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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:
1994
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:
Preparation of the inoculum: Higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines) and 4 instead of 5 test concentrations.
GLP compliance:
yes
Specific details on test material used for the study:
Code number: FAT 20036/F
Batch-No: 1
Purity: ca. 97.7%
Appearance: Solid
Solubility: 80 mg/L (in water)
Storage: room temperature
Expiration date: 07/99
Analytical monitoring:
no
Details on sampling:
Not available
Vehicle:
no
Details on test solutions:
Not available
Test organisms (species):
activated sludge
Details on inoculum:
- Organism: Activated sludge from a communal sewage treatment plant (ARA -Pro Rheno Basel)
- Sludge pretreatment: 3 times washing with tap water and addition of synthetic sewage (a day before the main test).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Remarks on exposure duration:
None
Post exposure observation period:
Not available
Hardness:
Not available
Test temperature:
20.8 °C
pH:
7.3 before the test beginning
Dissolved oxygen:
measured
Salinity:
Not applicable
Nominal and measured concentrations:
- Stock solutions: 500 mg/l test substance / reference substance in deionized water.
- Test concentrations : 320, 100, 32 and 10 mg/l of the test substance and 32, 10 and 3.2 mg/l of the reference substance
Details on test conditions:
- Temperature : 20.8 °C
- Sludge dry weight: 1.50 g/l
- Test volume : 100 ml
- Test duration: 3 h
- 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 : 7.3 before the test beginning

Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol (Merck 821768)
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
Remarks:
respiration rate
Details on results:
Not available
Results with reference substance (positive control):
The IC50 (3 h) of the reference substance (3,5-Dichlorophenol) was found to be 9.0 mg/l
Reported statistics and error estimates:
Not available

ACTIVATED - SLUDGE - INHIBITION / IC50 (3 h)

OXYGEN - CONSUMPTION - TEST

 Control  pH after 3 hrs 1) O2 -consumption (in cm)   2) Time (in cm)   mg O2/min/L   C=control1) 2 cm = 0.8 mg/l O22) 2 cm = 1 min
 C1  8.0 3.7  4.0   0.74  C1/C2: 0.00% C2/C1: 0.00%
 C2  7.8 3.5 3.8  0.74   Mean C: 0.74

 Test substance mg/L pH after 3 hour    1) O2 -consumption (in cm)   2) Time (in cm) mg O2 pro min/L  % of control  % inhibition 
 320  7.6  4.0  4.7  0.68  91.89 8.11 
 100  7.8  3.8  4.4  0.69  93.24 6.76 
 32  7.9  4.0  4.4  0.73  98.65 1.35 
 10  7.9  3.8  4.4  0.69  93.24 6.76 

3,5 -Dichlrophenoö (mg/L) pH after 3 hour    1) O2 -consumption (in cm)   2) Time (in cm) mg O2 pro min/L  % of control  % inhibition
 32  8.0  0.7  4.7  0.12  16.22 83.78 
 10  7.9  1.9  4.3 0.35  47.30 52.70 
 3.2  7.9  3.0  4.2  0.57  77.03 22.97 

Test substance IC50 (3 h) = > 320.0 mg/l

3,5-Dichlorophenol IC50 ( 3 h) = 9.0 mg/l

Validity criteria fulfilled:
yes
Conclusions:
The IC50 (3 h) of the test substance FAT 20036/F was found to be greater than 320 mg/l
Executive summary:

The toxicity of FAT 20036/F to activated sludge was determined in a 3-hours respiration inhibition test according to the EEC Method No. L 133/118 -122 and to the OECD Guideline No. 209. The test was performed in compliance with the Good Laboratory Practice (GLP) Regulations of Switzerland.

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.

The IC50 (3 h) of the test substance FAT 20036/F was found to be greater than 320.0 mg/l

IC50 (3 h) of the reference substance 3,5-Dichlorophenol was found to be 9.0 mg/l

Description of key information

A key study was performed to determine the toxicity of FAT 20036/F to activated sludge was determined in a 3-hours respiration inhibition test according to the EEC Method No. L 133/118 -122 and to the OECD Guideline No. 209. The test was performed in compliance with the Good Laboratory Practice (GLP) Regulations of Switzerland.

The IC50 (3 h) of the test substance FAT 20036/F was found to be greater than 320.0 mg/l

IC50 (3 h) of the reference substance 3,5-Dichlorophenol was found to be 9.0 mg/l.

Several studies, (supporting studies), were also performed on the different batches to test the toxicity on micro-organisms.

BST, (toxicity to micro-organisms), was found to be greater than 300 mg/L on batch A, B, C and D.

For the batch F, IC50 was found to be greater than 320 mg/L.

 

Key value for chemical safety assessment

EC50 for microorganisms:
320 mg/L

Additional information