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Abstract This article will identify the state of science on the generation, production, and transport of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Additionally, this article will focus on the transport of these environmental contaminants through air sources. It is important to explore why air exposure is critical to bring awareness to a problem that is not always immediately apparent. From a biological standpoint, clean air is necessary to sustain healthy life. Thus, it is key to understand the environmental transport of chemicals such as PFOS and PFOA with regard to their ability to migrate (i.e., air to water and water to air) and thus create unsafe air. The fluorinated backbone of these substances is both hydrophobic and oleophobic/lipophobic, while the terminal functional group is hydrophilic (water loving). Therefore, PFOS and PFOA compounds tend to partition to interfaces, such as between air and water with the fluorinated backbone residing in air and the terminal functional group residing in water. This article will identify opportunities for research to further the understanding of their potential impacts to human health.
Introduction
Since the late 1960s, perfluorinated compounds (PFCs) were originally produced for numerous industrial applications including refrigerants, polymers, pharmaceuticals, adhesives, and fire retardants (Key et al., 1997). PFCs comprise a large group of fluorinated chemicals that are synthetic and man-made with unique properties. PFCs are now recognized as a new class of emerging, persistent contaminants. Their basic structural elements include a partially or fully fluorinated alkyl chain typically 4-14 in length (hydrophobic part) and a terminated functional group (carboxylates, sulfonates, sulfonamides, phosphonates) that constitutes the hydrophilic part of the molecule. Due to the presence of both hydrophobic and hydrophilic parts, PFCs exhibit surfactant properties, reducing surface tension more strongly than all other major classes of surfactants. The carbon-fluorine bonds are the strongest bonds in organic chemistry because of a high electronegativity and the fluorine atom's small size (O'Hagan, 2008). PFCs are nonflammable and resistant towards acids, bases, oxidizers, and reductants (Ding & Peijnenburg, 2013). These chemical properties are utilized for numerous consumer products such as water-, oil- and stain-resistant coatings for clothing fabrics, leather, and carpets, as well as oil-resistant coatings for paper products for the food industry (Chen et al., 2012; Giesy & Kannan, 2001; Lindstrom,...
