Per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals” due to their persistence in the environment, have become one of the most talked-about contaminants in the realm of water and environmental testing. Not too long ago, these substances were unregulated and little-known to water providers and testing labs. Only over last two decades have PFAS come under the scrutiny of the government bodies such as the Environmental Protection Agency (EPA), thrusting PFAS testing methods into the spotlight.
Growing research has revealed not only the persistence and bioaccumulation of PFAS, but also the wide scope of PFAS pollution and its potential impact on human health. Still, testing requirements in the United States have largely been left up to state and local agencies. In March of this year, the EPA proposed the first-ever nationwide PFAS regulations for drinking water, which would require testing for six PFAS: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, also known as GenX chemicals), perfluorohexane sulfonic acid (PFHxS) and perfluorobutane sulfonic acid (PFBS). The proposed National Primary Drinking Water Regulation (NPDWR) sets maximum contaminant levels for each of these chemicals, which the EPA plans to finalize by the end of 2023.
Labcompare recently spoke with Chris Shevlin, scientific and educational affairs manager at Thermo Fisher Scientific, to discuss the recent developments in PFAS testing and standards, the impact of proposed national regulations and how labs might prepare for the future.
Q: Regulation of PFAS in the United States is relatively new, only really kicking off at the start of the 21st century. How have you seen the field of PFAS testing evolve since you first began your work in this area?
A: I first heard about PFAS in 2007. At the time, it was considered merely a potential contaminant that researchers were starting to investigate in greater detail and only two compounds were of particular interest: PFOA and PFOS. Fifteen years later, concerns around PFAS have significantly expanded. Today, there are more than 12,000 compounds worthy of investigation, and that number may continue to grow. Current targeted methods of testing cover only a handful of compounds, however, the US EPA Draft Method 1633 includes 40 PFAS analytes on the targeted list.
Another evolution is monitoring for PFAS in matrices. While much of the focus has been on testing water, especially drinking water, we are beginning to see labs investigating all sorts of materials. Soil is a big one, but some labs are also analyzing commercial goods, personal care products, and produce materials among many others.
Q: If the EPA finalizes and implements its proposed national PFAS restrictions, what do you see being the biggest challenges for water providers and testing labs to comply with new standards?
A: The standards outlined in the original EPA proposal would be very difficult for many labs to meet. EPA proposed health advisory limits of 0.004 part per trillion (ppt) for PFOA, 0.02 ppt for PFOS, and 10 ppt for GenX chemicals. The level of 0.004 ppt is extremely low and would require many labs to update their current analytical platforms.
The new hazard index for compounds PFNA, PFHxS, PFBS, and HFPO-DA (Gen X) is different and based on the detected levels of these compounds in ratio to an exposure metric, which may require some labs to make adjustments. The EPA may provide a calculator where the detected amounts can be plugged in, and the hazard index numbers automatically calculated.
The new proposed limits of 4.0 ppt for PFOA and 4.0 ppt for PFOS are much more attainable for most laboratories. I see sampling and sample prep as one of the biggest challenges for the majority of labs, primarily because of the overabundance of PFAS background sources. Many of the labs I have talked to about their PFAS work indicate that background is an issue. This is understandable since many items in the lab contain fluoropolymers, which are sources of PFAS. Background is also an issue during the sampling and transportation process, where it can be introduced even before the sample reaches the laboratory. However, labs can only control what happens at the lab. One of the strategies for reducing background is to automate sample prep.
Consider the example of solid phase extraction (SPE), which uses a manual vacuum manifold that is open to the lab environment and requires a lot of manual “touchpoints.” Every interaction within the SPE process using a manual manifold can potentially introduce unintended background. Using instrumentation provides more of a closed system for the sample prep procedure and more control over the process. For drinking water facilities, the main challenge is meeting the requirement for more testing and addressing any high levels that are encountered. Treatment options currently available are reverse osmosis or granulated activated carbon to remove PFAS. It’s unclear if all drinking water facilities have these treatment processes in place in order to achieve the required levels. Should high levels of contamination be detected, and advisories go out to communities, consumers may need to make investments in-home treatment options which can drive up the cost of safe water.
Q: How can laboratories begin to prepare for these potential new regulations?
A: Closely following the EPA as these new regulations unfold is extremely important. As new levels are proposed, labs should evaluate their current technology to make sure they are capable of measuring the required detection limits. Regulations are always changing, and new compounds of concern are constantly being identified, meaning labs must be in lockstep and making the appropriate investments.
Labs must also keep in mind that targeted workflows are only a part of what is needed for PFAS detection. As a member of the ASTM committees for PFAS in Consumer Products, I know there is a concerted effort to market products as PFAS-free or claim very low levels of PFAS. However, with so many compounds, targeted screening methods are simply not feasible. Since the list of potential compounds is now well over 10,000, an effective method and instruments are needed for general screening.
Current methods use a technology called Combustion Ion Chromatography (CIC). The technique is very helpful because it provides a mass of fluorine in the sample. Fluorine level is a good indicator of the presence or absence of PFAS in a given sample. Many labs will use CIC to compare the mass of fluorine they detect using targeted methods and compare the levels they see in the CIC screen. I must stress the word indicator because the presence of fluorine does not necessarily equate to the presence of PFAS. It’s important to keep in mind that there are other organic compounds that also contain fluorine.
Q: What methodological and technological considerations must be made in achieving the low limits of detection that would be required to comply with new regulations?
A: From a methodology standpoint for targeted methods, this is very much driven by the US EPA. Even labs that are not under EPA regulations use EPA methods, at least as a starting point. In regard to technology, some labs may need to update their systems. The key technology for this analysis is LC-triple quad. The sensitivity of these instruments gets better every year, making it prudent for labs with older instruments to modernize their platforms to meet the latest regulations.
Q: How do you see the field of PFAS testing transforming over the next few years as the EPA continues following along its PFAS Strategic Roadmap?
A: I expect more compounds to be added to targeted screening panels in the future. A good indicator is the Unregulated Contaminant Monitoring Rule (UCMR) list, which currently includes 30 targets -- 29 of which are PFAS compounds.
Q: Are there any other tips you have for labs and analysts as PFAS regulation ramp up?
A: It’s critical to stay current on what’s happening in the PFAS world. As concern around PFAS continues to grow, so will the need for sensitive testing and thorough analysis. Drinking water is just the start, and the need to analyze other matrices will become prevalent, especially solids and semi-solids. This will necessitate strong sample prep techniques and instruments and efficient extractions. Using modern extraction methods and instrumentation will significantly help with obtaining good recoveries and reproducibility. Thermo Fisher Scientific’s new EXTREVA ASE Accelerated Solvent Extractor is a key technology in this area. This is not only because it automates the extraction and evaporation, but it is a more powerful extraction technique using elevated temperatures.
About the Expert: Chris Shevlin is a Scientific and Educational Affairs Manager at Thermo Fisher Scientific. In his current role, he collaborates with scientists on new applications, developing scientific and educational content, and working with new products and innovations. Shevlin has worked in the pharmaceutical industry, running HPLC, LC-MS, and other chromatographic methods in a technical service and QC laboratory. He earned a BS degree in biotechnology and pharmacology from the University of Buffalo and an MBA from the University of Phoenix.