(ethyl acetoacetato-O1',O3)(pentane-2,4-dionato-O,O')[propane-1,3-diolato(2-)-O,O']titanium

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:

2016-08-24 to 2017-04-05

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)

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK
- Laboratory culture: The activated sewage sludge sample was washed twice by settlement and re-suspension in mineral medium to remove any excessive amounts of dissolved organic carbon (DOC). The washed sample was then maintained on continuous aeration at approx. 21ºC. Determination of the suspended solids level of the activated sewage sludge was carried out by filtering a sample (100 mL) of the washed activated sewage sludge by suction through pre-weighed GF/A filter paper* using a Buchner funnel. Filtration was then continued for a further 3 minutes after rinsing the filter three successive times with 10 mL of deionized reverse osmosis water. The filter paper was then dried in an oven at approximately 105 ºC for at least 1 hour and allowed to cool before weighing. This process was repeated until a constant weight was attained.

- Concentration of sludge: 3mg suspended solids per Liter

Duration of test (contact time):

28 d

Initial conc.:

19.8 mg/L

Based on:

test mat.

Initial conc.:

10 mg/L

Based on:

other: carbon

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium, recommendet in the OECD Guidelines
- Test temperature: 19 - 24°C
- pH: post adjustment: 7.4-7.6
- pH adjusted: yes (if necessary the pH was adjusted to pH 7.4±0.2)
- Aeration of dilution water: CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel and stirred continuously by magnetic stirrer
- Suspended solids concentration: Each test vessel was inoculated with the prepared inoculum at a final concentration of 30 mg suspended solids (ss)/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: sealed culture vessels
The following test preparations were prepared and inoculated in 5 liter test culture vessels each containing 3 liters of solution:
a) An inoculated control, in duplicate, consisting of inoculated mineral medium.
b) The procedure control containing the reference item (sodium benzoate), in duplicate, in inoculated mineral medium to give a final concentration of 10 mg carbon/L.
c) The test item, in duplicate, in inoculated mineral medium to give a final concentration of 10 mg carbon/L.
d) The test item plus the reference item in inoculated mineral medium to give a final concentration of 20 mg carbon/L to act as a toxicity control (one vessel only).
The test vessels were sealed and CO2-free air bubbled through the solution at a rate of 30 to 100 mL/min per vessel 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 (Carbosorb®) 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 water.

SAMPLING
- Sampling frequency: 0, 2, 6, 8, 10, 15, 21, 28 and 29
All samples were analyzed for IC immediately. The remainder of all samples with the exception of the Day 0 samples were frozen for further analysis if required.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
- procedure control; yes with sodium benzoate

Reference substance:

benzoic acid, sodium salt

Remarks:

Sodium benzoate

Parameter:

% degradation (CO2 evolution)

Value:

67

Sampling time:

28 d

Percentage Biodegradation Values

Day	% Biodegradation
	Procedure Control	Test Item	Toxicity Control
0	0	0	0
2	59	18	40
6	73	58	72
8	85	66	62
10	82	71	78
15	77	65	72
21	80	67	77
28	86	63	69
29*	88	67	66
* Day 29 values corrected to include any carry-over of CO2 detected in Absorber 2

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item attained 67% biodegradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Description of key information

The test item attained 67% biodegradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. The test item can therefore 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:

readily biodegradable