An Introduction to PFCs

While fluoride receives a fair bashing in the media for issues associated with possible over-exposure and the potential effects this may have on human and environmental health, many people I speak to aren't aware of some of the most ubiquitous fluorinated compounds that are now present pretty much everywhere that scientists look; perfluorinated compounds, or PFCs. 


Here is an image of a PFC - this one is Perfluorooctanesulfonic acid (aka PFOS):

(IMAGE: Wikipedia Commons)

As you can see, it looks a bit like a caterpillar; the green balls are the fluorine molecules, and the red / white 'head' of the caterpillar is the sulfonic acid. The fluorine - carbon bonds are some of the strongest chemical bonds known, meaning that once this cute little guy is created, he's pretty difficult to destroy.

The chemical structure of PFOS (and of other PFCs) result in some pretty neat properties; this compound can both attract and repel water at the same time, and it is very stable. As a result, perfluorinated compounds became very widely used in the mid-to-late 20th century, and were used for things as diverse as  Gore-tex ™, Scotchguard ™, fire-fighting foams, Teflon / non-stick coatings, paper products - basically a whole suite of consumer and industrial applications. 

In the late 1990s, increasing amounts of PFCs in blood serum set off warning bells. The manufacturer and the US EPA announced a voluntary phase-out of PFOS from production and use in the United States. PFOS was then listed under Annex B of the Stockholm Convention in 2009, with acceptable purposes and specific exemptions (decision SC-4/17). The Stockholm Convention is essentially a list of Persistent Organic Pollutants (POPs), the management of which tends to bring up HazMat images that tend to be plastered all over web-pages for shock-value:

(PHOTO: United States Department of Energy , Wikimedia Commons)

Scientists who tested the concentrations of PFCs across a wide range of environments found that PFCs were present in biota across the globe. 

So, what does this mean?

Well, because PFCs were only recently brought to the attention of environmental scientists, toxicity studies are still being done on them - we know that they can have some negative effects on organisms,  but we still don't fully understand just how toxic / non-toxic each of these compounds is. The other problem is that while some of the more persistent compounds (PFOS / PFOA) are being phased-out, their substitutes may come with a whole host of 'other' issues. For example:

1. If an oil terminal is on fire, do you use a fire-fighting foam that isn't as effective, possibly prolonging the length of the fire and putting lives and the environment at increased risk? 

2. What if the new foam is less persistent, but chews up oxygen, creating an oxygen deficient (and therefore more acutely deadly) environment for organisms? 

3. Should we apply the precautionary principle and assume that all of these compounds are highly toxic, and risk spending millions of dollars on 'over-remediation' (i.e. cleaning up more than is necessary)?

I'll talk more about PFCs in this blog, but these are issues that are currently being debated, as the legacy of the widespread historic use of PFCs is now coming to a head around the world.