cis-2-methyl-4-propyl-1,3-oxathiane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected February 2000; signature: April 2000

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): mixed population of sewage sludge micro-organisms was obtained from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
- Storage conditions: Room temperature (at 21°C).
- Storage length: Used on day of collection.
- Preparation of inoculum for exposure: The sample of effluent was filtered through coarse filter paper (first approximate 200 ml discarded) and the filtrate maintained on continuous aeration.
- Initial cell/biomass concentration: Not reported.
- Water filtered: yes (water used to prepare culture medium).
- Type and size of filter used, if any: Aerated reverse osmosis purified and deionised water (Elga Optima 15+). The 'dilution water' was kept in a temperature controlled room, at approximately 21 °C, under gentle aeration overnight prior to use.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Solution a: KH2PO4 8.50 g/L; K2HPO4 21.75 g/L; Na2HPO4.12H2O 33.40 g/L ; NH4Cl 0.50 g/L ; pH = 7.4 ; Solution c: MgSO4.7H2O 22.50 g/L ; Solution b: CaCl2 22.75 g/L ; Solution d: FeCl3.6H2O 0.25 g/L. 1 litre medium contains: 1 ml of solution (A to (D) and made up to 1 litre aerated reverse osmosis purified and deionised water (Elga Optima 15+). The concentration of dissolved oxygen was measured for control purposes. Test item concentration: In duplicate at 2 mg/l. Procedure control: Reference substance sodium benzoate, concentration 3 mg/L; Toxicity control: concentration 2 mg/l sodium benzoate plus 1.5 mg/l test item.
- Solubilising agent (type and concentration if used): None
- Test temperature: The BOD bottles were incubated in a temperature controlled water bath at 20°C.
- pH: Not reported.
- pH adjusted: No.
- Continuous darkness: Yes.

TEST SYSTEM
- Culturing apparatus: 250-300 ml BOD bottles with glass stoppers
- Number of culture flasks/concentration: In duplicate. The test media were transferred by siphon to BOD bottles, which were firmly stoppered to
exclude all air bubbles. Sufficient bottles were prepared to allow a single oxygen determination per bottle with duplicate bottles for each test medium at each sampling occasion.
- Measuring equipment: Yellow Springs oxygen meter and BOD Probe.
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: No.
- Details of trap for CO2 and volatile organics if used: Not applicable.

SAMPLING
- Sampling frequency: In duplicate; on Days 0, 3, 6, 9, 12, 14, 18, 21,24 and 28
- Sampling method: See measuring equipment and sampling frequency above.
- Sterility check if applicable: Not reported.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes.
- Abiotic sterile control: No.
- Toxicity control: Yes.
- Other: Positive control - using reference item (Sodium Benzoate) only.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

7

Sampling time:

28 d

Remarks on result:

other: mean % degradation; 2 mg/l test item concentration

Results with reference substance:

The results with the reference substance were valid.

Table 1. Dissolved oxygen measurements

Test Series	Day	Dissolved Oxygen (mg O2/l)
		0	3	6	9	12	14	18	21	24	28
a) Culture Medium with Inoculum	R1	8.90	8.70	8.60	8.50	8.35	8.40	8.20	8.10	7.90	7.90
	R2	8.90	8.80	8.60	8.50	8.40	8.30	8.10	7.95	7.90	7.80
b) Sodium Benzoate (3.0 mg/l) with Inoculum	R1	8.90	6.20	5.80	5.40	4.90	4.90	4.70	4.40	4.40	4.20
	R2	8.90	5.80	5.50	5.30	4.80	4.80	4.85	4.40	4.25	4.30
c) Test Material (2.0 mg/l) with Inoculum	R1	8.90	8.60	8.50	8.20	8.25	8.20	7.90	7.60	7.70	7.50
	R2	8.90	8.60	8.50	8.30	8.20	8.20	7.90	7.65	7.60	7.50
d) Test Material (2.0 mg/l) plus Sodium Benzoate (1.5mg/l) with Inoculum	R1	8.90	7.30	7.10	7.10	6.65	6.50	6.20	5.90	5.90	5.70
	R2	8.90	7.30	7.10	7.00	6.60	6.40	6.30	6.00	5.80	5.80

 

