by Nancy Maddox, MPH, writer
In the 1930s—when manufacturers began a frenzied period of product development, creating vinyl, nylon and a host of other synthetic materials—scientists made a seminal discovery: bonding fluorine atoms to a simple carbon backbone yields compounds with amazing chemical properties, such as ultra-low friction, fierce water repellency and exceptionally long half-lives.
Collectively known as per- and polyfluoroalkyl substances, or PFAS, these compounds now pervade almost every aspect of modern life.
Polytetrafluoroethylene (PTFE), the first in this huge family of compounds, was the basis for Teflon® non-stick coatings. Other PFAS repel water, oil and stains in umbrellas, tents, Gore-Tex® outerwear, carpets and upholstery. They repel grease and moisture in pizza boxes, fast food wrappers, microwave popcorn bags and pet food bags. And they have been incorporated into everything from cell phones to fabric softeners to Oral-B® Glide dental floss.
Beginning in the late 20th Century, they also began turning up in human blood, with the most heavily exposed populations located on or near industrial sites, such as chemical manufacturing plants, and the hundreds of airports, military facilities and fire departments that store and use PFAS-containing firefighting foams.
According to the US Centers for Disease Control and Prevention (CDC), in 2000, the average US resident had a blood perfluoroctane sulfonic acid (PFOS) level of 30 µg/L; 3M workers had roughly 500 µg/L.
Human exposure, in turn, has been associated with a long list of health problems, notably including kidney and testicular cancers, thyroid disease, pre-eclampsia, asthma diagnoses and decreased antibody response to vaccines, especially in children.
“People are scared,” said Doug Farquhar, JD, who analyzes environmental health legislation for the National Conference of State Legislators. “That’s putting a lot of pressure on [government] agencies to come up with some sort of response.”
And that, in turn, has created a growing—as yet, unmet—demand for laboratory testing to detect and measure the chemicals in people and in the environment.
PFAS testing: costly, complex
But laboratory testing for PFAS isn’t cheap. Or easy. Patrick Parsons, PhD, head of environmental health sciences at New York’s Wadsworth Center—the state public health laboratory—explained the hurdles. First is cost.
“Testing for PFAS in aqueous samples involves an extraction of the analytes using solid phase extraction (SPE) techniques and determination using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS),” he said.
“The type of LC/MS/MS instrumentation for this analysis costs between $250-300K and a further $140K for the automated 96-well plate technologies for SPE for serum testing, and a further $40K for the automated SPE for water testing.”
Older LC/MS/MS systems may be incapable of detecting PFAS at the low levels required, on the order of parts per trillion (ppt).
A second problem is contamination from PFAS already in the laboratory. Thus, sample introduction systems have to be stripped of Teflon® degassers, Teflon® SPE cartridges, PTFE vial caps and all other PFAS-containing components.
Of course, laboratories must also have staff experienced in mass spectrometry and assure additional, specialized training in trace analysis of the compounds.
And because there are few standardized test methods for these unregulated chemicals—and literally thousands of possible analytical targets in a variety of test matrices—scientists must often develop and validate their own testing protocols.
After all these tasks have been accomplished, laboratories still need approval from the Centers for Medicare & Medicaid Services before clinical test results can be reported to patients. “This requires a substantial amount of work to document the validation studies performed and to develop the protocols that meet clinical quality standards,” said Parsons.
Analyzing drinking water for PFAS, he said, “also requires a substantial effort to document validation and to develop the detailed protocols that meet environmental quality standards.”
Currently, state laboratories in at least ten jurisdictions—CA, IA, MI, MN, NH, NJ, NY, RI, UT, WI—have tested or currently test for select PFAS in human blood, drinking water or both. At least three of these states also test other matrices, such as groundwater, wastewater and surface water. Michigan has tested deer and fish.
Wadsworth, a leader in PFAS analytics, can measure up to 11 PFAS targets in human serum and up to 16 PFAS compounds and eight perfluoroalkyl ether carboxylic acids (a newer class of PFAS chemicals) in drinking water.
Additionally, Wadsworth scientists have developed more than ten novel methods for PFAS measurement in a variety of matrices, including newborn screening dried blood spots. The laboratory serves as a resource to neighboring states and contributes to a number of federal biomonitoring studies.
The California Department of Toxic Substances Control uses two test methods to detect PFAS in serum. One targets 12 long carbon chain perfluorochemicals—the most persistent, bioaccumulative and toxic compounds within the PFAS class (the same test panel historically used for CDC’s population-based PFAS surveillance). The other targets some of the newer, short carbon chain PFAS and precursor compounds.
But even with these state resources, Julianne Nassif, MS, director of APHL’s environmental health program, said national capacity for PFAS testing falls well short of demand, especially as the potential dangers of PFAS exposure become more publicized and as the chemicals turn up in more and more sites.
