Potassium Lauroyl Wheat Amino Acids

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:

From July 27, 2011 to Semtember 26, 2011

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 (adaptation not specified)

Details on inoculum:

- The source of test organisms was activated sludge freshly obtained from Cambridge Sewage Treatment Works, Cowley Road.
- Dry sludge solids: 7.4%
- Dry sludge solids in test: 0.03g/L
(Volume of mineral medium: 1.5L per biorector)

Duration of test (contact time):

ca. 28 d

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

- Flasks of nominal volume 2000 mL were filled with 500 mL of inoculated mineral medium. The blanks, reference (sodium acetate) and test bottles were set up in duplicate, with a single replicate for the toxicity control. Test and reference substances were added to a final concentration of 20 mg Carbon/L. Atmospheric air was pumped into the test system and scrubbed clean of CO2 by passing over soda lime. The air continued into the test vessel where it collected any evolved carbon dioxide before moving intothe CO2 traps, each containing 200 mL of 0.05M sodium solution. The test solutions were stirred for the duration of the study.
- The study consisted of six bottles:
2 inoculum blanks (no test substance),
2 test bottles,
1 positive control (sodium acetate) and
1 toxicity control (test substance plus sodium acetate).

Reference substance:

acetic acid, sodium salt

Preliminary study:

-

Test performance:

Measurement of the CO2

Key result

Parameter:

% degradation (CO2 evolution)

Value:

96

Sampling time:

28 d

Remarks on result:

other: potential for biodegradation

Details on results:

- The relative values calculated from the measurements performed during the test period revealed 88% and 103% biodegradation of the test substance (based on ThCO2), for the duplicate bottles tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was met.
- In the toxicity control, the test substance was found not to inhibit microbial activity.
- Since all criteria for acceptability of the test were met, this study was considered to be valid.
- The test substance was designated as readily biodegradable.

Results with reference substance:

The biodegradation value was calculated to be 84% after 14 d.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the ready biodegradability of the test substance, 'potassium lauroyl wheat amino acids' (active: 20%) using CO2 evolution test, according to OECD Guideline 301B, in compliance with GLP. Aerobic sludge inoculum was prepared with activated sludge collected from sewage plant (Cambridge Sewage Treatment Works, Cowley Road) and in order to have a concentration of suspended solid of about 0.03 g/L. The inoculum blank, reference and test substance bottles were prepared in duplicate, with a single replicate for the toxicity control. Test and reference substances (sodium acetate) at concentrations of 20 mg Carbon/L were added to appropriate bottles and rate and extent of biodegradation based on CO2 evolution was observed for 28 d. A toxicity control group treated with 20 mg carbon/L + 20 mg carbon/L of reference substance 20 mg Carbon/L, was included in the experiment. The evolved carbon dioxide was trapped in sodium hydroxide and was measured as dissolved inorganic carbon (DIC) using a Tekmar-Dhormann Phoenix 8000 (the UV persulfate Analyser). The amount of carbon dioxide produced (determined as DIC) is expressed as a percentage of the organic carbon in the test substance. Test and reference values were expressed as a percentage of the theoretical carbon dioxide (ThCO2). A value of 21.8 mg/L CO2 (6 mg/L C) was recorded for the inoculum blank. The reference substance achieved 71% biodegradation after 14 d, which demonstrated that the inoculum was biologically active. In the toxicity control, the test substance was found not to inhibit microbial activity (biodegradation was 68%). All the test validity criteria were achieved during the study. The test substance gave a positive result (>60% degradation relative to the ThCO2 value) with 96% degradation on Day 28 and a maximum of 105% recorded on Day 29. 10% degradation was achieved just before Day 1, and 60% biodegradation was reached after 4.5 d, thus the test substance was concluded to have achieved the 10-d window. Under the study conditions, the test substance was considered to be readily biodegradable (Chemex, 2011).

Description of key information

Based on the study results, the test substance was determined to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

A study was conducted to determine the ready biodegradability of the test substance, 'potassium lauroyl wheat amino acids' (active: 20%) using CO2 evolution test, according to OECD Guideline 301B, in compliance with GLP. Aerobic sludge inoculum was prepared with activated sludge collected from sewage plant (Cambridge Sewage Treatment Works, Cowley Road) and in order to have a concentration of suspended solid of about 0.03 g/L. The inoculum blank, reference and test substance bottles were prepared in duplicate, with a single replicate for the toxicity control. Test and reference substances (sodium acetate) at concentrations of 20 mg Carbon/L were added to appropriate bottles and rate and extent of biodegradation based on CO2 evolution was observed for 28 d. A toxicity control group treated with 20 mg carbon/L + 20 mg carbon/L of reference substance 20 mg Carbon/L, was included in the experiment. The evolved carbon dioxide was trapped in sodium hydroxide and was measured as dissolved inorganic carbon (DIC) using a Tekmar-Dhormann Phoenix 8000 (the UV persulfate Analyser). The amount of carbon dioxide produced (determined as DIC) is expressed as a percentage of the organic carbon in the test substance. Test and reference values were expressed as a percentage of the theoretical carbon dioxide (ThCO2). A value of 21.8 mg/L CO2 (6 mg/L C) was recorded for the inoculum blank. The reference substance achieved 71% biodegradation after 14 d, which demonstrated that the inoculum was biologically active. In the toxicity control, the test substance was found not to inhibit microbial activity (biodegradation was 68%). All the test validity criteria were achieved during the study. The test substance gave a positive result (>60% degradation relative to the ThCO2 value) with 96% degradation on Day 28 and a maximum of 105% recorded on Day 29. 10% degradation was achieved just before Day 1, and 60% biodegradation was reached after 4.5 d, thus the test substance was concluded to have achieved the 10-d window. Under the study conditions, the test substance was considered to be readily biodegradable (Chemex, 2011).

[Type of water: freshwater]