2,3-epoxypropyl o-tolyl ether

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2,3-epoxypropyl o-tolyl ether

EC Number:

218-645-3

EC Name:

2,3-epoxypropyl o-tolyl ether

Cas Number:

2210-79-9

Molecular formula:

C10H12O2

IUPAC Name:

oxirane

Specific details on test material used for the study:

Position of radiolabel: Aromatic ring of cresol structure to be radio labeled
Specific activity: 2.50 GBq/mmol (15.2 MBq/mg)
Source: Envigo
Lot number: FK12YK/OOE02/01
Radiochemical purity: The radiochemical purity will be measured prior to application and should be greater than 97%
Storage: -20 C +/- 10 C under nitrogen

Radiolabelling:

yes

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

Surface water was provided by Envigo as part of this study. Water was transported in containers and, upon receipt at the testing facility and prior to use, the surface water was passed through a 0.2 mm sieve and a coarse filter paper (GF/A). The surface water was used on the day of collection. Characterization of the surface water was carried out, not to GLP, by NRM Ltd, Bracknell, UK. Microbiological assays of the surface water were conducted at Envigo as part of this study.

Initial test substance concentration

Initial conc.:

50 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

Study Conduct
Preparation and Incubation of the Test Systems
Portions of filtered surface water (100 mL) were added to cylindrical 500 mL glass bottles.

For each concentration of 2,3-epoxypropyl o-tolylether, the following vessels were established:
Symbol Details Total vessels
FT Triplicate flasks at 7 sampling times plus six spare flasks 27
(duplicate flasks for determination of proportions of
2,3-epoxypropyl o-tolylether and degradates, a single flask for
measurement of 14CO2)

FS Duplicate sterile controls at 61 days, sterilized by autoclaving, 2
prior to addition of 2,3-epoxypropyl o-tolylether (a single flask for
determination of proportions of 2,3-epoxypropyl o-tolylether and
degradates, a single flask for measurement of 14CO2)

The following additional vessels were prepared:

Symbol Details Total vessels
FC Reference control containing [14C]-benzoic acid at 10 μg/L (to 2
confirm minimum microbial activity)
FSolvent Reference control containing [14C]-benzoic acid at 10 μg/L and 2
solvent used for the test item (to determine possible adverse
effects of solvent)

In addition, five vessels of surface water were set up for microbiological analysis. Two vessels were treated with the same proportion of solvent that was used to treat the 100 μg/L vessels in the main experiment and the three remaining vessels were not treated. These vessels were not treated with 2,3-epoxypropyl o-tolylether.
Two vessels were used for system parameter measurements (pH and oxygen content). These vessels were not treated with 2,3-epoxypropyl o-tolylether.
With the exception of the reference control vessels, all test vessels were sealed.

Samples established for treatment with the reference control [14C]-benzoic acid were incorporated into individual flow-through systems arranged as follows (Appendix 3).
 
(i) Humidifying vessel (with sintered stem for uniform gas dispersion) containing water to humidify the air-flow;
(ii) Test vessel containing the surface water;
(iii) Vessel containing 1 M aqueous potassium hydroxide solution with phenolphthalein indicator (to trap 14CO2);
(iv) Vessel containing 1 M aqueous potassium hydroxide solution with phenolphthalein indicator (to trap 14CO2);
(v) A non-return valve to prevent accidental backflow through the test apparatus.

Air was drawn through each system at a flow rate of approximately 50 mL/minute. Flow rates were checked and adjusted throughout the incubation period.
All test systems were stirred continuously to facilitate oxygen transfer and maintained in darkness at approximately 12C ± 2C in a temperature-controlled room. The temperature in the room was recorded electronically by REES (REES Scientific).

Preparation and Application of the Test Item
[14C]-2,3-Epoxypropyl o-tolylether was used without radiodilution. Aliquots of the test item stock solution, 2.65 mL (0.50 mg) and 1.33 mL (0.25 mg) were dispensed into individual vessels and diluted with water to 10 mL and 5 mL, respectively. The concentrations of the application solutions were 0.05 mg/mL.

Aliquots (202 µL or 39 µL) of the application solutions were applied to samples of surface water (vessels FT and FS). To accurately determine the amount of radioactivity (and 2,3-epoxypropyl o-tolylether) added to each sample, triplicate aliquots (as per application volume) were taken throughout the application process and diluted with a portion (20 mL) of acetonitrile. Duplicate aliquots (200 µL) were taken for LSC.

No 2,3-epoxypropyl o-tolylether was added to the samples established for microbiological activity determination or for measurement of system parameters.

Preliminary Experiments
Prior to the main experiment, preliminary experiments were performed with surface water to establish the analytical methodology and confirm the sampling schedule.
For the first preliminary experiment, three vessels were prepared and treated at the highest test concentration (100 g/L). One vessel was used for zero-time analysis; the other two vessels were incorporated into individual flow-through systems (as detailed in Section 3.5.1) and sampled after 2 and 7 days of incubation.

Due to a loss of recovered radioactivity observed after 7 days in the first preliminary experiment, a second preliminary experiment was conducted to investigate this further and establish the most appropriate experimental set-up for the main study in order to improve recovered radioactivity.
 
For the second preliminary experiment, four vessels were prepared and treated at the highest test concentration (100 g/L) as summarized below:
Sample identity Sampling interval (days) Incubation system Trapping media
SC55 0 - -
SC56 7 Constant flow-through Polyurethane bung, ethyl digol,
(as per Section 3.5.1) 2 x 1 M potassium hydroxide

SC57 7 Static (test vessel sealed N/A (analyzed immediately)
after test item application)

SC58 7 Static (test vessel sealed Polyurethane bung, ethyl digol,
after test item application) 1 M potassium hydroxideA

A All trapping media connected on sampling occasion and test vessel headspace purged at 30 mL/min for approx. 30 minutes

The weight of the surface water was recorded, and duplicate weighed aliquots (1.0 mL) were taken for LSC. Samples were analyzed directly for parent and metabolites by HPLC with radiodetection.

The volumes of trapping solutions were measured and duplicate aliquots (1.0 mL) taken for LSC.

The polyurethane bungs were extracted with acetonitrile, the weight of extract was recorded, and duplicate weighed aliquots (1.0 mL) taken for LSC.

Sampling Intervals (Main Experiment)
For each concentration of 2,3-epoxypropyl o-tolylether, triplicate samples of surface water were taken for analysis immediately after application and after 2, 7, 14, 30, 44 and 61 days of incubation. Duplicate sterile controls were taken for analysis after 61 days of incubation.

Sample Analysis (Main Experiment)
For the determination of total radioactivity in samples, total weights, aliquot weights and liquid scintillation counting data were recorded and processed using the DEBRA automated laboratory data capture and processing system (V5.5.4.49), LabLogic Systems Ltd, Sheffield, UK.

Samples for Chromatographic Analysis (FT): The weight of the surface water was recorded, and duplicate weighed aliquots (1.0 mL) were taken for LSC. Samples were analyzed directly for parent and metabolites by HPLC with radiodetection.

Samples for Direct 14CO2 Determination (FT and FS): Upon sampling vessels were immediately (with minimal delay) connected to a flow-through system of traps (as detailed in Section 3.5.1) for approximately 15 minutes. The surface water was then acidified (using concentrated hydrochloric acid to pH 2 - 3) and re-connected to the flow-through system, this time the glass tube bringing air flow into the test vessel was just below the surface of the water. After at least 1 hour the vessel was removed, the weight of the water was recorded, and duplicate weighed aliquots (1.0 mL) were taken for LSC. The volumes of trapping solutions were measured and duplicate aliquots (1.0 mL) taken for LSC.

Validity of Test Determination
Application of the Reference Control
Aliquots (94 µL) of a 0.01 mg/mL stock solution of [14C]-benzoic acid in acetonitrile were applied to samples of surface water (vessels FC and FSOLVENT). To accurately determine the amount of radioactivity (and benzoic acid) added to each sample, triplicate aliquots (94 μL) were taken throughout the application process and diluted with an aliquot (20 mL) of acetonitrile. Duplicate aliquots (200 µL) were taken for LSC.

