Reaction mass of 2-hydroxyethyl oleate, oleic acid, and 2-hydroxyethyl palmitate

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:

14 Nov 1997 - 09 Jan 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: ISO 10708: Determination of biochemical oxygen demand in a two-phase closed bottle test

Deviations:

yes

Remarks:

temperature variations of > 0.5 °C

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Sewage from the wastewater treatment plant 'Hochdahl', Germany
- Laboratory culture: No
- Concentration of sludge: 1 mL sewage / inoculum

Duration of test (contact time):

56 d

Initial conc.:

100 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 18-22 °C

TEST SYSTEM
- Culturing apparatus: bottles with conical shoulder (approx. 296 mL volume)
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: Stabilisation phase of one week (18-22 °C). Saturated with oxygen after stabilisation phase.
- Measuring equipment: WTW oxygen meter 'OXI 3000'
- Test performed in open system: no

SAMPLING
- Sampling frequency: Sampling was performed on day 0, 3, 7, 14, 21, 28, 56

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 replicates
- Abiotic sterile control: no
- Toxicity control: no
- Other: Positive control: sodium acetate, 3 replicates

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

61

St. dev.:

5

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

75

St. dev.:

5

Sampling time:

56 d

Details on results:

Day 3: 7%
Day 7: 22%
Day 14: 41%
Day 21: 53%
Day 28: 61%
Day 56: 75%

Results with reference substance:

The reference substance meets the 10-day window and was degraded by 89% after 28 days and by 92% after 56 days, respectively.

The chemical oxygen demand (COD) was defined using the Kelkenberg-method but there are indicators that is was not defined well (compared to the calculation of the theoretical oxygen demand (ThOD)). Anyway the COD was used for calculation.

According to “OECD Guidelines for the testing of chemicals – Revised introduction to the OECD guidelines for testing of chemicals, Section 3 – Part 1: Principles and strategies related to the testing of degradation of organic chemicals degradation” published by OECD (2006) the ready biodegradability data for mixtures of structurally similar chemicals should be evaluated carefully. For substances with different chain lengths the 10-day window should not be used for the interpretation of results. It is possible that a sequential biodegradation took place which might have led to a prolonged lag-Phase and therefore a slower biodegradation period although the test substance was biodegraded in a large amount after the test duration. In this case the pass level can be applied at 28 days and is therefore readily biodegradable (61% after 28 days).

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

According to “OECD Guidelines for the testing of chemicals – Revised introduction to the OECD guidelines for testing of chemicals, Section 3 – Part 1: Principles and strategies related to the testing of degradation of organic chemicals degradation” published by OECD (2006) the ready biodegradability data for mixtures of structurally similar chemicalsshould be evaluated carefully. For substances with different chain lengths the 10-day window should not be used for the interpretation of results. It is possible that a sequential biodegradation took place which might have led to a prolonged lag-Phase and therefore a slower biodegradation period although the test substance was biodegraded in a large amount after the test duration. In this case the pass level can be applied at 28 days and is therefore readily biodegradable (61% after 28 days).

Executive summary:

The chemical oxygen demand (COD) was defined using the Kelkenberg-method but there are indicators that is was not defined well (compared to the calculation of the theoretical oxygen demand (ThOD)). Anyway the COD was used for calculation.

According to “OECD Guidelines for the testing of chemicals – Revised introduction to the OECD guidelines for testing of chemicals, Section 3 – Part 1: Principles and strategies related to the testing of degradation of organic chemicals degradation” published by OECD (2006) the ready biodegradability data for mixturesof structurally similar chemicalsshould be evaluated carefully. For substances with different chain lengths the 10-day window should not be used for the interpretation of results. It is possible that a sequential biodegradation took place which might have led to a prolonged lag-Phase and therefore a slower biodegradation period although the test substance was biodegraded in a large amount after the test duration. In this case the pass level can be applied at 28 days and is therefore readily biodegradable (61% after 28 days).

Description of key information

A reliable biodegradation screening study was available on the read across substance, Fatty acids, C16-18, esters with ethylene glycol / 91031-31-1 / 292-932-1. At days 28 and 56 the percentage biodegradation was 61 and 75%, fulfilling the 60% biodegradation criteria.

According to “OECD Guidelines for the testing of chemicals – Revised introduction to the OECD guidelines for testing of chemicals, Section 3 – Part 1: Principles and strategies related to the testing of degradation of organic chemicals degradation” published by OECD (2006) the ready biodegradability data for mixtures of structurally similar chemicals should be evaluated carefully. For substances with different chain lengths the 10-day window should not be used for the interpretation of results. It is possible that a sequential biodegradation took place which might have led to a prolonged lag-Phase and therefore a slower biodegradation period although the test substance was biodegraded in a large amount after the test duration. In this case the pass level can be applied at 28 days and is therefore readily biodegradable (61% after 28 days).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable