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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
Study period:
23-Sept-2003 to 22-Oct-2003
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP, guideline, available as an unpublished report, acceptable with restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Heavy Pyrolysis Fuel Oil (Lab I.D. of substance: MRD-03-768)
CAS numbers included: 68513-69-9, 64741-62-4, 69013-21-4, 8002-05-9
A liquid under ambient laboratory conditions, and immiscible in water, methanol and hexane. Initial density at 20 °C was measured as 1.068 g/ml and the final density was 1.069 g/ml.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
no data

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Inoculum obtained from Clinton Sanitary Wastewater Treatment Plant, Annandale, NJ, USA.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
50 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Temperature: 22 ± 1 °C
test medium prepared one day before the test began, A total of 20 liters of glass distilled water was collected in a carboy then amended with mineral salt solutions and inoculum.
Apparatus used was an electrolytic respirometer.
No concentration verification was performed as the test substance is poorly soluble.
Blank, positive control and test substance test systems were tested in triplicate.
Dissolved organic carbon (DOC) analysis was not performed due to the poor solubility of the test substance
All test solutions were prepared with a solvent (methylene chloride)
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
not conducted
Test performance:
Sodium benzoate biodegraded to >60% of the ThOD by day 3 and the average of the cumulative oxygen consumed in the blank systems was 21mg/l
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
29
Sampling time:
28 d
Details on results:
mean percent biodegradation

BOD5 / COD results

Results with reference substance:
Sodium benzoate biodegraded to >60% of the ThOD by day 3

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
Degradation of Heavy Pyrolysis Fuel Oil was determined to be 29% after 28 days indicating that the test substance is not readily biodegradable.
Executive summary:

Heavy Pyrolysis Fuel Oil (CASRN: 68513-69-9) underwent 29% degradation during the 28-day test which means it cannot be considered readily biodegradable. The test was an OECD guideline study with no deviations that affected the integrity of the study, so it is considered acceptable for use in assessment.