Table 2. Oxygen Depletion and Mean Percentage Biodegradation Values

Test Series			Day
			3	6	9	12	14	18	21	24	28
a) Culture Medium with Inoculum	Mean O2 Depletion (mg O2/l)		0.150	0.300	0.400	0.525	0.550	0.750	0.875	1.000	1.050
b) Sodium Benzoate (3.0 mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	2.550	2.800	3.100	3.475	3.450	3.450	3.625	3.500	3.650
		R2	2.950	3.100	3.200	3.575	3.550	3.300	3.625	3.650	3.550
	% Degradation (mean)		55	59	63	70	70	68	72	72	72
c) Test Material (2.0 mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	0.150	0.100	0.300	0.125	0.150	0.250	0.425	0.200	0.350
		R2	0.150	0.100	0.200	0.175	0.150	0.250	0.375	0.300	0.300
	% Degradation (mean)		3	2	5	3	3	5	8	5	7
d) Test Material (2.0 mg/l) plus Sodium Benzoate (1.5mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	1.450	1.500	1.400	1.725	1.850	1.950	2.125	2.000	2.150
		R2	1.450	1.500	1.500	1.775	1.950	1.850	2.025	2.100	2.050
	% Degradation (mean)		19	19	19	23	25	25	27	27	28

 

Other information:

- The oxygen depletion of the inoculated control did not exceed 1.5 mg O2/l after 28 days, the residual oxygen concentration in the test bottles remained at 4.20 mg O2/l or greater in all test vessels.

- The difference between the extremes of replicate oxygen depletion values at the end of the test was less than 20% in all vessels thereby satisfying the validation criteria.

- On Day 12 the toxicity control had attained 23% degradation. Dissolved oxygen concentration measurements were taken on Day 14 in order to confirm that the test material had satisfied the validation criterion given in the test guidelines whereby > or = 25% degradation must be obtained by the toxicity control by Day 14 for the test material to be considered as non-inhibitory. After 28 days the toxicity control had attained 28% degradation.

- The positive control or standard material sodium benzoate, attained 72% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

Validity criteria fulfilled:

yes

Interpretation of results:

other: Not readily biodegradable

Conclusions:

The test item attained 7% mean degradation after 28 day in duplicate. The test item cannot be considered to be readily biodegradable.

Executive summary:

The ready biodegradability test was carried out according to OECD 301D (Ready Biodegradability: Closed Bottle Test), EU Method C4-E and EPA OPPTS 835.3110 guidelines under GLP. The test item, at a concentration of 2.0 mg/l, was exposed to sewage treatment micro-organisms with culture medium in sealed culture vessels in the dark at 20°C for 28 days. The degradation of the test item was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the standard item, sodium benzoate, together with a toxicity control were used for validation purposes. Oxygen concentration measurements were in duplicate; on Days 0, 3, 6, 9, 12, 14, 18, 21,24 and 28. In the toxicity control, the test substance was found not to inhibit microbial activity. All of the validity criteria for the test were met. Under the conditions of this study, the test item attained 7% degradation after 28 days and therefore cannot be considered as readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study performed under GLP. All relevant validity criteria were met. The source and target substances must have an ether group at the 1-position and a thioether at the 3-position of the cyclic six membered ring and thereby fulfil the 1,3-oxathiane definition. Single alkyl group (preferably smaller than an n-butyl group; should be present at the 2-position. Either a single or dual alkyl groups (preferable smaller than or equal to an n-butyl group) should be present at the 4-position. The target and source share common structural elements in the same relative positions. The source and target have very similar physico-chemical properties and therefore demonstrative chemical similarity.

