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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No information was available about the test substance. This study was a standardized method performed by japanese authorities. However, there is no information on test substance and test conditions are not sufficiently detailed.

Data source

Reference
Reference Type:
review article or handbook
Title:
Biodegradation and bioaccumulation data of existing chemicals based on the CSCL Japan
Author:
Edited by Chemicals Inspection and Testing Ins titute, Japan.
Year:
1992
Bibliographic source:
Chemical Products Safety Division, Basic Industries Bureau, Ministry if International Trade and Industry.

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
not specified
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
no data

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
- Source of inoculum/activated sludge:activated sludge were obtained from 10 locations in Japan, 4 times per year. Samples were taken from municipal sewage treatment plants, rivers, lakes and the sea.Surface water and surface soil samples were collected from rivers, lake and sea
- Laboratory culture: yes
- Method of cultivation: about 30 min after ceasing the aeration of the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed.
Then the equal volume of dechlorinated water was added to the remaining portion and aerated again, followed by addition of synthetic sewage, concentration of that portion was to be 0.1% (w/v). This procedure was repeated once every day. The culturing was carried out at 25+/-2°C.
- Storage conditions: no data
- Storage length: no data
- Preparation of inoculum for exposure: 5 L of the filtrate of the supernatant of an activated sludge in the present use were mixed with 500 ml of the filtrate of the supernatant from the newly collected sludge. The mixture was cultured at pH 7 +/- 1 under sufficient aeration (prefiltered air was used).
- Pretreatment: no
- Concentration of sludge: 30 mg/L
- Initial cell/biomass concentration: no data
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimationopen allclose all
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
TOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: Each 3 ml of solution A, solution B, solution C and solution D, which are prescribed in JIS K 0102-1986-21, were made up to 1000 ml with purified water, and then pH of this solution was adjusted to 7.
- Additional substrate: no
- Test temperature: 25+/-1°C
- pH: 7
- pH adjusted: yes
- Aeration of dilution water: no data
- Suspended solids concentration: 30 mg/L
- Continuous darkness: no data

TEST SYSTEM
- Culturing apparatus: closed system of 300 ml in volume
- Number of culture flasks/concentration: no data
- Method used to create aerobic conditions: absorbance of CO2
- Measuring equipment: dissolved oxygen concentrations
- Details of trap for CO2 and volatile organics if used: absorbent fro CO2: Soda lime n°1 (extra pure reagent, Wako Pure Chemical Industries, Ltd).

SAMPLING
- Sampling frequency: once at termination of experiment
- Sampling method: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1 flask
- Abiotic sterile control: yes with purified water but without biocide, 1 flask
- Toxicity control: no
- Other: flask with sludge+aniline= procedure control.

STATISTICAL METHODS: no data
Reference substance
Reference substance:
aniline

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
90
Sampling time:
28 d
Parameter:
% degradation (TOC removal)
Value:
97
Sampling time:
28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Remarks:
please refer to Conclusions below
Interpretation of results:
readily biodegradable
Conclusions:
Concerning the fullfilment of validity criteria: the report states that activity of the inoculum was checked by biodegradation testing of the reference substance aniline, which was expected to exceed 60% degradation by BOD by day 14. However, results are not reported for individual studies therefore it is not possible to confirm that the pass level was achieved for this study.

No kinetic data aere reported for the test substance, therefore it is not possible to confirm whether the 10-day window criterion was met. However, the substance attained 95-97% degradation in 14 days and it is therefore considered to be readily biodegradable.

There are insufficient data to confirm whether degradation of replicates was +/- 20% at the end of the test.
Executive summary:

This ready biodegradation study has been performed according to OECD test guideline (301C) by the Japanese Competent Authorities. The biodegradation of guaiacol was followed during 28 days, at an initial concentration of 100 mg/L using a mixed, non adapted inoculum (30 mg/L). After 28 days, the measured percentage of biodegradation was 90 % (based on Biological Oxygen Demand) and 97% (based on Total Organic Carbon). Even if it is not possible to verify that validity criteria were indeed fulfilled, one can conclude on the basis of this study that guaiacol is readily biodegradable.