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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:
1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to the currently available guideline, according to GLP and the validity criteria are considered as fulfilled.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1999

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
no
Details on test solutions:
The test substance was weighted directly to the activated sludge at concentrations of 100, 320, 1000, 3200 and 10 000 mg/L.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Source: Sewage treatment plant which receives predominantly domestic sewage.
-Origin: Municipal sewage treatment plant of 31137 Hildesheim, Germany
-Laboratory culture: No

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
not applicable

Test conditions

Hardness:
Not indicated
Test temperature:
20.9°C
pH:
7.22
Dissolved oxygen:
not indicated
Salinity:
not indicated
Nominal and measured concentrations:
A non-GLP rang-finding test was conducted before at nominal concentrations of 10, 100 and 1000 mg/L
Nominal: 100, 320, 1000, 3200 and 10 000 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 500 ml Erlenmayer flasks
- No. of vessels per concentration (replicates): 1
- No. of Controls: 2
-Aeration: Continuous aeration for 3 hours
- Suspended solids concentration: Nominal concentration in the inoculum solution 2.8 g/L


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Continuous measurement of oxygen content in the samples, the oxygen measurement was terminated after a 3-minute period.
Test parameter: Respiration rate (Oxygen consumption)

Reference substance (positive control):
yes
Remarks:
Copper (II) sulphate pentahydrate

Results and discussion

Effect concentrations
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
1 655 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 1380 - 1985
Details on results:
3h- EC20: 546 mg/L
3h-EC50: 1655 mg/L
3h-EC80: 4991 mg/L
Results with reference substance (positive control):
- Concentrations: 58, 100, 180 mg/L
- Results: EC50 = 101 mg/L
Reported statistics and error estimates:
Not indicated

Any other information on results incl. tables

Preliminary test (rang-finding): Performed

Concentration: 58, 100 and 1000 mg 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues/L

Main test:

Effect data: A respiration inhibition of 6, 11, 30, 76 and 90% was observed at the concentrations tested. The EC50 value was calculated to be 1655 mg 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues/L . All validity criteria are fullfilled.


 

Concentration [mg/L]

Respiration rate [mgO2/Lh]

Inhibition [%]

Test substance

10 000

4.0

90

3200

9.6

76

1000

27.6

30

320

35.4

11

100

37.2

6

Control 1

-

38.8

-

Control 2

-

40.4

-

Reference substance

180

10.8

73

100

15.6

61

58

32.0

19

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The difference of the two controls with respect to the respiration rates is below 15%. The RC50 of the reference substance is within the acceptable range of 56 - 146 mg/L.
Conclusions:
The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.
- The respiration rates of the two controls were found to be 38.8 and 40.4 mg O2/L/h, respectively. The difference between the two values (4.0 %) complies with the validity criteria of the test (respiration rates must be within 15 % of each other).
- The EC50 of the reference substance was determined to be 101 mg/L; this is in the accepted range of 56 to 146 mg/L for Copper (II) sulphate pentahydrate.
Executive summary:

The 3 hours respiration inhibition test with activated sludge to the test substance 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues was performed. The respiration rates of the controls, reference and test substance were measured after a contact time of 3 hours, and the inhibition effect of the test and reference substance were determined by comparison with the control respiration rates. The nominal test concentrations of 100, 320, 1000, 3200 and 10 000 mg/L were used. The EC50 of the test substance was determined to be 1655 mg/L.

The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.