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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:
April 18, 2005 to June 24, 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study followed the procedures indicated by the following internationally accepted guidelines and recommendations: OECD Guideline for Testing of Chemicals No. 301 F, Ready Biodegradability: Manometric Respirometry Test, 1992. EU Commission Directive 92/69 EEC, C.4-D, Manometric Respirometry Test, 1992.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report date:
2005

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
[(3aS,4S,6S)-6-methoxy-2,2-dimethyl-tetrahydro-2H-furo[3,4-d][1,3]dioxol-4-yl]methyl 4-methylbenzene-1-sulfonate
EC Number:
609-920-2
Cas Number:
4137-56-8
Molecular formula:
C16H22O7S
IUPAC Name:
[(3aS,4S,6S)-6-methoxy-2,2-dimethyl-tetrahydro-2H-furo[3,4-d][1,3]dioxol-4-yl]methyl 4-methylbenzene-1-sulfonate
Details on test material:
Identity: Tosylfuranosid
Expiration date: July 31, 2005
Solubility in water: Not miscible
Aggregate state/physical form
at room temperature: Solid
Color: White
Storage conditions: At room temperature at about 20 °C, away from direct sunlight

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland) treating predominantly domestic wastewater. The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated.
Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g (±10%) dry material per liter. During holding, the sludge was aerated at room temperature until use. Prior to use, the sludge was diluted with test water to a concentration of 1 g per liter (dry weight basis). This diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry material per liter.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST WATER
The test water was prepared according to testing guidelines. Analytical grade salts were dissolved in purified water to obtain the following stock solutions:
a) KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 x 2H2O 33.40 g/L
NH4Cl 0.50 g/L
The pH of this solution was 7.4.
b) MgSO4 x 7H2O 22.50 g/L
c) CaCl2 x 2H2O 36.40 g/L
d) FeCl3 x 6H2O 0.25 g/L, stabilized with one drop of concentrated HCl per liter
To obtain the final test water, 10 mL of stock solution a) and 1 mL each of stock solutions b) – d) were combined and made up to 1000 mL with purified water. The pH was adjusted from 7.7 to 7.4 with a diluted hydrochloric acid solution.

TEST CONCENTRATION
The test item was weighed by means of an analytical balance and transferred to the test flask with test water. No emulsifiers or solvents were used.
The reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. A stock solution containing 2.5 g sodium benzoate per liter test water was prepared by completely dissolving 250 mg sodium benzoate in 100 mL of test water. From this stock solution, 10 mL aliquots were added to the corresponding test flasks containing test water.
Finally, with the exception of the abiotic control flask, activated sludge was added to each test flask. The final volume was 250 mL per test flask.

CONDITIONS OF THE TEST
Apparatus: The test flasks (500-mL Erlenmeyer flasks, labeled with all necessary information to ensure unmistakable identification) were incubated under continuous stirring in a SAPROMAT D12 (Voith GmbH, Heidenheim, Germany). Oxygen consumption was recorded manually by taking a daily reading at least on each working day.
Principle: Electro-chemical analysis process:
The biodegradation process consumes the dissolved oxygen in the liquid and generates CO2. The CO2 is adsorbed by soda lime and the total pressure decreases in the airtight test flasks. The pressure drop is detected and converted into an electrical signal by means of an electrode type manometer. The consumed oxygen is replaced by electrolytically generated oxygen from a copper sulfate solution.
Test duration: 28 days
Light conditions: Darkness
Test temperature: 22 °C, maintained with a built-in thermostat and checked once per week.
pH: Prior to test start, the pH was measured in each test flask before the addition of the activated sludge inoculum. At the end of incubation, the pH was measured again in each test flask.
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
The reference item and the following information were supplied by Fluka (BioChemika): Identity: Sodium benzoate Product No.: 71295 Lot No.: 1085373 Purity: 99.8% Expiration date: April 2010 Storage conditions: In tightly closed original container, at room

Results and discussion

Test performance:
BIODEGRADATION OF THE TEST ITEM
The percent biodegradation of the test item was calculated based on the theoretical oxygen demand (ThOD) of 1.74 mg O2/mg test item.
The oxygen consumption of the test item Tosylfuranosid in the test media was in the normal range of the oxygen consumption in the inoculum controls throughout the study period of 28 days. Consequently, Tosylfuranosid was not biodegradable under the conditions of the test within 28 days.
Abiotic control:
No degradation of the test item occurred in the abiotic control under the conditions of the test.

BIODEGRADATION IN THE TOXICITY CONTROL
The percent biodegradation in the toxicity control containing both the test item and the reference item was calculated based on the sum of the ThOD of the test item and the reference item.
In the toxicity control, the course of biodegradation over the 28-day exposure period was similar to that in the two procedure controls containing the reference item, only. Within 14 days of exposure, biodegradation of 47% was calculated.
Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L because biodegradation in the toxicity control was >25% within 14 days.

MEASUREMENT OF pH
The pH measured in all flasks at the start of the test was 7.4. At the end of exposure (Day 28) pH values of 7.4–7.8 were measured.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Remarks on result:
other: The oxygen consumption of the test item Tosylfuranosid in the test media was in the normal range of the oxygen consumption in the inoculum controls. Consequently, Tosylfuranosid was not biodegradable under the conditions of the test within 28 days.

BOD5 / COD results

Results with reference substance:
BIODEGRADATION OF THE REFERENCE ITEM
The percent biodegradation of the reference item sodium benzoate was calculated based on the theoretical oxygen demand of 1.67 mg O2/mg (ThOD).
In the procedure controls, the reference item was degraded by an average of 86% by exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item degraded by an average of 88%.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Tosylfuranosid was not biodegradable under the conditions of the test within 28 days.
The test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L because biodegradation in the toxicity control was >25% within 14 days.
Executive summary:

The test item Tosylfuranosid was investigated for its ready biodegradability in a manometric respirometry test over 28 days according to EU Commission Directive 92/69 EEC, C.4-D (1992) and OECD Guideline for Testing of Chemicals No. 301 F (1992). The oxygen consumption of the test item Tosylfuranosid in the test media was in the normal range of the oxygen consumption in the inoculum controls. Consequently, Tosylfuranosid was not biodegradable under the conditions of the test within 28 days. No degradation of the test item occurred in the abiotic control under the conditions of the test. In the toxicity control, containing both Tosylfuranosid and the reference item sodium benzoate, no inhibitory effect on the biodegradation of the reference item was determined. Thus, Tosylfuranosid had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 100 mg/L. In the procedure controls, the reference item sodium benzoate was degraded by an average of 86% on exposure Day 14, and reached an average biodegradation of 88% by the end of the test (Day 28), thus confirming suitability of the activated sludge.