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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:
1993
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
Deviations:
yes
Remarks:
1. Deion. water instead of dest. water for the stock solution; 2. Preparation of the inoculum :higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines); 3. 4 instead of 5 test concentrations
Principles of method if other than guideline:
Guideline followed
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Code number: FAT - 92'348/A,
EN - number: 279291.26,
Purity: ca. 100 %,
Appearance: solid,
Solubility: 100g/l (in water),
Storage: room temperature,
Expiration date: 9/97,
Safety: Test substance will, unless otherwise specified, be handled using safety precautions "Sicherheit im Labor von A - Z", SAV: 00 303.
Analytical monitoring:
no
Details on sampling:
None
Vehicle:
no
Details on test solutions:
None
Test organisms (species):
activated sludge, domestic
Details on inoculum:
Test system / Test organism:
Organism: Activated sludge of a communal sewage treatment plant (ARA-Birsig Therwil)
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
Hardness:
no data
Test temperature:
20.8 °C
pH:
7.9 - 8.0
Dissolved oxygen:
No data
Salinity:
no data
Conductivity:
No data
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:
Temperature: 20.8 °C
Sludge dry weight: 1.5g/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: 7.9 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.
Results with reference substance (positive control):
The IC50 (3 h) of the reference substance 3,5-Dichlorophenol : 9.5 mg/l.

Table 1: Oxygen consumption test – test substance

Test substance (mg/l)

pH after 3 h

O2 consumption in cm

Time in cm

mg O2 pro min/l

% control

% inhibition

320

7.9

4.1

4.2

0.78

97.50

2.50

100

8.0

4.3

4.4

0.78

97.50

2.50

32

8.0

4.0

4.2

0.76

95.00

5.00

10

8.0

4.5

4.7

0.77

96.25

3.75

 

Table 2: Oxygen consumption test – reference substance

Test substance (mg/l)

pH after 3 h

O2 consumption in cm

Time in cm

mg O2 pro min/l

% control

% inhibition

32

8.2

1.0

5.6

0.14

17.50

82.50

10

8.1

2.5

5.1

0.39

48.75

51.25

3.2

8.0

3.9

4.6

0.68

85.00

15.00

Validity criteria fulfilled:
yes
Conclusions:
IC50 (3 h) of the test substance FAT - 92'348/A was determined to be > 320.0 mg/l.
Executive summary:

The toxicity of FAT - 92'348/A to activated sludge was detemiined in a 3-hours respiration inhibition test according to the GECO Guideline No. 209, and to the EG Method Nr.L 133/118.

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 - 92'348/A was determined to be > 320.0 mg/l, while IC50 (3 h) of the reference substance 3,5-Dichlorophenol was determined to be 9.5 mg/l.

Description of key information

The IC50 (3 h) of the test substance FAT 92348/A was noted to be: >320.0 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
320 mg/L

Additional information

The toxicity of FAT - 92'348/A to activated sludge was detemiined in a 3-hours respiration inhibition test according to the GECO Guideline No. 209, and to the EG Method Nr.L 133/118.

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 - 92'348/A was determined to be > 320.0 mg/l, while IC50 (3 h) of the reference substance 3,5-Dichlorophenol was determined to be 9.5 mg/l.