Sampling Intervals
Duplicate samples were taken for analysis after 14 days. Trapping solutions were taken for analysis after 2, 7, 9 and 14 days of incubation.

Sample Analysis
The weight of the surface water was recorded, and duplicate weighed aliquots (1.0 mL) were taken for LSC.
The volumes of trapping solutions were measured and duplicate aliquots (1.0 mL) taken for LSC.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

Preliminary Experiments
For preliminary experiment 1 the total recoveries decreased from 100.8% applied radioactivity at Day 0 to 82.7% applied radioactivity at Day 7. Volatile radioactivity accounted for a maximum of 1.0% applied radioactivity.

For preliminary experiment 2 the total recoveries decreased from 100.5% applied radioactivity at Day 0 to 86.0% applied radioactivity at Day 7 in the test vessel connected to the constant flow-through incubation system (same set-up as for preliminary experiment 1). For the static (sealed) test vessels the recovery of radioactivity remained between 100.1% and 100.2% applied radioactivity at Day 7, demonstrating that the static (sealed) test vessel set-up was the best set-up to use for the main experiment.

HPLC analysis of the samples from the static (sealed) test vessels showed 2,3-epoxypropyl o-tolylether degraded, accounting for between 84.3% and 85.2% applied radioactivity at Day 7.

Characterization of the Test System
Additionally, this table contains the results of various measurements (pH, oxygen saturation) made at the sampling site.

The surface water was microbiologically active throughout the incubation period and solvent treatment had no adverse effects on the microbial activity.

Incubation Conditions
During the incubation period, oxygen levels in the water (in the range 88.7 to 95.4% saturation) were indicative of an aerobic surface water.

Validity of Test Determination
The total recoveries of radioactivity in the surface water treated with the reference control [14C]-benzoic acid at a concentration of 10.5 g/L were 79.0 – 93.2% applied radioactivity after 14 days. Low recoveries are assumed to be due to incomplete trapping of CO2. Direct volatile radioactivity, all associated with 14CO2, accounted for 58.1 – 68.0% applied radioactivity after 14 days.

The test was shown to be valid as the reference control degraded within the expected time interval.

% Degradation

% Degradation 1

Key result

% Degr.:

96.4

Parameter:

test mat. analysis

Remarks:

20 ug/ml

Sampling time:

44 d

% Degradation 2

Key result

% Degr.:

100

Parameter:

test mat. analysis

Remarks:

20 ug/ml

Sampling time:

61 d

% Degradation 3

Key result

% Degr.:

98.9

Parameter:

test mat. analysis

Remarks:

100 ug/ml

Sampling time:

61 d

Half-life of parent compound / 50% disappearance time (DT50)

Half-life of parent compound / 50% disappearance time (DT50) 1

Key result

Compartment:

natural water: freshwater

DT50:

11.4 d

Type:

(pseudo-)first order (= half-life)

Temp.:

12 °C

Half-life of parent compound / 50% disappearance time (DT50) 2

Key result

Compartment:

natural water: freshwater

DT50:

11.8 d

Type:

(pseudo-)first order (= half-life)

Temp.:

12 °C

Transformation products:

yes

Identity of transformation products

No.:

#1

Reference

Reference substance name:

Unnamed

IUPAC name:

(2-methylphenoxy)acetic acid

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 217-517-4]

CAS number:

1878-49-5

Identity:

o-Methylphenoxyacetic acid

Molecular formula:

C9H10O3

Molecular weight:

166.174

SMILES notation:

Cc1ccccc1OCC(=O)O

InChl:

InChI=1/C9H10O3/c1-7-4-2-3-5-8(7)12-6-9(10)11/h2-5H,6H2,1H3,(H,10,11)

Details on transformation products:

(2-methylphenoxy)acetic acid A
(Metabolite C)

