Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (test mat. analysis)
Value:
0
Sampling time:
28 d
Remarks on result:
other: range of triplicate values, -1% to 2% by GC
Parameter:
% degradation (CO2 evolution)
Value:
> 17 - < 25
Sampling time:
28 d
Remarks on result:
other: range of triplicate values
Conclusions:
Novec 7700 is expected not to be biodegraded in an OECD 301C test (0% loss of material on GC analysis)
Executive summary:

Novec 7700 biodegradation is assessed by readacross from Novec 7800. Novec 7800 was tested in an OECD 301C test, using a mixed inoculum. The test system was modified per the guideline for use with a volatile test substance. Essentially no loss of test material was observed by GC analysis. Cumulative BOD in triplicate flasks was 17 - 25% of theoretical, but may have been an aberration due to oxygen demand comparable to historical controls. The aniline positive control was 78% degraded within 14 days. Novec 7800 is not readily biodegradable. As explained in the justification for type of information, the structural difference between Novec 7700 and Novec 7800 are unlikely to lead to a difference in biodegradation potential.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 Sept - 17 Oct 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Version / remarks:
Revised 17 Jul 1992
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Lot No.of test material: Lot number 1

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Roomt temperature, darkness
- Stability under test conditions: Stable
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
Mixed inoculum derived from 10 sources within Japan during June 2006:
Fushikogawa city sewage plant (Sapporo-shi, Hokkaido)
Fukashiba industrial sewage plant (Kamisu-shi, Ibaraki)
Nakahama sewage treatment plant (Osaka-shi, Osaka)
Ochiai treatment plant (Shinjuku-ku, Tokyo)
Kitakami River (Ishinomaki-shi, Miyagi)
Shinano River (Niigata-shi, Niigata)
Yoshino River (Tokushima-shi, Tokushima)
Lake Biwa (Otsu-shi, Shiga)
Hiroshima Bay (Hiroshima-shi, Hiroshima)
Dokai Bay (Kitakyushu-shi, Fukuoka)
Return sludges were collected from sewage plants. For environmental samples, surface water and soils in contact with the atmosphere were sampled.

- Laboratory culture: A five-liter mixed filtrate of sludges and environmental samples was cultured for 3 months as noted below. For the test, fresh samples from the above locations were blended to make a five-liter mixture and the two combined. The pH was adjusted to 7.0 and the mixture aerated.
- Method of cultivation: Each day, aeration was ceased for 30 minutes and ca. 1/3 of the volume removed as supernatant. The volume was brought back to 10 L with dechlorinated water plus 0.001 volume of synthetic sewage (50 g/L each glucose, peptone, and KH2PO4, pH to 7.0 with NaOH). Aeration was then restored. During cultivation, the appearance of the supernatant, sedimentation of the sludge, formation of flock, pH, dissolved oxygen concentration, and temperature were checked. Cultivation was carried out at 25 ± 1 °C.
- Storage conditions: Activated sludge was cultivated for 23 hours after addition of synthetic sewage before use.
- Concentration of sludge: 3390 mg/L suspended solids.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: Modified medium for volatile test substances, composition per JIS K0102-1998 sec. 21, adjusted to pH 7.0
- Test temperature: 25±1 °C
- Aeration of dilution water: dilution water aerated before use, no aeration during test (closed system).
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 300-mL bottles with a closed-system oxygen consumption measuring apparatus, recorded using a data sampler. Continuous magnetic stirring
- Number of culture flasks/concentration: 3 for test substance, 1 for inoculum blank, 1 for reference substance, no toxicity control
- Measuring equipment: Test substance analysis as noted. Dissolved oxygen measurement was using a closed system oxygen measuring apparatus with Temperature-controled bath, measuring unit, and data sampler (all from Asahi Techneion Co Ltd)
- Test performed in open system: No

SAMPLING
- Sampling frequency: Daily for DO measurement, test substance analysis and pH measurement at end of test only due to test substance volatility.
- Sample storage before analysis: None.
- Other: The theoretical oxygen demand was calculated from the molecular formula.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Contained only mineral media and inoculum
- Abiotic blank: Purified water and test substance only
- Positive control: 30 mg/L aniline
- Toxicity control: None
Reference substance:
aniline
Key result
Parameter:
% degradation (test mat. analysis)
Value:
0
Sampling time:
28 d
Remarks on result:
other: range of triplicate values, -1% to 2% by GC
Parameter:
% degradation (O2 consumption)
Value:
> 17 - < 25
Sampling time:
28 d
Remarks on result:
other: range of triplicate values
Details on results:
The test substance formed a colorless, undissolved phase throughout the experiment. The test substance showed 10.3-12.1 mg BOD, which is in the historical range for controls (ca. 4 - 13 mg BOD) using this test inoculum. The control flask in this experiment had 6.7 mg BOD. Given the essential lack of biodegradation shown by analysis of the test substance, the BOD is considered an aberration.
Validity criteria fulfilled:
yes
Remarks:
Range of test substance biodeg <20%, BOD of control <60 mg/L, BOD of reference ≥40% after 7 days and ≥65% after 14 days
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Novec 7800 was not biodegraded in an OECD 301C test (0% loss of material on GC analysis)
Executive summary:

Novec 7800 was tested in an OECD 301C test, using a mixed inoculum. The test system was modified per the guideline for use with a volatile test substance. Essentially no loss of test material was observed by GC analysis. Cumulative BOD in triplicate flasks was 17 - 25% of theoretical, but may have been an aberration due to oxygen demand comparable to historical controls. The aniline positive control was 78% degraded within 14 days. Novec 7800 is not readily biodegradable.

The test was done according to internationally accepted guidelines under GLP criteria. This study is considered reliable without restrictions and is suitable for Risk Assessment, Classification & Labeling, and PBT Analysis.

Description of key information

Novec 7700 is expected not to be biodegraded in an OECD 301C test (0% loss of material on GC analysis)

Key value for chemical safety assessment

Additional information

Novec 7700 biodegradation is assessed by readacross from Novec 7800. Novec 7800 was tested in an OECD 301C test, using a mixed inoculum. The test system was modified per the guideline for use with a volatile test substance. Essentially no loss of test material was observed by GC analysis. Novec 7800 is not readily biodegradable. As explained in the Analog Reporting Format justifying readacross, the structural difference between Novec 7700 and Novec 7800 is unlikely to lead to a difference in biodegradation potential.