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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1985-01-18 till 1985-02-15
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
other: MITI (I) method (1974)
Deviations:
not specified
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
not specified
Principles of method if other than guideline:
not applicable
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material: not applicable
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Test organisms
- Type: mixed population of aquatic microorganisms (activate sludge)
- Source of inoculum/activated sludge: Sludge sampling were made at 10 places in Japan.
Fukogawa city sewage plant, Fukashiba industry sewage plant, Nakahama city sewage plant, Ochiai city sewage plant, Kitakami river, Shinano river, Yoshino river, Lake Biwa, Hiroshima bay and Dookai bay.
- Preparation of inoculum for exposure: 5 L of the filtrate of the supernatent of an activated sludge in the present use was mixed with 500 mL of the filtrate of the supernatent of a newly collected sludge respectively and the mixture was cultured at pH 7.0 +-1.0 under the sufficient aeration (prefiltered open air was used).
- Date of collection: September 1984
- Concentration of sludge: 30 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
Details on study design:
TEST CONDITIONS
1. Measurment of concentration of suspended solids
- Method: In accordance with Japanese Industrial Standard (JIS) K0102-1986-21
2. Preparation of basal culture medium
- Each 6 mL of solution A, solution B, solution C and solution D, which are prescribed in JIS K0102-1986-21, were made up to 2L with purified water, and the pH of this solution was ajusted to 7.0
3. Reference substance
- Aniline, purchased from Showa Chemicals Inc., reagent grade
4. Preparation of test solutions
- a: Water + 2,2'-methylenebis(6-tert-butyl-4-methylphenol)
A test vessel containing 300 mL of purified water into which 30 mg or 9 mg* of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) was added. [n = 3]
-b: Sludge + 2,2'-methylenebis(6-tert-butyl-4-methylphenol)
Each test vessel containing 300 mL of basal culture medium into which 30 mg or 9 mg * of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) was added. [n = 1]
- c: Sludge + aniline
A test vessel containing 300 mL of basal culture medium into which 30 mg or 9 mg* of aniline was added. [n = 1]
- d: Control blank
A test vessel containing 300 mL of basal culture medium into which was not added 2,2'-methylenebis(6-tert-butyl-4-methylphenol) nor aniline. [n = 1]
* The suspended solids concentration of the standard activated sludge was 7200 mg/L. 1.25 mL = 9 mg suspended solids.
5. Test volume: 300 mL
6. Temperature: 25 ± 1 °C
7. During the exposure: 28 days





Reference substance:
aniline
Remarks:
from Kishida Chemical Co.; purity not reported
Preliminary study:
not appliable
Test performance:
not applicable
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Parameter:
% degradation (test mat. analysis)
Value:
1
Sampling time:
28 d
Remarks on result:
other: (based on HPLC analysis for the parent)
Details on results:
2,2'-methylenebis(6-tert-butyl-4-methylphenol) was not ready biodegradable.
Results with reference substance:
Kinetic of reference substance (degradation):
70 % after 7 days
75 % after 14 days
The test is valid.

no remarks

Validity criteria fulfilled:
yes
Remarks:
(- ready biodegradability of reference compound ≥ 60 percent within 14 days.)
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Whitin 28 days, a degradation rate of 0 % was determined. 2,2'-methylenebis(6-tert-butyl-4-methylphenol) is considered to be "Not readly Biodegradable". The reference compound aniline showed 75 % degradation after 14 days.
Executive summary:

To test for its biodegradabbility potential of 2,2'-methylenebis(6 -tert-butyl-4 -methylphenol was incubated for 28 days in continuously stirred closed flask (in triple) in the dark with an inoculum originally collected from ten local sludge in Japan. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was measured with HPLC detection. The incubation temperature was 25 +/- 1 °C, pH was 7.0. The concentration of Innoculum was 30 mg/L and the one of 2,2'-methylenebis(6 -tert-butyl-4 -methylphenol) was 100 mL.

DBMC was tested in a biodegradation test under the conditions of the MITI (I) method. The test resulted in 0% degradation after 28 days (1% based on HPLC analysis) and the test substance was classified as "Not Ready Biodegradable". The reference substance aniline showed a degradation after 14 days of 75 %.

Description of key information

Within 28 days, a degradation rate of 0 % was determined. 2,2'-methylenebis(6-tert-butyl-4-methylphenol) is considered to be "Not readily Biodegradable". The reference compound aniline showed 75 % degradation after 14 days.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Based on the results of a MITI (I) test, DBMC is not readily biodegradable.