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Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22.03.1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
1993
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Xyligen 30F is a 30% aqueous solution of K-HDO.
Specific details on test material used for the study:
Test substance K-HDO, techn. 30%ig
Chemical name N-Cyclohexyldiazeniumdioxy-potassium
Molecular formula C6H13N203K
Molecular weight 200.28 (pure substance)
Batch number 74 N 9702
Odour Weak odour
Colour Colourless
Aggregate state Liquid
Density 1.13
Solubility in water Fully miscible
Instability against Acids
Storage Room temperature, darkness
Homogeneity Homogenous
Purity of the test substance Technical purity, 30 % active substance content

Sampling and analysis

Analytical monitoring:
not required
Remarks:
The test substance is fully miscible with water
Details on sampling:
O2 consumption has been determined after 30 minutes.

Test solutions

Vehicle:
no
Details on test solutions:
test concentrations: 2.8, 7.8, 39, 84, 202, 403, 812 mg/L

Test organisms

Test organisms (species):
activated sludge
Details on inoculum:
Inoculum: Activated sludge from laboratory sewage treatment plants running with municipal and synthetic waste water
Concentration in the test: 1 g/L dry substance
Synthetic nutrition medium: 8 ml/ test assay, 100-times concentrated OECD medium
Volume of the test assay: 250 ml
Incubation temperature: 20 ± 2°C

Study design

Test type:
not specified
Water media type:
other:
Remarks:
not applicable for an activated sludge test
Limit test:
no
Total exposure duration:
30 min
Post exposure observation period:
Not required

Test conditions

Hardness:
not required
Test temperature:
not specified
pH:
not specified
Dissolved oxygen:
not specified
Salinity:
not required
Conductivity:
not required
Nominal and measured concentrations:
Results are given as nominal values.
Details on test conditions:
The test has been performed according to the annex of the EEC directive 88/302/EEC 18 Nov. 1987 (Activated sludge respiration inhibition test)
This method corresponds to:
– OECD guidelines for testing of chemicals Activated sludge, respiration inhibition test 209; Paris 1993
– International standards ISO 8192-(1994) Water quality – test for inhibition of oxygen consumption by activated sludge
In the short-term respiration test, the effect of a test substance on the respiration of aerobe microorganisms after a short exposure time (30 up to 80 minutes) will be tested. The effective concentrations at which the respiration compared to a control value without test substance is inhibited for 20, 50 and 80 % (EC20, EC50, EC80) are the determined test results.
The EC20 value is the limit concentration at which toxic effects in biological sewage treatment plants have to be expected. The test concentration used for biological degradation tests should not exceed the EC20 value.
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
30 min
Dose descriptor:
other: EC20
Effect conc.:
ca. 4.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
ca. 30 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
30 min
Dose descriptor:
other: EC80
Effect conc.:
> 812 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
See tables below
Results with reference substance (positive control):
See tables below
Reported statistics and error estimates:
None reported

Any other information on results incl. tables

Results with test substance:

 

Reference values

Mean value (reference substance)

Test substance concentrations

Concentration of test substance (mg/L)

-

-

-

-

812

403

202

84

39

7.8

2.8

O2consumption after 30 min. (mg O2/L·h)

22

23

23

23

5

6

7

9

11

14

23

Inhibition of respiration (%) after 30 min.

-

-

-

-

78

74

70

61

52

39

0

Results with positive control substance:

 

Reference substance (MV)

Control substance

Substance concentration (mg/L)

 

1

10

100

O2consumption (mg O2/L x h)

23

20

8

2

Respiration inhibition (%)

0

-13

-65

-91

Effective concentrations EC-values:

 

EC20(mg/L)

EC50(mg/L)

EC80(mg/L)

Maximum test concentration

K-HDO, techn. 30%

4.8

30

-

812

3,5-Dichlorophenol

ca. 1

ca. 5

ca. 38

1000

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
No respiration inhibition up to 4.8 mg/L
Executive summary:

The effect of the test substance (30% K-HDO in water) on the respiration of aerobe microorganisms in activated sludge after a short exposure time of 30 has been tested. According to the results of the study the effective concentrations after 30 minutes are as follows:

EC20: 4.8 mg/L corresponds to 1.44 mg K-HDO/L (nominal)

EC50: 30 mg/L corresponds to 9 mg K-HDO/L (nominal)

EC80: > 812 mg/L* corresponds to > 243.6 mg K-HDO/L (nominal)

*At the highest concentration tested (812 mg/L 30% K-HDO in water) an inhibition of 78% was observed.