Butanedioic acid, sulfo-, C-[2-[(1-oxododecyl)amino]ethyl] ester, monosodium salt

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 December 2004 (experimental starting) to 31. Deember 2004 (experimental completion)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from municipal sewage STP D-31137 Hildesheim. The sludge of that STP comprises mostly municipal sewage and hardly industrial chemical waster.
- Laboratory culture: Not applicable.
- Method of cultivation: Not applicable.
- Storage conditions: The activated sludge was maintained in an aerobic condition by aeration for four hours and then homogenized with a mixer.
- Storage length: 4 hours under aerobic conditions, prior to use.
- Preparation of inoculum for exposure: The sludge was homogenized with a mixer and filtered thereafter (filtration conditions unknown). 30 mL of the filtrate were used to start inoculation.
- Pretreatment: No data.
- Concentration of sludge: See below, biomass concentration.
- Initial cell/biomass concentration: 10^5 to 10^6 CFU/L under test conditions, i.e., in test vessels.
- Water filtered: See above.

Duration of test (contact time):

28 d

Initial conc.:

11.1 mg/L

Based on:

other: Organic Carbon

Initial conc.:

50 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

TOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 20 to 24 °C
- pH adjusted: No data.
- pH during study: Between 7.5 and 7.9 (all test groups), on day 28.
- CEC (meq/100 g): No data are reported.
- Aeration of dilution water: Aeration with CO2 free air.
- Suspended solids concentration: Not determined.
- Continuous darkness: No information.

TEST SYSTEM
- Culturing apparatus: Several bottles in series (reactor system): 5 L reactor (containing 3 L inoculum) connected to 3 x 250 mL gas-washing bottles (in series), filled with Ba (OH2) adsorption solution.
- Number of culture flasks/concentration:
Reactors 1 and 2: Test concentration 11.1 mg/L organic carbon.
Reactors 3 and 4: Blank control.
Reactor 5: Reference substance at 10.2 mg C/L (35 mg/L reference substance).
Reactor 6: Toxicity control, i.e. 11.1 mg/L organic carbon test substance + 10.2 mg/L organic carbon reference substance).
- Method used to create aerobic conditions: Continuous aeration with CO2 free air, mixing of the test solutions by magnetic stirring.
- Method used to create anaerobic conditions: NA.
- Measuring equipment: Titration equipment (type not specified).
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: Sealed vessels, but aerated with CO2 free air.
- Details of trap for CO2 and volatile organics if used: Yes. Aliquots from these traps were removed to measure TIC (indirect method via non precipated Ba(OH2).

SAMPLING
- Sampling frequency: days 1, 4, 6, 8, 11, 14, 18, 21, 25 and 28 after incubation initiation.
- Sampling method: Non precipitated Ba (OH)2 was titrated by hydrocloric acid to the phenolphthaleine endpoint.On day 29 TOC was determined after removal of CO2 from test solutions by HCl (the samples had been taken on day 28.
- Sterility check if applicable: NA.

- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, two replicates.
- Abiotic sterile control: No.
- Toxicity control: Yes (one replicate).
- Reference substance: Yes (one replicate).
- Other:.

STATISTICAL METHODS: NA

Reference substance:

benzoic acid, sodium salt

Test performance:

No events are reported, which might have affected the quality of the study.

Parameter:

% degradation (TOC removal)

Value:

94

Sampling time:

28 d

Remarks on result:

other: Test concentration 25 mg/L OC

Details on results:

The substance was degraded within 28 days by average 93.5% (mean of 87% and 100%). The substance was not toxic to the activated sludge, since 59 % of the reference substance was degraded within 14 days in the presence of the test substance (trigger is 25%).

Results with reference substance:

Biodegradation of the reference substance reached 68 % within 14 days of incubation. Trigger for validity is 60%. Hence the test is rendered valid.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance is readily biodegradable since 93.5% were mineralized within 28 days durnig a valid OECD 301 B study.

Executive summary:

In a valid GLP study according to OECD 301B the test item was aerobically exposed at 11.1 mg C/L to standard OECD mineral medium and activated sludge obtained from a domestic STP (non-adapted, 10^5 x 10^6 CFU/L in the test). Exposure was for 28 days, under stirring conditions and between 20 and 24°C. Six brown glass reactors with a volume of 5 L were stocked with 3 L volume, which was constantly aerated with CO2 free air. Each reactor had received inocculum and of mineral medium. CO2 as produced by the inocculum was adsorbed by Ba(OH2) precipitation, which had been exposed in 3 serial 250 mL gas-washing bottles, connected serially to the reactors. Trapped inorganic carbon was determined indirectly by titration of unreacted Ba(OH)2 with hydrochloric acid to the phenolphthalein endpoint. Five test groups were incubated: Test item (11.1 mg C/L, two replicates), blank control (two replicates), reference substance (10.2 mg C/L of sodium acetate, one replicate) and a toxicity control (11.1 mg C/L test substance plus 10.2 mg C/L reference substance, one replicate). Biodegradation was determined on days 1, 4, 6, 8, 11, 14, 18, 21, 25 and 28. In addition inorganic carbon was determined on day 29 after release of CO2 from the 28 day inocculum by HCL and measurement of unreacted Ba(OH2), as described above. The results show that all validity criteria were fulfilled. Hence the results of this study are valid. The reference substance was degraded by 68% on day 14 (trigger is 60%). Test items results show that 87 % and 100% of the test material were mineralized within 28 days, i.e. average 93.5%. The 10% trigger for biodegradation elimination was reached by day 4 of the test where 25% and 16% had been mineralized. The pass level for ready biodegradation was reached between days 11 and 14, where average 58% and 67% mineralization had been found, respectively. This indiates that the10 -day window was met (the 10 window reached from day 4 to day 14). The substance is not toxic to STP microorganisms, since 59% of CO2 were evolved by the toxicity control witin 14 days (trigger is 25%).

Description of key information

The results of the key study, which is appropriate for the assessment of ready biodegradability show  that the substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable