Reaction mass of hentriacontan-16-one and pentatriacontan-18-one and tritriacontan-16-one

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:

From 2017-10-18 to 2017-11-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: FK650468
Purity: 100%

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

- The inoculum: Secondary effluent, microorganisms from a domestic waste water treatment plant.
- Origin: The secondary effluent was supplied from the sewage plant for domestic sewage in Veszprém, Hungary.
- Conditioning: The secondary effluent used for this study was allowed to settle approximately for an hour, then the decanted effluent was aerated until use (not later than an hour).

Duration of test (contact time):

28 d

Initial conc.:

5.3 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

RECONSTITUTED WATER
- Stock solutions: In deionised water analytical grade salts were added to prepare the following stock solutions: a) Solution: KH2PO4, K2HPO4, Na2HPO4 x 12H2O, NH4Cl, Deionised water; b) Solution: MgSO4 x 7 H2O; Deionised water; c) Solution: CaCl2 x 2 H2O, Deionised water; d) Solution: FeCl3 x 6 H2O; Deionised water
- Ratio of ingredients: Adequate amount of the stock solutions a) - d) were combined and filled up with deionised water to the appropriate final volume. The test medium was aerated for 20 minutes and allowed to stand for about 20 hours at the test temperature. The dissolved oxygen concentration was 8.9 mg/L at about 22 °C.
TEST UNITS
- Type and Size: BOD bottles (300 ml) with special neck and glass stoppers.
TEST CONDITIONS
- Temperature: 20.8 - 23.3°C
- pH: 7.32
- Continuous darkness: yes
PREPARATION OF THE TEST SOLUTIONS
- Test Item: 18.0 mg of test item was thoroughly mixed into 3.40 litres of aqueous test medium
- Procedure Control: stock solution (360 mg/L) corresponding to 12.24 mg of Sodium benzoate was mixed into 3.40 litres of aqueous test medium
- Inoculum Control: Only filtered inoculum was added to 3.40 litres of aqueous test medium
- Toxicity Control: Test item (18.0 mg) and reference item stock solution (360 mg/L, 34.0 mL) were mixed into 3.40 litres of aqueous test medium
COURSE OF THE TEST
- Test Bottles: 10 bottles each
MEASUREMENTS
- COD Measurement: determined using Lovibond® COD Measuring System.
- Measurement of Oxygen: measured with an oxygen meter with a stirring O2 electrode. Oxygen measurements were performed in duplicate on days 0, 7, 14, 21 and 28.
- Measurement of Temperature: measured continuously and registered on weekdays

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0.8

Sampling time:

28 d

Details on results:

Under the test conditions the percentage biodegradation of test item reached a mean of 0.8 % after 28 days based on the COD of the test item.

Parameter:

COD

Value:

1.13 g O2/g test mat.

Results with reference substance:

The reference item was sufficiently degraded to a mean of 79.2 % after 14 days, and to a mean of 91.7 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 41.4 % biodegradation was noted within 14 days and 46.2 % biodegradation after 28 days of incubation.

According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 5.3 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.

The study met the validity criteria.

The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item is considered not readily biodegradable.

Executive summary:

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days according to OECD 301D. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was allowed to settle and then aerated until use.

Under the test conditions the percentage biodegradation of test item reached a mean of 0.8 % after 28 days based on the COD of the test item.

 The reference item Sodium benzoate was sufficiently degraded to a mean of 79.2 % after 14 days, and to a mean of 91.7 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

The study met the validity criteria.

The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.

Based on the results of this study, the test item is considered not readily biodegradable.

Description of key information

Under the test conditions the percentage biodegradation of test item reached a mean of 0.8 % after 28 days based on the COD of the test item. Therefore, the test item is considered not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days according to OECD 301D. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was allowed to settle and then aerated until use.

Under the test conditions the percentage biodegradation of test item reached a mean of 0.8 % after 28 days based on the COD of the test item. The study met the validity criteria. The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms. Based on the results of this study, the test item is considered not readily biodegradable.