Evaporation of parent compound:

no

Volatile metabolites:

no

Any other information on results incl. tables

Table 1            Surface Water Sampling Information

Envigo batch numbers	E170418A & E170418B
Origin	River Waveney, Palgrave, Diss, Norfolk, UK
Geographic co-ordinates	52°22’2’’ N, 1°7’21’’ E
Date of sampling	17 April 2018
Water body type	River
Water:
Appearance	Green hue, clear
Sampling depth (cm)	30
Temperature (°C), just below water surface	11.5
pH	7.52
Oxygen saturation (%), just below water surface	65.4

Surface water was obtained, and measurements made, by Envigo

The values in this table are field measurements made at the time of collection

 

 

 

Table 2            Physical and Chemical Characteristics of the Surface Water

Total organic carbon (mg/L)		11.7
Dissolved organic carbon (mg/L)		11.3
Biological oxygen demand (mg/L)		<2
Total nitrogen (mg/L)		5.9
Total phosphorus (mg/L)		0.3
Ammonium nitrogen (mg/L)		0.3
Nitrate nitrogen (mg/L)		5.1
Nitrite nitrogen (mg/L)		<0.1
Soluble reactive phosphorus (µg/L)		41.6
Total suspended solids (mg/L)		10
Hardness as CaCO3(mg/L)		514

These parameters were measured in separate studies, not to GLP, by NRM Ltd. Some additional measurements were made at the time of collection; the results of these are shown inTable 1.

 

 

Table 3            Microbiological Characterization of the Surface Water

	Start of incubation (untreated)	End of incubation (untreated)	End of incubation (solvent treated)
Aerobic bacteria	7.30 x 10^5	4.40 x 10^5	3.45 x 10^5
Aerobic bacterial spores	<10	70	10
Actinomycetes	<10	<10	<10
Fungi	<10	<10	55

Results are expressed as colony forming units/g

 

 

Table 4            Recoveries of Radioactivity from Incubated Surface Water Treated with [¹⁴C]-Benzoic Acid at 10 µg/L

F_Csamples:

Time after application (days)		Sample identity		Surface water		Volatiles		Total recovery
14		SC50		28.2		58.1		86.3
		SC51		15.9		63.1		79.0

Results expressed as % applied radioactivity

 

F_Solventsamples:

Time after application (days)		Sample identity		Surface water		Volatiles		Total recovery
14		SC52		17.4		64.6		82.0
		SC53		25.2		68.0		93.2

Results expressed as % applied radioactivity

 

 

Table 5            Recoveries of Radioactivity from Incubated Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolyletherat 20 µg/L

F_Tsamples:

Time after application (days)		Sample identity		Surface water			Volatiles		Total recovery
			Non-acidified		Post-acidification
0		SC25		100.5		na		na		100.5
		SC26		100.4		na		na		100.4
		SC27		100.1		na		na		100.1
2		SC28		96.8		na		na		96.8
		SC29		100.3		na		na		100.3
		SC30		na		92.2		<0.1		92.2
7		SC31		99.3		na		na		99.3
		SC32		98.4		na		na		98.4
		SC33		na		97.3		nd		97.3
14		SC34		97.3		na		na		97.3
		SC35		96.9		na		na		96.9
		SC36		na		98.5		0.1		98.6
30		SC37		98.9		na		na		98.9
		SC38		81.2		na		na		81.2
		SC39		na		77.0		16.8		93.8
44		SC40		83.6		na		na		83.6
		SC41		80.7		na		na		80.7
		SC42		na		61.1		30.2		91.3
61		SC43		64.8		na		na		64.8
		SC44		71.0		na		na		71.0
		SC45		na		56.9		20.5		77.4

Results expressed as % applied radioactivity

na          not applicable

nd          not detected

 

Table 6            Recoveries of Radioactivity from Incubated Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolylether at 100 µg/L

F_Tsamples:

