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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:
2003-02-18 - 2003-02-19
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The test was performed according to relevant guidelines and compliant with GLP. It is sufficiently documented and the results are plausible. For a limit test, no details in OECD guideline 209 are specified. However, one replicate for the test item would have been desirable.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Principles of method if other than guideline:
not applicable
GLP compliance:
yes
Remarks:
Principles of Good Laboratory Practice (GLP) § 19a, German Chemical Act (ChemG)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Name: Licowax OP
Montan acids, ester of
Appearance: flakes
Colour: light yellow
Smell: characteristic
For substance characterization, an IR-Spectrum of the test substance had been prepared.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
not applicable

Test solutions

Vehicle:
no
Details on test solutions:
The test substance is of poor solubility in water. It was tested as a water accomodated fraction (WAF). To gain the water accomodated fraction, 10 g/L of the test substance was stirred for 24 hours in a 2 L glass beaker such, that the evolving swirl reached a depth of 10% of the waterlayer. After a 1 hour halt for settling of particles, the fraction was filtered through a paper filter to remove fine particles and was used in the test.

Test organisms

Test organisms (species):
activated sludge, domestic
Details on inoculum:
The fresh sludge had been washed three times with dechlorinated tap water and the amount of dry weight determined according to the guideline. In the test an equivalent of 4g dry weight/L had been used , corresponding to 19.32 g wet sludge per 500 mL of test water in this test.

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 applicable
Test temperature:
18.5 - 19.9 °C
pH:
not applicable
Dissolved oxygen:
> 6.5 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
Limit test, a water accomodated fraction (WAF) had been used.
Details on test conditions:
The test had been conducted exactly as described in the OECD-guideline 209. However, instead of the 5 different concentrations of the test item, a limit test with the water accomodated fraction (without replicates) had been performed (nominal 10 000 mg/L).
Reference substance (positive control):
yes
Remarks:
3,5-dichlorphenol - 3, 10 and 30 mg/L

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 10 g/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: lmit test, due to the low solubility of the test item
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 10 g/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: limit test, due to the low solubility of the test item
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
10 g/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: limit test, due to the low solubility of the test item
Details on results:
The test substance did only induce a very slight respiration inhibition of the activated sludge used.
Results with reference substance (positive control):
For the reference substance 2,3-dichlorophenol an EC50 (3 h) of 5 mg/L had been determined graphically on probability paper.

Any other information on results incl. tables

 

 

concentration
[mg/L]

Respiration rate
[mg O2/L x h]

Inhibition
[%]

control

K 1

-

51.6

-

reference

R 1

3

29.6

40.6

 

R 2

10

16.6

66.7

 

R 3

30

6.0

88.0

Test substance

T1

10 000

47.2

5.2

control

K 2

-

48.0

-

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The two control respiration rates differ no more than 15% from each other (7% in this study). The EC50 (3 h) of 3,5-dichlorophenol is in the accepted range of 5 to 30 mg/L (5 mg/L in this study).
Conclusions:
A respiration inhibition test with acitvated sludge from a municipal sewage treatment plant performed according to OECD 209 and GLP (reliability category 2) had been performed as a limit test with the test item due to its poor solubility. The test item (Licowax S) did only have a very slight inhibitory effect on microbial respiration at a nominal concentration of 10 g/L. The EC10 (3 h) and EC50 (3 h) had been determined as larger than 10 g/L nominal concentration, the NOEC as being equal to 10 g/L nominal concentration.
Executive summary:

A respiration inhibition test with acitvated sludge from a municipal sewage treatment plant performed according to OECD 209 and GLP (reliability category 2) had been performed as a limit test with the test item due to its poor solubility. The test item (Licowax S) did only have a very slight inhibitory effect on microbial respiration at a nominal concentration of 10 g/L. The EC10 (3 h) and EC50 (3 h) had been determined as larger than 10 g/L nominal concentration, the NOEC as being equal to 10 g/L nominal concentration.