3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooct-1-ene

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:

01 Feb - 01 Mar 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP Guideline Study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: "Method for testing the biodegradability of chemical substances by microorganisms" stipulated in the "Testing methods for new chemical substances" (November 21, 2003; No. 1121002, Pharmaceutical and food safety bureau)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

mixture of sewage, soil and natural water

Details on inoculum:

- Source of inoculum/activated sludge: The inoculum consists of sewage sludge, surface water and surface soil which was in contact with the atmosphere. Sampling locations were: Fushikogawa city sewage treatment plant, Fukashiba industrial sewage plant, Nakahama city sewage plant, Ochiai city sewage plant, Kitakami river, Shinano river, Yoshino river, Lake Biwa, Hiroshima bay, Dokai bay. All samples were taken in December 2006.
- Laboratory culture: no
- Method of cultivation: Activated sludge was prepared by mixing a filtrate of the supernatant of the sludge collected at sampling sites with the filtrate of the supernatant of the activated sludge previously cultivated for about three months. The mixed filtrate was aerated after the pH was adjusted to 7.0 ± 1.0. After ceasing aeration of the sludge mixture for approx. 30 min, supernatant corresponding to about one third of the whole volume was removed. Dechlorinated water was added to the remaining portion so that the total volume was 10 L. This mixture was aerated for 30 min or more, and then a predetermined amount of synthetic sewage was added to the mixture so that the concentration of the synthetic sewage was 0.1% in the volume of dechlorinated water added. Cultivation was carried out at 25 ± 2 °C. The activated sludge, which was cultivated for 18.5 h after it was added to the synthetic sewage was used.
- Suspended solids concentration: 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes
- Other: All test solutions were stirred with a magnetic stirrer.

TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (volume: 300 mL)
- Number of culture flasks/concentration: 3 bottles
- Measuring equipment: The BOD was measured automatically with a closed system oxygen consumption measuring apparatus.
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: Soda lime No. 1 was used for absorption of CO2
- Other:

SAMPLING
- Sampling frequency: Sampling was done continuously by an automatic measuring system (BOD measurement). The GC analysis was done at the end of the study.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, one bottle
- Abiotic sterile control: no
- Toxicity control: no
- Other: reference substance: yes, one bottle; test substance + water: yes, one bottle

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Parameter:

% degradation (test mat. analysis)

Value:

0

Sampling time:

28 d

Results with reference substance:

68% degradation after 14 d

Table 1: BOD measurements and % degradation during the study period

	BOD [mg] and percent degradation
Test vessel	7th day	%	14th day	%	21st day	%	28th day	%
Water + test item	0.9	-	3.1	-	4.7	-	6.1	-
Sludge + test item	0.9	-1	4.3	-3	6.4	-4	9.3	-4
Sludge + test item	0.8	-1	4.9	0	7.4	0	9.9	-1
Sludge + test item	0.7	-2	4.5	-2	6.9	-2	10.3	0
Control blank	1.1	-	5.0	-	7.3	-	10.2	-
Sludge + aniline	63.3	69	66.5	68	68.3	68	70.6	67

The test substance could not be measured by GC analysis at the end of the study. Therefore, it was considered that the substance may have been degraded to CO2 and absorbed by soda lime. After analysis the substance could not be measured in the absorber and only 1% of the substance was measured in test solution containing only test material and water. The reason of the low recovery in the test could not be revealed finally. One reason could be a loss of the substance by evaporation.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Not readily biodegradable: 0% (O2 consumption) after 28 d (OECD 301C)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

One experimental study is available investigating the biodegradation of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooct-1-ene (CAS 25291-17-2; Daikin Industries, 2007). The study was performed according to OECD 301C (GLP) using sewage sludge, surface water and surface soil which was in contact with the atmosphere from different locations as inoculum. An initial concentration of 100 mg/L was added to the test system and the biodegradation was measured by O2 consumption and by analytical determination via GC-analysis within a timeframe of 28 d. No biodegradation was recorded after 28 d and the substance is not considered to be readily biodegradable according to the OECD criteria (0% based on O2 consumption and test material analysis). Even though the substance has a high vapour pressure no decline of the initial test item concentration was measured at the end of the study period. The reference substance was degraded to 68% after 14 d confirming the suitability of the inoculum and the test system.