complex mixture from biological origin

Endpoint summary

Description of key information

The test item is considered as being readily biodegradable.

Testing of hydrolysis and adsorption/desorption behaviour was not conducted because the test item is readily biodegradable and has a LogKow <3.

Additional information

Biodegradation:

The biodegradability of Sophorolipids: fermentation products of glucose and fatty acids, C18-unsatd., esters with glycerol with yeast Candida Bombicola, partially hydrolysed, EC 941-809-7, was investigated in two guideline studies.

a. OECD guideline 301F

The biodegradation of the test substance was investigated over a 28 day period in a manometric Respirometry Test according to OECD Guideline 301 F (1992). The test medium was inoculated with microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater.

The rate of degradation was monitored by measuring the quantity of oxygen required to maintain a constant gas volume in the respirometer flasks over 28 days.

Sodium benzoate was used as a degradable reference substance at a concentration of 100 mg/L, along with a toxicity control at 100 mg/L test substance and 100 mg/L sodium benzoate. The biodegradation of the test substance was found to be at mean 69 % with a standard deviation of 0.8 % for a concentration of 100 mg test substance/L and at mean 85 % with a standard deviation of 5.4 % for a concentration of 60 mg test item/L. For a concentration of 100 mg test substance/L biodegradation within the 10-day-window was found to be 61 %. For a concentration of 60 mg test substance/L biodegradation within the 10-day-window was found to be 75 %. The degradation of of the reference substance sodium benzoate had reached 83 % within the first 14 days. According to the guideline, the test item is considered as being readily biodegradable under the test conditions.

b. OECD guideline 311

The anaerobic biodegradation of the test substance was determined in a test according to OECD guideline 311 (2006) and EN ISO 11734 (1998). Biodegradation was monitored by continuous measurement of the gas developed until the end of the test. Anaerobic sludge was used as inoculum.

After 61 days a degradation of 110.7 % was observed. The degradation exceeding 100 % might be explained by the following: In the test flasks bacterial growth was enhanced by the well biodegradable test substance. After digestion of the test substance the biomass started self-digestion. Self-digestion of the previously increased biomass in the test flasks might very well be higher than the control flasks.

Except for the degradation of the positive control, the validity criteria were met. As the test item was readily and completely biodegradable under test conditions, this deviation from the guideline can be stated as uncritical. Therefore, the test item is stated to be biodegradable under anaerobic conditions.

Discussion

The test item Sophorolipids: fermentation products of glucose and fatty acids, C18-unsatd., esters with glycerol with yeast Candida Bombicola, partially hydrolysed, EC 941-809-7, was readily biodegradable in both an OECD guideline 301F and an OECD guideline 311 test.

This information is used in a read-across approach in the assessment of the target substance. For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Hydrolysis

Testing is not required. According to the REACH Regulation, Annex VIII, column 2 the study does not need to be conducted if the substance is readily biodegradable. Handbook data describe that the test substance hydrolyses under to both acid and alkaline conditions. Transformation products are sophorose and deacetyled free acids.

This information is used in a read-across approach in the assessment of the target substance. For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Adsorption / desorption

The log Koc of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Starmerella bombicola, hydrolysed was estimated to be 4.46 using the QSAR model KOCWIN v2.00 leading to an estimated Koc of 29000 L/kg.