Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The range finding test was conducted on 2005-09-14 and the definitive test on 2005-09-21. Study signed off 2005-11-10.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as Reliable without restriction according to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
For the purpose of the definitive study the test substance was dissolved directly in water. The test material has an impurity of 14.4% therefore all test concentrations were corrected to account for this.

- Preparation of Test Solutions: An amount of the test substance was dissolved in water and the volume adjusted to 1000ml to give a 2000 mg active ingredient (ai)/l stock solution. An aliquot of this stock solution was dispersed with synthetic sewage, activated sewage sludge and water to a final volume of 500ml to give the required test concentration of 1000 mg/l. The volumetric flask containing the stock solution was inverted several times to ensure homogeneity of the stock solution.

This method of preparation was performed for 3 separate replicate test vessels.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
A mixed population of activated sewage sludge micro-organisms was obtained on 21 September 2005 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK which treats predominantly domestic sewage.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h

Test conditions

Test temperature:
21 deg. C
pH:
pH at end of the test ranged 8.1-8.4
Nominal and measured concentrations:
The test substance has an impurity value of 14.4%. Therefore all test concentrations were corrected to account for this and expressed as active ingredient (ai) per litre. Definitive test concentration of 1000 mg ai/l (nominal) of test substance.
Details on test conditions:
TEST SYSTEM
- Test vessel: 500ml conical flask
- No. of organisms per vessel: 200ml of sewage inoculum
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 2

TEST WATER PARAMETERS
- Source/preparation of dilution water: Laboratory tap water (Safepharm Laboratories) dechlorinated and partly softened.

Typical lab water quality characteristics prior to dechlorination and softening
- Total organic carbon: 1.7 mg/l
- Total Chlorine: <0.153 mg/l
- Conductivity: 437.3 uS/cm at 20 deg C

EFFECT PARAMETERS MEASURED: After 30 min. and also after 3h contact time an aliquot was removed from the conical flask and measured for dissolved oxygen content using a BOD probe.

TEST CONCENTRATIONS
- Range finding study: 100 and 1000 mg ai/l
- Results used to determine the conditions for the definitive study: 100 mg ai/l 1% inhibition after 3h, 1000 mg ai/l 4% inhibition after 3h.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Observations made throughout the test period showed that at the test concentration of 1000 mg ai/l no undissolved test material was visible.
Results with reference substance (positive control):
The reference material gave a 3h EC50 of 8.8 mg/l. This satisfied the validation criteria for the reference material

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The effect of the test substance on the respiration of actvated sewage sludge gave a 3h EC50 of >1000 mg ai/l. The NOEC after 3h exposure was 1000 mg ai/l. It is concluded that in this study the test substance at 1000 mg ai/l did not have a toxic effect on the respiration rate of activated sludge micro-organisms.
Executive summary:

Introduction

The study was performed to assess the effect of the test substance on the respiration of activated sewage sludge. The method was designed to be compatible with the following guidelines:

OECD Guidelines for Testing of Chemicals (1984) No 209 'Activated Sludge, Respiration Inhibition Test'

US EPA Draft Ecological Effects Test Guidelines OPPTS 850.6800

Results and Conclusions

The effect of the test substance on the respiration of actvated sewage sludge gave a 3h EC50 of >1000 mg ai/l. The NOEC after 3h exposure was 1000 mg ai/l. It is concluded that in this study the test substance at 1000 mg ai/l did not have a toxic effect on the respiration rate of activated sludge micro-organisms.