(E)-1,2-difluoroethylene

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:

26 May 2020 - 30 July 2020

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)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

TEST MATERIAL
- Source and lot/batch number of test material: N1200115
- Purity: 99.9989%
- Storage: gas cylinder
- Appearance: colourless gas

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Secondary effluent of a sewage treatment plant treating predominantly domestic sewage in Kurame-shi, Fukuoka, Japan.
- Sampling date: 27 May 2020

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 7.62 mg/L

Details on study design:

Preparation of test
a) Preparation of inoculum: the collected secondary effluent was filtered through a No. 2 filter paper and the filtrate was used as inoculum. The inoculum was kept under aerobic conditions until used.
b) Preparation of mineral medium: The mineral medium (6L) was prepared: each 1 mL of stock solutions (a), (b), (c) and (d) prescribed in the test guideline were made up to 1 L with purified water. After the preparation, it was aerated for 20 min and stood still for 24.0 hours at a test temperature.
c) Addition of inoculum: The prepared inoculum (a) was added into the mineral medium at the rate of 0.05 mL of the inoculum per litre of the mineral medium.

Preparation of test solutions
The following test solutions were prepared by using 3 test bottles and incubated.
a) Abiotic control: test solutions (water + teste item, n=2): each test bottle with purified water and 200 µL of the test item aqueous solution (0.762 mg as the test item) was added into it with a microsyringe, giving he concentration of the test item of 7.62 mg/L.
b) Test suspension: test solution (inoculum + test item, n=12): each test bottle was filled with inoculated mineral medium and 200 µL of the test item aqueous solution (0.762 mg as the test item) was added into it with a microsyringe, giving final test item concertation of 7.62 mg/L.
c) Control: Test solution (inoculum + sodium benzoate, n=10): Each test bottle was filled with 3.00 mg/L was prepared with the inoculated mineral medium.
d) Blank inoculum (n=11): Each bottle was filled with inoculated mineral medium.

Conditions of incubation:
Test vessel: glass bottle (100 mL)
Temperature: 20±1° (measured value: 19.3 – 20.6 °C)
Incubation duration: 28 days (under dark condition)
Observation: during the incubation period, appearances of the test solutions were observe once a day. The incubation temperature was measured and recorded once a day.

Reference substance:

benzoic acid, sodium salt

Test performance:

The validity criteria of the test were met.

Key result

Parameter:

% degradation (O2 consumption)

Remarks:

BOD

Value:

ca. -1

Sampling time:

28 d

Key result

Parameter:

% degradation (test mat. analysis)

Remarks:

by GC

Value:

ca. 0

Sampling time:

28 d

Results with reference substance:

Percentage biodegradation of sodium benzoate by BOD on Day 14: 71%, 70%

Analytical results of the test solutions on Day 28:

		Water + test item		Inoculum + test item		Theoretical amount
BOD	mg O2/L	-	-	-0.05	-0.05	7.62
Residual amount and percentage residue of test item (by GC)	mg	0.761	0.746	0.756	0.754	0.762
	%	100	98	99	99	-

 

Percentage biodegradation:

		Inoculum + test item [mean value]
		Day 7	Day 14	Day 21	Day 28
Percentage biodegradation by BOD	%	2 2 [2]	1 2 [1]	0 1 [0]	-1 -1 [-1]
Percentage biodegradation of test item (by GC)	%	- - -	- - -	- - -	0 0 [0]

 

Averages of the percentage biodegradation on Day 28 by BOD and GC were -1% and 0%, respectively. Moreover, no peak corresponding to a degradation product was detected on the GC chromatograms. The results showed that the test item was not biodegraded under the test conditions of this study.

Validity of test condition

The test was valid:

		Value in this test	Value of criterion
Difference between extremes of replicate values of percentage biodegradation on test solutions (inoculum + test item) on Day 28	BOD	0%	< 20 %
	Test item (by GC)	0%
Percentage biodegradation of sodium benzoate by BOD on Day 14		71%, 70%	> 60 %
Amount of oxygen depletion in test solution (inoculum blank) on Day 28		0.56 mg O2/L	≤ 1.5mg O2/L
Residual concentration of oxygen in each bottle during the incubation period		≥5.04 mg O2/L	≥0.5 mg O2/L

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item was not biodegradable under the test conditions of this study.

Executive summary:

Summary:

Objetive: This study was aimed at evulationg the biodegradability of TKN1 by microorganisms.

Test Guideline: OECD No 301D "Ready Biodegradability: Close Bottle Test

Conditions of incubation:

Concentration of test item: 7.62 mg/L

Inoculum: Filtrate of secondary effluent of a sewage treatment plant treating predominatly domestic sewage.

Concentration of inoculum: 0.05 mL/L

Volume of test solution: 100 mL

Incubation temperature: 20°C

Incubation condition: Stationary incubation in sealed bottles.

Incubation duration: 28 days (under dark condition)

 

Measurement and analysis for calculation of percentage biodegradation:

a) Measurement of disssolved oxygen (DO) by diaphragm electrode mehtod.

b) Determination of test item by gas chromatography (GC).

 

Results:

Percentage biodegradation by biochemical oxygen demand (BOD) at Day 28: average -1%

Percentage biodegradation of test item (by GC) at Day 28: average 0%

 

Conclusion:

The test item was not biodegraded under the test conditions of this study. 

Description of key information

The ready biodegradability of TKN1 was assessed (CERI, 2020, Study 16698). The procedure was designed to be compatible the OECD test guidelines 301D, and was conducted in compliance with GLP.

The parameter determined in the test was the percentage biodegradation by biochemical oxygen demand after 28 days of incubation at temperatures nominally in the range 20 ± 1°C. TNK1 was added to bottles containing mineral salts medium inoculated with activated sludge at a nominal test concentration of 7.62 mgO2/L. Control cultures contained inoculated mineral salts medium alone and inoculated mineral salts medium plus the reference substance sodium benzoate (3.0 mgO2/L). 

Averages of the percentage biodegradation on Day 28 by BOD and GC were -1% and 0%, respectively. Moreover, no peak corresponding to a degradation product was detected on the GC chromatograms. The results showed that the test item was not biodegraded under the test conditions of this study.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater