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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: screening test, other
Remarks:
Inherent biodegradation Modified MITI test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 24, 1996 to June 17 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Deviations:
yes
Remarks:
The test substance was running in duplicate instead in triplicate. Inoculum control and reference control were running alone instead in duplicate. The title must be written: "1st Amendment to Study Plan" instead of "3rd Amendment to Study Plan"
GLP compliance:
yes
Specific details on test material used for the study:
Test medium:
3 ml of each following stock solutions were added per 1 litre distilled water to form the test medium:

Stock solution A:
8,50 g of potassium acid phosphate, 21,75 g of di-potassium hydrogen phosphate, 22,18 g of di-sodium hydrogenphosphate dihydrate and 1,70 g of ammonium chloride were dissolved in distilled water and adjusted to 1 litre. The pH value of this solution was 7,2.

Stock solution B: 22,50 g of magnesium sulfate heptahydrate were dissolved in distilled water and adjusted to 1 litre.
Stock solution C: 36,40 g of calcium chloride dihydrate were dissolved in distilled water and adjusted to 1 litre.
Stock solution D: 0,25 g of ferric chloride hexahydrate were dissolved in distilled water and adjusted to 1 litre.
Oxygen conditions:
aerobic
Inoculum or test system:
other: Mixture of polyvalent bacteria collected on April 23, 1996 in the aeration tank of a domestic sewage treatment plant, PRO RHENO Basel communal.
Details on inoculum:
Mixture of polyvalent bacteria collected on April 23, 1996 in the aeration tank of a domestic sewage treatment plant, PRO RHENO Basel communal. Bacteria concentration: 100 mg/l suspended solids.
Duration of test (contact time):
28 d
Initial conc.:
30 mg/L
Based on:
test mat.
Details on study design:
Performance of the test:
This test method was based on the following conditions:
- test chemicals as sole organic carbon sources
- no adaptation of micro-organisms to the test chemicals
Tested chemicals were inoculated in the testing vessels with micro-organisms. During the test period, the Biochemical Oxygen Demand was measured continuously by means of a BOD-meter. Biodegradability was calculated on the basis of the theoretical oxygen demand (ThOD) or less satisfactorily COD, if the ThOD could not be calculated. Optionally, primary biodegradation could be determined by analysis of dissolved organic carbon (DOC) at the beginning and the end of the test.
Reference substance:
benzoic acid, sodium salt
Remarks:
Sodium benzoate
Preliminary study:
None
Key result
Parameter:
other: Biodegradation measured as BOD versus ThOD
Value:
12
Sampling time:
28 d
Remarks on result:
other: Standard deviation is not available
Details on results:
Test substance:
The biodegradation of FAT 40034/D corrected by the inoculum control and measured as
BOD versus ThOD was: 12 % after 28 days
The BOD5 after 5 days was: 100 mg O2/g

Abiotic control:
The abiotic degradation at the end of the test and measured as BOD versus ThOD was: 0 %
Parameter:
BOD5
Value:
100 mg O2/g test mat.
Results with reference substance:
The biodegradation of the reference substance corrected by the inoculum control and measured as BOD versus ThOD was 84 % after 7 days; 94 % after 14 days and 100% after 28 days.

The abiotic degradation at the end of the test and measured as BOD versus ThOD was 0 %.

Validity criteria fulfilled:
yes
Interpretation of results:
not inherently biodegradable
Conclusions:
Biodegradation of FAT 40034/D after 28 days was 12 %.
Executive summary:

An inherent biodegradability of FAT 40034/D was determined in a 28 days MITI (II) - Test according to the OECD Guideline for Testing of Chemicals, No. 302C. The test substance was tested in a concentration of 30 mg/l. The reference substance (Sodium benzoate) was tested in a concentration of 100 mg/l. Based on the results of the study, biodegradation of the test substance after 28 days was 12 % and the BOD5 after 5 days was : 100 mg 02/g.

Description of key information

An inherent biodegradability of FAT 40034/D was determined in a 28 days MITI (II) - Test according to the OECD Guideline for Testing of Chemicals, No. 302C. The test substance was tested in a concentration of 30 mg/l. The reference substance (Sodium benzoate) was tested in a concentration of 100 mg/l. Based on the results of the study, biodegradation of the test substance after 28 days was 12 % and the BOD5after 5 days was : 100 mg O2/g. Supporting studies were also performed to determine the chemical oxygen demand of FAT 40032/D which was found to be 798mg O2/g test material whereas the biological oxygen demand was found to be '0'mg O2/g test material.The relevant BOD5/COD quotient is <0.5 , therefore, the substance is not indicative of rapid degradation. Taking the data from key study and supporting studies into account, the test substance FAT 40034 is considered to be not biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable
Type of water:
freshwater

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