The newly launched National Biomonitoring Network (NBN) is preparing to offer training and technical assistance to states seeking to institute clinical PFAS testing programs, but there is no comparable entity to boost capacity for environmental PFAS testing.
“NBN funding comes from CDC, so it’s limited in how it can be used,” said Nassif. “We’d love to have a similar structure to build capability and capacity for PFAS water testing in the state laboratories,” perhaps supported by the US Environmental Protection Agency (EPA) and US Department of Defense.
At present, much of this environmental work has been handed off to commercial laboratories. While “expedient,” Nassif said, “I don’t think [reliance on contractors] is a good long term solution. ... States should have capability to perform that testing. It would be prioritized; it would be high quality testing.” Moreover, a state “primacy” laboratory for environmental PFAS testing could be responsible for quality oversight in the commercial sector and for confirmatory testing in cases where contract labs report differing results.
“The public is just up in arms”
While laboratory data are critical to inform PFAS investigations and response, the utility of the data is limited by serious scientific gaps. For example, since 1999 CDC has been measuring serum levels of select PFAS chemicals as part of its National Health and Nutrition Examination Survey (NHANES), but there is no national standard for human PFAS exposure to explain what those findings mean.
Eden Wells, MD, MPH, FACPM, former chief medical officer for the state of Michigan, said, “There is no blood level that can advise clinical response, because there’s so little known about PFAS clinically. We don’t know what a level in the blood may mean in terms of past exposure, current risks or future health outcomes.”
NHANES data are, however, critical for establishing national background levels—against which local test data can be compared to identify cases of elevated exposure—and for monitoring exposure trends. For example, after manufacturers began voluntarily phasing out use of PFOS around 2000, average US blood concentrations fell by more than 80% over the next 14 years.
Yet CDC tracks only a small handful of the thousands of PFAS compounds in existence.
The California Department of Public Health (CDPH)—the first state to begin population-wide PFAS biomonitoring—noted in an e-mail the challenges associated with this broad class of chemicals:
“Developing methods to identify and measure new compounds is difficult and time consuming, all the more so because we usually do not know what compounds are being used commercially. There are also many analytical complications. Analytical standards (needed for method development) are not readily available. Some of the newer replacement PFAS, such as shorter chain and ether-based compounds, require specialized analytical methods to detect, and there isn’t a consensus yet about how to interpret and report results. These issues are difficult to resolve, and new chemicals are being used in products and released into the environment every day.”
The environmental side of the issue is similarly fraught. In 2016, EPA lowered its drinking water health advisory limit for PFOS and perfluorooctanoic acid (PFOA)—two of the best studied PFAS legacy compounds—from 200 ppt PFOS and 400 ppt PFOA down to 70 ppt for both chemicals combined. But this is a nonbinding limit. (A draft CDC toxicology report released last June suggests a much lower lifetime exposure limit for the same compounds.) While the agency is evaluating the need for a Safe Drinking Water Act maximum contaminant level for PFOA and PFOS, a final determination and enforceable regulation are likely years away.
In the meantime, EPA is also developing draft toxicity values for the PFOS/PFOA replacement chemicals GenX (HFPO dimer acid) and perfluorobutane sulfonic acid.
In the absence of stronger federal action, states have begun their own PFAS monitoring and interventions. Last June, for example, the North Carolina Department of Environmental Quality filed a court order requiring Chemours Company—a DuPont spinoff—to drastically reduce its release of GenX and other PFAS into the air and into the Cape Fear River watershed, where they had contaminated drinking water supplies and alarmed residents. Local communities blame GenX for a cluster of unexplained pediatric cancer cases there.
NCSL’s Farquhar said, “People are very, very concerned. They want a solution. North Carolina is not known as a very environmentally rigorous state, which is probably part of the reason [Chemours] built there. Now [the issue has] come back to the state. The public is just up in arms.”
Last February, 3M agreed to pay the state of Minnesota $850 million to settle a lawsuit related to PFAS drinking water contamination in the area surrounding the company’s Cottage Grove manufacturing plant, just ten miles south of St. Paul.
A notable feature of the policy environment, said Farquhar, is that PFAS are a “very bipartisan” issue, as “reflective of public opinion.” He said, “The state legislatures are not waiting for the federal government. It’s not that they don’t trust the government, they’re just moving ahead.”
During 2017-2018, at least ten states (CA, MI, MN, NC, NH, NY, PA, RI, VT, WA) enacted PFAS-related laws. Washington, for example, passed legislation banning the use of certain PFAS-containing food packaging and severely restricting the sale and use of PFAS-containing firefighting foam, beginning in 2022 and 2020, respectively.
