3-((3,4-dicyanophenyl)sulfonyl)-N-(2-hydroxypropyl)propane-1-sulfonamide

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:

Experimental phase: 19th April 2017 to 20th April 2017. Report issued: 28 July 2017.

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 (Carbon and Ammonium Oxidation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

For the purpose of the definitive study the test substance was dissolved directly in water. At time "0" 16ml of synthestic sewage was diluted to 250mL with water and 250mL of innoculum and added in a 500 mL conical flask (first control). The mixture was aerated with clean, oil-free compressed air via narrow bore glass tubes at a rate of 0.5 to 1.0 liter per minute. Thereafter, at 15 minute intervals the procedure was repeated for the second control followed by the reference item vessels with appropriate amounts of the reference item being added. Finally two further control vessels were prepared.The test was conducted under normal laboratory lighting in a temperature controlled room at measured temperatures of approximately 22 ºC.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A mixed population of activated sewage sludge- micro-organisms was obtained on 19th April 2017 from the aeration stage of the Severn Trent water Plc sewage treatment plant at Loughborough, Leicestershire , UK which treats predominantly domestic sewage.

Test type:

static

Water media type:

other: Deionised reverse osmosis water containing less than 1mg/L dissolved organic carbon ( DOC)

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

None

Test temperature:

Approx 22°C

pH:

pH of test item varied over the 3 hours between 7.3-7.6.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

EC 10 >1000mg/l
EC 20 >1000mg/l
EC50>1000mg/l
EC80>1000mg/l
NOEC 1000mg/l

Results with reference substance (positive control):

The reference substance, 3,5-dichlorophenol, caused substantial inhibition of the respiration rate of the activated sludge. From the results obtained the 3 hour EC50 value was calculated to be 6.9 mg/l and was within the expected normal range of 2 to 25 mg/l indicating the sludge was responding normally and confirming the viability of the sludge organisms.

Validity criteria fulfilled:

yes

Conclusions:

The test item inhibition of the respiration of activated sewage sludge 3-Hour EC50 value was > 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L.

Executive summary:

Introduction

The study was performed to assess the effect of the test substance on the respiration of activated sewage sludge micro-organisms typical of those found in domestic sewage treatment. The method was designed to be compatible with OECD Guideline 209 'Activated Sludge, Respiration Inhibition Test' (Carbon and AmmoniumOxidation) (Adopted 22 July 2010).

Method

Activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of 10, 100 and 1000 mg/L (3 replicates of the 1000 mg/L test concentration) for a period of 3 hours at measured temperatures of approximately 22 °C with the addition of a synthetic sewage as a respiratory substrate.

 

The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item, 3,5-dichlorophenol.

Results and Conclusions

The test item inhibition of the respiration rate of activated sewage sludge 3-Hour EC50 value was > 1000 mg/L. The NOEC after 3 hours exposure was 1000 mg/l. It is concluded that in this study the test substance at 100 mg/l did not have a toxic effect on the respiration rate of activated sludge micro-organisms.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L