Reaction mass of 1-(2,3-epoxypropoxy)-2,2-bis ((2,3-epoxypropoxy)methyl) butane and 1-(2,3-epoxypropoxy)-2-((2,3-epoxypropoxy)methyl)-2-hydroxymethyl butane

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

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

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 December 2018 - 08 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Non-Radiolabeled Test Item

Source: Sigma Aldrich
Lot number: MKBP9215V
Purity: Not provided
Storage: 15 to 25°C
Expiry date: 19 July 2019

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

Surface water was provided by Covance as part of this study. Water was transported in containers at ambient temperature and was received at the testing facility within 30 minutes of collection. Upon receipt, and prior to use, the surface water was passed through a coarse filter paper (GF/A). The surface water was used on the day of collection for the main experiment. Characterisation of the surface water was carried out, not to GLP, by NRM Ltd, Bracknell, UK. Microbiological assays of the surface water were conducted at Covance as part of this study.

Duration of test (contact time):

59 d

Initial conc.:

10 µg/L

Based on:

test mat.

Initial conc.:

100 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
Portions of filtered surface water (100 mL) were added to cylindrical 500 mL glass bottles.
In addition, five vessels of surface water were set up in series for microbiological activity measurements and two vessels were set up in series for system parameter measurements (pH and oxygen content). These vessels were not treated with trimethylolpropane, triglycidyl ether.
Samples established for treatment with the test or reference item were incorporated into individual flow-through systems arranged as follows.
(i) Water bottle to humidify the air flow;
(ii) Test vessel containing the surface water;
(iii) Trap 1, containing 1 M aqueous potassium hydroxide solution with phenolphthalein indicator (to trap 14CO2);
(iv) Trap 2, containing 1 M aqueous potassium hydroxide solution with phenolphthalein indicator (backup 14CO2 trap);
(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 maintained in darkness at approximately 12°C ± 2°C in a temperature-controlled room.
[14C]-trimethylolpropane, triglycidyl ether was used without radio-dilution. Portions of stock solution (0.107 mg/mL), 280 µL and 2.8 mL were dispensed into individual flasks and diluted to volume (3 mL) with acetonitrile to prepare the treatment solutions (concentrations 9.50 µg/mL and 95.4 µg/mL, respectively).
Aliquots (0.1 mL) of the application solutions were applied to samples of surface water (FT and FS). To accurately determine the amount of radioactivity added to each sample, aliquots (0.1 mL) were taken at the start, during and end of the application, diluted to volume (4 or 10 mL) with acetonitrile and triplicate aliquots (25 µL) taken from each dilution for LSC. This achieved nominal application rates of 9.5 µg/L and 95.4 µg/L in surface water.
For the samples assigned for microbiological activity determination, two vessels were treated with the same proportion of solvent that was used to apply the test item to the vessels in the main experiment and the three remaining vessels were not treated. No trimethylolpropane, triglycidyl ether was added to the samples established for microbiological activity determination or for measurement of system parameters.

SAMPLING
In the main experiment for each concentration of trimethylolpropane, triglycidyl ether, duplicate samples of surface water were taken for analysis immediately after application, and after 2, 7, 14, 30, 45 and 59 days of incubation. Duplicate sterile vessels were taken for analysis after 59 days of incubation.
Trapping media were taken for analysis with the associated samples at sampling. In addition, trapping media associated with all remaining vessels were taken for analysis after 14 days and subsequently at approximately two-weekly intervals, to coincide with vessel sampling intervals.

DESCRIPTION OF CONTROL AND/OR BLANK TREATMENT PREPARATION :
Preparation of Reference Item [14C]-Benzoic Acid Treatment Solution
An aliquot (79 µL) of a 0.126 mg/mL stock solution of [14C]-benzoic acid in ethanol was made to volume (1 mL) with acetonitrile (dose concentration 8.57 µg/mL).
Aliquots (100 μL) of the application solution were applied to samples of surface water (vessels FC and FSolvent). To accurately determine the amount of radioactivity ([14C]-benzoic acid) added to each sample, aliquots (100 μL) were taken at the start, middle and end of the application, diluted to volume (5 mL) with acetonitrile and triplicate aliquots (25 µL) from each dilution taken for radio-assay by LSC.

STATISTICAL METHODS:
The kinetic analysis of the decline of trimethylolpropane, triglycidyl ether in surface water was performed using the software CAKE (version 3.1, Tessella Ltd., Abingdon, Oxfordshire, UK)

Reference substance:

other: 14C-Ring Benzoic acid

Test performance:

The total recoveries of radioactivity from the reference controls treated at 10 µg/L with reference item, [14C]-benzoic acid, in the main experiment were 66.5 – 98.5% applied radioactivity after 14 days. Low recoveries occurred due to incomplete trapping of CO2. Direct volatile radioactivity, all associated with 14CO2, accounted for 20.5 – 49.9% AR after 14 days. Therefore, the test was shown to be valid as the reference item mineralised within the expected time interval.

Compartment:

natural water: freshwater

% Recovery:

100

Remarks on result:

other: 10 µg/L on day 59

Remarks:

% recovery is 104.4

Compartment:

natural water: freshwater

% Recovery:

100

Remarks on result:

other: 100 µg/L on day 59

Remarks:

% recovery is 105.05

Key result

Compartment:

natural water: freshwater

DT50:

ca. 12.6 d

Type:

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

Temp.:

12 °C

Remarks on result:

other: 10 µg/L

Mineralization rate (in CO2):

49.9 other: recovered as 14CO2 after 14 days

Transformation products:

yes

Details on transformation products:

At 10µg/L there were 19 distinct unidentified metabolites totalling 88.7%. Other minor metabolites accounted for 8.7% of radioactivity.
At 100µg/L there were 10 distinct unidentified metabolites totalling 97.3%. Other minor metabolites accounted for 6.2% of radioactivity.

