4,4'-dioxo-4,4'-dioxydibutyric acid

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:

from 2017-09-13 to 2017-11-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

see 'Principles of method if other than guideline'

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

yes

Remarks:

see 'Principles of method if other than guideline'

Qualifier:

according to guideline

Guideline:

ISO 10707 Water quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)

Deviations:

yes

Remarks:

see 'Principles of method if other than guideline'

Principles of method if other than guideline:

Minor deviations from the guidelines of the Closed Bottle test (OECD TG 301) were introduced; a) ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound), and b) river water instead of an effluent/extract/mixture was used as inoculum.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot/Batch: 1504501023
Purity: 4,4'-dioxo-4,4'-dioxydibutyric acid - 70.5 %
Water - 30.4 %

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Remarks:

river water

Details on inoculum:

River water was sampled from the Rhine near Heveadorp, The Netherlands. The nearest plant (Arnhem-Zuid) treating domestic wastewater biologically was 3 km upstream. The river water was aerated for 7 days before use to reduce the endogenous respiration. River water without particles was used as inoculum. The particles were removed by sedimentation after 1 day while moderately aerating.

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

DEIONIZED WATER
- Deionized water containing no more than 0.01 mg/L Cu was prepared in a water purification system.

TEST BOTTLES
- The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.

NUTRIENTS AND STOCKS
- The river water used was spiked per liter of water with 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.4 mg Na2HPO4·2H2O, 22.5 mg MgSO4·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. Ammonium chloride was not added to the river water to prevent nitrification. The test substance and sodium acetate were added to the bottles using aqueous stock solutions of 1.42 (1.0 g/L active) and 1.0 g/L, respectively.

TEST PROCEDURE
- Use was made of 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance. The concentrations of the active ingredient of test substance, and sodium acetate in the bottles were 5.0 mg/L and 6.7 mg/L, respectively. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.

Reference substance:

acetic acid, sodium salt

Remarks:

anhydrous

Preliminary study:

Two preliminary tests with activated sludge from a domestic wastewater treatment plant and river water were performed. The test item was tested at a concentration of 6 mg/L. With both activated sludge and river water a biodegradation of more than 80 % (80 5 in the activated sludge and 86 % in the river water) was observed. The test item was determined as readily biodegradable and river water was chosen as media for the main test.

Test performance:

pH of the media at the start of the test was 8.0 and at the 28th day was 8.0 in the control and 8.1 in the test solutions. The temperature ranged from 23.1 to 23.5 °C.

Key result

Parameter:

% degradation (O2 consumption)

Value:

84

Sampling time:

28 d

Details on results:

- The calculated theoretical oxygen demand (ThOD) of the active ingredient of the test item is 0.9 g O2/g. The ThOD of sodium acetate is 0.8 g O2/g.
- The test item showed no inhibitory effects at the tested concentration.

Results with reference substance:

The reference substance was degraded by 81 % of its ThOD after 14 days.

Table I Oxygen consumption (mg/L) and the percentages biodegradation of the test substance (BOD/ThOD) and reference substance (sodium acetate) (BOD/ThOD) in the Closed Bottle test.

Time (days)	Oxygen consumption (mg/L)		Biodegradation (%)
	Test Substance	Reference Substance	Test substance	Reference substance
0	0.0	0.0	0	0
7	2.9	3.8	64	70
14	3.4	4.4	76	81
21	3.7		82
28	3.8		84

 

Validity of the test

The validity of the test is demonstrated by an endogenous respiration of 0.9 mg/L at day 28.

Furthermore, the differences of the replicate values at day 28 were less than 20 %.

The biodegradation percentage of the reference compound, sodium acetate, at day 14 was 81 %.

Finally, the validity of the test is shown by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item was biodegraded by 84 % at day 28 of the closed Bottle Test. Over 60 % biodegradation was achieved within the 10-day window. Therefore, the test item is considered as readily biodegradable.

Executive summary:

The ready biodegradability of the test item was determined with river water over a test period of 28 days in the Closed bottle test according to OECD 301D, Regulation (EC) No. 440/2008 Method C.4 -E and ISO 10707 and under GLP. The test item was tested at a concentration of 5 mg/L. The calculated theoretical oxygen demand of the test item was 0.9 mg O2/g. The oxygen concentration was measured with an O2 electrode. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The biodegradation of the test item came to 84 % after 28 days. In conclusion, the test item is readily biodegradable as the pass level of 60 % degradation was reached in a 10-d-window within the 28 days period of the study.

Description of key information

The test item was biodegraded by 84 % at day 28 of the closed Bottle Test. Over 60 % biodegradation was achieved within the 10-day window. Therefore, the test item is considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of the test item was determined with river water over a test period of 28 days in the Closed bottle test according to OECD 301D, Regulation (EC) No. 440/2008 Method C.4 -E and ISO 10707 and under GLP. The test item was tested at a concentration of 5 mg/L. The calculated theoretical oxygen demand of the test item was 0.9 mg O2/g. The oxygen concentration was measured with an O2 electrode. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The biodegradation of the test item came to 84 % after 28 days. In conclusion, the test item is readily biodegradable as the pass level of 60 % degradation was reached in a 10-d-window within the 28 days period of the study.