Lab Note 5: Forever chemicals (PFAS)
Environmental contaminants or environmental chemicals are two terms used to describe chemicals that are present and persistent in the environment that can lead to harmful effects when organisms are exposed to them. One such group of environmental contaminants are Per- and polyfluorinated alkyl substances (PFAS).
PFAS, otherwise known as “forever chemicals” represent many synthetically created compounds that are used for consumer and industrial applications. The reason for their use comes down to their chemical properties. At their most basic PFAS represent compounds that have fluorine bound to carbon, or more specifically they contain at least one per-fluorinated methyl group (-CF3) or per-fluorinated methylene group (-CF2-) and a variable amount of fluorine bound carbon atoms in a chain. Carbon and fluorine together create polar covalent bonds, in which the two oppositely charged atoms C+ and F- share electrons. These strong bonds help make PFAS so exceptionally stable. For example, they are highly thermostable and resistant to chemical degradation. However, those same properties that make them so great for applications also make them extremely environmentally persistent in the environment.
PFAS contamination has been detected across the globe from a wide array of sources from aquatic and terrestrial environments to food and drinking water, and even tissues taken from wildlife and humans (De Silva et al. 2021) (Stoiber et al. 2020) (Ramirez et al. 2021). The presence of PFAS contamination and potential routes of exposure are staggering, due in part to both their current presence and movement in the environment (Evich et al. 2022) (Joerss et al. 2019) and our continued use of some in consumer products. Only recently has the full scope of the PFAS problem become clear and we are just beginning to understand the possible adverse health effects associated with PFAS exposure. In humans, PFAS exposure has been associated with endocrine disruptive effects that affect fertility, body weight control and development in adolescents and newborns (Panieri et al. 2022). Said health effects are going to be dependent on several factors such as dose/concentration and duration of exposure as well as characteristics of the exposed target such as age, sex, genetic predisposition (Fenton et al. 2021).
Like other environmental contaminants, PFAS can bioaccumulate across taxa. They have been documented in both freshwater and marine environments across food webs from invertebrates to most major vertebrate groups (refs). PFAS are not as well studied in freshwater systems, specifically in semi-aquatic mammals. But given their high prevalence in the environment and their documented ability to accumulate in marine systems including marine mammals, it is plausible that animals like the muskrat are frequently exposed.
To understand the effects PFAS may have on muskrat health, you must start by screening muskrats for PFAS and then quantifying the degree and make up of their exposure. This is one of the primary goals of our proposed work. Exploratory monitoring of muskrats for PFAS will take us a step further at delineating the cause(s) of range wide muskrat declines.
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