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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:
1992-11-09 - 1993-05-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Also complies with OECD GLP regulations. Deviations from GLP are limited, listed below, and are not believed to impact the reliability of the test results.
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes
Remarks:
It is unknown whether the stability, identity, strength and composition or other characteristics for the test material and positive control are documented in a GLP compliant manner.
Specific details on test material used for the study:
- Name of test material (as cited in study report): MRD-92-436; CT-519-92-C
- IUPAC nomenclature - Sodium diisobutyldithiophosphinate
- Appearance - Liquid
- CAS No. 13360-78-6
- Molecular Formula - C8H18PS2.Na
- Molecular Weight - 232 g/mole
- Purity 50% aqueous solution
- Storage condition of test material: At room temperature in the dark
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Details on inoculum:
Fresh activated sludge was used as the inoculum. The activated sludge was obtained from the Somerset-Raritan Valley sewage Authority in Bridgewater, New Jersey. There were no known contaminants present believed to be at levels high enough to interfere with this study. The inoculum was blended and filtered before use. The bacteria level of the inoculum, in Colony Forming Units (CFU), was determined using Easicult TTC dip slides (1x10^4 colony).
The final bacteria count was calculated to be 45 CFU/ml.
Duration of test (contact time):
28 d
Initial conc.:
2.1 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
-This test procedure was used to determine biodegradability by measuring dissolved oxygen concentrations in closed test systems (300mL BOD bottle). the test systems contained aqueous solutions consisting of a microbial inoculum in contact with test or reference material. Oxygen depletion by the microorganisms for oxidation of test material was periodically measured during a 28 day testing period. Blank test systems, which did not contain the test or reference material were also run concurrently with the other test systems. Microbial colony forming units (CFU/mL) in the inoculum were enumerated using the Easicult TTC dip slides, according to manufacturer's instructions.

Reported biodegradtion results are based on chemical oxygen demand (COD) of test material.

Administration of either the test material or aniline to the appropriate BOD bottle was accomplished by dilution of an aliquot of each stock solution with nutrient solutions, inoculum and glass distilled water.

Triplicate test systems were prepared for each of the days requiring dissolved oxygen analysis (days 0, 5, 15 and 28).
Reference substance:
aniline
Remarks:
-Manufacturer: Aldrich Lot No. 00613AZ
Parameter:
% degradation (O2 consumption)
Value:
78.8
Sampling time:
28 d

MEAN PERCENT BIODEGRADABILITY RESULTS

Test System       Day 5       Day 15       Day 28

MRD-92-436             0       41.89        78.84

Analine               40.68       56.55       92.24

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance achieved 78.8% degradation within 28 days.
Executive summary:

The biodegradability of the test material, and a positive control material (aniline) was studied in an aerobic, aqueous test system. This procedure was based on that outlined in the Organization for Economic Co-operation and Development (OECD) Test Guideline 301D, "Ready Biodegradability: Closed Bottle Test". This procedure was used to determine biodegradability by measuring the amount of oxygen utilized by a microbial population during the oxidation of a test material added to a dosed test system.

 

The substance biodegraded to 78.8% after 28 days, using a test concentration of 2.10 mg/L.

 

Since aniline, the positive control material, exceeded the pass level by degrading to 92.2%, this test can be considered valid.

Description of key information

The test material achieved 78.8% biodegradation within 28 days, using a test concentration of 2.10 mg/L.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The biodegradability of the test material, and a positive control material (aniline) was studied in an aerobic, aqueous test system. This procedure was based on that outlined in the Organization for Economic Co-operation and Development (OECD) Test Guideline 301D, "Ready Biodegradability: Closed Bottle Test". This procedure was used to determine biodegradability by measuring the amount of oxygen utilized by a microbial population during the oxidation of a test material added to a dosed test system.

 

The substance biodegraded to 78.8% after 28 days, using a test concentration of 2.10 mg/L.

 

Since aniline, the positive control material, exceeded the pass level by degrading to 92.2%, this test can be considered valid.