PFAS – Putting the Cart Before the Horse
Per- and polyfluoroalkyl substances (PFAS) have been in use, and in the environment, with exposure to humans for a very long time. PFAS are man-made chemicals that have been used in industry and consumer products worldwide since the 1950s. They have been used as coatings to make fabrics and carpets stain resistant, firefighting foams (most notably aqueous film-forming foam [AFFF]), and numerous consumer products (such as food packaging) to make them resistant to grease, water, and oil.
PFAS are a complex family of more than 3,000 man-made organic chemicals, although most of these are not currently in use or production. Certain PFAS, most notably some of the perfluoroalkyl acids (PFAAs), such as perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), are mobile, persistent and are known to not degrade in the environment. Other PFAS compounds that have limited toxicity studies include perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA).
With lots of press on the topic of PFAS in our water supplies, the question at hand is whether they are harmful and if so, at what levels. While the Agency for Toxic Substances and Disease Registry (ATSDR) admits it is currently difficult to show that these substances directly cause adverse health conditions in humans, public outcry has pressured many regulatory agencies to mandate sampling, analysis and even initiate rule-making and regulating the levels of some PFAS in drinking water.
Regarding the toxicity of PFAS, ATSDR recently stated, “scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals. More research is needed to better understand the health effects of PFAS exposure.” Conducting transparent research and avoiding overreacting to the part-per-trillion (ppt) presence of PFAS in groundwater is critically important. Many of the current arguments about regulating PFAS are all too similar to those observed during the campaign against bisphenol A (BPA). Bad policy is too often built on faulty premises, shaky science, and flawed data.
Accreditation, Analytical Methods and the Availability of Reference Materials
Although the initial US EPA publish date of Method 537 for analysis of PFAS in drinking water was 2009, the massive PFAS sampling and analysis campaigns currently underway are relatively new, with most commercial laboratories having less than 2 years of experience performing these complex PFAS analyses. As the proper analysis of PFAS in environmental samples is not a trivial undertaking, the lack of long-term experience should be significant concern to regulators and the public alike. The initial published drinking water method (Method 537) included a limited 14 PFAS and was recently revised to include only 18 PFAS.
Until recently, the only published PFAS method was the drinking water method, Method 537. Since then ASTM Method 7968 (up to 21 PFAS in non-drinking water aqueous and sludge samples), ASTM 7979 (up to 30 PFAS in soil samples) and the recent June 21, 2019 release of US EPA draft Method 8327 (See our article on draft Method 8327 with a link to comments submitted to the docket) were published. Because of the lack of US EPA published methods, many commercial laboratories have developed their own (and different) methods for the analysis of environmental media for a varying number PFAS. Commercial laboratories have cleverly referenced their methods as “Method 537- modified.” These high-variable modifications have led to significant inconsistency across the monitoring spectrum. In fact, it has been shown that split samples sent to multiple accredited laboratories routinely yield alarming differences in the reported PFAS concentrations.
Recent Orders issued by the California State Water Resources Control Board (CA SWRCB) requested the recipients to collect samples and analyze those samples for 38 PFAS, yet there is no published method for the analysis of all these 38 PFAS. Additionally, there is currently only one provider of laboratory reference standards for all these 38 compounds, which means laboratories are not able to use a true second-source standard to verify proper calibration of their instruments.
Of greater concern is the questionable rapid accreditation of PFAS laboratories by the State of California’s Environmental Laboratory Accreditation Program (ELAP). Specifically, ELAP is issuing rapid “grandfathered” accreditation based on third-party audits, which did not include analysis of 38 PFAS. Perhaps most egregious is the fact that ELAP is NOT requiring the successful analysis for the 38 PFAS in performance testing (PT) samples as an important part of the accreditation process.
With up to 38 PFAS being requested by regulators, some of these PFAS are not water soluble even at the ppt range. In fact, within Section 1.3 of the draft Method 8327, there are compounds that have very limited solubility, even at the ppt range. Many scientists must ask – why are we even looking for these PFAS if they are not water soluble?
Section 1.3 – During method development the following compounds showed a potential for reduced solubility either during standard preparation (resulting in low bias to calibration and high recoveries for samples) or during sample preparation (resulting in low recoveries). Extra care should be taken to ensure that the composition of the stock and intermediate standards maintain enough organic cosolvent, ≥ 95%, to keep longer chain PFAS in solution: N-EtFOSAA, N-MeFOSAA, PFTeDA, PFTrDA, PFDoA and PFUdA.
The Ever Growing PFAS List – Based on What Exactly?
While over a thousand individual PFAS are included on the Toxic Substances Control Act (TSCA) Inventory, less than half have been in commercial use during the last decade. These PFAS have undergone US EPA review, and even fewer PFAS were deemed to be a priority, as recently presented at the California Office of Environmental Health Hazards Assessment (OEHHA) webinar. After reviewing the CA SWRCB Order for most of the 38 PFAS, there is little scientific or health-related basis justifying this expansive PFAS list.
A limited number of select PFAS analytes have a robust amount of toxicity data (e.g., PFOA and PFOS); however, limited toxicity information exists for many of the PFAS analytes. At this time, until toxicity values are established for the CA SWRCB list of 38 PFAS, requesting monitoring for all 38 PFAS is (at best) premature. Stepping back from the press-driven hysteria, requiring PFAS analysis without toxicological interpretation appears irresponsible and inappropriate, doing a disservice to the public and resulting in unnecessary effort, cost, and concern. Specifically, without waiting for the results of systematic scientific toxicological review for these 38 PFAS, the public will have no basis upon which to draw conclusions about PFAS in the environment. In fact, compelling lines of reasoning easily found in scientific literature suggest that 33 of the 38 PFAS are not a human health priority.
Genuine “must analyze” PFAS must have a reasonable health risk-based scientific basis for risk communication to be meaningful to the public. Given that the remaining PFAS on the list have varying levels of toxicity information, it is unclear what hazard (health effect) or (exposure -based) risk these PFAS would pose, if any, given a lack of direct exposure to environmental media at any facility. Therefore, the risk communication of “possible health effects” for any analyte list must be carefully crafted after a systematic review of the quality of the underlying science.
In the final analysis, while it is prudent and appropriate to monitor and evaluate environmental pollutants where there are compelling toxicity studies. Absent compelling toxicity data and requiring monitoring without a health-based benchmark is synonymous with defining PFAS in a new way – Public Fear Absent Science.
If you have PFAS concerns, please contact Rock Vitale or David Blye for expert assistance.