2-isobutyl-4-vinyl-1,3-dioxolane

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 2017-06-14 to 2017-08-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992-07-17

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: A fresh sample of activated sludge was collected from the aeration tank of Shenyang North Sewage Treatment Plant.
- Method of cultivation: Coarse particles were removed by filtration through a fine sieve and the sample was settled. After the supernatant was discarded, the sludge was washed twice with mineral medium and the concentrated sludge was suspended in mineral medium. 4 replicates of 10 mL suspended sludge was weighed and dried at 105 °C for 2 hours and 7 minutes and reweighed to calculate initial sludge concentration (4 g/L).
- Storage conditions: aerobic at 21.7 - 23.1 °C
- Storage length: 5 days
- Preparation of inoculum for exposure: 10 mL sludge were weighed and dried at 105 °C for about 1 hour and 35 minutes and reweighed (3306 mg/L). Mineral medium (991 mL) was added to a 1 L flask, followed by the addition of 9.0 mL of the prepared activated sludge and the mixture was made up to volume to give a concentration of about 30 mg/L.
- Concentration of sludge: 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

37.09 mg/L

Based on:

test mat.

Initial conc.:

91.45 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
A KH2PO4, 2.1253 g add 250 mL water
K2HPO4, 5.4372 g
Na2HPO4 • 2H2O, 8.3507 g
NH4Cl, 0.1253 g
B CaCl2, 2.7503 g, add 100 mL water
C MgSO4 • 7H2O, 2.2501 g, add 100 mL water
D FeCl3 • 6H2O, 0.0251g, add 100 mL water

For 1 liter of mineral medium, 10 mL stock solution A was added to approximately 800 mL distilled water and the mixture stirred before adding, sequentially, 1 mL each of stock solutions B, C, and D. Aftermixing, the mixture was made up to 1 L with distilled water.

- Test temperature: 22 °C ± 1 °C (actual temperature range 21.4 - 22.9 °C)
- pH: 7.83/7.78 (adjusted 7.45/7.46)
- pH adjusted: yes, HCl

TEST SYSTEM
- Culturing apparatus: 1 L flask
- Number of culture flasks/concentration: 2 test substance, 2 inoculum blank control, 1 reference substance
- Measuring equipment: CES, U.K.Co-ordinated Environmental Services Ltd.
- Details of trap for CO2: The reference chamber contained air and was used as a reference pressure. The electrolyte bottle was filled with 45 mL of 25% (w/v) CUSO4 • 5H2O solution and 2 - 3 g CuO, fitted into the probe housing and tightened. The magnetic stirring rods were inserted into each flask, the CO2 trap cuvettes were filled with 4 mL of 10 mol/L NaOH solution and pushed onto the sensor head. CO2 trap cuvettes were inserted into the neck of each sample flask to absorb carbon dioxide produced metabolically by bacteria. The test flasks were attached to the sensor head. The assembled sensor head and sample flasks were immersed in the water bath (22 °C ±1 °C).

SAMPLING
- Sampling frequency: 234 h
- Sampling method: automated respirometer

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: Yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Details on results:

In the Toxicity Control (TC) test mixture, 43.9 % degradation occurred within 14 days and the value exceeded 25 % based on total ThOD, which indicated that the test item can be assumed to be not inhibitory under the conditions of this test.

Results with reference substance:

Biodegradation of the reference substance (Sodium benzoate) attained 61.4 % after Day 5, 82.3 % after Day 14 and 89.0 % after Day 28.

The following validity criteria were met by this test:

1) The oxygen uptake of the inoculum blank was 23.20 mg O2/L in 28 days, which did not exceed 60 mg O2/L.

2) The pH values were in the range of 7.46 - 7.69 (within the range 6 - 8.5).

3) The difference of extremes of replicate values of the removal of the test item at the end of the test was 4.2 % less than 20 %, which is specified criterion in test guideline.>

4) The percentage degradation of the reference item reached 61.1% after day 6, and was 64.8% after day 14 which exceeded the required pass level (the percentage degradation of reference item after day 14 > 60 %).

