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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:
18 November to 14 December, 1993
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:
Deion. water instead of dest. water for the stocksolution. 4 instead of 5 test concentrations and higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines)
GLP compliance:
yes
Specific details on test material used for the study:
Test substance
Code number: FAT - 36'038/F
En-Nr.: 409753.32
Purity 69.4 %
Appearance: solid
Solubility: inslouble
Storage: room temperature
Expiration date: 09/98
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
yes
Details on test solutions:
Not applicable
Test organisms (species):
other: Activated sludge of a communal sewage treatment plant (Ara-BIRSIG Therwil)
Details on inoculum:
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:
not specified
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
21.0 °C
pH:
7.8 before start of the test
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations for FAT 36038/F: 320, 100 and 10 mg/l of the test substance
Nominal concentrations for reference substance: 32, 10 and 3.2 mg/l of the reference substance.
Details on test conditions:
- Sludge dry weight: 1.44 g/l
- Test volume: 100 ml
- Estimation technique: Aeration:O2 - consumption, measured with an oxygen sensitive electrode system: OXI DIGI 530 (SAV : 00 109) 0.1 - 0.2 l/min by pasteur-pipette
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol (Merck 821768).
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:
The test substance concentrations tested were 320, 100, 32 and 10 mg/L, at which the % inhibition observed were 0, 0, 0 and 1.71% respectively.
Results with reference substance (positive control):
The % inhibition observed were 84.00, 40.57 and 10.86 at 32,10 and 3.2 mg/L concentrations respectively. Hence, the IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 13.0 mg/l.
Reported statistics and error estimates:
None
Validity criteria fulfilled:
yes
Conclusions:
The IC50 (3 h) of the test substance FAT 36038/F was determined to be >320.0 mg/L.
Executive summary:

The toxicity of FAT 36038/F to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209, and to the EEC Method No. L 133/118. The test substance concentrations tested were 320, 100, 32 and 10 mg/L, at which the % inhibition observed were 0, 0, 0 and 1.71% respectively. Hence the IC50 (3 h) of the test substance FAT - 36'038/F was determined to be >320.0 mg/L.

Description of key information

The 3 h IC50 value for FAT 36038 was found to be >320 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
320 mg/L

Additional information

The toxicity of FAT 36038/F to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209, and to the EEC Method No. L 133/118. The test substance concentrations tested were 320, 100, 32 and 10 mg/L, at which the % inhibition observed were 0, 0, 0 and 1.71% respectively. Hence the IC50 (3 h) of the test substance FAT - 36'038/F was determined to be >320.0 mg/L.

 

The supporting studies performed to determine the toxicity of FAT 36038/A, FAT 36038/C and FAT 36038/D to microorganisms according to Internal Method B-10 reported the IC50 greater than 300 mg/L in all the cases.

Based on the data from these studies the 3 h IC50 of FAT 36038 can be considered to be greater than 320 mg/L.