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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Deviations:
not specified
GLP compliance:
not specified
Oxygen conditions:
not specified
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
- Source of inoculum/activated sludge: Sludge sampling were made at the following 10 places in Japan: Fukogawa city sewage plant (Sapporo-shi Hokkaido);
Fukashiba industry sewage plant (Kashima-gun Ibaragi);
Nakahama city sewage plant (Osaka-shi Osaka);
Ochiai city sewage plant (Shinjuku-ku Tokyo);
Kitakami river (Ishinomaki-shi Miyagi);
Shinano river (Nishikanbara-gun Niigata);
Yoshino river (Tokushima-shi Tokushima);
Lake Biwa (Otsu-shi Shiga);
Hiroshima bay (Hiroshima-shi Hiroshima);
Dookai bay (Kitakyushu-shi Fukuoka).
- Method of cultivation: About 30 min after ceasing the aeration to the sludge miture, supernatant corresponding to about 1/3 of the whole volume was removed. Then the equal volule of dechlorination 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.
*: Glucose, peptone and monopotassium phosphate were dissolved in dechlorination water respectively. Each concentation of them was to be 5(W/V)% and the solution was adjusted to pH 7.0 +/-1.0 with sodium hydroxide.
- Concentration of sludge: 30 mg/L
Duration of test (contact time):
4 wk
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
BOD
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
GC
Details on study design:
TEST CONDITIONS
- Concentration of test substance : 100mg/L
- Suspended solids concentration: 30 mg/L
- Volume of test solution 300mL
- Cultivation temperature : 25°C
- Cultivation duration : 28 days

PREPARATION OF BASAL CULTURE MEDIUM
- Each 3 mLof solution A, B, C and D, which are prescribed in JIS K 012-1986-21, were made up to 1000 mL with purified water, and then pH of this solution was adjusted to 7.0

SAMPLING
- Sampling frequency: March, June, September, and December in every year.
- Sampling method: Returned sluge of sewage plants were collected.

STATISTICAL METHODS
- Percentage biodegradation (%) = 100 x [BOD - B ] / TOD
- BOD: Biochemical Oxygen Demand in
- B: Biochemical Oxygen Demand in control blank
- TOD: Theorical Oxygen Demand required when the test substance was completely oxidized
Reference substance:
aniline
Remarks:
(guaranteed reagent, Showa Chemicals Inc.)
Test performance:
ANALYSIS OF THE TEST SOLUTION
After the termination of cultivation, total organic carbon and the test substance in the test solutions were determined. The pH of the test solutions of [water + test substance] and [sludge + test substance] were measured.
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
BOD
Value:
82
Sampling time:
4 wk
Key result
Parameter:
% degradation (test mat. analysis)
Remarks:
GC
Value:
96
Sampling time:
4 wk
Details on results:
BOD : 92, 79 and 76% biodegradation.
GC : 100, 88 and 100% biodegradation

Validity of test conditions

When percentage biodegradations of aniline calculated by BOD value were beyond 40% and 60% at the 7th and 14th day, respectively, it was concluded that the test condtion was valid.

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable, not fulfilling specific criteria
Conclusions:
Biodegradation was found above 70% of theoretical (measured as BOD, GC) so it can be regarded as evidence of inherent, ultimate biodegradability.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data provided by a reference in the OECD Toolbox
Principles of method if other than guideline:
28d BOD test (MITI-test).
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
other: Microorganisms
Duration of test (contact time):
28 d
Details on study design:
No details.
Preliminary study:
.
Parameter:
% degradation (O2 consumption)
Value:
84
Remarks on result:
other: No further details available.
Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable, but failing 10-day window

Description of key information

Data based on 2 references (reliable with restrictions), which are both used for environmental risk assessment of chemicals by the Japanese government.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

According to the OECD guideline for biodegradation biodegradation above 70% of theoretical (measured as BOD, DOC removal or COD) should be regarded as evidence of inherent, ultimate biodegradability. Since the 10-day window criterion was not fulfilled, diallyl phthalate could not be considered as readily biodegradable. Within the REACH regulation, such substances are considered as readily biodegradable but failing the 10-day window.