[No public or meaningful name is available]

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:

June 2009 - October 2009

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-amino-5-cyano-N,3-dimethylbenzamide

EC Number:

619-946-6

Cas Number:

890707-29-6

Molecular formula:

C10H11N3O

IUPAC Name:

2-amino-5-cyano-N,3-dimethylbenzamide

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Sludge collected from sewage treatment works predominantly treating domestic waste was aerated and activated in the laboratory. Aliquots of homogenized samples were filtered and the solids level in the sludge was determined.
Final suspended solids concentration of 30 mg/L in control and test vessels.Test medium and activated sludge was mixed and aerated for 5 days to remove carbon dioxide.

Duration of test (contact time):

29 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301
- pH: 6.0-6.4
- pH adjusted: no
- Aeration of dilution water: yes
- Suspended solids concentration: 30 mg solids/L

TEST SYSTEM
- Culturing system: Five-litre amber-glass bottles connected to three dreschel bottles in series, each containing barium hydroxide (CO2 trap)
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: Interval of two days during the first 10 days of test, then a least once a week

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, 2 replicates
- Reference control: Sodium benzoate, 1 replicate
- Inhibition control: Sodium benzoate + test item, 1 replicate

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

74

Remarks on result:

other: 64% miniralisation was achived within 14 d

Details on results:

The cumulative level of CO2 production in sample controls after 29 days was 32 - 34 mg of CO2, was within the acceptable range (recommended maximum = 120 mg CO2 for a three-litre culture). These results confirm that the inoculum was viable and that the test was valid.
The degradation observed for sodium benzoate in presence of test item (Inhibition) after 14 days was 52% which was above the pass level of ≥25% required within 14 days.
The percentage degradation by samples containing only test item had achieved, 64% of the theoretical value (TCO2, 110.1 mg CO2) after 14 days and at the end of test (Day 29) the CO2 production was 74%.

BOD5 / COD results

Results with reference substance:

The reference item sodium benzoate biodegraded to 71% of its theoretical CO2 after 14 days and 84% after 29 days, confirming the validity of the test.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item is considered to be biodegradable according to the OECD test guideline (301B) for screening chemicals for ready biodegradability in an aerobic aqueous medium.

Executive summary:

The present study was conducted to determine the ready biodegradation of the test item according to guideline OECD 301B, Modified Sturm test.
The biodegradability of the test item was studied by dissolving the test item in inoculated mineral salt medium at 10 mg C/L. A control containing the inoculated mineral medium was studied in parallel to check the viability of the inoculum. To check the validity of the test, evolution of CO2 from the sodium benzoate reference item was measured as a positive control. To assess the potential inhibitory effects of the test item on the microbial activity of the inoculum, a mixture containing the reference item and the test item was studied.
Inoculums containing reference item, inhibition mixtures and test item were aerated for 29 days with air that had been treated to remove carbon dioxide (CO2). The CO2 produced by each culture was trapped in a series of dreschel bottles containing barium hydroxide, which were connected to the outlet from each test vessel. The residual barium hydroxide was determined at intervals by titration.
Items are considered to be readily biodegradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within 14 days of achieving the 10% level. The test item reached 64% degradation after 14 days when tested at a concentration of 10 mg C/L and at the end of test (Day 29) the CO2 production was 74%. Test test is therfore considered readily biodegradable.