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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:
24 January 2007 to 06 February 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable.
Analytical monitoring:
no
Details on sampling:
Test concentrations (mg/l) : 100, 1000 & 10000
** Test item concentration in physico-chemical oxygen consumption control (mg/l) : 10000
Vehicle:
no
Details on test solutions:
Type of application: direct weighing
Test concentration of the activated sludge: 960 mg/l suspended solids
Test temperature: 20 ± 2° C
Stirring period of test item before start of incubation time: 16 hours
Incubation time: 3 hours with permanent aeration
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Type: mixed population of aquatic microorganisms (activated sludge)
Origin: aeration tank of a domestic sewage treatment plant (Municipal STP Cologne-Stammheim)
Date of collection: 2007-01-29
Pretreatment: activated sludge, daily fed with synthetic medium
pH of the suspension before application: 7.8
Synthetic sewage feed:A synthetic sewage feed is made by dissolving the following amounts of substance in 1 litre of water:
16.0 g peptone
11.0 g meat extract
3.0 g urea
0.7 g NaCl
0.4 g CaCl2 - 2H20
0.2 g MgS04 – 7H20
2.8 g K2HP04

pH of the synthetic sewage feed: 7.5 ± 0.5
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
No post exposure observation period
Hardness:
No data
Test temperature:
18.8 - 19.5C
pH:
7.1 - 8.0
Dissolved oxygen:
4.7-5.5 mg/l (Start of test)
3.0-3.8 mg/l (End of test)
Salinity:
Not applicable.
Nominal and measured concentrations:
Test concentrations (mg/l) : 100, 1000 & 10000 (nominal)
Details on test conditions:
Test concentrations (mg/l): 100, 1000 & 10000
** Test item concentration in physico-chemical oxygen consumption control (mg/l) : 10000
Concentration reference substance 3.5-Dichlorophenol (mg/l): 5, 10 & 20

The test item and reference substance concentrations are not confirmed by analytical methods; they are based on nominal concentrations.

Type of application: direct weighing
Test concentration of the activated sludge: 960 mg/l suspended solids
Test temperature: 20 ± 2° C
Stirring period of test item before start of incubation time: 16 hours
Incubation time: 3 hours with permanent aeration

The physico-chemical oxygen consumption control is carried out, since some substances may consume oxygen by chemical reactivity. In order to be able to differentiate between physico-chemical oxygen consumption and biological oxygen consumption (respiration), at least the maximum concentration of the test item is additionally tested without activated sludge.
Reference substance (positive control):
yes
Remarks:
3.5-Dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
The substance showed 0.0% inhibition of the sewage sludge at a concentration of 10000 mg/l
Results with reference substance (positive control):
EC5o of the reference substance 3.5-dichlorophenol is in the range 5 - 30 mg/l
Reported statistics and error estimates:
All validity criteria of the test method were met:
respiratory rates of the 2 controls differ less than 15 %
respiratory rate of the controls < 60 mg 02 /l - h

RESULTS

 

Test item:Gelb 176 Sulfato

Test concentration

Respiratory rest test item

Phys-chem. O2 consumption

Respiratory rate – phys.-chem. O2 consumption

Inhibition

[mg/l]

[mg/l – h]

[mg/l – h]

[mg/l – h]

[%]

100

34.0

*0.0

34.0

0.0

1000

34.0

*0.0

34.0

0.0

10000

36.0

0.0

36.0

0.0

Control. mean

32.0

 

Control 1

30.0

Control 2

34.0

Comments relevant to result: test conditions are given as nominal concentrations and have not been confirmed by analytical methods.

*The physico-chemical oxygen consumption has been determined at 10000 mg/l test item concentration. As no physic-chemical oxygen consumption was observed at that test item concentration this observation also holds true for the lower test item concentrations.

 

Reference substance: 3.5-Dichlorophenol

Test concentration

Respiratory rate

Inhibition

[mg/l]

[mg/l – h]

[%]

5

24.0

25.0

10

20.0

37.5

20

7.2

77.5

Control. mean

32.0

 

Control 1

30.0

Control 2

34.0

Comments: the reference substance concentrations result from the quantities used in the preparations and have not been confirmed by analytical methods.

Validity criteria fulfilled:
yes
Conclusions:
Gelb Sulfato showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.
EC50> 10000 mg/l
Executive summary:

A study was performed to assess the toxicity of Gelb Sulfato to bacteria.

 

The study was conducted according to the Commission Directive 88/302/EEC; Part C.11 Activated Sludge Respiration Inhibition". This test method is in most parts identical with OECD Guideline 209"Activated Sludge, Respiration Inhibition Test". Study performed in accordance with the Principle of Good Laboratory Practice (GLP) and reported with a GLP certificate.

 

The activated sludge was exposed to Gelb 176 Sulfato at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours.

 

Gelb 176 Sulfato showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.

 

The EC50 is higher than 10000 mg/l.

 

The effect value related to nominal concentration, since no analytical monitoring was performed.

Description of key information

Gelb Sulfato showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.

The EC50(3 h) is higher than 10000 mg/L test mat. based on respiration rate

Key value for chemical safety assessment

Additional information

A study was performed to assess the toxicity of Gelb Sulfato to bacteria. The study was conducted according to the Commission Directive 88/302/EEC; Part C.11 Activated Sludge Respiration Inhibition". This test method is in most parts identical with OECD Guideline 209"Activated Sludge, Respiration Inhibition Test".

The activated sludge was exposed to Gelb Sulfato at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours.

Gelb Sulfato showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.

The EC50 is higher than 10000 mg/l.