Evaporation of parent compound:

not measured

Volatile metabolites:

yes

Residues:

not measured

Details on results:

TEST CONDITIONS
- Aerobicity, moisture, temperature and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): no
The surface water was microbiologically active throughout the incubation period.

Recovery and Distribution of Radioactivity
The total recoveries of radioactivity (‘mass balances’, i.e. the sum of radioactivity in the water layer and volatile radioactivity) from samples in the main experiment were 98.7 – 105.2% applied radioactivity. Volatile radioactivity, assumed all associated with 14CO2, accounted for a maximum of 3.4% AR. The total recoveries of radioactivity in the sterile surface water (FS samples) were between 103.9 – 105.4% AR after 59 days. Volatile radioactivity (14CO2) was not detected.

MINERALISATION
- For both the reference and solvent controls, [14C]-benzoic acid was mineralised in the surface water, showing the test to be valid, with up to 49.9% AR recovered as 14CO2 after 14 days.

VOLATILIZATION
- Volatile radioactivity, assumed all associated with 14CO2, accounted for a maximum of 3.4% AR.

Results with reference substance:

For both the reference and solvent controls, [14C]-benzoic acid was mineralised in the surface water, showing the test to be valid, with up to 49.9% AR recovered as 14CO2 after 14 days.

Validity criteria fulfilled:

yes

Conclusions:

Trimethylolpropane, triglycidyl ether degraded in the surface water with estimated DT50 values of 12.6 days (at 10 µg/L) and 16.2 days (at 100 µg/L).

Trimethylolpropane, triglycidyl ether degraded to up to eight major unidentified degradates (10.4 – 37.0% AR). In addition, eleven minor unidentified degradates were present at low levels (≤7.3% AR). Volatile radioactivity, assumed all associated with 14CO2, accounted for a maximum of 3.4% AR.

Identification of the degradation products has not been possible. Please see attached justification statement enclosed in background material and section 13.2.
Analysis was conducted using high performance liquid chromatography (HPLC) with radiodetection. It was not feasible to identify the degradates due to their likely chemical properties.
- The trimethylolpropane, triglycidyl ether has no UV chromophore and so identification by co-chromatographic comparison with a reference standard using HPLC with UV detection was not an option. In addition, any likely degradates would have no UV chromophore.
- Confirmation of trimethylolpropane, triglycidyl ether was carried out using thin layer chromatography (TLC) with potassium permanganate solution to stain the non-radiolabeled trimethylolpropane, triglycidyl ether reference standard. No reference standards for potential degradates were available.
- NMR is unlikely to be a suitable method for attempting identification as the low test concentrations mean that only very low levels of degradates are potentially available.
- As the structure of the radiolabeled trimethylolpropane, triglycidyl ether was successfully confirmed by mass spectroscopy a possible option would be to investigate the degradates by mass spectroscopy. However the likely low molecular weight and low concentration of the degradates may mean that analysis by mass spectroscopy is challenging and there is no guarantee of success.

In conclusion, the information which can be gained about the degradates from this study may be limited by the nature of the test material, in particular its lack of UV chromophore and low molecular weight.

Executive summary:

The biodegradation and fate of trimethylolpropane, triglycidyl ether has been studied at two concentrations in surface water under laboratory conditions. Surface water was treated with [14C]-trimethylolpropane, triglycidyl ether at nominal application rates of 10 µg/L and 100 µg/L. Treated surface water samples were attached to air flow lines with traps to collect carbon dioxide and incubated with continuous stirring to maintain aerobic conditions at about 12degrees C in darkness for periods of up to 59 days.
Total recoveries of radioactivity (mass balances) for samples treated at 10 ug/L and 100 ug/L were between 98.7% and 105.2% applied radioactivity. Carbon dioxide accounted for a maximum of 3.4% applied radioactivity.
Separate sterile samples were treated to provide controls (FS). Total recoveries of radioactivity for samples treated at 10 and 100 ug/L were between 103.9% and 105.4% applied radioactivity. Carbon dioxide was not detected.
For both the reference and solvent controls, [14C]-benzoic acid was mineralised in the surface water, showing the test to be valid, with up to 49.9% AR recovered as 14CO2 after 14 days.

DT50 and DT90 values for the decline of trimethylolpropane, triglycidyl ether from the surface water are shown below;

Concentration	DT50 (days)	DT90 (days)
10 ug/L	12.6	41.9
100 ug/L	16.2	53.7

Trimethylolpropane, triglycidyl ether in surface water treated at 10 ug/L and 100 ug/L, degraded to up to 19 unidentified degradates. Eight unidentified degradates accounted for 10.4 – 37.0% AR. The remaining 11 degradates were present at levels of ≤7.3% AR.

Description of key information

 In a study carried out according to OECD guideline 309, Trimethylolpropane, triglycidyl ether degraded in the surface water with estimated DT50 values of 12.6 days (at 10 µg/L) and 16.2 days (at 100 µg/L).  The substance degraded to up to eight major unidentified degradates (10.4–37.0% AR). In addition, eleven minor unidentified degradates were present at low levels (≤7.3% AR). Volatile radioactivity, assumed all associated with 14CO2, accounted for a maximum of 3.4% AR. 

Key value for chemical safety assessment

Half-life in freshwater:

12.6 d

at the temperature of:

12 °C