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

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Remarks:

OECD 301 Enhancement: Prolongation of the test to day 60

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Date of study plan revision: June 28, 2019, Completion of study: September 30, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

enhanced to 60 days

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: Innospec, BX029373
- Purity, including information on contaminants, isomers, etc.: 56.1%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Well closed container, at 8 - 30°C.
- Expiry date: May 30, 2020

TYPE OF BIOCIDE/PESTICIDE FORMULATION (if applicable)
- Translucent Gel.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Fresh samples of activated sludge were withdrawn on October 01st, 2019 from the sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany, which is mainly fed with municipal wastewater.
The samples were 2mm sieved after the arrival at the laboratory, washed once with mineral medium and kept aerobic until use. The sludge was left for settlement for ca. one hour. Subsequently the supernatant was discarded and the concentration of suspended solids was measured in the remaining sludge. The concentration was adjusted to 4.4 g/L and verified by dry mass measurement. The concentration used in the test was 29.6 mg dry mass/L (7.40 mg dry mass/250 mL).

Duration of test (contact time):

60 d

Initial conc.:

55.6 mg/L

Based on:

ThOD

Initial conc.:

56 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

A measured volume of inoculated mineral medium, containing a known concentration of test item (giving 50 - 100 mg ThOD/L) as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature of 22 °C ± 1°C for an extended period of 60 days. In this study, the test item concentration is 56 mg test item/L equivalent to 55.6 mg ThOD/L. The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask. Evolved carbon dioxide is absorbed in a suitable absorbent. The amount of oxygen taken up by the microbial population during biodegradation of the test item (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD. The test was performed according to the guideline OECD 301 F [5] and EC method C.4-D [6].

Reference substance:

benzoic acid, sodium salt

Test performance:

The solution of the reference substance in the mineral medium equivalent to a concentration of 100 mg/L was prepared using a stock solution (10 g/L). The solution of the test item in the mineral medium equivalent to a concentration of 56 mg/L was prepared by adding the required amount to ensure a final concentration of 56 mg/L (14 mg/250 mL) directly on a weight basis via Teflon discs to the test vessels. Subsequently, the mineral medium was added to the vessels. Further flasks with mineral medium only were prepared for inoculum controls. A further solution containing both test and reference item at the same concentrations as in the individual solutions (56 mg/L and 100 mg/L, respectively) was prepared to determine the possible toxic/inhibitory effects of the test item on the microorganisms within the inoculum.
.
Before test start the pH values of all solutions were determined and adjusted to 7.4 ± 0.2 with H2SO4 (50 g/L). The vessels were allowed to reach the desired temperature and were inoculated with prepared activated sludge to give a concentration of suspended solids not greater than 30 mg/L (in fact 29.6 mg/L). The total volume of solution was 250 mL in 500 mL respirometer flasks. The solutions were stirred during the whole test duration. In this way, dispersion of the test item and the contact between inoculum and test item was maximized. Twice a week the correct incubation temperature of the water bath and an adequate stirring were checked. At the end of the test the pH values of all solutions were determined.
The test was run for an extended period of 60 days, in darkness at 22°C ± 1°C in a water bath. The consumed oxygen was replaced by electrolytically generated oxygen.

Key result

Parameter:

% degradation (O2 consumption)

Value:

53.4

St. dev.:

8.3

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

70.8

St. dev.:

11

Sampling time:

60 d

Results with reference substance:

The percentage degradation of the reference item was average 87.9% and hence exceeded the pass level of 60% by day 14

No inhibitory effects of the test item were observed: more than 25% biodegradation (69.6% biodegradation based on ThOD) was determined in the toxicity control within 14 days (as specified in the validity criteria in paragraph 25 of the OECD 301 guidelines).

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Remarks:

One of 3 replicates reached the trigger of 60% for biodegratation (61%). The 10 day window is not applicable for a UVCB.

