Fluorotelomer-based polymers, used to provide many commercial products with stain and water-repellent properties, have the potential to biodegrade in the environment to form perfluorooctanoate (PFOA), according to a Canadian study.
Industry in Europe and North America has phased out PFOA because of concerns over its persistence and possible health effects.
Fluorotelomer alcohols, used to make the polymers, have been shown to be present in small concentrations in final products. Studies suggest that these can biodegrade to form perfluoroalkyl carboxylic acids (PFCAs), such as PFOA (CW 19 December 2013). However, the fluorotelomer-based polymers themselves have been thought to be resistant to degradation.
Guided by commercial patents, a team led by Scott Mabury at the University of Toronto made its own version of an industrial fluorotelomer-based acrylate polymer, with eight-carbon side chains. They then removed traces of residual ingredients before assessing degradation in three different soil conditions, over a period of five months. Two of the sample sets had plants growing in the soil, while one also contained sludge from wastewater treatment plants, which is routinely spread on agricultural land.
After five months, the plants contained a range of PFCs, but predominantly PFOA. Biodegradation occurred at a significantly higher rate in the presence of a plant and sludge.
Further studies are required, using commercial fluorotelomers, in order to “properly evaluate the contribution these materials have on global PFCA levels,” say the researchers.
The FluoroCouncil, which represents global fluoro-technology companies, points to “extensive studies” in peer-reviewed journals, showing that “the commercial fluorotelomer-based acrylate polymers are very stable in the environment, as would be required in order for them to perform as durable water-repellents.”
“The FluoroCouncil is committed to the global transition from long-chain fluorochemicals to alternative chemistries such as short-chain fluorochemicals, which cannot break down to PFOA in the environment,” it adds.
The study will be published in Environmental Science and Technology.