Other states have instituted drinking water standards more stringent than EPA’s 70 ppt health advisory level for PFOS and PFOA. For example, California requires public drinking water systems to notify residents when PFOA exceeds 14 ppt or PFOS exceeds 13 ppt. Vermont allows no more than 20 ppt for the sum of five PFAS, including PFOS and PFOA. New Jersey has a 13 ppt limit for perfluorononanoic acid, a particularly toxic PFAS discharged into the southern Delaware River area by a specialty polymers plant.
“Everyone carries a body burden of these persistent chemicals”
Michigan began detecting PFAS in sites around the state as early as 2012, beginning with the area around the Wurtsmith Air Force Base (WAFB) in Oscoda and the Army & Air National Guard Training Center at Camp Grayling.
“We learned the military, right about that time, had begun to test their bases for PFAS, because firefighting foams carry these ‘forever’ chemicals, and they have to do a lot of training and put out a lot of fires,” said Wells. “After that, we had citizen concerns.”
Today, Wells serves on the Michigan PFAS Action Response Team (MPART), the first multi-agency, state PFAS working group in the country. Launched in 2017 at the behest of Governor Rick Snyder, MPART has statehouse support and funding. One indication of the group’s stature is its initial leader, a former deputy attorney general of Michigan.
One of team’s first actions was to convene a scientific panel to advise the state on response, mitigation and recovery activities.
So far, the state has proactively tested every public water utility in Michigan for select PFAS. It is in the process of testing drinking water from all schools, childcare providers and Head Start programs using well water, with results posted online.
After finding combined PFAS levels as high as 1,828 ppt in treated drinking water from the tiny town of Parchment (population 3,174), officials acted swiftly, directing the digging of a tunnel to service Parchment with drinking water from nearby Kalamazoo.
“We had a municipal water hook-up in about a month’s time between when we got the test results back and when there was basically a permanent solution in place,” said Wells. “The key is that a lot of that came about because of MPART; leadership could quickly grasp what needed to be done.”
The MPART website includes a map showing 36 sites under investigation for PFAS contamination, including military facilities, tanneries (which often apply PFAS-containing ScotchguardTM to leather goods), the site of a tanker spill, metal plating facilities, a commercial laundry, a Superfund site, landfills and other locations. A separate webpage identifies lakes and streams affected by PFAS.
Wells said authorities are also investigating possible PFAS contamination in deer and fish consumed in this “hunting state,” and are considering testing wild birds. Another concern, she said, is waste that is converted into biosolids and added to agricultural fertilizers.
Half a continent away, California has been focused on PFAS for over a decade via a state biomonitoring program established by law in 2006. Historically, the program has received baseline state funding of $2.2 million per year, supplemented in most years with CDC funding ranging from $1 million to $2.5 million. Individual biomonitoring studies measure PFAS in maternal and infant populations, firefighters and Asian/Pacific Islanders. And a separate statewide surveillance project assesses the PFAS exposure of the general California population.
According to CDPH, “What we find, in every study, is that just about every person has been exposed to PFAS. Regardless of where you live or what kind of work you do, everyone carries a body burden of these persistent chemicals.”
More heavily exposed groups in the California studies include firefighters—found to have significantly elevated levels of perfluorodecanoic acid relative to NHANES adults—and Asians, found to have higher levels of PFOS than Asians in NHANES. Overall, California men were found to have higher levels of PFOS and PFOA than California women, although levels of these two legacy compounds are decreasing.
As PFAS exposure routes become better understood and the public health response evolves, state laboratories
will continue to play a vital role. Andy Gillespie, PhD, executive lead for EPA’s PFAS research and development, said laboratory testing to assess human exposure “is key to understanding risk and to understanding risk management options,” such as carbon filtration or ion exchange to remove the chemicals from drinking water.
Gillespie expects LC/MS/MS testing technology to become less costly and more accessible over time, with improved tools to support data analysis. The laboratory response, he said, must progress “not only in terms of bandwidth—greater testing capacity—but also pushing the science to more advanced capability.”
Currently, Gillespie said, EPA is doing considerable research into non-targeted PFAS testing, using high-resolution mass spectrometry (HRMS). Whereas targeted analysis measures “maybe 18 to 24 analytes and that’s all the method can see,” he said non-targeted analysis detects “everything that’s in a sample,” followed by “a lot of detective work ... to figure out what you’re seeing.” The technology is mostly used in research laboratories today.
Asked if he had any message for state laboratories, Gillespie responded with three. First, he said, “PFAS are likely to be contaminants of concern for a long time to come,” due to the persistence of legacy compounds and the ongoing production of new ones. Second, he said, “Increased analytical capacity for analyzing samples will be needed and welcome.” And lastly, he encouraged scientists to follow HRMS advances: “Follow that science and be ready to move in that direction.”