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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
6-10 August 1990
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
not specified
Specific details on test material used for the study:
Test material: DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) (CAS No. 7651-02-7).
Date of receipt: 24 July 1990.
Description: White waxy solid.
Storage: In original container at room temperature.
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Method of preparation: Direct dispersion in water.
Test organisms (species):
activated sludge
Details on inoculum:
Inoculum: A mixed population of activated sewage sludge microorganisms.
Source: The aeration Stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
Preparation: The sample was maintained at 21°C with continuous aeration and used on the day of collection. The pH was buffered to pH 7.0 with sodium hydroxide solution and the suspended solides level adjusted to 3.9 g/L priori to use.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
21°C
pH:
7.0
Nominal and measured concentrations:
RANGE FINDING STUDY:
Nominal concentrations: 1, 10, 100, 1000 mg/L.

DEFINITIVE STUDY:
Nominal concentrations: 100 mg/L (three repetitions).
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
Please refer to the tables below in "Any other information on results incl. tables".
Results with reference substance (positive control):
Please refer to the tables below in "Any other information on results incl. tables".

Table 1: Range-finding study

 Concentration (mg/L)   

 O2 Consumption rate [mgO2/L/min]

3-hour contact time

 % Inhibition
 Control     Repetition 1  0.27  -
 Repetition 2  0.26
          Test item  1.0  0.26  2
 10 0.25   6
 100  0.27  -2
 1000  0.18  32
    Reference (positive control)  3.2  0.25  6
 32  0.02 92 

Table 2: Definitive study

    Concentration (mg/L)

 O2 consumption rate [mgO2/L/min]

3-hour contact time

 % Inhibition
    Control  Repetition 1  0.36  -
 Repetition 2  0.34  -
       Test item  100, Repetition 1  0.34  3

100, Repetition 2

 0.33

 6

 100, Repetition 3

 0.36

 -3

    Reference (positive control)

 3.2

 0.31

 11

 32

 0.03

 91

Validity criteria fulfilled:
not specified
Conclusions:
The 3-hour EC50 value for acute toxicity to activated sludge of DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) was determined to be > 100 mg/L.
Executive summary:

Respiration inhibition of DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) on activated sludge was studied. The activated sludge was subjected to various concentrations of test substance for 3 consecutive hours.

A preliminary study was carried out with test substance concentrations of 1, 10, 100 and 1000 mg/L.

Based on the results obtained in this preliminary test, it was decided to make new measurements on 100 mg/L replicates.

No significant respiration inhibition was found based on the 100 mg/L replicates.

The EC50 for respiration inhibition of activated sludge by DMAPSA after 3 hours of exposure was therefore determined to be > 100 mg/L.

Description of key information

Respiration inhibition of DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) on activated sludge was studied. The activated sludge was subjected to various concentrations of test substance for 3 consecutive hours.

A preliminary study was carried out with test substance concentrations of 1, 10, 100 and 1000 mg/L.

Based on the results obtained in this preliminary test, it was decided to make new measurements on 100 mg/L replicates.

No significant respiration inhibition was found based on the 100 mg/L replicates.

The EC50 for respiration inhibition of activated sludge by DMAPSA after 3 hours of exposure was therefore determined to be > 100 mg/L.

Key value for chemical safety assessment

Additional information