If you’re reading this blog and hoping for a sneak peek at the list of contaminants that will be on the next UCMR list, you’ll want to keep reading…
… because this post reviews the UCMR program and it’s importance in monitoring and collecting data for emerging contaminants. (You didn’t think I had an early un-published version of the UCMR 5 list, did you?)
The third UCMR list was responsible for the addition of six perfluorinated compounds to the list of monitored compounds. Two of those – perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) – have gained the most attention due to their known prevalence and potential to harm people. Both compounds have been added to a U.S. EPA Health Advisory for drinking water and PFOS has been added to the official Stockholm Convention list of “persistent organic pollutants” which are more commonly referred to as POPs.
The fourth UCMR list included cyanotoxins, metals, pesticides, haloacetic acids, alcohols, a few semivolatile compounds and two indicators. Perfluorinated compounds weren’t included. Since the UCMR 4 list was published (2016), perfluorinated compounds have consistently made news headlines. These compounds have been manufactured for decades and have been used everywhere. It might be quicker to list the applications for which PFC compounds haven’t been used!
Perfluorinated compounds get their name from their most notable feature – their carbon-fluorine structure. They’re now commonly referred to as per- and polyfluoroalkyl substances, or PFAS compounds, but the name is still a tribute to those C-F bonds. For anyone who doesn’t know, C-F bonds are just about the strongest bonds that exist between two atoms.
What’s the benefit of this strong bond? It’s hard to break.
What’s the downside to this strong bond? It’s hard to break.
In other words, their ability to resist breaking down makes these compounds great for use in producing things that need to withstand harsh environments (water-repellant clothing, fire-fighting foams, nonstick cookware coatings, to name a few). But that same resistance makes it possible for them to hang around in the environment and accumulate in our water supplies.
And they are.
PFAS compounds are being found in cities and countries around the globe. They’re being found at alarmingly high concentrations. They’re being found in our drinking water, groundwater, wastewater, and now they’re being found in other things – our food, our cosmetics, our food packages.
So if you look at when PFAS compounds were last monitored under the UCMR program (UCMR 3 list, published in 2012) and if you look at how much information has since been gathered about these compounds, I think the UCMR 5 list will feature PFAS compounds.
Do I know this for sure? No.
But I do have a strong suspicion that PFAS compounds will make an appearance and I want to be as prepared as I can be. One of the best ways to do this is to be familiar with the methods and the media types that are used for extracting PFAS from water samples. If you’re following a specific method, like ISO 21675 or EPA Method 537.1, you may have some of your method and media choices structured for you. But if you’re following a different method, or if you’re looking for a set of PFAS compounds that aren’t outlined in a published method, you may have to make some adjustments to meet the challenge of your particular application.
One of the application notes I found useful involves the use of a weak anion exchanger – more commonly referred to as WAX media. This application note video has some great method highlights. [Download the application note]