complex mixture from biological origin

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details and justification of read-across please refer to the report attached in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

69

St. dev.:

0.8

Remarks on result:

other: continous measurement

Key result

Parameter:

% degradation (O2 consumption)

Value:

85

St. dev.:

5.4

Remarks on result:

other: continous measurement

Details on results:

The biodegradation within the 10-day-window was 61 % and 75 % in the assays with 100 mg/L and 60 mg/L, respectively. The 10-day-window started at day 1 for a concentration of 60 mg/L and at day 2 for a concentration of 100 mg/L

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of the test substance Sophorolipids: fermentation products of glucose and fatty acids, C18-unsatd., esters with glycerol with yeast Candida Bombicola, partially hydrolysed, EC 941-809-7 after 28 days incubation in the static test was found to be 69 % and 85 % in the assays with 100 mg/L and 60 mg/L, respectively.
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).

Executive summary:

The biodegradation 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 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.

 

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).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

other: Pressure of developed gas

Value:

110.7

Remarks on result:

other: Mean value from three vessels

Details on results:

The degree of biodegradation reached 100 %.
Lag-Phase: after 3 days, significant increase of pressure was detectable
Plateau-Phase: after 40 days, no significant pressure increase could be observed
Degradation at the end of the test: 100 % (calculated value 111 %)
The calculated degradation at the end of the test was more than 100 %. This might be due to the following: in the test flasks, bacterial growth was enhanced by the well biodegradable test item. After digestion of the test item, the biomass started self-digestion as no other organic nutrients were available. Self-digestion of the previously increased biomass in the test flasks might very well been higher than in the control flasks.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance 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 under anaerobic conditions.
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).

Executive summary:

The anaerobic biodegradation of the test substance Sophorolipids: fermentation products of glucose and fatty acids, C18-unsatd., esters with glycerol with yeast Candida Bombicola, partially hydrolysed, EC 941-809-7, 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.

 

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).

Description of key information

In a read-across approach it was shown that the substance is readily biodegradable under aerobic and anaerobic conditions.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

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).