Time after application (days)		Sample identity		Surface water			Volatiles		Total recovery
			Non-acidified		Post-acidification
0		SC66		99.0		na		na		99.0
		SC67		99.8		na		na		99.8
		SC68		99.5		na		na		99.5
2		SC07		98.7		na		na		98.7
		SC08		98.5		na		na		98.5
		SC09		na		96.4		<0.1		96.4
7		SC10		97.5		na		na		97.5
		SC11		97.9		na		na		97.9
		SC12		na		96.3		<0.1		96.3
14		SC13		97.3		na		na		97.3
		SC14		97.1		na		na		97.1
		SC15		na		97.1		0.1		97.2
30		SC16		98.1		na		na		98.1
		SC17		97.6		na		na		97.6
		SC18		na		95.4		1.0		96.4
44		SC19		94.7		na		na		94.7
		SC20		96.4		na		na		96.4
		SC21		na		92.1		2.2		94.3
61		SC22		95.6		na		na		95.6
		SC23		76.9		na		na		76.9
		SC24		na		78.6		9.6		88.2

Results expressed as % applied radioactivity

na          not applicable

 

Table 7            Recoveries of Radioactivity from Incubated Sterile Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolylether at 20 µg/L

F_Ssamples:

Time after application (days)		Sample identity		Surface water			Volatiles		Total recovery
			Non-acidified		Post-acidification
61		SC48		100.3		na		na		100.3
		SC49		na		97.2		0.1		97.3

Results expressed as % applied radioactivity

na          not applicable

 

 

 

Table 8            Recoveries of Radioactivity from Incubated Sterile Surface Water Treated with [¹⁴C]- 2,3-Epoxypropyl o-tolylether at 100 µg/L

F_Ssamples:

Time after application (days)	Sample identity	Surface water		Volatiles	Total recovery
		Non-acidified	Post-acidification
61	SC46	96.3	na	na	96.3
	SC47	na	94.4	<0.1	94.4

Results expressed as % applied radioactivity

na          not applicable

 

 

Table 9            Proportions of Radioactive Components in Surface Water Treated with[¹⁴C]-2,3-Epoxypropyl o-tolylether at 20 µg/L

	Time after application (days)
	0		2		7		14
Sample identity	SC25	SC26	SC28	SC29	SC31	SC32	SC34	SC35
Met E (Rt ~3.9 mins)	-	-	-	-	-	-	-	-
Met B (Rt ~10.5 mins)	-	-	-	-	-	-	-	-
Met F (Rt ~11.8 mins)	-	-	-	-	-	-	-	-
Met A (Rt ~12.8 mins)	-	-	5.1	4.8	22.6	20.3	50.7	43.4
2-MP (Rt ~14.7 mins)		-		-		-		-		-		-		-		-
Met C (Rt ~15.7 mins)		-		-		-		-		-		-		-		-
Met D (Rt ~16.5 mins)		-		-		-		-		-		-		-		-
2,3-EPTE	99.3	100.2	91.4	95.0	76.6	74.8	46.1	53.2
Others (a)	1.2	0.2	0.3	0.4	0.2	3.3	0.6	0.3

 

	Time after application (days)
	30		44		61
Sample identity	SC37	SC38	SC40	SC41	SC43	SC44
Met E (Rt ~3.9 mins)	-	23.9	25.2	18.7	9.4	17.5
Met B (Rt ~10.5 mins)	-	-	2.8	-	1.2	-
Met F (Rt ~11.8 mins)	-	-	-	-	-	-
Met A (Rt ~12.8 mins)	75.8	18.9	8.1	16.5	14.2	13.8
2-MP (Rt ~14.7 mins)	2.6	-	-	-	-	-
Met C (Rt ~15.7 mins)	4.8	29.0	44.4	40.5	39.7	38.3
Met D (Rt ~16.5 mins)	3.3	-	-	-	-	-
2,3-EPTE	3.7	8.4	2.3	4.4	-	-
Others (a)	8.8	1.0	0.7	0.5	0.2	1.3

Results are expressed as % applied radioactivity

(a) Radioactivity distributed throughout regions of the chromatogram other than those specified and which did not contain any discrete radioactive components

-              Not apparent or below the limit of detection

 

 

 

 

Table 10          Proportions of Radioactive Components in Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolylether at 100 µg/L

		Time after application (days)
		0			2			7			14
Sample identity		SC66		SC67		SC07		SC08		SC10		SC11		SC13		SC14
Met E (Rt ~3.9 mins)		-		-		-		-		-		-		-		-
Met B (Rt ~10.5 mins)		-		-		-		-		-		-		0.7		1.0
Met F (Rt ~11.8 mins)		-		-		-		-		-		-		-		-
Met A (Rt ~12.8 mins)		-		-		6.7		6.3		21.2		22.9		45.8		46.3
2-MP (Rt ~14.7 mins)		-		-		-		-		-		-		-		-
Met C (Rt ~15.7 mins)		-		-		-		-		-		-		-		-
Met D (Rt ~16.5 mins)		-		-		-		-		-		-		-		-
2,3-EPTE		98.7		95.8		91.1		89.4		74.7		72.0		49.3		48.0
Others (a)		0.3		4.0		1.0		2.8		1.7		2.9		1.6		1.9

 

		Time after application (days)
		30			44			61
Sample identity		SC16		SC17		SC19		SC20		SC22		SC23
Met E (Rt ~3.9 mins)		-		-		4.2		0.9		1.1		21.9
Met B (Rt ~10.5 mins)		0.6		1.1		-		-		1.0		2.0
Met F (Rt ~11.8 mins)		-		-		1.3		-		1.5		2.8
Met A (Rt ~12.8 mins)		76.2		77.2		76.7		83.2		84.5		21.1
2-MP (Rt ~14.7 mins)		0.4		0.9		0.6		0.6		-		-
Met C (Rt ~15.7 mins)		2.2		1.1		6.3		2.0		4.6		22.7
Met D (Rt ~16.5 mins)		1.5		1.0		2.4		1.5		1.1		-
2,3-EPTE		10.9		9.7		2.2		4.7		1.4		0.8
Others (a)		6.4		6.6		1.0		3.4		0.2		5.6

Results are expressed as % applied radioactivity

(a) Radioactivity distributed throughout regions of the chromatogram other than those specified and which did not contain any discrete radioactive components

-              Not apparent or below the limit of detection

 

 

 

 

Table 11          Proportions of Radioactive Components in Sterile Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolylether at 20 µg/L

		Time after application (days)
		61
Sample identity		SC48
Met E (Rt ~3.9 mins)		-
Met B (Rt ~10.5 mins)		-
Met F (Rt ~11.8 mins)		-
Met A (Rt ~12.8 mins)		72.8
2-MP (Rt ~14.7 mins)		-
Met C (Rt ~15.7 mins)		-
Met D (Rt ~16.5 mins)		-
2,3-EPTE		26.9
Others (a)		0.6

Results are expressed as % applied radioactivity

(a) Radioactivity distributed throughout regions of the chromatogram other than those specified and which did not contain any discrete radioactive components

-              Not apparent or below the limit of detection

 

 

 

Table 12          Proportions of Radioactive Components in Sterile Surface Water Treated with [¹⁴C]-2,3-Epoxypropyl o-tolylether at 100 µg/L

		Time after application (days)
		61
Sample identity		SC46
Met E (Rt ~3.9 mins)		-
Met B (Rt ~10.5 mins)		-
Met F (Rt ~11.8 mins)		-
Met A (Rt ~12.8 mins)		68.5
2-MP (Rt ~14.7 mins)		-
Met C (Rt ~15.7 mins)		-
Met D (Rt ~16.5 mins)		-
2,3-EPTE		26.4
Others (a)		1.4

Results are expressed as % applied radioactivity

(a) Radioactivity distributed throughout regions of the chromatogram other than those specified and which did not contain any discrete radioactive components

-              Not apparent or below the limit of detection

 

 

 

Table 13          Kinetic Data for the Decline of 2,3-Epoxypropyl o-tolylether and Metabolites A, C and E in Surface Water

