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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:
November 15, 1994 to December 29, 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
None
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
April 4, 1984 (Edition : Paris, 1993).
Deviations:
yes
Remarks:
1. Preparation of the inoculum: higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines). 2. 4 instead of 5 test concentrations.
Principles of method if other than guideline:
Guideline followed
GLP compliance:
yes
Specific details on test material used for the study:
Code number: FAT 20063/C
Batch-Nr.: 3.46
Purity: 81.9 %
Appearance: solid
Solubility: >10 g/l [in water]
Storage: room temperature
Expiration date: 04/99
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Stock solutions : 500 mg/l test substance or reference substance in deionized water.
Test organisms (species):
activated sludge
Details on inoculum:
- Name and location of sewage treatment plant where inoculum was collected: Communal sewage treatment plant (ARA-Pro Rheno Basel)

- Pretreatment: 3 times washing with tap water and addition of synthetic sewage (a day before the main test)
Test type:
static
Water media type:
not specified
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20 ± 2 °C
pH:
6.9 before the test beginning (Sludge)
Nominal and measured concentrations:
320, 100, 32 and 10 mg/l of the test substance.
32, 10 and 3.2 mg/l of the reference substance.
Details on test conditions:
TEST MEDIUM / WATER PARAMETERS
Sludge dry weight: 1.38 g/l
Test volume: 100 ml
Test duration: 3h
Estimation technique: O2 - consumption, measured with an oxygen sensitive electrode
system: OXI DIGI 530 (SAV : 00 109)
Aeration: 0.1 - 0.2 l/min by pasteur-pipette
pH of sludge: 6.9 before the test beginning
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 320 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Results with reference substance (positive control):
The IC50 (3 h) of the reference substance 3,5-Dichlorophenol : 11 mg/l

None

Validity criteria fulfilled:
yes
Conclusions:
IC50 (3 h) of the test substance FAT 20063/C was determined to be >320 mg/l.
Executive summary:

The toxicity of FAT 20063/C to activated sludge was determined in a 3-hours respiration inhibition test according to the EEC Directive 87/302, L 133/118 -122 and to the OECD Guideline 209, in compliance with GLP. The test substance concentrations tested were 320, 100, 32 and 10 mg/l. The reference substance, 3,5-Dichlorophenol was tested in concentrations of 32, 10 and 3.2 mg/l. Based on the findings of the study, IC50 (3 h) of the test substance FAT 20063/C was determined to be >320 mg/l, while the IC50 (3 h) of the reference substance 3,5-Dichlorophenol was 11 mg/l.

Description of key information

The 3 hour IC50 for the substance >300 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
300 mg/L

Additional information

Three studies are available for assessment of toxicity potential of FAT 20063 to bacterial population.

In a key study, the toxicity of FAT 20063/C to activated sludge was determined in a 3-hours respiration inhibition test according to the EEC Directive 87/302, L 133/118 -122 and to the OECD Guideline 209, in compliance with GLP. The test substance concentrations tested were 320, 100, 32 and 10 mg/l. The reference substance, 3,5-Dichlorophenol was tested in concentrations of 32, 10 and 3.2 mg/l. Based on the findings of the study, IC50 (3 h) of the test substance FAT 20063/C was determined to be >320 mg/l, while the IC50 (3 h) of the reference substance 3,5-Dichlorophenol was 11 mg/l.

Two supporting studies conducted in 1975 and 1981, also support the conclusion that the IC50 for the substance is >300 mg/L.