Uridine, 2'-deoxy-5-ethyl-, 3',5'-bis(4-chlorobenzoate)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 04st 2000 - March 27st 2001

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Name of test material (as cited in study report): 2'DEOXY-5-ETHYL-URIDINE, 3', 5'-BIS (4- CHLOROBENZOATE)
- Description : white crystalline powder
- Lot number : β-CEDU 2/98-G
- Date received : 06 December 2000
- Storage conditions : ambient conditions

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): activated sludge from the aeration tank of the facility’ s sewage treatment plant.
- Preparation of inoculum for exposure: Coarse particles were removed by filtration through a fine sieve and the sample was then centrifuged at 1100 g for 10 minutes. The resulting supernatant was discarded. The pellet of sludge was washed with the mineral medium and centrifuged for a second time. The concentrated sludge was then suspended in mineral medium to yield a concentration of 3 g suspended solids/l. This was aerated until required.
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium acc. to OECD 301 F
- Additional substrate: No
- Test temperature: 20°C
- pH: 6 – 8.5
- pH adjusted: no

TEST SYSTEM
- Culturing apparatus: Incubator
- Number of culture flasks/concentration: 6

SAMPLING
- Sampling frequency: daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, containing inoculum only.
- Abiotic sterile control: No
- Toxicity control: yes, containing test item, reference item and inoculum
- Positive control: yes, containing reference item and inoculum

STATISTICAL METHODS:
At each time point, the oxygen uptake (mg/l) of the test item was calculated as the mean of the two replicate flasks and corrected against uptake of the inoculum control (blank) at the same time point. Uptake of the inoculum control was similarly calculated as the mean of the two replicate flasks. The value obtained was divided by the concentration of test item in the flask to yield the Biochemical Oxygen Demand (BOD) expressed as mg oxygen/mg test item.
The percentage (biodegradation) was calculated from the observed BOD relative to the ThOD for the substance. Calculation was performed using the ThOD (NH4) as low degradation of the test item was observed.

Reference substance:

other: sodium benzoate

Key result

Parameter:

% degradation (O2 consumption)

Value:

< 20

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The results of this study indicate that the test item 2’deoxy-5-ethyl-uridine,3’,5’-bis(4-chlorobenzoate) is not readily biodegradable in the manometric respirometry test.

Executive summary:

The ready biodegradability of 2’deoxy-5-ethyl-uridine,3’,5’-bis(4-chlorobenzoate) in an aerobic aqueous medium was assessed according to OECD Guideline for the testing of Chemicals No. 301F.

A measured volume of inoculated mineral medium, containing the test item at a nominal concentration of 100 mg/l as the nominal sole source of organic carbon, was stirred in a closed flask at constant temperature for 28 days. Evolved carbon dioxide was adsorbed and pressure changes measured by a manometer. Oxygen consumption by the test item was expressed as a percentage of the Theoretical Oxygen Demand (ThOD). The validity of the test System was assessed by concurrent use of a positive control reference item (sodium benzoate).

The observed low oxygen consumption and the derived BOD (Biochemical Oxygen Demand) indicate that no significant degradation has occurred. Values obtained with sodium benzoate, resulted in calculated biodegradation in excess of 60% of the theoretical value demonstrating validity of the test System in assessing biodegradability. The toxicity control (test and reference items combined) indicated that the test item was slightly inhibitory to the test System. Measured pH at the start and end of the 28 day test period was within specified limits.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of 2’deoxy-5-ethyl-uridine,3’,5’-bis(4-chlorobenzoate) in an aerobic aqueous medium was assessed according to OECD Guideline for the testing of Chemicals No. 301F.

A measured volume of inoculated mineral medium, containing the test item at a nominal concentration of 100 mg/l as the nominal sole source of organic carbon, was stirred in a closed flask at constant temperature for 28 days. Evolved carbon dioxide was adsorbed and pressure changes measured by a manometer. Oxygen consumption by the test item was expressed as a percentage of the Theoretical Oxygen Demand(ThOD). The validity of the test System was assessed by concurrent use of a positivecontrol reference item (sodium benzoate).

The observed low oxygen consumption and the derived BOD (Biochemical Oxygen Demand) indicate that no significant degradation has occurred. Values obtained with sodium benzoate, resulted in calculated biodegradation in excess of 60% of the theoretical value demonstrating validity of the test System in assessing biodegradability.

The toxicity control (test and reference items combined) indicated that the test item was slightly inhibitory to the test System. Measured pH at the startand end of the 28 day test period was within specified limits.