Pentafluoroethane

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Pentafluoroethane

EC Number:

206-557-8

EC Name:

Pentafluoroethane

Cas Number:

354-33-6

Molecular formula:

C2HF5

IUPAC Name:

1,1,1,2,2-pentafluoroethane

Details on test material:

- Name of test material (as cited in study report): HFC-125
- Substance type: organic
- Physical state: Liquefied gas
- Analytical purity: 99.63% w/w
- Impurities (identity and concentrations): Flon 115 (monochloro-pentafluoro-ethane), 0.369% w/w
- Isomers composition: n/a
- Purity test date: not reported
- Lot/batch No.: C-9931
- Expiration date of the lot/batch: not reported
- Storage condition of test material: Cool dark place

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Return sludge from the city sewage plant of Tsubuku (Japan).
- Storage conditions: inoculum kept under aerobic conditions at room temperature until used
- Storage length: less than 1 day
- Preparation of inoculum for exposure: Inoculum sample was filtered, the first 200ml were disregarded and the rest was used as the inoculum
- Pretreatment: no
- Concentration of sludge: not reported
- Initial cell/biomass concentration: 2.8 x 10exp8 bacteria/ml
- Water filtered: purified water was used. No details are available
- Type and size of filter used, if any: not available

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2.99 mg/L

Based on:

test mat.

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium with composition as indicated in the OECD GL 301D
- Additional substrate: no
- Solubilising agent (type and concentration if used): not used
- Test temperature: 20 +/-1 °C
- pH: 7.2
- pH adjusted: yes
- CEC (meq/100 g):
- Aeration of dilution water: not reported
- Suspended solids concentration: not calculated
- Continuous darkness: yes
- Other:


TEST SYSTEM
- Culturing apparatus: Incubator Sanyo Electric Co.
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: Not reported
- Method used to create anaerobic conditions: n/a
- Measuring equipment: titration equipment to perform the Winkler method
- 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: not used
- Other:


SAMPLING
- Sampling frequency: Day 0, 5, 15 and 28 of the study
- Sampling method: for each sample 3 flask/timepoint were prepared
- Sterility check if applicable: n/a
- Sample storage before analysis:not reported
- Other:


CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: Yes
- Toxicity control: No
- Other: positive control, Sodium dodecylsulfate 3 mg/l

Reference substance

Reference substance:

laurylsulfonate

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

ca. 5

Sampling time:

28 d

Details on results:

Degradation of test substance (in %):
= 2 after 5 day(s)
= 5 after 15 day(s)
= 5 after 28 day(s)

Degradation products: no

BOD5 / COD results

Results with reference substance:

degradation of reference substance (in %):
= 30 after 5 day(s)
= 92 after 28 day(s)

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Not readily biodegradable

Executive summary:

HFC-125 ready biodegradability was studied by means of a closed bottle test.

The active sludge was sampled from a city sewage plant and filtered. The activated sludge contained 2.8 x 10^8 bacteria/ml. One drop was added to one liter of final test solution. A stock solution of the test substance was prepared by adding gaseous HFC-125 to a vacuum tube containing water until saturation (ca. 0.5 g/l). 600 ul of the stock solution were added to 100 ml of mineral medium  containing the inoculum. Sodium laurylsulfate was used as positive control
The test was run at a temperature of 20 ± 1 C.
Biodegradation of tested substance was measured by gas chromatography and biochemical oxygen demand methods.
Degradation of 2, 5 and 5% was calculated from the BOD measurements after 5, 15 and 28 days of incubation of the test substance with the inoculum, respectively. A biodegradation of 30, 57 and 92% was measured for the positive control after 5, 15 and 28 days, respectively.

HFC-125 resulted as non readily biodegradable under aerobic conditions.