6-ethyl-5-fluoro-4(3H)-pyrimidone

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 1996-06-28 to 1996-07-26

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

Specific details on test material used for the study:

Batch No.: 950704
Purity: 95.7%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of activated sludge: The aeration stage of the Anglian Water sewage treatment plant (Godmanchester) treating predominantly domestic sewage.
- Preparation of inoculum for exposure: The sample was allowed to settle for approximately 30 minutes and the supernatant filtered through Whatman GFA coarse filter paper (first 250 mL discarded). The filtrate was maintained under aeration and used within 24 hours of collection.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: see "APPENDIX 1 Standard mineral medium" in attached background material

- Preparation:
The test and standard substances were dispersed directly in mineral medium without the aid of auxiliary solvents or dispersing agents to give the following series:
(a) Inoculated mineral medium.
(b) Test substance (2 mg/L).
(c) Sodium benzoate (3 mg/L).
(d) Test substance (2 mg/L) plus sodium benzoate (3 mg/L).
The stock mineral medium with activated sewage sludge filtrate (at the rate of 1 mL of inoculum per litre) was inoculated immediately prior to the preparation of series (a), (b), (c) and (d).

- Procedure:
Biochemical Oxygen Demand bottles (280 mL) of darkened glass, fitted with ground glass stoppers, were filled by siphon and firmly stoppered to exclude all air bubbles. Sufficient bottles were prepared in each test and control series to allow a single oxygen determination per bottle to be made at 0, 4, 7, 11, 14, 18, 21, 25 and 28 days (duplicate bottles at each sampling time). Sufficient bottles for series (d) were prepared to provide information on inhibitory effects on Days 0, 14 and 28 only.
The bottles were incubated in a water bath at 20  1°C until removed for measurement of dissolved oxygen concentration by means of a Yellow Springs BOD Meter (Model 59).

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

4

Sampling time:

4 d

Parameter:

% degradation (O2 consumption)

Value:

5

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

11 d

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

11

Sampling time:

18 d

Parameter:

% degradation (O2 consumption)

Value:

14

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

5

Sampling time:

25 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

10

Sampling time:

28 d

Details on results:

Cultures containing both test and standard substances combined showed an oxygen depletion value 6% lower than that anticipated on the basis of results from separate cultures at Day 14. Consequently the test item is not considered to have had an inhibitory effect on sewage bacteria under the conditions of this test.
Oxygen depletions in the inoculated control series were within the prescribed limits ( ≤1.5 mgO2/L after 28 days).

Results with reference substance:

Sodium benzoate attained 86% biodegradation within 28 days.

Validity criteria fulfilled:

no

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item attained 10% degradation after 28 days.

Executive summary:

A study was performed to assess the ready biodegradability of test item in accordance with OECD 301 D.

 

Sealed bottles containing the test substance and inorganic mineral medium were inoculated with activated sewage sludge bacteria and incubated for up to 28 days at 20±1°C. On Days 0, 4, 7, 11, 14, 18, 21, 25 and 28 duplicate bottles were taken and dissolved oxygen measured electrochemically.

The test item attained only 10% biodegradation after 28 days and therefore may not be termed as readily biodegradable.

The test item was not found to be inhibitory to activated sewage sludge bacteria under the conditions of this test.

Description of key information

A study was performed to assess the ready biodegradability of test item in accordance with OECD 301 D.

The test item attained only 10% biodegradation after 28 days and therefore may not be termed as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater