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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
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 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
yes
Remarks:
For the IC50 calculation of the reference substance used SOP: A.11.701.01 instead of SOP: 00 509 01
Qualifier:
according to guideline
Guideline:
other: 87/302/EEC, L 133, Part C
GLP compliance:
yes (incl. QA statement)
Remarks:
Swiss GLP
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: TVR50
- Expiration date of the lot/batch: Sep 2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Solubility of the test substance in the solvent/vehicle: > 80 g/l (in water)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
A synthetic sewage feed was made by dissolving the following amounts of substances in 1 litre of deionized water :
- 16.0 g peptone
- 11.0 g meat extract
- 3.0 g urea
- 0.7g NaCl
- 0.4 g CaCl2 • 2H2O
- 0.2 g MgSO4 • 7H2O
-2.8g K2HPO4
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
The inoculum was preparated 1 day prior to the experimental start. The freshly collected activated sludge was washed 3 times with tap water. Subsequently the sludge was aerated. A sample of the activated sludge was taken to determine the dry weight of the suspended solids.
The final concentration of the inoculum was adjusted to about 5.0 g/l suspended solids. For the storage over night synthetic sewage feed was added depending on the sludge concentration.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20.9 - 21.1 °C
pH:
6.6
Nominal and measured concentrations:
25.6, 64, 160, 400 and 1000 mg/l of the test substance
3.2, 10, and 32 mg/l of the reference substance
Details on test conditions:
The inoculum was preparated 1 day prior to the experimental start. The freshly collected activated sludge was washed 3 times with tap water. Subsequently, the sludge was aerated. A sample of the activated sludge was taken to determine the dry weight of the suspended solids.
The final concentration of the inoculum was adjusted to about 5.0 g/l suspended solids. For the storage overnight synthetic sewage feed was added depending on the sludge concentration.
The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed was measured after a contact time of 3 hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test substance under otherwise identical conditions was also measured. The inhibitory effect of the test substance at a particular concentration was expressed as a percentage of the mean respiration rates of two controls. An IC50 value was calculated from inhibition values at different concentrations.
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 1 000 mg/L
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/L
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
The test was considered valid because:
• the respiration rates of the two controls were within 15 % of each other and
• the IC50 of the reference substance was in the range of 5 to 30 mg/l.
Results with reference substance (positive control):
IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 10 mg/l.
 Test substance  (mg/1)  pH after 3h O2 consumption (in cm) time (in cm) mg O2 Pro min./l % of control % inhibition
1000 7.8 7.7 6.8 0.91 97.31 2.69
400 8 9.6 8.5 0.9 97.05 2.95
160 8 9.5 8.4 0.9 97.19 2.81
64 8.1 8.5 7.3 0.93 100.06 0
25.6 8.1 9.1 7.9 0.92 98.99 1.01
Validity criteria fulfilled:
yes
Conclusions:
IC50 (3 h) of the FAT 40571/A : > 1000 mg/l and NOEC (3 h) is 1000 mg/l.
Executive summary:

Bacteria Toxicity of FAT 40571/A was carried out to determine the IC50 (concentration of the test substance which inhibits the respiration activity of the activated sludge by 50%) according to OECD 209 and 87/302/EEC, L 133, Part C guideline.

Activated sludge obtained from a communal wastewater treatment plant and tested for 3 h duration using static test. The test concentrations used were 25.6, 64, 160, 400 and 1000 mg/l of the test substance and 3.2, 10, and 32 mg/l of the reference substance to analyze determination of the consumption of dissolved oxygen

 

Based on the study results IC50 (3 h) of FAT 40571/A is > 1000 mg/l while of refernce substance is 10 mg/l. The NOEC (3 h) of the FAT 40571/A is 1000 mg/l.

Description of key information

IC50 (3 h) of the Reactive Brown 49 is > 1000 mg/l and NOEC (3 h) was 1000 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

Bacteria Toxicity of Reactive Brown 49 was carried out to determine the IC50(concentration of the test substance which inhibits the respiration activity of the activated sludge by 50%) according to OECD 209 and 87/302/EEC, L 133, Part C guideline.


Activated sludge obtained from a communal wastewater treatment plant and tested for 3 h duration using static test. The test concentrations used were 25.6, 64, 160, 400 and 1000 mg/l of the test substance and 3.2, 10, and 32 mg/l of the reference substance to analyze determination of the consumption of dissolved oxygen


 


Based on the study results IC50(3 h) of Reactive brown 49 is > 1000 mg/l while of refernce substance is 10 mg/l. The NOEC (3 h) of the Reactive Brown 49 is 1000 mg/l.