Fatty acids, C16-18, reaction products with ethanolamine

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:

2019

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:

Type: Activated Sludge
Source: Cambridge Sewage Treatment Works, Cowley Road
Sludge pre-treatment: Sieved to 850μm to remove coarse particulates, settled and centrifuged at approximately 4000rpm for approximately 5-10 minutes. The supernatant was discarded and the sludge pellet re-suspended in mineral media. The sludge was centrifuged again at 4000rpm for approximately 5-10 minutes and then the supernatant discarded. The resulting sludge pellet was homogenised thoroughly by mechanical stirring. Dry sludge solids content determined on the homogenised pellet.
Dry sludge solids: 4.79%
Volume of mineral medium: 1.5L per bioreactor
Dry sludge solids in test: 0.03g/L

Duration of test (contact time):

28 d

Initial conc.:

61.3 mg/L

Based on:

TOC

Remarks:

Test 1

Initial conc.:

61.2 mg/L

Based on:

TOC

Remarks:

Test 2

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Conical flasks of nominal volume 2000ml were filled with 1500mL of inoculated mineral medium. The blanks, reference and test bottles were set up in duplicate, with a single replicate for the toxicity control. Test and reference materials were added to appropriate bottles to a final concentration of 20 mg Carbon/L. Atmospheric air was pumped into the test system and scrubbed clean of carbon dioxide by passing over soda lime. The air continued into the test vessel where it collects any evolved carbon dioxide before moving into the carbon dioxide traps, each containing 200 mL of 0.05M sodium hydroxide solution. The test solutions were stirred and maintained between 22.0 – 23.8°C over the duration of the study.

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

50

Sampling time:

7 d

Parameter:

% degradation (CO2 evolution)

Value:

90

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

101

Sampling time:

23 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

105

Sampling time:

28 d

Results with reference substance:

A maximum average value of 89% degradation of the sodium acetate was achieved on day 29.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance was readily biodegradable under the conditions of this test.

Executive summary:

The ready biodegradation of Fatty acids, C16-18, reaction products with ethanolamine was evaluated during a GLP-compliant study conducted according to the OECD Testing Guideline 301B.

The test substance gave a positive result (>60% degradation relative to the ThCO2 value) with a maximum of 116% recorded on day 29 (values in excess of 100% may be a result of analytical variation). It may therefore be concluded that there is a potential for biodegradation under environmental conditions.

The inoculum blank should not normally produce more than 70 mg/L CO2 (19.1 mg/L C) for the test to be valid. A value of 28.1 mg/L CO2 (7.7 mg/L C) was recorded.

The guideline requires that the reference material degrades by at least 60% of its ThCO2 value, a maximum average value of 89% degradation of the sodium acetate was achieved on day 29.

The test protocol requires that a 10-day window is applied to the degradation results (60% degradation to be reached within 10 days of 10% of the theoretical carbon dioxide produced). Fatty acids, C16-18, reaction products with ethanolamine reached 69% degradation within 9 days, therefore the 10-day window was achieved.

Mean reference degradation also achieved 62% within 9 days, passing the 10-day window.

Fatty acids, C16-18, reaction products with ethanolamine was insoluble in water at the required level for this test, therefore measured quantities of the test item were added directly into the test bioreactors.

The final conclusion of this study is that Fatty acids, C16-18, reaction products with ethanolamine was readily biodegradable under the conditions of this test.

Description of key information

The ready biodegradation of Fatty acids, C16-18, reaction products with ethanolamine was evaluated during a GLP-compliant study conducted according to the OECD Testing Guideline 301B.

The test substance gave a positive result (>60% degradation relative to the ThCO2 value) with a maximum of 116% recorded on day 29 (values in excess of 100% may be a result of analytical variation). It may therefore be concluded that there is a potential for biodegradation under environmental conditions.

The inoculum blank should not normally produce more than 70 mg/L CO2 (19.1 mg/L C) for the test to be valid. A value of 28.1 mg/L CO2 (7.7 mg/L C) was recorded.

The guideline requires that the reference material degrades by at least 60% of its ThCO2 value, a maximum average value of 89% degradation of the sodium acetate was achieved on day 29.

The test protocol requires that a 10-day window is applied to the degradation results (60% degradation to be reached within 10 days of 10% of the theoretical carbon dioxide produced). Fatty acids, C16-18, reaction products with ethanolamine reached 69% degradation within 9 days, therefore the 10-day window was achieved.

Mean reference degradation also achieved 62% within 9 days, passing the 10-day window.

Fatty acids, C16-18, reaction products with ethanolamine was insoluble in water at the required level for this test, therefore measured quantities of the test item were added directly into the test bioreactors.

The final conclusion of this study is that Fatty acids, C16-18, reaction products with ethanolamine was readily biodegradable under the conditions of this test.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater