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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
10 - 22 January 1992
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
not specified
Specific details on test material used for the study:
Test material: NSABZ (2-(Naphthalene-2'-sulphonylamino)-benzoic acid)
Date of receipt: 20 December 1991.
Description: Very light brown powder.
Method of preparation: Direct dispersion in water.
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 an used on the day of collection. The pH was buffered to pH 6.7 with sodium hydroxide solution and the suspended solids 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:
6.7
Nominal and measured concentrations:
NOMINAL CONCENTRATIONS:
Range finding study: 10, 100, 1000 mg/L.
Definitive study: 10 mg/L (3 repetitions).
Reference substance (positive control):
no
Remarks:
3,5 dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 10 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  0.48  
 Repetition 2  0.46  
       Test item  10  0.46  2
 100  0.36  23
 1000  0.15  68
    Reference (positive control)  3.2  0.40  15
 32  0.06  87

Table 2: Definitive study.

    Concentration (mg/L)

O2 consumption rate [mgO2/L/min]

3-hour contact time

 % Inhibition
    Control  Repetition 1  0.58  -
 Repetition 2  0.57  -
       Test item  10  0.6  - 4
10   0.59  - 3
 10  0.59  - 3
    Reference (positive control)  3.2  0.54  6
 32  0.16  72
Validity criteria fulfilled:
not specified
Conclusions:
The 3-hour EC50 value for acute toxicity to activated sludge of 2-(Naphthalene-2'-sulphonylamino)-benzoic acid was determined to be > 10 mg/L.
Executive summary:

Respiration inhibition of 2-(Naphthalene-2'-sulphonylamino)-benzoic acid 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 10, 100 and 1000 mg/L.

Based on the results obtained in this preliminary test, it was decided to make new measurements on 10 mg/L replicates.

No significant respiration inhibition was found based on the 10 mg/L replicates.

The EC50 for respiration inhibition of activated sludge by 2-(Naphthalene-2'-sulphonylamino)-benzoic acid after 3 hours of exposure was therefore determined to be > 10 mg/L.

Description of key information

Respiration inhibition of 2-(Naphthalene-2'-sulphonylamino)-benzoic acid 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 10, 100 and 1000 mg/L.

Based on the results obtained in this preliminary test, it was decided to make new measurements on 10 mg/L replicates.

No significant respiration inhibition was found based on the 10 mg/L replicates.

The EC50 for respiration inhibition of activated sludge by 2-(Naphthalene-2'-sulphonylamino)-benzoic acid after 3 hours of exposure was therefore determined to be > 10 mg/L.

Key value for chemical safety assessment

Additional information