sodium 3-[(3,4-dicyanophenyl)thio]propane-1-sulfonate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study Test Phase 2013-05-02 to 2013-08-08.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study meets the criteria for classification as reliable without restriction according to Klimisch et al (1997).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate

EC Number:

700-787-7

Cas Number:

769953-18-6

Molecular formula:

C11H9N2O3S2Li

IUPAC Name:

lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Each test flask contained an excess of the synthetic sewage, sufficient activated sludge to give final solids concentration of 1500 mg/L, an appropriate quantity of the test material stock solution and RO water to give a final flask contents volume of 150ml.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Method of cultivation: Activated sludge was obtained from Totnes Sewage Works, Totnes, Devon, UK 1 day prior to exposure.
- Preparation of inoculum for exposure: The activated sludge was settled and the supernatant decanted. The settled sludge was fed with 50 mL of OECD synthetic sewage feed per litre of sludge and aerated at room temperature, until it was used in the test.

The total filterable solids concentration was determined on the day of the test and was found to be 3307 mg/L. The pH was measured as 5.9, and was subsequently adjusted to 7.0 with 2M sodium hydroxide prior to use.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

20 +/-2 C

Details on test conditions:

On the basis of the results of the range finding test the definitive test was run with nominal test material concentrations of 10, 32, 56, 100 and 320 mg/L, with five replicates per concentration. The reference substance, 3,5 dichlorophenol, was run with single replicates of nominal concentrations of 1.0, 2.0, 5.0, 10 and 20 mg/L. One control vessel was prepared and run with each set of replicates.

Each flask contained an excess of the synthetic sewage, sufficient activated sludge to give final solids concentrations of 1500 mg/L, an appropriate quantity of either test material or 3,5 dichlorophenol stock solution and RO water to give a final flask contents volume of 150 mL. The pH of each flask was measured at the start and end of the test.

Flasks were set up in batches of six and aerated at 20 ± 2˚C for 3 hours. Each batch included a control flask and five test or reference substance flasks. The temperature of the flask contents was measured at the end of the 3 hours aeration using a thermometer.

The respiration rate of each culture was measured after 3 hours and compared with the mean respiration rate of the six control cultures. The rate of oxygen uptake of six test vessels was measured simultaneously using a Strathtox respirometer. Microcathode oxygen electrodes measured the oxygen concentration of the test solutions. The electrodes were connected to an interface unit, these were in turn transferred to a computer, where the Strathtox software calculated the respiration rate in each flask, expressed as mg O2/L/h.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

EC20 >320 mg/L
EC80 >320 mg/L

Results with reference substance (positive control):

- Results with reference substance valid
- Relevant effect levels: DCP 3h EC50 6.3 mg/L. This is within the normal expected range of 2 to 25 mg/L indicating the sludge was responding normally and confirming the viability of the sludge organisms. The coefficient of variance between the respiration rates in the six control flasks was 5.1%, less than the value of 30% required by the test guideline. Therefore, the mean control respiration rate was used in the calculation of the percentage inhibition.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 3h EC50 of the test material was found to be >320 mg/L based on nominal concentrations. The 3h NOEC was determined to be 100 mg/L.

Executive summary:

Introduction

This study was undertaken to assess the effect of the test material on the respiration rate of activated sludge micro-organisms typical of those found in domestic sewage treatment, determined by a respirometric method. The method was designed to be compatble with the following guideline:

OECD Guidelines for the testing of Chemicals, Test Guideline 209, Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation). Adopted 22 July 2010.

Results & Conclusions

The 3h EC50 of the test material was found to be >320 mg/L based on nominal concentrations. The 3h NOEC was determined to be 100 mg/L.