Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD 301F guideline study under GLP on the registered substance itself with onlly deviations (uncritical concerning the outcome of the study).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

adopted 17. Jul. 1992

Deviations:

yes

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

adopted 31. May 2008

Deviations:

yes

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

other: SOP 118 00 615 edition 5 valid from 02. May 2014 "Abbaubarkeit nach OECD 301F"

Deviations:

yes

Principles of method if other than guideline:

The following deviation from the guideline was documented:
- Temperature range was 19.5 – 20.8 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range this is considered as uncritical concerning the outcome of the study.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

EC Number:

242-644-7

EC Name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Cas Number:

18880-36-9

Molecular formula:

C6H13NO3S3.Na

IUPAC Name:

sodium 3-[(dimethylcarbamothioyl)sulfanyl]propane-1-sulfonate

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate, DPS
- Substance type: pure substance
- Storage condition of test material: The test item was stored in a tightly closed vessel at 15.2- 20.9 °C under dry conditions in the dark.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from a biologic sewage treatment plant was used. The chosen plant is treating mostly household sewage. The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
- Pretreatment: The sludge was filtrated, washed with tap water twice, then washed with and re-suspended in test medium. It was then aerated.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

61 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

99.85 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock solutions
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl and 1000 mL H2O demin. ad
b) 36.4 g CaCl2 x 2H2O and 1000 mL H2O demin. ad
c) 22.5 g MgSO4 x 7H2O and 1000 mL H2O demin. ad
d) 0.25 g FeCl3 x 6H2O, 0.4 g Na2EDTA x 2H2O and 1000 mL H2O demin. ad
Test Medium
10 mL solution a
1 mL solution b
1 mL solution c
1 mL solution d
1000 mL H2O demin. ad
- Test temperature: 19.5 - 20.8 °C
- pH: 7.2 - 7.5
- pH adjusted: no
- Suspended solids concentration: 24.9 mg/L

TEST SYSTEM
- Number of culture flasks/concentration: 3 (test item, medium and inoculum)
- Other:
Volume of test vessels: 500 mL
Volume test solution: 250 mL (toxicity control flask 125 mL)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 (medium and inoculum)
- Abiotic sterile control: 1 (test item and 10 mL 1% HgCl2 solution)
- Toxicity control: 1 (99.85 mg ThOD of test item and 100.08 mg ThOD of positive control)
- Other: Number of positive control vessels: 3 (sodium benzoate, medium and inoculum)

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

No information about a preliminary study are available.

Test performance:

No unusual observations during test period observed.

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Degradation after 4 days > 60% (validity criterion fulfilled)
Positive control 1: 92.4 % degradation after 28 days
Positive control 2: 94.4 % degradation after 28 days
Positive control 2: 85.4 % degradation after 28 days

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The study was performed according to OECD TG301F and EU Method C.4-D (GLP) with only minor deviations (uncritical concerning the outcome of the study) and therefore considered to be of the highest quality (reliability Klimisch 1). The validity criteria of the test system are fulfilled. Within 28 days, no degradation (0%) was determined for the test substance. Therefore, the test substance is considered to be not readily biodegradable.

Executive summary:

The biodegradability of the test substance was investigated according to EU method C.4 -D and OECD guideline 301 F (GLP, 2016). A measured volume of inoculated mineral medium, containing the test item in a concentration of 61 mg/L (corresponding to a ThOD of 99.85 mg/L), was stirred in a closed flask at a constant temperature for up to 28 days. Activated sludge from a biologic sewage treatment plant was used as inoculum. The chosen plant is treating mostly household sewage. Analytical grade salts were added to deionised water to prepare the stock solutions. Sodium benzoate was used as positive control. Also a toxicity control (test item and positive control mixed) and an abiotic control (test item and 10 mL 1% HgCL2 solution/L) was run in parallel, to ensure, that the chosen test concentration was not inhibitory to microorganims. The degradation rate of the test item was calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

Oxygen consumption in the blank controls and in the positive controls was normal, indicating that the test system has worked properly.

No degradation was detected within the test duration of 28 days.

No observations were made which might cause doubts concerning the validity of the study outcome.

The result of the test can be considered valid.

Therefore, regardless of the 10-day-window, sodium 3-[[(dimethylamino)thioxomethyl]thio] propanesulphonate is classified as not readily biodegradable following OECD 301F/EU C.4-D.