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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2003-09-30 to 2003-12-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Version / remarks:
OECD, 1992
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: crystalline powder
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: between 2 and 4°C
- Solubility and stability of the test substance in the solvent/vehicle: The water solubillty of 1,4-Dithiane-2,5-diol was given as 3.9 g/L.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Final preparation of a solid: Preliminary solubility testing indicated that a concentrated stock solution of the test item could not be prepared. Therefore, a dilute test item solution, with a ThOD of 4.23 mg/L, was prepared by adding 20,12 mg of the test item to 2-L of inoculated nutrient dilution water.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Supernatant from settled domestic activated sludge, Source: Galt Wastewater Treatment Plant, Cambridge, Ontario, Canada; Date Collected: 2003-11-11; Date Used: 2003-1 1-1 I
- Inoculum concentration: Approximately 1.0 mL/L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
2.52 mg/L
Based on:
test mat.
Remarks:
Based on molecular structure, the calculated ThOD was 1.68 mg ThOD / mg test item
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium, pH 7.2
- Additional substrate: reference substrate for inhibition testing: phthalic acid
- Solubilising agent (type and concentration if used): Dilution water: Deionized water with nutrients
- Test temperature: 22 +/- 2 °C
- pH: 7.4 +/- 0.2
- pH adjusted: no
- Continuous darkness: yes
- Other: a dilute test item solution, with a ThOD of 4.23 mg/L, was prepared by adding 20,12 mg of the test item to 2-L of inoculated nutrient dilution water. Based
on visual observations made after three hours and ten minutes of stirring the test item solution, some small dust-like particles remained undissolved in the solution. This
test item solution was divided between the BOD bottles for the Test Series and the Inhibition Series.

TEST SYSTEM
- Culturing apparatus: Non-renewal, closed bottle; Glass, with ground glass stoppers and plastic
seals; Test volume: 300 ml
- Number of culture flasks/concentration: 2 replicates
- Measuring equipment: Oxygen electrode

SAMPLING
- Sampling frequency: 7 day interval

CONTROL AND BLANK SYSTEM
- Toxicity control: reference substrate for inhibition testing: phthalic acid; Reference Concentration: 2.76 mg/L; ThOD Reference Substance: 1.44 mg ThOD/mg reference substance

Reference substance
Reference substance:
other: Phthalic Acid, ACS, 99.5+% (Assay)
Remarks:
CAS # 88-99-3, Lot Number: C14K39, Chemical Name/ Synonym: 1,2-Benzenedicarboxylic acid; o-dicarboxybenzene Chemical Formula: C6H4(COOH)2

Results and discussion

Test performance:
A reference substance testing was conducted in parallel with the definitive test to demonstrate consistency in laboratory test performance that might be affected by such factors as inoculum quality and performance of technical staff. The reference substance used in this study was phthalic acid.
REFERENCE TEST: The reference substance test passed the criteria for acceptability of the results (i.e., >60% degradation in 14 days).
INIHIBITION TEST: Inhibition not observed (i.e., >25% degradation)
% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
0 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
4.7
Sampling time:
7 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
40.2
Sampling time:
14 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
55.5
Sampling time:
21 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
47.2
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
REFERENCE TEST: The reference substance test passed the criteria for acceptability of the results (i.e., >60% degradation in 14 days).
INIHIBITION TEST: Inhibition not observed (i.e., >25% degradation)

Any other information on results incl. tables

REFERENCE SUBSTANCE AND INHIBITION DATA

Reference: Phthalic Acid

 Day  0

7

 14  21  28

Reference, % degradation at time = x

 0.0

75.5

 78.0

 84.3

 83

 Inhibition,  % degradation at time = x

 0.0

 >25

 >25

 >25

 >25

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
A test according to OECD 301D showed the test substance being not readily biodegradable (47.2% degradation after 28 days). The test substance was not inhibitory for the degradation (>25%) of the reference substance at 2.52 mg/L).