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included in attachment to IUCLID section 13.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across is based on the hypothesis that the source and target substances have common structural features in the same relative positions. The source and target have similar physico-chemical, toxicological properties and because of common metabolism they share common or have similar breakdown products and therefore potential mechanisms of action. Further information is included in attachment to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source and target chemicals have comparable chemical similarity. Further information is included in attachment to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
The source substance is a chemically similar substance with common metabolism and common or similar degradants of the target substance. Further information is included in attachment to IUCLID section 13

4. DATA MATRIX
Further information is included in attachment to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected February 2000; signature: April 2000

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): mixed population of sewage sludge micro-organisms was obtained from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
- Storage conditions: Room temperature (at 21°C).
- Storage length: Used on day of collection.
- Preparation of inoculum for exposure: The sample of effluent was filtered through coarse filter paper (first approximate 200 ml discarded) and the filtrate maintained on continuous aeration.
- Initial cell/biomass concentration: Not reported.
- Water filtered: yes (water used to prepare culture medium).
- Type and size of filter used, if any: Aerated reverse osmosis purified and deionised water (Elga Optima 15+). The 'dilution water' was kept in a temperature controlled room, at approximately 21 °C, under gentle aeration overnight prior to use.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Solution a: KH2PO4 8.50 g/L; K2HPO4 21.75 g/L; Na2HPO4.12H2O 33.40 g/L ; NH4Cl 0.50 g/L ; pH = 7.4 ; Solution c: MgSO4.7H2O 22.50 g/L ; Solution b: CaCl2 22.75 g/L ; Solution d: FeCl3.6H2O 0.25 g/L. 1 litre medium contains: 1 ml of solution (A to (D) and made up to 1 litre aerated reverse osmosis purified and deionised water (Elga Optima 15+). The concentration of dissolved oxygen was measured for control purposes. Test item concentration: In duplicate at 2 mg/l. Procedure control: Reference substance sodium benzoate, concentration 3 mg/L; Toxicity control: concentration 2 mg/l sodium benzoate plus 1.5 mg/l test item.
- Solubilising agent (type and concentration if used): None
- Test temperature: The BOD bottles were incubated in a temperature controlled water bath at 20°C.
- pH: Not reported.
- pH adjusted: No.
- Continuous darkness: Yes.

TEST SYSTEM
- Culturing apparatus: 250-300 ml BOD bottles with glass stoppers
- Number of culture flasks/concentration: In duplicate. The test media were transferred by siphon to BOD bottles, which were firmly stoppered to
exclude all air bubbles. Sufficient bottles were prepared to allow a single oxygen determination per bottle with duplicate bottles for each test medium at each sampling occasion.
- Measuring equipment: Yellow Springs oxygen meter and BOD Probe.
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: No.
- Details of trap for CO2 and volatile organics if used: Not applicable.

SAMPLING
- Sampling frequency: In duplicate; on Days 0, 3, 6, 9, 12, 14, 18, 21,24 and 28
- Sampling method: See measuring equipment and sampling frequency above.
- Sterility check if applicable: Not reported.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes.
- Abiotic sterile control: No.
- Toxicity control: Yes.
- Other: Positive control - using reference item (Sodium Benzoate) only.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

7

Sampling time:

28 d

Remarks on result:

other: mean % degradation; 2 mg/l test item concentration

Results with reference substance:

The results with the reference substance were valid.

Table 1. Dissolved oxygen measurements

Test Series	Day	Dissolved Oxygen (mg O2/l)
		0	3	6	9	12	14	18	21	24	28
a) Culture Medium with Inoculum	R1	8.90	8.70	8.60	8.50	8.35	8.40	8.20	8.10	7.90	7.90
	R2	8.90	8.80	8.60	8.50	8.40	8.30	8.10	7.95	7.90	7.80
b) Sodium Benzoate (3.0 mg/l) with Inoculum	R1	8.90	6.20	5.80	5.40	4.90	4.90	4.70	4.40	4.40	4.20
	R2	8.90	5.80	5.50	5.30	4.80	4.80	4.85	4.40	4.25	4.30
c) Test Material (2.0 mg/l) with Inoculum	R1	8.90	8.60	8.50	8.20	8.25	8.20	7.90	7.60	7.70	7.50
	R2	8.90	8.60	8.50	8.30	8.20	8.20	7.90	7.65	7.60	7.50
d) Test Material (2.0 mg/l) plus Sodium Benzoate (1.5mg/l) with Inoculum	R1	8.90	7.30	7.10	7.10	6.65	6.50	6.20	5.90	5.90	5.70
	R2	8.90	7.30	7.10	7.00	6.60	6.40	6.30	6.00	5.80	5.80

 

