Global Risk Reduction Approaches Put Pressure on PFAS Environmental Screening

In the age of personalized health, it is vital that environmental chemicals that can impact human health are monitored, analyzed and controlled. Exposure to high levels of different per- and polyfluoroalkyl substances (PFAS) can be damaging to human health, and is associated with complications in reproduction, immune responses and some types of cancer. These issues, coupled with growing concerns about the impact of PFAS on the environment, mean that the detection and identification of PFAS has become a top priority for environmental testing laboratories worldwide.

PFAS came into common use in the 1950s and are valuable for their extensive surfactant and flame-retardant properties. Many compounds fall under the class of PFAS, but all are structurally similar. The legacy PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) compounds were recognized as toxic as well as resistant to degradation and subsequently phased out from use in industry. However, a plethora of structurally similar compounds with shorter or longer carbon chain lengths, or other structural functional groups, are still in production, with new replacement chemicals being phased in. The adverse effects of PFAS on human health and the environment seemed to remain (1) even as new classes of PFAS replacement compounds are introduced. Recently, public attention has focused on several of these so-called GenX chemicals – PFOS and PFOA replacements - which have been found in surface water, groundwater, drinking water and air emissions in some areas (2). GenX chemicals are currently considered less toxic than PFOA, but depending on the amount of exposure, they remain an important concern.

There are PFAS everywhere

PFAS are frequently used in a wide range of consumer products including nonstick cookware, water-resistant clothing, personal care products and cosmetics. Along with the shift toward alternative PFAS, there has also been a geographic shift of PFAS manufacturers from North America and Europe to China (3). The chemicals can enter ecosystems and move up food chains, accumulating in animal and human tissue, including the liver and blood. Due to their extensive use, PFAS are found almost ubiquitously throughout the environment, and have even been found in the blood of isolated polar bears in the arctic circle (4).

Even though PFAS have been known to be an environmental contaminant for a long time, the field is expanding, and previously unknown compounds are continuously being detected in water and soil samples. Managing the monitoring and detection of these new compounds is an ongoing concern for regulation.

Why PFAS testing is challenging

Since PFAS cannot be seen, tasted or smelled, the only way to know if your water is contaminated is through laboratory testing. To further complicate PFAS investigation, samples from the laboratory and the environment are prone to contamination from commonly used consumer products and sampling materials, or potentially even the clothing used during the sampling procedure. PFAS can leach from these materials, potentially resulting in “false positives” and the presence of low concentrations of PFAS in water supplies is a concern when that water is used during screening.

Traditional methods to identify contaminants in environmental samples are often plagued with protracted sample preparation protocols, a lack of sensitivity, and limitations in the number and classes of compounds targeted per analysis.

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technology offers the most comprehensive approach for the screening, identification, and quantitation of low-level chemical contaminants in the environment.

Screening for PFAS

By combining minimal sample preparation with cutting-edge data processing tools and robust equipment, samples can be screened for an entire library of PFAS in a single experiment – a valuable feature for maintaining drinking water safety.

With new, unknown PFAS compounds continuously emerging the only way to identify them is by using a non-targeted screening approach. To provide near-complete characterization of PFAS contaminants in water and soil, samples can be analyzed by using a data independent acquisition strategy on a quadrupole time-of-flight LC-MS/MS system, such as the SWATH® Acquisition on the SCIEX X500R QTOF. Combining this data acquisition strategy, ensuring that no potential compounds of interest are missed, with a large-scale library provides quick and efficient screening of all suspect PFAS chemicals, even GenX compounds, based on the measured exact mass, isotope, and fragmentation patterns. The signature fragmentation patterns identify the PFAS identities and these data can be used to track and monitor any PFAS contamination in environmental samples.

Limiting our exposure to PFAS in drinking water is a priority, but evaluation and characterization of the ever-changing compounds need to go beyond monitoring drinking water to developing standard, non-regulatory human toxicity values. It would be exceedingly valuable to observe changes over a longer time. Instead of looking at a single point, more data can better inform the regulatory authorities and better provide for the future. Samples might change and degrade over time, or accumulate in water and soil, and this method helps to provide better answers for decision-making for global health and environment.

References

1.    Wang Z, Cousins IT, Scheringer M, Hungerbühler K. Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors. Environment International. 2013;60:242–248.

2.    https://www.epa.gov/sites/production/files/2018-11/documents/factsheet_pfbs-genx-toxicity_values_11.14.2018.pdf.

3.    https://www.oecd.org/env/ehs/risk-management/PFC_FINAL-Web.pdf.

4.    Smithwick M, Muir DC, Mabury SA, Solomon KR, Martin JW, Sonne C, Born EW, Letcher RJ, Dietz R.Environ Perflouroalkyl contaminants in liver tissue from East Greenland polar bears (Ursus maritimus).Toxicol Chem. 2005 Apr;24(4):981-6.