference 1

Reference 2

Reference 3

0.00

0.00

32.00

10.00

3.20

48.75

44.66

7.90

32.03

36.11

-4

4

83

31

23

Test conc. 1

Test conc. 2

Test conc. 3

Test conc. 4

Test conc. 5

100.58

32.19

10.10

3.22

1.01

8.71

12.59

28.22

39.69

43.97

81

73

40

15

6

Validity criteria fulfilled:
not specified
Conclusions:
Toxicity studies to determine the inhibitory concentration of test substance on the respiration of aerobic waste water bacteria were conducted according to EEC L 133, p. 118-122 (30. May 1988) guideline. The test was conducted on activated sludge from a sewage treatment plant for 3 hours at 20°C. The results were graphically determined based on nominal concentrations and IC50 value was determined to be 15 mg/L
Executive summary:

Toxicity studies to determine the inhibitory concentration of test material on the respiration of aerobic waste water bacteria were conducted according to EEC L 133, p. 118-122 (30. May 1988) guideline. The test was conducted on activated sludge from a sewage treatment plant for 3 hours at 20°C. The results were graphically determined . Activated sludge collected from the sewage treatment plant of CH-4106 Therwil on 16/10/89. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation. 3,5-Dichlorophenol was used as referance substance. The inhibitory concentration (IC50) value was determined to be 15 mg/l.

Description of key information

Toxicity to microorganism:

Toxicity studies to determine the inhibitory concentration of test material on the respiration of aerobic waste water bacteria were conducted according to EEC L 133, p. 118-122 (30. May 1988) guideline. The test was conducted on activated sludge from a sewage treatment plant for 3 hours at 20°C. The results were graphically determined . Activated sludge collected from the sewage treatment plant of CH-4106 Therwil on 16/10/89. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation. 3,5-Dichlorophenol was used as referance substance. The inhibitory concentration (IC50) value was determined to be 15 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
15 mg/L

Additional information

Toxicity to microorganism:

Toxicity of test material on microorganism was evaluated using two experimental reports described as follows:

In the first toxicity studies to determine the inhibitory concentration of test material on the respiration of aerobic waste water bacteria were conducted according to EEC L 133, p. 118-122 (30. May 1988) guideline. The test was conducted on activated sludge from a sewage treatment plant for 3 hours at 20°C. The results were graphically determined . Activated sludge collected from the sewage treatment plant of CH-4106 Therwil on 16/10/89. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation. 3,5-Dichlorophenol was used as referance substance.The inhibitory concentration (IC50) value was determined to be 15 mg/l.

Similarly in the second study, respiratory inhibition study ofactivated sludge by test material was conducted according to EC Directive 88/302/EEC - activated sludge: verificationof the inhibition of respiration;corresponds to the OECD Guidelines for Testing of Chemicals 209 and ISO Standard 8192.In the short-term respiration test, the effect of test substance on the respiration of aerobicMicroorganisms (activated sludge) after a short exposure time (30 to 180 min) were investigated.As the test result, the effective concentrations are determined, in which the breathinginhibited relative to a reference value without Priifsubstanz by 20, 50 and 80% (EC20,EC50, EC80).  Effect of the test substance on the respiration of municipal activated sludge were found asEC20: after 30 min about 40 mg / l ,EC50: - After 30 min> 1000 mg /l, respectively.