Non-targeted PFAS: Discovering what we don’t know
Waters Food and Environment Testing Solutions
Enabling technologies for ensuring food and environmental safety, authenticity, and quality.
Waters Corporation | Frank Dorman
PFAS Background:?
It is no secret that Perfluoroalkyl substances (PFAS), controversially referred to as “forever chemicals”, have been under great scrutiny in the last decade. The prevalence and exposure of this class of compounds is arguably of high interest as far as environmental contaminants go.?
PFAS compounds, recently considered ubiquitous in nature, are exogenous (human-made) and are developed and utilized with intent.? They are high-volume use chemicals present in numerous commercial formulations and products. In one report, [1] the USEPA estimates that there are around 118 active PFAS formulations, which result in 85,000 tons produced domestically in the US each year. According to this report, the US production of PFAS amounts for a large portion of global PFAS production and usage.???
The usage of these materials covers a wide range of applications; some have clear beneficial impacts, while others are seemingly less obvious or even arguably unnecessary. PFAS compounds have become detectable in almost any sample studied, including human blood levels, ranging from fire-fighting materials to stain resistance modifiers for various cosmetic applications. A summary from The National Institute of Environmental Health Sciences (NIEHS) has highlighted results dating back approximately ten years [3] from the Centers of Disease Control (NHANES), showing measurable levels of PFAS compounds found in approximately 97% of all human samples studied.?
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Understanding PFAS Analysis: Why is this concerning???
Studies have concluded that while there are potential beneficial impacts from these materials, maybe the most noteworthy being rapid fire suppression, in difficult situations, there are also many human and animal health impacts. PFAS compounds are considered persistent and bioaccumulative. The range of potential compounds has been estimated as a few hundred to several thousand in the current environment. Several studies [4] to date demonstrate human exposure to PFAS is directly linked to metabolic changes, fertility problems, increased risk of certain cancers, thyroid disease, and a reduction in immune system effectiveness.?
Due to these being commercial products, our current analytical understanding of the range of PFAS that we are exposed to is quite limited in scope, and thus, their exact chemical formulations are rarely made public. As a result, we must determine composition through a lengthy process of non-targeted analytics. Given the cost and complexity of non-targeted analysis, as compared to targeted methodology, a large percentage of what we currently understand about PFAS in the environment is based on a limited set of chemical compounds, or targets, that are contained in the standard regulatory methods. This comprises approximately 36 total compounds as compared to the hundreds or thousands that are suspected in circulation.? Regarding possible transformation and/or degradation of products that may arise from industry-use PFAS entering the environment, the current analytical investigations have merely scratched the surface.?
So, is the analytical landscape all doom and gloom?? In a word, no. We have been collecting a significant amount of data on these limited target compounds that have caused some decisions, both by regulatory bodies and the industry, to modify formulations or withdraw the use of certain materials. As an analytical community, we have also refined protocols and have consolidated methods to a few types of instrument platforms and sample preparation techniques, all of which have allowed for more robust testing and higher sample throughput. The net effect of this is that we have a reasonable characterization of the scope of this situation, at least for the targets we currently measure.?
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New Advances in PFAS Analysis: What we do we know???
Our analytical understanding of specific PFAS chemicals reflects 1%, or less, of the compounds projected to be relevant to the environment. Regulatory protocols may be good at their intended purpose but do not help to elucidate the current non-targets. While it is not likely that all of these “unknowns” are detrimental to human exposure, it is highly likely that at least some are.? A significant concern arises when considering that the numbers of these compounds may range into thousands.? Furthermore, we cannot study the toxicology of these possible materials if we do not know what they are.?The impact of these compounds on humans is quite concerning and poses conjecture without proper identification. Significant inroads towards developing non-targeted analytics have been made using a combination of gas chromatographic separation coupled with an atmospheric ionization source to an Ion-mobility spectrometer and a high-resolution mass spectrometer (HRMS) has been made by Jobst et.al, in series.?This instrument (Waters APGC?-cIMS) has a tremendous ability to allow the user to focus on the per- and poly-fluoroalkyl substances as a subset of everything in the sample matrix and only perform HRMS on this subset.? This has led to the first reports of a number of previously undetermined PFAS compounds. [5] This APGC-cIMS technique was then used to evaluate several environmental samples for these newly discovered fluorotelomer ethoxylates (FTEO’s). [6] Locations associated with healthcare had some of the highest found concentrations, presumably due to the high use of stain-resistant products.? Additionally, facilities specializing in the laundering of hospital materials (lab coats, linens, etc.) were also found to have the highest concentrations of these materials in their wastewater. Finally, there are proposed degradation routes for these FTEO’s which may form the carboxy-functionalized counterparts through environmental degradation/transformation and some of these are compounds that are linked to human disease. These non-targeted compounds may actually create targets of concern in addition to having possible health impacts on their own.?
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The Importance of Non-Targeted Analytics in PFAS Characterization: What does this actually mean??
We need to investigate the non-targeted analytics and do a much better job of characterizing the extent of the impact. It is arguable that we should really do this before we develop regulatory, targeted, methods. This situation should also lead to discussions revolving around the role of industry in disseminating compositional information of their materials. In any event, it is hoped that we can better characterize PFAS entry to the environment and the effect on humans and other organisms rapidly to mitigate the future impact. Lastly, as an analytical community, we should be more vocal about defining the scope of a chemical impact through non-targeted work and not minimize it because it is much more challenging than targeted analytics.? When we merely focus on a small subset of compounds, we surely miss important information, and this can lead to less-than-ideal decisions about regulations and health impacts.?
References:?
Technical Sales Specialist @ ThermoFisher Scientific | Driving Business Growth
1 年I've just spent a couple of days learning about PFAS from our colleagues at Wilmslow and their numbers and ubiquitousness at various levels would worry my lead breathing generation.