N-butylbenzenesulphonamide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

sewage, industrial

Details on inoculum:

- Source: collected from Sri Venkateswara Sugar Mill, Palayasivaram, Kancheepuram District, Tamil Nadu.
- Dry weight was determined and enriched by adding synthetic waste-water (50 ml per litre of sewage sludge)
- Mixture was aerated overnight at 20 +/- 2°C and used for the study
- Sludge containing 3.7 g/L dry weight solid, filterable components

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

pH:

7.46-7.53

Nominal and measured concentrations:

200.86; 500.34; 1002.68; 2027.42; 6092.4 mg/L + control

Details on test conditions:

SEWAGE FEED
- synthetically prepared by dissolving following ingredient in one liter of water: 16.0 g peptone, 11 g meat extract, 3 g urea
0.7 g sodium chloride, 0.4 g calcium chloride, 0.2 g magnesium sulphate and 2.8 g dipotassium hydrogen phosphate.

TEST PROCEDURE
- Preparation of stock solution
- Aeration
- the following were added into 500 ml flat bottom flask and aerated for 3h: 16 ml synthetic sewage feed; X ml stock solution (5; 10; 20; 10 and 80 ml) of 3,5-dichlorophenol/ x mg of N-n-butylbenzenesulphonamide (100.43; 250.17; 501.34; 1013.71 and 3046.2 mg); 200 ml water; 400 ml aerated sewage sludge and made up to 500 ml using water
- After the end of 3h, the aeration was stopped. The decrease in oxygen was determined over a period of 10 minutes by reading off the oxygen concentration at every minute.
- The measurements of the oxygen concentrations were carried out with calibrated dissolved oxygen meter.

Reference substance (positive control):

yes

Remarks:

500 mg of 3,5-dichlorophenol was dissolved in 10 ml of 1N NaOH and diluted to 30 ml with distilled water. Then 8 ml of 1N H2SO4 was added by continuous stirring and finally the volume was made upto 1L with distilled water. The pH stock solution = 7.04

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 6 000 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

3h EC50: 16.67 mg/L (measured) with 3,5-dichlorophenol

the respiration rate was determined from the linear range of the oxygen decrease. From the rates of oxygen decrease, the inhibition of the respiration rate of the sewage sludge was calculated by using the following formula:

%inhibition = 1 - (2Rs/(Rc1 +Rc2)) x 100

where Rs = oxygen consumption rate at tested concentration of test substance

Rc1 = oxygen consumption rate, control 1

Rc2 = oxygen consumption rate, control 2

the decrease in oxygen was determined over a period of 10 minutes by reading off the oxygen concentration at every minute.

Validity criteria fulfilled:

yes

Conclusions:

From the results it was observed that the test item is non-inhibitory to the microbial organisms up to 6000 mg/L. The EC50 for N-n-butylbenzenesulphonamide (Proviplast 024) after an exposure time of 3 hours was >6000 mg/L.

Description of key information

Activated sludge inhibition was measured in the standard OECD209 test. From the results it was observed that BBSA is non-inhibitory to the microbial organisms up to 6000 mg/L. The EC50 for N-n-butylbenzenesulphonamide (Proviplast 024) after an exposure time of 3 hours was >6000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

6 000 mg/L