Table 2. Oxygen Depletion and Mean Percentage Biodegradation Values

Test Series			Day
			3	6	9	12	14	18	21	24	28
a) Culture Medium with Inoculum	Mean O2 Depletion (mg O2/l)		0.150	0.300	0.400	0.525	0.550	0.750	0.875	1.000	1.050
b) Sodium Benzoate (3.0 mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	2.550	2.800	3.100	3.475	3.450	3.450	3.625	3.500	3.650
		R2	2.950	3.100	3.200	3.575	3.550	3.300	3.625	3.650	3.550
	% Degradation (mean)		55	59	63	70	70	68	72	72	72
c) Test Material (2.0 mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	0.150	0.100	0.300	0.125	0.150	0.250	0.425	0.200	0.350
		R2	0.150	0.100	0.200	0.175	0.150	0.250	0.375	0.300	0.300
	% Degradation (mean)		3	2	5	3	3	5	8	5	7
d) Test Material (2.0 mg/l) plus Sodium Benzoate (1.5mg/l) with Inoculum	O2 Depletion (mg O2/l)	R1	1.450	1.500	1.400	1.725	1.850	1.950	2.125	2.000	2.150
		R2	1.450	1.500	1.500	1.775	1.950	1.850	2.025	2.100	2.050
	% Degradation (mean)		19	19	19	23	25	25	27	27	28

 

Other information:

- The oxygen depletion of the inoculated control did not exceed 1.5 mg O2/l after 28 days, the residual oxygen concentration in the test bottles remained at 4.20 mg O2/l or greater in all test vessels.

- The difference between the extremes of replicate oxygen depletion values at the end of the test was less than 20% in all vessels thereby satisfying the validation criteria.

- On Day 12 the toxicity control had attained 23% degradation. Dissolved oxygen concentration measurements were taken on Day 14 in order to confirm that the test material had satisfied the validation criterion given in the test guidelines whereby > or = 25% degradation must be obtained by the toxicity control by Day 14 for the test material to be considered as non-inhibitory. After 28 days the toxicity control had attained 28% degradation.

- The positive control or standard material sodium benzoate, attained 72% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

Validity criteria fulfilled:

yes

Interpretation of results:

other: Not readily biodegradable

Conclusions:

The target substance: is expected to not be ready biodegradable.

Executive summary:

The ready biodegradability test was carried out on a source substance according to OECD 301D (Ready Biodegradability: Closed Bottle Test), EU Method C4-E and EPA OPPTS 835.3110 guidelines under GLP. The test item, at a concentration of 2.0 mg/l, was exposed to sewage treatment micro-organisms with culture medium in sealed culture vessels in the dark at 20°C for 28 days. The degradation of the test item was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the standard item, sodium benzoate, together with a toxicity control were used for validation purposes. Oxygen concentration measurements were in duplicate; on Days 0, 3, 6, 9, 12, 14, 18, 21,24 and 28. In the toxicity control, the test substance was found not to inhibit microbial activity. All of the validity criteria for the test were met. Under the conditions of this study, the test item attained 7% degradation after 28 days and therefore cannot be considered as readily biodegradable.

The target substance: is not expected be ready biodegradable in accordance with Regulation (EC) 1272/2008.

Description of key information

Ready Biodegradability (Read-Across: 2-Ethyl-4,4-dimethyl-1,3-oxathiane): not readily biodegradable, 7 % mean degradation (28-d) , OECD TG 301D, 2003

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

Key Study: OECD TG 301D, 2003 : Read-Across SOURCE (2-Ethyl-4,4-dimethyl-1,3-oxathiane) : The ready biodegradability test was carried out according to OECD 301D (Ready Biodegradability: Closed Bottle Test), EU Method C4-E and EPA OPPTS 835.3110 guidelines under GLP. The test item, at a concentration of 2.0 mg/l, was exposed to sewage treatment micro-organisms with culture medium in sealed culture vessels in the dark at 20°C for 28 days. The degradation of the test item was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the standard item, sodium benzoate, together with a toxicity control were used for validation purposes. Oxygen concentration measurements were in duplicate; on Days 0, 3, 6, 9, 12, 14, 18, 21,24 and 28. In the toxicity control, the test substance was found not to inhibit microbial activity. All of the validity criteria for the test were met. Under the conditions of this study, the test item attained 7% degradation after 28 days and therefore cannot be considered as readily biodegradable.