5) In Toxicity Control (TC) test mixture, containing both test item and reference item, 26.1 % ThOD degradation occurred within 3 days and 43.9 % ThOD within 14 days based on total ThOD. Since these values exceeded the 25 % ThOD limit for (test item) toxicity, it was concluded that the test item is not inhibitory to sludge micro-organisms.

Table 1: Biodegradation Results of Test Item, Toxicity Control, and Reference Item

Day	O2 -Uptake [mg O2/L]					BOD [mg O2/mg test item]		Biodegradation [%]
	IC	TC	PC	TS 1	TS 2	TS mean	PC	TS mean	TC	PC
1	6.71	13.77	29.57	6.21	6.04	0.000	0.397	0.0	3.8	23.8
3	11.71	60.73	60.04	11.70	12.04	0.005	0.838	0.2	26.1	50.2
7	16.73	81.70	82.90	16.78	16.87	0.003	1.148	0.1	34.6	68.7
10	19.41	91.78	92.80	19.87	19.53	0.008	1.273	0.3	38.5	74.1
14	20.57	103.08	99.81	22.97	21.26	0.042	1.375	1.7	43.9	82.3
21	21.40	113.79	108.77	26.57	22.66	0.086	1.516	3.5	49.1	90.8
28	23.20	118.14	108.85	27.88	23.99	0.074	1.486	3.0	50.5	89.0
IC Inoculum Control TS Test Suspension TC Toxicity Control PC Procedure Control

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The ready biodegradability of the test substance was investigated according to the OECD guideline 301F. Under the test conditions, the test substance was found to be not readily biodegradable over the test period of 28 days. Furthermore, the test substance showed no inhibitory effect on the microorganisms. At the end of the test, the test substance did not reach the 10 % level of degradation.

Executive summary:

The ready biodegradability of the test substance was investigated in accordance with the OECD guideline 301 F: Ready Biodegradability: Manometric Respirometry Test (1992). The biodegradation of the test substance was followed by exposing it to microorganisms from sewage (predominantly domestic, non-adapted) over 28 days. The method assesses the ready biodegradability of a test substance under aerobic conditions at 22 ± 1°C in diffuse light. During this period the biodegradation was determined on the basis of the reduction of dissolved oxygen. The degree of biodegradation was calculated by the amount of oxygen taken up by the test substance (corrected for that in the blank inoculum control) as a percentage of ThOD or BOD. As a reference compound (functional control control), 57.65 mg/L of sodium benzoate was tested simultaneously under the same conditions. In the toxicity control, the test substance showed no inhibitory effect on the microorganisms at the test concentrations of 36.8 and 58.24 mg/L. In the functional controls, the reference compound sodium bemnzoate was readily biodegraded by an average of 89 % after 28 days of exposure. At the end of the test (28 days), the test substance was biodegraded by an average of 3 % (2 replicates). Therefore, for the test substance no biodegradation was observed under the test conditions.

Description of key information

The ready biodegradability of the test substance was investigated according to the OECD guideline 301F (2017). Under the test conditions, the test substance was found to be not readily biodegradable over the test period of 28 days. Furthermore, the test substance showed no inhibitory effect on the microorganisms. At the end of the test, the test substance did not reach the 10 % level of degradation.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of the test substance was investigated in accordance with the OECD guideline 301 F: Ready Biodegradability: Manometric Respirometry Test (2017). The biodegradation of the test substance was followed by exposing it to microorganisms from sewage (predominantly domestic, non-adapted) over 28 days. The method assesses the ready biodegradability of a test substance under aerobic conditions at 22 ± 1°C in diffuse light. During this period the biodegradation was determined on the basis of the reduction of dissolved oxygen. The degree of biodegradation was calculated by the amount of oxygen taken up by the test substance (corrected for that in the blank inoculum control) as a percentage of ThOD or BOD. As a reference compound (functional control control), 57.65 mg/L of sodium benzoate was tested simultaneously under the same conditions. In the toxicity control, the test substance showed no inhibitory effect on the microorganisms at the test concentrations of 36.8 and 58.24 mg/L. In the functional controls, the reference compound sodium bemnzoate was readily biodegraded by an average of 89 % after 28 days of exposure. At the end of the test (28 days), the test substance was biodegraded by an average of 3 % (2 replicates). Therefore, for the test substance no biodegradation was observed under the test conditions.