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Administrative data

activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
GLP compliance:
yes (incl. certificate)

Test material

Test material form:

Study design

Test type:
not specified
Water media type:
Total exposure duration:
3 h

Results and discussion

Effect concentrations
Key result
3 h
Dose descriptor:
Effect conc.:
32.14 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
inhibition of respiration due to nitrification

Applicant's summary and conclusion

3-(Isodecyloxy) Propylammonium Acetate is non- toxic at the concentration of 10 mg/L to activated sludge activated sludge of a sewage treatment plant.
The EC20, EC50 and EC 80 of the test item are 16.83 mg/L, 32.14 mg/L and 61.39 mg/L.
Executive summary:

Activated Sludge Respiration Inhibition Test was conducted according to OECD Guideline No. 209 carried out with the test item 3-(Isodecyloxy) Propylammonium Acetate. 

Test system was activated sludge of the treatment plant. The main test was carried out under the test conditions with the test item concentrations 10 mg/L, 17.8 mg/L,         31.6 mg/L, 56.3 mg/L, and 100.1 mg/L.

The blank controls (without the test item or reference substance) mean oxygen uptake rate was less than 20 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour.

The coefficients of variation (RSD) of oxygen uptake rate in positive control with six replicates were less than 30 % at the end of main test.


The respiration rates of the positive control, reference substance and test item replicates were measured after the exposure period of three hours, and the inhibitory effects of the test item and reference substance were determined in comparison to the positive control respiration rates.


The mean inhibition of respiration for the test item 3-(Isodecyloxy) Propylammonium Acetate with five replicates at the concentrations of 10 mg/L, 17.8 mg/L, 31.6 mg/L, 56.3 mg/L, and 100.1 mg/L were -28.4%, 25.19%, 44.29%, 74.88% and 93.98% respectively.


In order to check the activity of the test system and the test conditions a reference substance was carried out with 3, 5-dichlorophenol and the reference toxicity was determined. The EC50-value for the reference substance was found to lie between the 2 to 25 mg/L.

The NOEC of the test item is 10 mg/L, the test item is non-toxic at the concentration to the activated sludge of a sewage treatment plant. The EC20, EC50 and EC 80 of the test item are 16.83 mg/L, 32.14 mg/L and 61.39 mg/L.