Sodium 1,4-bis(1,3-dimethylbutyl) sulphonatosuccinate

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

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))

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Per replicate synthetic sewage feed (prepared in accordance with OECD Guideline 209), tap water and activated sludge (to achieve 1.5 g suspended solids/L) were pipetted into an incubation vessel (1 L glass flask). Afterwards, the test item was added and mixed with the solution.

- Controls: Untreated activated sludge suspension.

- Test concentration separation factor: 2

- Evidence of undissolved material (e.g. precipitate, surface film, etc.): not reported

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Activated sludge suspension, sampling: 29 Mar 2022, source: waste water treatment plant “Abwasserzweckverband Parthe” (Am Klärwerk, 04451 Borsdorf, Saxony, Germany)
- Method of cultivation: Since the test was performed one day after the day of collection, the activated sludge was fed with synthetic sewage feed (50 mL synthetic sewage feed/L activated sludge).The sludge was aerated prior to use.
- Preparation of inoculum for exposure: The concentration of suspended solids of the activated sludge was checked before test start and was determined to be 3.76 g/L (required: 2 - 4 g/L). Before test start the activated sludge was diluted with deionised water to achieve a concentration of 3 g suspended solids/L.

- Initial biomass concentration: 3g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

18.0 - 19.2 °C

pH:

pH of the test solutions: 7.3 - 7.6

Nominal and measured concentrations:

nominal 125, 250, 500, 1000, 2000 mg a.s./L equivalent to 125.7, 251.3, 502.6, 1005.2, 2010.5 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 L glass flask
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 500 mL
- Aeration: yes, 0.5 - 1 L/min
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 6
- No. of vessels per abiotic control (replicates): Based on the structure of the substance the test substance is not suspected to have strong reducing properties. Therefore, the
abiotic oxygen consumption is considered to be neglectable and hence an abiotic control was not set up.
- Sludge concentration (weight of dry solids per volume): 1.5 g suspended solids/L
- Nutrients provided for bacteria: 50 mL synthetic sewage feed/L activated sludge
- Nitrification inhibitor used (delete if not applicable): N-allylthiourea
- Biomass loading rate: 1.5 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:


OTHER TEST CONDITIONS
- Photoperiod: in the dark
- Light intensity: in the dark
- Details on termination of incubation: After three hours of incubation, for each replicate, 20 mL test solution was poured into a glass tube (containing a stir bar) which was placed into the water bath (water temperature: about 20 °C) of the respirometer. Afterwards, an oxygen electrode of the respirometer was placed into the solution and the oxygen content was continuously measured and recorded for a period 5 to 10 minutes.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Dissolved oxygen

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of heterotrophic respiration

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of respiration due to nitrification

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of heterotrophic respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of respiration due to nitrification

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

191.3 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

199.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of heterotrophic respiration

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

418.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of respiration due to nitrification

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not reported, no analytical dose verification
- Effect concentrations exceeding solubility of substance in test medium: no
- Adsorption (e.g. of test material to the walls of the test container): not reported
- Blank controls oxygen uptake rate: 36.1 mg O2/g activated sludge (dry weight of suspended solids)/h
- Coefficient of variation of oxygen uptake rate in control replicates: 9.2%

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels:
EC50 total respiration: 4.7 mg/L
EC50 heterotrophic respiration: 8.0 mg/L
EC50 nitrification respiration: 1.3 mg/L

Reported statistics and error estimates:

Calculation of NOEC
Williams-t-test or Multiple Sequentially-rejective Welsh-t-test after Bonferroni-Holm one-sided smaller, α = 0.05

Calculation of ECx-value
Probit analysis using linear maximum likelihood regression;
4-param. normal CDF (cumulative distribution function);
Weibull analysis using max. likelihood regression

The statistical analyses were performed with the software ToxRat Professional 3.3.0 (RATTE 2018).

Validity criteria fulfilled:

yes

Conclusions:

EC10 total respiration: 191.3 mg a.s./L
EC50 total respiration: > 2000 mg a.s./L

Executive summary:

In the Klimisch 1 study from Schulz (2022) according to OECD 209 the inhibition of the activity of sludge micro-organisms by the registered substance was determined. Total respiration was the most sensitive endpoint. The EC10 and EC50 of total respiration were 191.3 and > 2000 mg a.s./L.

 The results of the study are considered relevant and reliable for the risk assessment of the registered substance.

Description of key information

EC10 = 191.3 mg/L
EC50 > 2000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

2 000 mg/L

EC10 or NOEC for microorganisms:

191.3 mg/L