Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Uvasorb HEB
- Physical state: off white powder
- Lot/batch No.: 1508G21
- Storage condition of test material: room temperature in the dark

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 for the range-finding test and for the definitive test from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK .

Study design

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

Test conditions

Hardness:
Laboratory tap water dechlorinated
140 mg/l as CaCO3
Test temperature:
about 21 °C
pH:
8.1 at the start of the experiment
8.5 at the end of the experiment
Reference substance (positive control):
yes
Remarks:
3.5 -dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal

Any other information on results incl. tables

Range-finding Test

No significant effect on respiration wa observed at either test concentration employed. Based on this information, a single test concentration, in triplicate, of 1000 mg/l was selected for the definitive test.The test material was insoluble in water and it was justifiable to conduct the definitive test at a single concentration of 1000 mg/l in excess of the water solubility level of the test material.

Definitive test

It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/l.

The initial and final dissolved oxygen concentrations wwere below those recommended in the test guidelines (6.5 and 2.5 mg O2/l respectively). This was considered to have had no adverse effect on the results of the study given that in all cases the oxygen consumption rate was determined over the linear portion of the oxygen consumption trace.

The validation criteria for the control respiration rates have been satisfied.

Observations made showed that at the test concentration of 1000 mg/l at 0 hours and 30 mins contact time there was a dark brown dispersion with particles of test material on the surface and dispersed throughout. a pale brown dispersion with particles of test material dispersed homogenously throughout was observed at 3 hours contact time.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The effect of the test material on the respiration of activated sewage sludge micro-organisms gave a 3-h EC50 of greater than 1000 mg/l. The NOEC after 3 h exposure was 1000 mg/l.