Methyl 5-deoxy-2,3-O-isopropylidene-β-D-ribofuranoside

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:

26 February 2013 to 13 June 13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Fully GLP compliant and in accordance with current test guidelines

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Methylfuranoside

IUPAC Name:

Methylfuranoside

Constituent 2

Reference substance name:

Methyl 5-deoxy-2,3-O-isopropylidene-β-D-ribofuranoside

EC Number:

245-485-1

EC Name:

Methyl 5-deoxy-2,3-O-isopropylidene-β-D-ribofuranoside

Cas Number:

23202-81-5

Molecular formula:

C9H16O4

IUPAC Name:

methyl 5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranoside

Test material form:

other: Pale yellow liquid

Details on test material:

Name: Methylfuranoside
CAS number: 23202-81-5
Batch number: 201111082008#
Quantity received: 1.5 kg
Purity: 99.7%
Expiry date: November 2013
Date of receipt: 20 February 2013
Storage details: stored in a sealed container, at room temperature (15 to 30°C) in the dark

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
The reference substance used in this study was sodium benzoate (VWR, AnalaR). Based on the molecular formula of sodium benzoate, its carbon content expressed as a percentage by weight is 58.3%. This value was used in setting the test concentration of sodium benzoate.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

A sample of activated sludge was collected from one of the return lines at Burley Menston sewage treatment works (West Yorkshire, UK), which has a predominantly domestic waste-water catchment. The sample was transported to Smithers Viscient in a closed container, but with an adequate headspace, to prevent the sample becoming anaerobic.
On arrival, the sample was aerated by means of a compressed air supply.
The suspended solids concentration of the activated sludge was determined by filtering a subsample (25 mL) through a pre-dried and pre-weighed glass microfibre filter (Whatman GF/C). The filter and retained solids were then dried in an oven and re-weighed. The weight of the sludge solids was determined from the difference in the weights before and after drying.
The activated sludge used in this study was not deliberately acclimatised or adapted to methylfuranoside before exposure under test conditions.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

15 other: mg carbon/L

Based on:

other: carbon content

Details on study design:

The study consisted of four treatment groups as described below:
Blank control containing inoculated mineral salts medium
Test substance containing inoculated mineral salts medium and test substance
Reference substance containing inoculated mineral salts medium and sodium benzoate
Toxicity control containing inoculated mineral salts medium, test substance and sodium benzoate

The purpose of the toxicity control was to assess the biodegradation of the reference substance in the presence of the test substance.
Duplicate vessels were prepared for the test substance, reference substance and blank control groups. A single vessel was prepared for the toxicity control.

Reference substance

Reference substance:

other: Sodium benzoate

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

29 d

Details on results:

Inorganic Carbon (IC) Content of the Test Medium
The IC concentration of the test inoculated mineral salts medium concentrate was 0.32 mg carbon/L. The validity criterion of less than 5% carbon loading (2.25 mg carbon/L) was therefore met.
Measured CO2 Yields as a Percentage of Theoretical
The total carbon dioxide production in the blank control vessels was 97 and 95 mg for the two vessels, satisfying the validity criterion of less than 120 mg.
Methylfuranoside
To be considered readily biodegradable, a test substance must achieve 60% biodegradation by the end of the test. Additionally, the rate of biodegradation must be sufficient to reach 60% within ten days of reaching 10%. Since no biodegradation was observed, methylfuranoside cannot be considered readily biodegradable. Percent biodegradation values at each sampling interval, for the two replicates containing methylfuranoside, did not vary, therefore satisfying the validity criterion of less than 20% difference.
Sodium Benzoate
Rapid CO2 generation commenced immediately and declined to a more gradual rate over the period of the incubation. The mean percentage biodegradation had reached 75% by Day 14 and 85% by Day 28. The validity criterion of 60% biodegradation at 14 days was therefore met.
Toxicity Control
Assessment of biodegradation in the toxicity control was calculated for the sodium benzoate fraction. The rate of biodegradation of the reference substance in the presence of methylfuranoside (77% at 14 days and 88% at 28 days) was comparable to that of the reference substance alone, suggesting that methylfuranoside did not have an inhibitory effect on the sludge microorganisms under the test conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

All validity criteria were satisfied and the results of this study are therefore considered to be valid.
Mean CO2 evolution from methylfuranoside remained at 0% of the theoretical CO2 yield over the 28 days. The level of biodegradation failed to meet the requirements for ready biodegradability and methylfuranoside cannot, therefore, be classified as readily biodegradable. However, the results of this study do not necessarily suggest that methylfuranoside would persist or accumulate in the aerobic environment.

Executive summary:

The ready biodegradability of methylfuranoside was assessed by measurement of carbon dioxide (CO₂) evolution under standard conditions. The procedure followed was that of OECD Guideline 301B, Ready Biodegradability (Adopted 1981, Revised 1992).

The test substance, methylfuranoside, was added to the test system in an aqueous solution. Buffered mineral salts medium was added to give a test substance concentration equivalent to 15 mg organic carbon/L. The medium was inoculated with microorganisms derived from a sample of activated sludge not previously intentionally exposed to the test substance. Test vessels were incubated in darkness at 22 ± 2°C for 28 days and their contents continuously sparged with a supply of CO₂-free air. The exhaust air from each vessel was passed through a series of traps containing a barium hydroxide solution, to trap evolved CO₂.

At regular intervals during the incubation, traps were detached and their contents titrated with hydrochloric acid to determine the quantity of CO₂ evolved from the respective test vessels. At the end of incubation, the test vessel contents were acidified to release any residual CO₂ that may have remained in solution. Titration of the traps was performed following overnight aeration.

The procedure and the activity of the inoculum were checked by measuring the CO₂ evolved from vessels containing a reference substance, sodium benzoate. An additional vessel containing a combination of the test and reference substances served as a toxicity control to assess whether the test substance was inhibitory to biodegradation at the test concentration. Two blank control vessels were also prepared containing inoculated medium only. The results of these vessels were used to check the validity of the test and to correct the evolved CO₂ values.

Mean CO₂ evolution from methylfuranoside remained at 0% of the theoretical CO₂ yield over the 28 days. The level of biodegradation failed to meet the requirements for ready biodegradability and methylfuranoside cannot, therefore, be classified as readily biodegradable. However, the results of this study do not necessarily suggest that methylfuranoside would persist or accumulate in the aerobic environment.

Mean total CO₂ production in the blank control vessels was 96 mg at the end of the test, satisfying the validity criterion of < 120 mg.

Mean biodegradation of the reference substance was 75% on Day 14, and 85% at the end of the test. The rate of biodegradation of the reference substance in the presence of methylfuranoside (88% at 28 days) was comparable to that of the reference substance alone, suggesting that methylfuranoside did not have an inhibitory effect on the sludge microorganisms under the test conditions.

All validity criteria were satisfied and the results of this study are therefore considered to be valid.