2-Propenoic acid, γ-ω-perfluoro-C8-14-alkyl esters

Biodegradation in soil

Description of key information

All results based on studies with the read across substance and main degradation product 8:2 FTOH
Aerobic transformation in soil: DT50 = 27.0 days (absorbed 8-2 FTOH at Day 0); DT50 = 13.5 years (absorbed 8-2 FTOH in the polymer) (worst-case estimated values)
Landfill simulation reactor (LSR study): DT50 >>31 years for the polymer (OECD 307)
--------------------------
Formation of PFOA (main transformation metabolite in both studies):
- OECD 307 : PFOA formed after 2 years is < 60% Mol-% of the amount of residual 8 -2 FTOH at Day 0. After Day 104, PFOA is still being formed, this is an indication of slow migration of 8 -2 FTOH out of the polymer. .
- LSR : All but one measurement of PFOA were below the LOQ although some were above the LOD allowing for estimation. A total of 0.02 Mol-% (cotton) and 0.05 Mol- % (polyester) of residual  8-2 FTOH was transformed to PFOA.

Additional information

Read Across substance 8:2 FTOH

OECD 307:

---------------

One study on the aerobic transformation in soil of the polymer TRP-1989 which contains residual 8-2 FTOH (CAS No. 678-39-7) is available (Clariant GmbH, 2011a). The test was conducted according to OECD Guideline 307 and it fulfills the GLP criteria. The biotransformation potential was monitored by analysing 3 potential transformation products: 8 COOH (PFOA), 8-2 COOH (FTA), 8-2 U COOH (8 -2 FTuA). The initial test substance concentration in the test soil was 1000 mg/kg soil dw. The study was conducted over 24 months. The biodegradation was followed by analytical measurement of all analytes and parent substance. PFOA formed after 2 years is < 60% Mol-% of the amount of residual 8 -2 FTOH at Day 0.

After 104 days (ca. 3 months) 8 -2 FTOH could no longer be measured as the concentration was below LOQ and LOD. After Day 104, PFOA is still being formed, this is an indication of slow migration of 8 -2 FTOH out of the polymer. If any would come from the acrylate cleavage in the polymer the cleavage rate would be very low, otherwise 8 -2 FTOH would have been measureable after Day 104.

In the headspace gas no biotransformation products could be detected during the course of the study. For the calculation of DT50 values two models were used, both models fit the measured data well but the overall outcome is somewhat different. The worst cases were DT50 values for the initial available residual alcohol of 27 days and 13.5 days taking into account all diffused alcohol that has migrated from the polymer (absorbed 8-2 FTOH).

 

Landfill simulation study:

-----------------------------

A landfill simulation study with coated fabric (cotton and polyester) was carried out to mimic a residence time of 30-40 years by accelerating the ageing process through higher water circulation when compared to a typical landfill (Clariant GmbH, 2011b). No guideline is available at the moment and the test is non-GLP but it is a well documented report which meets basic scientific principles. The time span of 9 month in the simulation study corresponds to 31 years on a landfill. The test item was cotton and polyester coated with TRP-1255. TRP-1255 contains as active ingredient the polyfluorinated acrylate polymer TRP-1989. The low molecular weight polyfluorinated telomer substances such as 8-2 FTOH can be found as residuals in the polyfluorinated acrylate polymer and these may be transformed to polyfluorinated acids such as PFOA which are persistent in the environment. The biotransformation potential was monitored by analysing 3 potential transformation products: 8 COOH (PFOA), 8-2 COOH (FTA), 8-2 U COOH (FTuA) in leachate samples and headspace gas. The available test item amounts were 5.3 mg 8-2 FTOH in the lysimeters filled with cotton samples and 3.1 mg in the lysimeters filled with polyester samples. The biodegradation was followed by analytical measurements of all analytes and parent substance. The landfill simulation study shows that the formation of PFOA from residual 8-2 FTOH in the TRP-1989 included in the textile coating is very slow; the yield at the study end was 0.02 Mol-% (cotton) and 0.05 Mol-% (polyester) PFOA. More than 98.5 Mol-% (polyester) and 99.1 Mol-% (cotton) of residual 8-2 FTOH remained in the reactor after the 9-month study. The DT50 was estimated to be more than 38 years.