EPA-Expo-Box (A Toolbox for Exposure Assessors)
Perfluorinated Compounds (PFCs)
Perfluorinated Compounds (PFCs) contain a carbon chain with fluorine atoms attached in the place of hydrogen atoms and one or more atom or functional groups attached to the end. These compounds are synthetic and used in a variety of manufacturing and industrial applications, including fire resistance and non-stick surfaces. A wide variety of consumer products contain varying levels of PFCs. These chemicals have been used for many decades in products that resist or repel oil, grease, and water-based liquids. These include products advertised as stain resistant or non-stick, such as cookware, carpets, upholstered furniture, or other fabrics, as well as non-advertised products that have repellent qualities, such as microwave popcorn bags and food packaging.
|Example PFC Structures|
|8:2 Fluorotelomer Alcohol (8:2 FTOH)
Perfluorooctanoic acid (PFOA)
||Perfluorooctanesulfonic acid (PFOS)
PFCs are generally resistant to further degradation in the environment or within biota (Olsen et al., 2007; Harada et al., 2004). The carbon-fluorine bonds that characterize PFCs are very strong and stable in air at high temperatures; are not readily degradable by strong acids, alkalis, or oxidizing agents; and generally do not undergo photolysis (Lau et al., 2007). In general, the atmospheric lifespan of long-chain PFCs (LCPFCs) (i.e., 8 or more carbons) is on the order of days to weeks under most atmospheric conditions (Lau et al., 2007). The compounds tend to partition into other environmental media. The half-lives in soil of the C6 through C11 alkylates range from about 1 to 3 years and increase with increasing chain length (Washington et al., 2010). Based on the physicochemical characteristics of these compounds, the half-lives of LCPFCs and precursors in water also are expected to be very long.
The table below provides a summary of key physicochemical factors that are likely to affect partitioning and fate of select PFCs in the environment. For chemical-specific values, consult the resources provided in the introduction to this module.
|Property||Fate and Transport Implications|
|Vapor pressure at 25°C (atm)||
Vapor pressure varies depending on the alkyl chain-length of the PFC. Low vapor pressure of some PFCs contributes to the phenomenon of Long-Range Atmopsheric Transport (LRAT). PFCs remain in the vapor state for extended periods and move readily through the atmosphere, resulting in PFC contamination in areas far from the source of release.
|Solubility in water (mg/L)||
While PFCs are lipid soluble, they are also moderately water-soluble. Many PFCs are acids that will dissociate in freshwater, which increases their solubility. This allows them to remain in the water column.
|Octanol-Water Partition Coefficient (log value)||
PFCs are specifically designed to be hydrophobic and oleophobic, making it difficult to determine a Kow value. However, biomonitoring studies have indicated a tendency to partition into organic fractions (biota), where they bind to proteins in blood serum rather than partition to fats. PFCs with longer alkyl chains are more likely to bioaccumulate and biomagnify than those with shorter chains.
|Summary: PFCs are a unique type of compound in that they are both hydrophobic and oleophobic. They can be measured in the water column, but will also bioaccumulate in biota. They move readily out of products into the air, and can spread long distances through the atmosphere due to their low vapor pressure, meaning exposure can occur far from the source.|
Ingestion is the primary pathway identified for human exposures to PFCs. Exposures from inhalation and dermal contact can also occur. The Routes Tool Set of EPA-Expo-Box provides additional information and resources organized by route.
|Route||Potential Sources of PFC Exposure|
Although exposure from dermal contact to PFCs is not considered a dominant route of exposure, people could be exposed via uptake from carpets or other surfaces such as clothing.
LCPFCs and precursors can be released to various environment media through multiple scenarios. PFCs can be released from manufacturing sites or from use of consumer or industrial products, and secondary releases at sites such as waste water treatment plants (WWTPs) and landfills are possible. These releases generally result in PFCs directly entering water or air, however, release to soils and sediment is also possible, particularly for secondary release scenarios such as application of biosolids to agricultural fields. The Media Tool Set of EPA-Expo-Box provides additional information and resources organized by media.
|Media||Sources of PFCs|
|Water and Sediment||
PFCs may be found in consumer products, household products, and food packaging, resulting in exposure to the general population. However, some populations may be at risk of higher exposure levels:
- PFCs are persistent in the environment and may be subject to long-range atmospheric transport, resulting in higher environmental contamination levels in certain regions. Therefore, people who live in certain regions, may be at higher risk of exposure.
- The lipophilic nature of PFCs may contribute to the accumulation of these chemicals in breast milk. Infants who are breastfed may be exposed to the chemicals through ingestion. Additionally, in utero exposure can occur due to transfer through cord blood. Infant food and formula have also been shown to contain PFCs, probably due to migration from food packaging.
- Because PFCs bioaccumulate, individuals who consume high amounts of fish or aquatic mammals (i.e., seal, whale), may be exposed to high levels of PFCs, particularly if the fish is sourced from contaminated waters. Fatty cuts of beef or other meats may also contain measureable PFC contamination.
- Residents who live near certain industrial sites may be at risk of exposure through contaminated drinking water, soil, or air.
See the Lifestages and Populations Tool Set of EPA-Expo-Box for resources related to particular population groups and lifestages.