Trimethoxy(3,3,3-trifluoropropyl)silane

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental start date: 19 August 2019, Experimental completion date: 15 October 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Trimethoxy(3,3,3-trifluoropropyl)silane

EC Number:

207-059-3

EC Name:

Trimethoxy(3,3,3-trifluoropropyl)silane

Cas Number:

429-60-7

Molecular formula:

C6H13F3O3Si

IUPAC Name:

trimethoxy(3,3,3-trifluoropropyl)silane

Test material form:

liquid

Specific details on test material used for the study:

Identification: ST2092NM
Batch: 802496
Purity: 100%
Physical State/Appearance: Clear colorless liquid
Expiry Date: 13 March 2020
Storage Conditions: Room temperature in the dark

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

Test system:
A mixed population of sewage treatment micro-organisms was obtained on 30 September 2019 from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.

Preparation of Inoculum:
The sample of effluent was filtered through coarse filter paper (first approximate 200 mL discarded) and maintained on aeration in a temperature controlled room at 21 ±1 °C prior to use.

Duration of test (contact time):

13 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Mineral Medium:
The mineral medium usedwas that recommended in the OECD Guidelines.
The deionized reverse osmosis water used for the preparation of the mineral medium and the mineral medium used for the test contained less than 1 mg/L Total Organic Carbon (TOC).

Test Item Preparation:
For the purpose of the test, due to the volatile nature of the test item, and following the recommendations of the International Standards Organisation (ISO 10634, 1995) the test item was added directly to the test vessels using a micro-pipettor.

An initial test was terminated after 21 days due to a significant increase in the biological oxygen demand (BOD) values in the inoculum control vessels to values of over 60 mg O2/L which is the limit when critical examination of the data was required. It was therefore considered justifiable to terminate the test due to a significant decrease in the biodegradation values being observed for some of the vessels.

A further test was performed whereby an aliquot of mineral medium (495 mL) was dispensed into each test vessel prior to an amount of test item (42.1 µL, equivalent to 50 mg of test item determined by preliminary weighings) being added. The pH values were then measured using a Hach HQ40d Flexi handheld meter prior to an aliquot of inoculum (5 mL) being dispensed into the test vessel to give the test concentration of 100 mg/L. Due to the volatile nature of the test item each vessel was placed on the respirometer within 1 minute after the addition of the test item.

The inoculum control vessels were prepared in a similar manner without the addition of test item.

A test concentration of 100 mg/L was selected for use in the study following the recommendations of the Test Guidelines.

Reference Item Preparation:
A reference item, aniline (C6H5NH2), was used to prepare the procedure control vessels. An initial stock solution of 1000 mg/L was prepared by dissolving a nominal amount of the reference item, which was freshly distilled (500 mg), directly in mineral medium (500 mL) with the aid of ultrasonication for approximately 20 minutes and allowed to cool to a temperature of approximately 21 °C. An aliquot (50 mL) of this stock solution was diluted with mineral medium (350 mL) prior to measurement of the pH value using a Hach HQ40d Flexi handheld meter and then addition of inoculum (5 mL) and adjusting to a final volume of 500 mL with mineral medium, to give the test concentration of 100 mg/L. The volumetric flask containing the stock solution was inverted several times to ensure homogeneity.
The pH of the reference item stock solution was 7.4. The pH value was measured using a Hach HQ40d Flexi handheld meter.

Toxicity Control:
A toxicity control, containing the test item and aniline, was prepared in order to assess any toxic effects of the test item on the sewage treatment micro-organisms used in the test.
An aliquot of mineral medium (445 mL) was dispensed into each test vessel with an aliquot (50 mL) of the 1000 mg/L aniline stock solution prior to the addition of an amount of test item (42.1 µL, equivalent to 50 mg of test item determined by preliminary weighings). The pH values were then measured using a Hach HQ40d Flexi handheld meter prior to an aliquot of inoculum (5 mL) being dispensed into the test vessel to give the test concentration of 100 mg test item/L and 100 mg aniline/L. Due to the volatile nature of the test item each vessel was placed on the respirometer within 1 minute after the addition of the test item.

Preparation of Test System:
The following test preparations were prepared and inoculated in 500 mL bottles:
a) Three replicate bottles containing inoculated mineral medium to act as the inoculum control.
b) Two replicate bottles containing inoculated mineral medium and the reference item, aniline, at a concentration of 100 mg/L to act as the procedure control.
c) Three replicate bottles containing test item and inoculated mineral medium at a concentration of 100 mg/L.
d) Two replicate bottles containing the test item at a concentration of 100 mg/L in inoculated mineral medium and the reference item, aniline, at a concentration of 100 mg/L to act as toxicity control vessels.

Additional replicate vessels were prepared and incubated in order that in the event of a leak in the test system a replicate vessel could be discarded without jeopardizing the integrity of the study. From those samples prepared, on Day 13, two inoculum controls, one procedure control, two test item and one toxicity control vessel were sampled for pH analysis. The other vessels were discarded.

In this instance, some of the additional replicate vessels had some erroneous results and were not reported (one inoculum control vessel and one test item vessel). The procedure control and toxicity control vessels did not show any erroneous results so the first vessel in the test series was reported.

All vessels were inoculated with the prepared inoculum at a rate of 1% v/v.

On Day 0, the test and reference items were added to the mineral medium. The pH of all vessels was measured using a Hach HQ40d Flexi handheld meter prior to the addition of the inoculum and the volume in the procedure control vessels being adjusted to 500 mL by the addition of mineral medium.

In order to confirm that the aniline stock solution was prepared correctly, a diluted 100 mg/L stock solution (in reverse osmosis water) was also sampled for TOC analysis.

The test was conducted in diffuse light at temperatures between 22 and 23°C.

Reference substance

Reference substance:

aniline

Results and discussion

Test performance:

The difference between extremes of replicate BOD values at the time the plateau was reached and at the end of the 10 Day window was less than 20% and therefore satisfied the validation criterion given in the OECD Test Guidelines.
The toxicity control attained 72% biodegradation after 13 days thereby confirming that the test item was not toxic to the sewage treatment micro organisms used in the test.

Total Organic Carbon Confirmation: Total Organic Carbon of the diluted aniline stock solution confirmed that it had been prepared correctly.

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

68

Sampling time:

13 d

Details on results:

The test item attained 68% biodegradation after 13 days, calculated from the oxygen consumption values, and satisfied the 10 Day window validation criterion, whereby 60% biodegradation must be attained with 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

BOD5 / COD results

Results with reference substance:

Aniline (procedure control) attained 83% biodegradation after 13 days with greater than 60% degradation being attained in a 10-day window.

Any other information on results incl. tables

Table 1            Biological Oxygen Demand Values

Day	BOD (mg O2/L)
	Inoculum Control		Procedure Control	Test Item		Toxicity Control
	R1	R2		R1	R2
0	0.00	0.00	0.00	0.00	0.00	0.00
1	0.04	0.00	0.12	0.34	0.42	0.34
2	0.74	0.00	1.04	12.38	9.58	10.92
3	1.70	0.00	31.82	49.78	47.14	48.82
4	2.66	0.00	86.72	59.36	50.60	66.44
5	3.74	0.46	138.40	65.80	59.76	118.92
6	4.66	1.70	185.80	69.56	64.26	166.40
7	5.84	3.08	215.62	71.92	67.88	212.00
8	6.84	4.28	227.62	73.76	70.52	254.48
9	7.16	5.04	236.86	74.92	72.14	271.02
10	8.24	6.50	246.86	76.80	73.98	283.56
11	9.70	7.50	255.18	78.30	75.34	294.18
12	11.00	9.08	262.60	80.56	77.22	301.72
13	11.78	10.02	268.46	82.44	78.66	308.04

R= Replicate

Table 2            Percentage Biodegradation Values

Day	Biodegradation (%)
	Procedure Control	Test Item			Toxicity Control
		R1	R2	Mean
0	0	0	0	0	0
1	0	0	0	0	0
2	0	12	9	11	3
3	10	48	45	47	12
4	28	56	48	52	16
5	44	62	56	59	28
6	59	64	59	62	40
7	68	65	62	64	50
8	72	66	63	65	60
9	75	67	64	66	64
10	78	67	65	66	67
11	80	68	65	67	69
12	82	68	65	67	71
13	83	69	66	68	72

 

R= Replicate

Table 3     pH Values of the Test Preparationson Days 0 and 13

Test Vessel	pH
	Day 0	Day 13
Inoculum ControlR1	7.4	7.7
Inoculum Control R2	7.4	7.7
Procedure Control	7.4	7.9
Test Item R1	7.4	7.6
Test Item R2	7.4	7.6
Toxicity Control	7.4	7.8

 R  =   Replicate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item attained 68% biodegradation after 13 days and satisfied the 10 Day window validation criterion, whereby 60% biodegradation must be attained with 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

Executive summary:

Introduction:

The study was performed to assess the ready biodegradability of the test item in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301F, “Ready Biodegradability; Manometric Respirometry Test” referenced as method C.4-D of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (q)).

Methods:

The test item at a concentration of 100 mg/L was exposed to sewage treatment micro‑organisms with mineral medium in sealed culture vessels in diffuse light at temperatures of between 22 and 23ºC for 13 days. The study was terminated after 13 days as degradation of the test item had reached a plateau and the test item attained greater than 60% biodegradation within 10 days of the test item attaining 10% biodegradation.

The biodegradation of the test item was assessed by the measurement of daily oxygen consumption values for 13 days. Control solutions with inoculum and the reference item, aniline, and a toxicity control were used for validation purposes.

Results:

The test item attained 68% biodegradation after 13 days and satisfied the 10‑Day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

Aniline (procedure control) attained83% biodegradation after 13 dayswith greater than 60% degradation being attained in a 10-Day window.