Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-04-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
new guideline study according to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no
Details on test solutions:
Sludge concentration in the test: 1.5 g/L Dw
Test concentrations: 1000, 500, 250, 125, 62.5 mg/L as nominal concentration based on test substance

Preparation of the test
The test substance was added in the required amounts according to the test concentrations directly to the test vessels with 234 mL deionized water. Aliquots of the reference substance stock solution were dosed to the test vessels and made up with deionized water to a volume of 234 mL. 16 mL synthetic medium were dosed to each test vessel with test substance and reference substance afterwards. To prepare the blank control assays 234 mL of deionized water and 16 mL synthetic medium were mixed. The pH-values in all test vessels were checked and adjusted.
After addition of 250 mL of inoculum suspension (3 g/L DW) the incubation was started by aeration of the test vessels with pressured air. The vessels for the blank control assays were prepared to the same procedure without addition of test- or reference substance. After 3 hours incubation at 20 ± 2°C the mixtures in the test vessels were placed subsequently for oxygen measuring. The temperature was measured for seven times in a separate vessel filled with aerated deionized water during incubation phase. The content of oxygen at the start of the measurements was > 7 mg/L. The total oxygen consumption of was measured in the sequence BC1-3 and RS1, RS2-5, RS6 and TS1-3, TS4-7, TS8-11 and TS12-15. The oxygen consumption of the blank control BC4-6 were measured at last. No abiotic control was tested. The oxygen uptake was measured for a period of about 8 to 10 minutes.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Test system: Activated sludge from a municipal wastewater treatment plant
Origin of the test system: Municipal wastewater treatment plant of Mannheim, Germany

Study design

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

Test conditions

Test temperature:
20.1 - 20.8 °C
Nominal and measured concentrations:
Test concentrations: 1000, 500, 250, 125, 62.5 mg/L as nominal concentration based on test substance
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 510 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 510 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test item was tested in an OECD 209 test. The EC10 was > 1000 mg/L product corresponding to > 510 mg/l a.i.