Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-11-08 o 2003-01-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD guideline study, GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2003

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source: Activated sludge of a communal sewage treatment plant (ARA Therwil)
- Preparation of inoculum for exposure: The inoculum was prepared the day before experimental start. The freshly collected activated sludge was washed 3 times with tap water. Subsequently the sludge was aerated. The day the test started, a sample of the activated sludge was taken to determine the dry weight ofthe suspended solids. The pH ofthe inoculum was 7.5.
- Initial biomass concentration: 3.75 g/L suspended solids

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h

Test conditions

Test temperature:
20 °C
pH:
7.7
Nominal and measured concentrations:
Nominal: 11, 19, 33, 57, and 100 mg/L.
Details on test conditions:
TEST SYSTEM
- Aeration: 0.1 - 0.2 L/min/100 mL by Pasteurpipette
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Sludge dry weight: 1.5 g/L suspended solids

TEST MEDIUM / WATER PARAMETERS
- Synthetic sewage feed: in accordance to the guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: no

EFFECT PARAMETERS MEASURED
O2 consumption: measured with an oxygen sensitive electrode system: OXI 530
pH: measured at the end of the test
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol (3.2, 10, and 32 mg/L)

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
At all applied test concentrations, the test item showed no significant toxic effects (inhibition of the respiration rate < 15%) to the activated sludge.
Results with reference substance (positive control):
The 3-hour EC50 of the reference item 3,5-dichlorophenol (positive control) was calculated to be 9 mg/L.

Applicant's summary and conclusion