Fatty acids, C16-18 and C18-unsatd., compds. with triethanolamine

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:

16.5.1997 to 13.6.1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted according to OECD 301D non-GLP. However some experimental details are missing, like e.g., exact source of the sewage and whether the sewage was adapted or not. Dimensions and size of the test vessels were not reported. Result tables state that the test was conducted with seawater, however this seems to be wrong, as it is stated that aged distilled water was used to prepare the nutrient medium. Furthermore sewage microorganisms will not survive marine conditions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

other: NS-EN-ISO 10634 - 1995: Water Quality - Guideance for the preparation of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium

Qualifier:

according to guideline

Guideline:

other: Norwegian Standards Association, 1979. Biokjeminsk oksygenforbruk; BOD7. Fortynningsmetode NS 4749, Norges Standariseringsforbund.

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/sewage (e.g. location, sampling depth, contamination history, procedure): Sewage of a municipal STP.

Duration of test (contact time):

28 d

Initial conc.:

ca. 1.84 mg/L

Based on:

test mat.

Initial conc.:

4.54 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium. Basis for the medium was distilled water, aged for 24 hours between 18 and 22 °C. the nutrients were added one hours before test initiation.
- Test temperature: 18 to 22 °C.

TEST SYSTEM
- Number of culture flasks/concentration: Two bottles per test group.
- Measuring equipment: WTW Oxi 196 oxygen meter equipped with WTW EO 196-1,5 oxygen electrode.
- Test performed in closed vessels due to significant volatility of test substance: Yes, since the test design is a closed bottle test

SAMPLING
- Sampling frequency: Samples were analyzed on days 0, 7, 14, 21 and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, in duplicate
- Abiotic sterile control: No
- Toxicity control: Yes, in duplicate
- Other: Reference substance (one concentration): Sodium benzoate, in duplicate

PREPARATION OF TEST ITEM
- Glass fiber filters were used as an inert carrier for the test substance. The test substance was applied to the filters as a solution in ethanol. The filters were carefully tried for one hour at room temperature, and then placed in the test bottles. Filters treated similarly with ethanol only, were placed in the control bottles.

STATISTICAL METHODS: NA

Reference substance:

benzoic acid, sodium salt

Test performance:

No events are reported, which might have affected the quality of the study.

Parameter:

other: BOD

Value:

81

Sampling time:

28 d

Results with reference substance:

Within 28 days of incubation, average 92% of the reference substance had been degraded of which 60% was produced within 7 days. This result validates the testing procedure.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The results of the study show that the substance is not toxic to STP microorganisms and readily biodegradable.

Executive summary:

In a non-GLP study according to OECD 301 D, the test item was exposed in closed bottles at a concentration of 1.84 mg/L test material to a nutrient medium and sewage from an unspecified municipal STP. The test substance had been mounted on glass fibre filters, since the substance is not soluble in water. Exposure was for 28 days at 18-22°C. 4 test groups were incubated in duplicate: Test item (1.84 mg/L test material), blank control, reference substance (2.54 mg/L sodium benzoate) and toxicity control (1.84 mg/L test substance plus 1.27 mg/L sodium benzoate). DOC was determined by a WTW Oxi 196 oxygen meter equipped with WTW EO 196-1,5 oxygen electrode. Biodegradation was determined by DOC measurements on days 0, 7, 14, 21 and 28. Within 28 days of incubation, average 92% of the reference substance had been degraded of which 60% was produced within 7 days. This result validates the testing procedure. Test item results shows that average 81% of the test substance was degraded within 28 days of which 60% was reached within 14 days. The BOD of the toxic control was at least average 82%. The results show that the substance is not toxic to STP microorganisms and is readily biodegradable.

Description of key information

The result of the key study, which is appropriate for the assessment of ready biodegradability in freshwater according to OECD 301 clearly shows that the substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Biodegradation results of the key study are supported by the results of a valid GLP and a valid non GLP study which were conducted with seawater according to OECD 306 at 2 and 17.5 mg/L substance, respetively. The results show that the substance is ultimately biodegradable in seawater.