Benzene, poly(propene) derivatives

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

14 August 2007 to 12 September 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): AL305B
- Physical state: clear, colourless, slightly viscous liquid
- Lot/batch No.: TS07003
- Expiration date of the lot/batch: 24 May 2007
- Storage condition of test material: room temperature, in the dark

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was obtained from the aeration stage of Severn Trent Water Plc sewage treatment plant at Loughborough, UK, which treats predominantly domestic sewage.

The activated sewage sludge sample was washed three times by settlement and resuspension in culture medium to remove any excess amounts of dissolved organic carbon (DOC). The washed sample was them maintained on continuous aeration at a temperature of approx 21 ºC and used on the day of collection. Determination of the suspended solids levels of the sludge was carried out by filtering a sample (100 mL) of the washed sludge by suction through pre-weighed GF/A paper using a Buchner funnel. Filtration was then continued for a further 3 minutes after rinsing the funnel three successive times was 10 mL of deionised reverse osmosis water. The filter paper was then dried in an oven ay approx 105 ºC for at least 1 hour and allowed to cool before weighing. This process was repeated until a constant weight was attained. The suspended solids concentration was equal to 3.1 g/L prior to use.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

other: total carbon

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TOXICITY CONTROL
For the purposes of the test, a toxicity control, containing the test material and sodium benzoate, was prepared in order to assess any toxic effect of the test material on the sewage sludge micro-organism used in the test. 34.5 mg of test material was adsorbed onto the surface of 100mg of granular silica gel prior to dispersal in approximately 400 mL of culture medium with the aid of higher shear mixing (approx 7500 rpm, 15 minutes). The test material/silica gel/culture medium dispersion was then dispersed in inoculated culture medium and 51.4 mL of the sodium benzoate stock solution added. The volume was adjusted to 3 litres to give a final concentration of 11.5 mg test material/L plus 17.1 mg sodium benzoate/L, equivalent to a total of 20 mg carbon/L.

PREPARATION OF TEST SYSTEM
The following test preparations 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 plus 100 mg silica gel;
b) sodium benzoate, in duplicate, in inoculated culture medium plus 100 mg silica gel to give a final concentration of 10 mg carbon/L;
c) the test material, in triplicate, in inoculated culture medium plus 100 mg silica gel to give a final concentration of 10 mg carbon/L;
d) the test material plus sodium benzoate in inoculated culture medium plus 100 mg silica gel to give a final 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 mf suspended solids/L. The test was carried out in a temperature controlled room at approx 21 ºC in darkness.

The CO2 produced by degradation was collected in two 500 mL Dreshcel bottles containing 350 mL of 0.05 M NaOH.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

not applicable.

Test performance:

The total CO2 evolution in the control vessels on day 28 was 20.01 mg/L and therefore satisified the validation criterion in the OCED Guideline. The IC content of the test material suspension in the mineral medium at the start of the test was below 5% of the TC content and hence satisfied the validation criterion in the OECD Guideline. The difference between the values for CO2 production at the end of the test for the replicate vessels was <20% and hence satisifed the validation criterion given in the OECD Guideline.

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

70

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Sodium benzoate attained 85% degradation after 14 days and 72% dgradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

Any other information on results incl. tables

The test material attained 70% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No 301B the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within l0 days of the degradation exceeding 10%. However, the test material has exhibited the potential for rapid degradation.

The test material was not found to be toxic to the sewage treatment micro-organisms used in the test.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test material attained 70% degradation after 28 days although failed to satisfy the validation criteria to be considered readily biodegradable. However, the test material exhibited the potential for rapid degradation.

Executive summary:

Introduction.

A study was performed to assess the ready biodegradability of the test material in an aerobic aqueous medium. The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No. 301B, "Ready Biodegradability; CO, Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), US Code of Federal Regulations Title 40, Part 796, Section 3260 and US EPA Fate, Transport, and Transformation Test Guidelines OPPTS 835.3110 Paragraph (m).

 

Methods.

The test material, at a concentration of 10 mg Carbon/L, was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at approximately 21°C for 28 days. Following the recommendations of the International Standards Organisation (ISO 1995) and the published literature (Handley et al,2002), the test material was adsorbed onto granular silica gel prior to dispersion in the test medium to aid dispersion of the test material in the test medium and to increase the surface area of the test material exposed to the test organisms. 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 70% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No 30IB the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation exceeding 10%. However, the test material has exhibited the potential for rapid degradation.