Methyl benzoylformate

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:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany.
The inoculum was collected on 22 October 2014 from the aeration tank of the plant. A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size about 1 mm. To reduce the content of inorganic carbon in the blank controls the activated sludge was aerated with carbon dioxide free air for about 24 hours at 22 ± 2° C.
At the day of exposure the suspension was washed one time with drinking water. Subsequently the aeration was stopped and the sludge was allowed to settle. After settling the supernatant was discarded and the remaining sludge suspension was filled up with drinking water and the concentration of the sludge was adjusted to 6.0 g/L dry weight.
Aliquots of 7.5 mL were added to the test vessels to obtain an activated sludge concentration of 30 mg/L dry weight.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: TOC

Initial conc.:

31 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
The used mineral medium complies with the test guideline OECD 301B. It was prepared as follows:
Solution A: KH2PO4 : 8.50 g
K2HPO4 : 21.75 g
Na2HPO4 × 2 H2O : 33.40 g
NH4Cl : 0.50 g
The compounds were dissolved with deionized water to 1000 mL; the pH value was adjusted to 7.4.
Solution B: CaCl2 × 2 H2O : 36.40 g
The compound was dissolved with deionized water to 1000 mL
Solution C: MgSO4 × 7 H2O : 22.50 g
The compound was dissolved with deionized water to 1000 mL
Solution D: FeCl3 × 6 H2O : 0.25 g
The compound was dissolved with deionized water to 1000 mL
15 mL solution A, 1.5 mL solution B, 1.5 mL solution C and 1.5 mL solution D was used for the preparation of the test assays.
- Test temperature: 22 ± 2° C
- pH: 7.4 ± 0.2,
- pH adjusted: yes (if necessary)
- Aeration: At begin of the exposure phase the test vessels were connected with an aeration unit and the bubble aeration with carbon dioxide free air was started after connecting the several test vessels with the absorption units.

TEST SYSTEM
- Culturing apparatus: 2 L incubation bottles filled up to a volume of 1.5 L
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions:
- Measuring equipment: The TIC- and DOC-analyses were performed as repeat determination, using a TOCanalyzer equipped with an auto sampler (Shimadzu TOC-5000A and/or TOC-L CSH/CSN). The system works with a combustion/non-disperse infrared gas analysis method. For calibration of the TOC-Analyzer, standard samples were measured before start of measurements to prove the conformity with the calibration curve. The samples for TICanalysis (absorption solution) were measured without further treatment.
The samples for the DOC-analysis were centrifuged for about 15 minutes at 4000 rpm. The samples were analyzed on the day of sampling.
-Experimental procedure: The Carbon Dioxide Evolution Test was performed in 2 L incubation bottles filled up to a volume of 1.5 L. The bottles were connected to two serial scrubbing bottles (total volume 250 mL) filled with 100 mL 0.05 mol sodium hydroxide solution for the adsorption of carbon dioxide from biodegradation processes. Usually twice a week the Total Inorganic Carbon (TIC) values of the adsorption solutions of the first trap were determined and used for the calculation of the produced carbon dioxide. After each sampling the second trap was moved forward and the new trap with fresh sodium hydroxide solution was placed into the second position. Each trap was analyzed separately.
The TIC-value of the freshly prepared sodium hydroxide solution was determined and considered by the calculation of biogenic produced carbon dioxide amount. The incubation bottles were stirred on magnetic stirrers; the aeration was performed with carbon dioxide free air at a flow of approximately 800 mL per hour.

At the end of exposure, the pH values were measured in each test vessel. For stripping of carbon dioxide, dissolved in the test medium, each test vessel was acidified by adding 2 mL of concentrated hydrochloric acid. The concentration of dissolved organic carbon in the blank controls and reference substance assays were determined. Since the test substance was sufficiently soluble in water, DOC measurements could be also performed from the inhibition control and test substance assays.
The aeration was continued for about 24 hours and the released carbon dioxide amounts in both traps of each test vessel were determined and added to the calculated amount of the previous day.

Reference substance:

aniline

Parameter:

% degradation (CO2 evolution)

Value:

90 - 100

Sampling time:

28 d

Details on results:

The required pass level for ready biodegradability within a ten days window was reached. The degree of biodegradation at the end of the ten day window was approx. 82% CO2/ThCO2.
Degree of DOC removal of test substance at the end of exposure: 90-100 %
Degree of biodegradation of the test substance at the end of exposure, mean value: 90-100 % CO2/ThCO2

Results with reference substance:

Degree of biodegradation of the reference substance (aniline) after 14 days: 92 % CO2/ThCO2
Degree of biodegradation in the inhibition control after 14 days: 79 % CO2/ThCO2

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance is readily biodegradable according OECD criteria.

Executive summary:

In this guideline (OECD 301 B) study, the test material (EC 239-263-3) was determined to be "readily biodegradable". The test material achieved 82% degradation (CO2/ThCO2) at 10 days, and 90 -100% degradation (CO2/ThCO2) at 28 days. The test material was determined to meet the criteria to be considered "Readily biodegradable" in accordance with the OECD 301 guideline.

Description of key information

 Study carried out according to guideline and with GLP compliance.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

A GLP guideline study according to OECD 301B has been conducted (BASF SE 2015). After 28 d of exposure 90 - 100 % biodegradation was observed in the carbon dioxide evolution test based on the quantitative determination of the formed carbon dioxide in the test substance assays by comparison with the calculated maximal theoretical carbon dioxide production. Since the required pass level for ready biodegradability within a ten days window was reached the test substance is regarded as readily biodegradable.