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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Details on test material:
- Purity: 100%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Kurume central sewage treatment center (Kurume-shi, Fukuoka, Japan)
- Method of cultivation: Basal culture medium (2 L) was prepared by the method as follows: 10 mL of solution A and each 1 mL of solutions B, C and D prescribed in Guideline 301F were made up to 1 L with purified water (The Japanese Pharmacopoeia, Takasugi Pharmaceutical), and then the pH of this solution was adjusted to 7.4.
- Concentration of sludge in test vessel: 30 mg/L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Basal culture medium (2 L): 10 mL of solution A and each 1 mL of solutions B, C and D prescribed in Guideline 301F were made up to 1 L with purified water (The Japanese Pharmacopoeia, Takasugi Pharmaceutical), and then the pH of this solution was adjusted to 7.4.
- Test temperature: 22±1°C
- pH: 7.4
- pH adjusted: yes
- Continuous darkness: yes
- Suspended solids concentration: Decision of additive amount of activated sludge: Additive amount of activated sludge into the test vessel was 3.06 mL on the basis of the concentration of suspended solid in the activated sludge which was determined by in accordance with Japanese Industrial Standards (llS) K 0102-2008 Section 14.1
Result - 2940 mg/L

TEST SYSTEM
- Culturing apparatus: Glass vessel
- Number of culture flasks/concentration: Test solution (sludge + test item) (n=2, Vessel Nos. 1 and 2)
In each test vessel, 30 mg of the test sample was accurately weighed by an electronic analytical balance and added to the mineral medium [the volume subtracting the volume (3.06 mL) of activated sludge from 300 mL], so that the concentration of the test item reached 100 mg/L.
- Measuring equipment: Closed system oxygen consumption measuring apparatus: Temperature controlled bath with measuring unit 0M3100A (OhkuraElectric)
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: Absorbent for carbon dioxide: Soda lime No. 1 (for absorption of carbon dioxide, Wako Pure chemical Industries)
- Other: Incubation duration 28 days (under dark conditions); Volume of test solution - 300 mL

CONTROL AND BLANK SYSTEM
- Test solution (sludge + sodium benzoate) (n=l, Vessel No.5)
In one test vessel, 30 mg of sodium benzoate was accurately weighed by an electronic analytical balance and added to the mineral medium [the volume subtracting the volume (3.06 mL) of activated sludge from 300 mL], so that the concentration of sodium benzoate reached 100 mg/L.
- Test solution (control blank) (n=2, Vessel Nos. 3 and 4)
In each test vessel, nothing was added to the mineral medium [the volume subtracting the volume (3.06 mL) of activated sludge from 300 mL].

Observation of test solution: During the incubation period, the appearance of the test solution was observed once a day.
Measurement of biochemical oxygen demand (BOD): During the incubation period, BOD of the test solutions was measured continuously by a closed system oxygen consumption measuring apparatus. The incubation temperature was measured and recorded once a day.
Measurement of pH: After the end of the incubation, the pH of the test solutions (sludge + test item) and the test solutions (control blank) were measured.

Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
or acetic acid, sodium salt

Results and discussion

Test performance:
This test was judged to be valid because all the values in this test met the criteria. No adverse effects on the reliability of this test were noted.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
88
Sampling time:
28 d
Remarks on result:
other: The percentage biodegradation by the BOD were 85% and 90%. Mean = 88%
Details on results:
The results indicate that almost all the test item underwent complete degradation under the test conditions of this study. Substances are considered to be readily biodegradable if percentage biodegradation by BOD is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. The percentage biodegradations after the l0-day window were 62% and 70% in this study. Therefore, the test item is a readily biodegradable substance.

BOD5 / COD results

Results with reference substance:
Percentage biodegradation of sodium benzoate by BOD after 14 days was 92%.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The results of this test indicate that the test item is a readily biodegradable substance.
Executive summary:

A 28-day biodegradation study was conducted according to OECD Guidelines for Testing of Chemicals, No 301F, July 17, 1992, "Ready Biodegradability: MANOMETRIC RESPIROMETRY TEST". Test, control and reference vessels were incubated at 22±1°C in the dark. The oxygen content was measured continuously by a closed system oxygen consumption measuring apparatus. The percentage biodegradation was calculated and rounded off to the whole number. Blank and reference substance tests met validation criteria and the test was judged acceptable.

The percentage biodegradations by the BOD were 85% and 90% for the two test vessels. These results indicate that almost all the test item underwent complete degradation under the test conditions of this study. Substances are considered to be readily biodegradable if percentage biodegradation by BOD is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. The percentage biodegradations after the l0-day window were 62% and 70% in this study. Therefore, the test item is a readily biodegradable substance.