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Removal of Perfluorocarboxylic Acids (PFCAs) from Carpets Treated with Stain-protection Products by Using Carpet Cleaning Machines
Hubbard, H., Z. Guo, Ken Krebs, S. Metzger, C. Mocka, R. Pope, AND N. Roache. Removal of Perfluorocarboxylic Acids (PFCAs) from Carpets Treated with Stain-protection Products by Using Carpet Cleaning Machines. US Environmental Protection Agency, Cincinnati, OH, EPA/600/R/12/703, 2012.
Consumer products that are made from or treated with perfluorinated polymers and telomers may contain low levels of perfluorocarboxylic acids (PFCAs), which have adverse health effects, such as developmental toxicity and potential carcinogenicity in laboratory animals. Thus, the discovery that PFCAs have been detected worldwide in surface water, soil, humans, and a variety of wildlife is of concern. The fact that some of the PFCAs have been shown to have half lives on the order of several years has heightened this concern.
PFCAs are found in a variety of consumer products, including, but not limited to, treated clothing and textiles, floor care products, paper containers for food, and carpets. For example, carpet that has been treated with stain-protection, carpet-care solutions, either by the manufacturer or after installation has been identified as a significant source of PFCAs in an indoor environment. Although the PFCA content in today’s mill-treated carpet is far less than it used to be as a result of new carpet manufacturing processes, after-market, carpet stain-protection treatments that contain PFCAs are still available for use by home owners or carpet care professionals. These optional treatments may increase the concentration of PFCAs in the environments where they are used. Furthermore, PFCAs are semivolatile compounds that can be absorbed by household dust, limiting removal options and leading to a long residence time in the indoor environment. Because of these potential methods of indoor exposure to PFCAs, it is important to understand the feasibility of in-situ removal of PFCAs from treated carpet. To our knowledge, this issue has not been addressed by any publications in the existing literature. Experiments were performed in the U.S. EPA Research House in Cary, NC to investigate levels of PFCAs in two types of carpets that had been treated with one of two commercial carpet stain-protection treatment solutions. Household and commercial carpet cleaning machines using hot water or steam extraction were employed to study the potential removal of specific PFCAs from the treated carpeting. Carpet cleaning detergents were also used in the cleaning machines in some tests. Both household and commercial carpet cleaning machines without detergent were able to reduce total PFCA levels in carpets between 20% and 60% after three rounds of cleaning. The addition of a detergent, which presumably increased PFCA solubility, resulted in more than 70% of the total PFCAs removed. It is estimated that approximately six rounds of cleaning with detergent would reduce total PFCA levels by 90%. The measured levels of PFCAs represent the total PFCA concentration in the carpet fibers after a methanol-based extraction method, which may differ from the total available concentration under typical household conditions. As carpets age through foot traffic and daily use, the total available PFCA level found in the household may increase. More studies are needed to better understand PFCA transport from carpets throughout the indoor environment, such as attachment to indoor dust. Additionally, further studies will help to better understand PFCA exposure routes and methods that can be used to reduce PFCA exposure in indoor environments.