Conclusions:

The substance can be readily biodegradable: Although the key result shows average ultimate biodegradation on day 28 at 53 ± 8%, i.e. below the trigger of 60%, one of triplicate sample showed 61% of ultimate biodegradation on day 28, indicating potential for ready biodegradation, according to the criteria of OECD 301 test guideline. Furthermore, enhanced biodegradation assessment shows that the substance is ultimately biodegradable within 60 days of OED 301 F test design incubation since it reached 71 ± 11% (60-71-82%) on day 60. Hence the substance is not persistent.

Executive summary:

A study was performed at the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) to investigate the biodegradation of Sodium 1,4-bis(1,3-dimethylbutyl) sulphonatosuccinate in a Manometric Respirometry Test according to OECD guideline 301 F (1992) [5] and EC method C.4-D (440/2008/EEC) [6], enhanced by prolongation of the test period up to 60 days. The test medium was inoculated with microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater.

 

The test solutions were stirred in closed flasks at 22 °C ± 1°C for 60 days. The rate of degradation was monitored by measuring the quantity of oxygen required to maintain a constant gas volume in the respirometer flasks over a 60-d period. The amount of oxygen taken up by the microbial population during biodegradation of the test item at a concentration of 56 mg/L (ThOD = 55.6 mg/L), corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of the ThOD (theoretical oxygen demand). In order to check the procedure, sodium benzoate was used as a readily degradable reference item at a concentration of 100 mg/L, along with a toxicity control at a concentration of 56 mg test item/L combined with 100 mg/L reference item/L.

 

The test fulfills the following validity criteria of the guideline 301 F (28 day ready biodegradation endpoint):

(1) the percentage degradation of the reference item was average 87.9% and hence exceeded the pass level of 60% by day 14:

(2) the oxygen uptake of the inoculum blank was < 60 mg/L in 28 days;

(3) the pH value was inside the range of 6.0 - 8.5;

(4) the difference of extremes at the end of the individual 10-day windows and on day 28 was less than 20%.

 

No inhibitory effects of the test item were observed: more than 25% biodegradation (69.6% biodegradation based on ThOD) was determined in the toxicity control within 14 days (as specified in the validity criteria in paragraph 25 of the OECD 301 guidelines).

 

The biodegradation curves of the 3 replicates show that biodegradation exceeded 10% after 5 to 7 days. All three replicates exhibited similar kinetic degradation patterns and reached 54%, 45% and 61% biodegradation after 28 days(mean average 53.4%). Similar biodegradation of three replicates is shown by comparison of the individual 10-day window results:  Biodegradation at the end of the individual 10-day-windows – which started at day 5 to 7 – was found to average 48.2% with a standard deviation of 2.9% and a difference of extremes of 5.7%, i.e. less than 20%. All three replicates reached 71%, 60% and 82% of biodegradation, after 60 days (mean average 70.8%).

 

 

Description of key information

A key study for ready and enhanced biodegradability is available. The test was performed according to OECD 301 F in triplicate and is valid according to the guideline criteria. After incubation for 28 days, 53 ± 8% (45-54-61%) of the test material was ultimately degraded. After incubation for 60 days, 71 ± 11% (60-71-82%) of the test material was ultimately degraded.

 

A second study with the substance for ready and enhanced biodegradability is available, in support of the results of the key study. It includes 2 different set-ups: (1) Stock solutions were not homogenized prior to use (2) Stock solutions were homogenized by ultrasonic treatment prior to use. Rationale for two set-up 2: Minimizing variability between the replicates. The test was performed according to OECD 301 B with four replicates and is valid according to the guideline criteria. Set-up 1: After incubation for 28 days, 46 ± 2% (43-47-48%) of the test material was ultimately degraded. After incubation for 60 days, 52 ± 3% (49-51-56%) of the test material was ultimately degraded. Set-up 2: After incubation for 28 days, 47 ± 4% (43-44-49-53%) of the test material was ultimately degraded. After incubation for 60 days, 58 ± 2% (56-57-59-62%) of the test material was ultimately degraded.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Type of water:

freshwater