2,3-Epoxypropyl o-tolylether

Concentration	Error %	r^2	DT50(days)	DT90(days)
20mg/L	9.11	0.9745	11.4	37.8
100mg/L	7.75	0.9875	11.8	39.2

 

Metabolite A

Concentration	Error %	r^2	DT50(days)	DT90(days)
20mg/L	21.0	0.4301	10.4	34.5
100mg/L	nd	0.2663	28.4	94.4

 

Metabolite C

Concentration	Error %	r^2	DT50(days)	DT90(days)
20mg/L	nd	0.5810	139	462

 

Metabolite E

Concentration	Error %	r^2	DT50(days)	DT90(days)
20mg/L	nd	0.5726	24.1	79.9

 

nd          Only two time intervals therefore no error % calculated

Kinetic model: SFO = single first order

The kinetic analysis is described in more detail inAppendix 8

Applicant's summary and conclusion

Validity criteria

Validity criteria fulfilled:

yes

Conclusions:

2,3-Epoxypropyl o-tolylether degraded rapidly in the surface water with DT50 values of 11.4 days (at 20 ug/L) and 11.8 days (at 100 ug/L).

2,3-Epoxypropyl o-tolylether degraded to Metabolites A, C and E, accounting for maximums of 84.5, 44.4 and 25.2% applied radioactivity, respectively.

Identification of the major degradation products designated as Metabolites A, C and E was attempted by liquid chromatography with mass spectrometry. Metabolite C was tentatively identified as (2-methylphenoxy)acetic acid, Metabolites A and E are unidentified. Metabolite E is considered as polar material.

Executive summary:

The biodegradation and fate of 2,3-epoxypropyl o-tolylether has been studied at low concentrations in surface water under laboratory conditions. Surface water was treated with [¹⁴C]-2,3-epoxypropyl o-tolylether at nominal application rates of 20 µg/L and 100 µg/L. Treated surface water samples were incubated with continuous stirring to maintain aerobic conditions at 12 ± 2°Cin darkness for periods of up to 61 days. 

Total recoveries of radioactivity (mass balances,post-acidification samples) for samples treated at 20 µg/L and 100 µg/L were between 77.4 and 100.1% applied radioactivity. 

Separate samples were treated for the determination of¹⁴CO₂at 20 µg/L. After acidification to strip off any¹⁴CO₂, the total radioactivity in the surface water decreased from 92.2% applied radioactivity at Day 2 to 56.9% applied radioactivity after 61 days. Direct volatile radioactivity (¹⁴CO₂) accounted for a maximum of 30.2% applied radioactivity after 44 days.

Separate samples were treated for the determination of¹⁴CO₂at 100 µg/L. After acidification to strip off any¹⁴CO₂, the total radioactivity in the surface water decreased from 96.4% applied radioactivity at Day 2 to 78.6% applied radioactivity after 61 days. Direct volatile radioactivity (¹⁴CO₂) accounted for a maximum of 9.6% applied radioactivity after 61 days.

Separate sterile samples were treated to provide controls (F_S). Total recoveries of radioactivity (mass balances, post-acidification samples) for samples treated at 20 µg/L and 100 µg/L were 97.3% and 94.4% applied radioactivity, respectively. Carbon dioxide accounted for a maximum of 0.1% applied radioactivity.

DT₅₀and DT₉₀values for the decline of 2,3-epoxypropyl o-tolylether from the surface water are shown below.

Concentration	DT50(days)	DT90(days)
20mg/L	11.4	37.8
100mg/L	11.8	39.2

 

Analysis of the surface water samples showed that 2,3-epoxypropyl o-tolylether degraded to Metabolites A, C and E, accounting for maximums of 84.5, 44.4 and 25.2% applied radioactivity, respectively. 

Identification of the major degradation products designated as Metabolites A, C and E was attempted by liquid chromatography with mass spectrometry. Metabolite C was tentatively identified as (2-methylphenoxy)acetic acid, Metabolites A and E are unidentified. Metabolite E is considered as polar material.

All other (unidentified) degradation products were present at levels of ≤3.3% applied radioactivity.