L-Valine, N-(methoxycarbonyl)-3-methyl-

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:

Between 10 November 1998 and 9 December 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Commission Directive 92/69/EEC, C.4-C (CO2 Evolution test).

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

referenced as Method C4-C of Commission Directive 92/69/EEC

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was obtained on 9 November 1998 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Belper, Derbyshire, UK, which treats predominantly domestic sewage.
The sample of activated sewage sludge was maintained on continuous aeration upon receipt. A sample of the activated sewage sludge was washed three times by settlement and resuspension in culture medium to remove any excessive amounts of dissolved organic carbon (DOC) that may have been present. A sub-samle of the washed sewage sludge was then removed and the suspended solids concentration determined.

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 10 mg/L

Based on:

other: total carbon from test material

Remarks:

theoretical amount present as test material is 50.78% or 30 mg TOC

Initial conc.:

ca. 10 mg/L

Based on:

other: total carbon from standard material (sodium benzoate)

Remarks:

Theoretical amount of C present as standard material is 58.34% or 30 mg TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The following test solutions were prepared and inoculated in 5 litre glass culture vessels each containing 3 litres of solution:
a) A control, in duplicate, consisting of inoculated culture medium
b) The standard material (sodium benzoate), in duplicate, in inoculated culture medium to give a final test concentration of 10 mg carbon/l.
c) The test material, in duplicate, in inoculated culture medium to give a final test concentration of 10 mg carbon/l
d) The test material plus the standard material in inoculated culture medium to give a final test concentration of 20 mg carbon/l to act as a toxicity control (one vessel only)

Each test vessel was inoculated with the prepared inoculum at a final concentration of 30 mg suspended solids (ss)/l. The study was carried out in a temperature controlled room at 21 C, in darkness.
Approximately 24 hours prior to addition of the test and standard materials, the vessels were filled with 2400 ml of culture medium and 32.1 ml of inoculum and aerated overnight. On day 0 the test and standard materials were added and the volume in all the vessels adjusted to 3 litres by the addition of culture medium.
The culture vessels were sealed and CO2-free air bubbled through the solution at a rate of approximately 40 ml/minute and stirred continuously by magnetic stirrer.
The CO2-free air was produced by passing compressed air through a glass column containing self-indicating soda lime (Carbosoab(r)) granules.
The CO2 produced by degradation was collected in two 500 ml Dreschel bottles containing 350 ml of 0.05 M NaOH. The CO2 absorbing solutions were prepared using purified de-gassed water.

A toxicity control (BMS 214702-01 and sodium benzoate) was included in the study to assess any toxic effect of the test material on the seage sludge micro-organisms used in the study.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not relevant

Test performance:

- Total CO2 evolution in control vessels on day 28 was 40.3 mg/l. Although the CO2 evolution was in excess of 40 mg/l at the end of the test, this is considered not to affect the integrity of the study given that the upper level of 70 mg CO2/l given in the OECD Guidelines was not exceeded.
- The results of the inorganic carbon analysis of samples from both absorber vessels on day 29 confirmed that no significant amounts of CO2 were present in solution in the culture vessels as inorganic carbonate.
- IC analysis of the samples from the second absorber vessels on day 29 confirmed that no significant carry-over of CO2 into the second absorber vessels occurred.
- The TC/IC ration of the test material dispersions was in excess of the recommended level of 5% given in the Test Guidelines. This is considered to be due to the low TC concentration in the test medium and hence the IC contribution is relatively large. This is considered not to affect the integrity of the study or the results obtained given the low level of IC in the test vessels and that the CO2 evolution in the control vesseld did not exceed the upper limit of 70 mg/l given in the OECD Guidelines.
- The degradation rates calculated from the results of the DOC analyses were higher than those calculated from inorganic carbon analysis. This is considered to be due to incorporation of the test material into the microbial biomass prior to degradation and hence CO2 evolution occurring.
- The toxicity control attained 54% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment micro-organisms used in the stury.
- Sodium benzoate attained 85% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

47

Sampling time:

28 d

Details on results:

Points of degradation plot (test substance):
3 % degradation after 1 d
11 % degradation after 8 d
30 % degradation after 16 d
39 % degradation after 24 d
47 % degradation after 28 d

Results with reference substance:

Points of degradation plot (reference substance):
13 % degradation after 1 d
68 % degradation after 8 d
81 % degradation after 16 d
82 % degradation after 24 d
85 % degradation after 28 d

Detailed result tables and degradation graph can be found in attached document.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test material attained 47% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Executive summary:

Methods

A study was performed/ to assess the ready biodegradability of the test material in an aerobic aqueous media. The method followed is that described in the OECD Guidelines for Testing of Chemicals (1992) No 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/574/EEC) and US EPA Ecological Effects Test Guidelines OPPTS 835.3110 Paragraph (M).

Procedures

The test material was exposed to activated sewage sludge micro-organisms at a concentration of 10 mg C/l with culture medium in sealed culture vessels in the dark at 21 C for 28 days. The degradation of the test material was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes.

Results

The test material attained 47% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Description of key information

Ready biodegradability of the test material in an aerobic aqueous media was assessed using the method followed is that described in the OECD Guidelines for Testing of Chemicals (1992) No 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/574/EEC) and US EPA Ecological Effects Test Guidelines OPPTS 835.3110 Paragraph (M).

The test material attained 47% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed