4,6-Dichloro-5-fluoropyrimidine

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:

09 Jan - 16 Mar 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): secondary effluent of a domestic sewage treatment plant (Odenthal)
- Method of cultivation: aeration of mineral medium plus inoculum (filtrate) for 6 days
- Concentration of sludge: 5 mL/L
- Water filtered: Yes

Duration of test (contact time):

28 d

Initial conc.:

18.3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium
- Test temperature: 20 +/- 1 °C
- Aeration of dilution water: Aeration for 6 days
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Glass bottles
- Number of culture flasks/concentration: 10 bottles
- Method used to create aerobic conditions: aeration of solution
- Measuring equipment: Dissolved oxygen was measured by chemical uptake
- Test performed in closed vessels due to significant volatility of test substance: Closed bottles

SAMPLING
- Sampling frequency: Every seven days
- Sample storage before analysis: No storage of samples

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, 10 bottles
- Abiotic sterile control: No
- Toxicity control: Yes, 10 bottles
- Reference substance: Yes, 10 bottles

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

7 d

Details on results:

The toxicity control was degraded to 25% after 14 and 28 d, respectively. Thus, the test item is not toxic to the inoculum.

Results with reference substance:

81 % degradation of reference substance over 28 days was observed.

Validity criteria for the measurement of the biodegradation according to OECD 301:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
In order to check the procedure, reference compounds which meet the criteria for ready biodegradability are tested by setting up an appropriate vessel in parallel as part of normal test runs. Suitable compounds are aniline (freshly distilled), sodium acetate and sodium benzoate.	Benzoic acid, sodium salt was used as a reference compound.	Yes
A test is considered valid if the difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20% and if the percentage degradation of the reference compound has reached the pass levels by day 14.	% degradation of the two measured values of the test substance at the end of the test (28 d) range between 0 - 0% There was 81 % degradation of the test substance after 14 d - the pass level (60 % for ThOD) was reached.	Yes
If in a toxicity test, containing both the test substance and a reference compound, less than 35% degradation (based on total DOC) or less than 25% (based on total ThOD or ThCO2) occurred within 14 days, the test substance can be assumed to be inhibitory. The test series should be repeated, using a lower concentration of test substance (if this can be done without seriously impairing the accuracy of the DOC determination) and/or a higher concentration of inoculum, but not greater than 30 mg solids/L.	The used concentrations of the test substance did not show toxic effects to bacteria (after 14, 21 and 28 d, 25 % degradation was measured based on ThOD).	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on results incl. tables'.

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test substance showed: 0 % degradation after 28 days. Therefore the test substance has to be classified as "Not Readily Biodegradable".

Executive summary:

The test substance in a mineral medium was inoculated with secondary effluent and incubated for 28 d under aerobic conditions in completely full, closed bottles. During this period the biodegradation is followed by analysis of dissolved oxygen. The amount ofoxygen taken up by the test chemical, corrected for uptake by the blank inoculum run in parallel, is expressed as a percentage of theoretical oxygen demand (ThOD) or chemical oxygen demand (COD). The test substance showed: 0 % degradation after 28 days. Therefore the test substance has to be classified as "Not Readily Biodegradable". The reference compound showed 81 % degradation after 28 days.

Description of key information

The test substance in a mineral medium was inoculated with secondary effluent and incubated for 28 d under aerobic conditions in completely full, closed bottles. During this period the biodegradation is followed by analysis of dissolved oxygen. The amount of oxygen taken up by the test chemical, corrected for uptake by the blank inoculum run in parallel, is expressed as a percentage of theoretical oxygen demand (ThOD) or chemical oxygen demand (COD). The test substance showed: 0% degradation after 28 days. Therefore, the test substance has to be classified as "Not Readily Biodegradable". The reference compound showed 81% degradation after 28 days.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater