You are here:
DEGRADATION OF FLUOROTELOMER-BASED POLYMERS
Impact/Purpose:
The general goals of this research are to meet OPPT's need for data and information regarding the stability of TBPPs in soils. We plan to address these needs with a series of lab experiments in which FBPs are exposed to selected natural and amended soils. We anticipate that, as we learn about the general behavior of FBPs in soils, we will develop a protocol for testing FBPs in soils that has procedures similar to the guidelines described in OECD 307.
Description:
Perfluoroalkyl telomers are used to synthesize a variety of telomer-based polymer products (TBPPs). These TBPPs are used to impart soil- and liquid-repellent properties to a wide range of modern products including paper, textiles, leather and carpeting. Because of their remarkable stain- and wetting-resistance, TBPPs are highly valued by industry and consumer alike, and, consequently, represent a huge commercial market world-wide.
Several species of perfluoroalkyl telomers are volatile, and, when released into the environment, they can volatilize and become widely dispersed. Furthermore, when perfluoroalkyl telomers are subjected to common environmental conditions, oftentimes they can be oxidized to highly persistent acids. Given the volatility of the telomer compounds and the persistence of the perfluoroalkyl acids, perfluoroalkyl compounds have the potential for widespread dispersal.
One of the chief perfluoroalkyl telomers in production today is the 8-2 perfluorinated telomer alcohol, a highly volatile compound. Under oxidizing conditions, the 8-2 perfluorinated telomer alcohol is oxidized to perfluorinated octanoic acid (PFOA) and this acid is highly persistent under common environmental conditions. Recognition of the wide dispersal of PFOA is only recent and some toxicity studies on the molecule are underway only now.
There are recognized sources to the environment of the 8-2 perfluorinated telomer alcohol; however, weighty questions remain regarding what role, if any, TBPPs might play as potential sources of PFOA and its precursors: are residual impurities in TBPPs able to leach to the environment; and, are the TBPPs themselves subject to degradation under environmental conditions? Resolution of these questions is essential for understanding the source term for PFOA to the environment because, if TBPPs are a source for PFOA precursors, the source term for PFOA to the environment might be orders of magnitude greater than that of the presently confirmed sources.
To address uncertainties regarding sources of PFOA in the environment, the Office of Pollution Prevention and Toxics (OPPT) plans to prepare a risk assessment. However, required elements for such an assessment have not been determined. In an effort to fill these data gaps, OPPT has been negotiating with a consortium of industries that work with perfluoroalkyl telomers, the Telomer Research Program (TRP). One of OPPT's objectives in these negotiations has been to form an Enforceable Consent Agreement (ECA) that would call for TRP to conduct tests on fluorotelomer-based polymers (FBPs), the purified components of the commercial TBPPs. The objectives of this testing are to evaluate the stability of TBPPs in the environment and whether TBPPs might be a source of PFOA. Progress toward an ECA for these tests has been slow. Consequently, OPPT has approached the ORD to request that a research program be undertaken to answer the questions OPPT had hoped to address through an ECA with the TRP. Two ORD national labs have been asked to develop research programs to address OPPT's needs:
1) the Ecosystems Research Division of the National Exposure Research Laboratory (ERD/NERL) has been asked to develop a program to evaluate the biodegradability of FBPs in soils and sediments; and
2) the Land Remediation and Pollution Control Division of the National Risk Management Research Laboratory (LRPCD/NRMRL) has been asked to develop a program to evaluate the biodegradability of FBPs in sewage and sludge.
This Task Plan (RP) describes ERD/NERL's plans to address the OPPT research needs regarding FBPs in soil settings.