2-(Naphthalene-2'-sulphonylamino)-benzoic acid

Toxicity to microorganisms

Link to relevant study record(s)

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

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.