A greater threat to human health from 'forever chemicals' may exist than was previously recognised.

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For decades, chemicals that make our hectic contemporary lives simpler have been hailed as miraculous. Eggs no longer cling to the pan, stains can be wiped away, and rain just rolls off your coat and boots. DuPont's hopeful tagline, "Better goods for better life... via chemistry," was created when the corporation developed the chemical covering Teflon.

However, the price of this improved standard of life is now under more scrutiny. Because of their persistence in the environment, these compounds have been given the moniker "forever chemicals," and they are showing to have long-lasting effects on human health. There is mounting evidence connecting per- and polyfluoroalkyl substances (PFAS, for short) to anything from abnormal blood lipid levels and pregnancy difficulties to cancer.

Concern over these chemicals' effects on human health has recently prompted a flurry of activity on the part of public health and regulatory authorities in the United States. The U.S. Environmental Protection Agency issued a far more stringent set of guidelines for acceptable PFAS levels in drinking water in June, warning that these chemicals represent a larger health danger than was previously believed.

Radhika Fox, assistant administrator of the EPA's Office of Water, said in June at the Third National PFAS Conference in Wilmington, N.C., "The updated advisory levels are based on new science, including more than 400 recent studies which indicate that negative health effects may occur at extremely low levels, much lower than previously understood."

Rapidly after this announcement, the National Academies of Sciences, Engineering, and Medicine published the first clinical recommendations identifying certain PFAS blood concentrations at which health risks became apparent. The 300-page paper recommends monthly blood testing for anybody exposed to high amounts of the chemicals and provides advice on how to prevent exposure, such as installing specific filters proven to lower PFAS in drinking water.

Researchers from New York University revealed on July 26 in Exposure and Health that PFAS exposure is associated to at least five disease disorders, with the total yearly cost of medical treatment and lost productivity in the United States alone estimated at at least $5.5 billion. Low birth weight, childhood obesity, hypothyroidism in women, and malignancies of the kidney and testicles are all examples of such disorders.

Pediatrician and environmental health specialist at NYU Langone Health, Leonardo Trasande, says, "We just looked at two of the much than 9,000 chemicals in the PFAS family, so we're only seeing the top of an iceberg."

Common substances

Since PFAS are used to make firefighting gear more watertight and are also included in a commonly used fire suppressing foam, firefighters are among those most at risk of exposure. According to the CDC, however, PFAS may be found in the bodies of almost everyone. Exposure often arises from swallowing PFAS-infected drinking water or food cultivated in land treated with fertilisers manufactured from sewage tainted with the chemicals (SN: 11/24/18, p. 18). An estimated 2,854 places in the United States have PFAS pollution.

“People and communities have had extensive exposure to these poisons. If they can ID that they are in an area of considerable exposure, they should seek testing via their normal source of care,” says Ned Calonge, an epidemiologist at the Colorado School of Public Health in Aurora who headed the team that prepared the National Academies study. The committee connected PFAS exposure to a somewhat different set of disorders than the NYU researchers, finding “sufficient evidence” tying PFAS to four conditions: inadequate antibody response to immunisation, unusually high cholesterol levels, impaired newborn and foetal development, and kidney cancer. There was "suggestive" evidence for a link between breast and testicular malignancies, thyroid issues, and ulcerative colitis (an inflammatory bowel illness).

The study asks for greater research into the health impacts of PFAS, highlighting gaps in information on anything from neurological disorders to bone density. These compounds have a broad variety of affects on numerous systems in the body, Calonge explains. And they’re “ubiquitous in the environment.”

Contrary to popular belief, being newer does not make anything safer.

Since the 1940s, the United States has been a major producer of PFAS. Carpeting, furniture, food packaging, and even dental floss have all benefited from the compounds' ability to resist oil and water, endure high temperatures, and reduce friction. Yet, only few of the 9,000 or so variations of these synthetic compounds have been examined for their toxicologic effects.

Many PFAS have recently been identified as endocrine disruptors, meaning they are known to cause havoc with the body's natural hormone production. Other consequences of PFAS, such as reduced immunity, increased cell proliferation, and changed gene activity, also increase cancer risk. One study indicated a higher than twofold increase in kidney cancer risk between persons with the highest versus lowest blood levels of one prevalent PFAS termed perfluorooctanoic acid, or PFOA, researchers reported in 2021 in the Journal of the National Cancer Institute.

It was thought that newer PFAS would be safer since they would accumulate less in the body. But these newer chemicals are chemically identical to the older ones and may be just as damaging to health as their relatives, Trasande argues. It's becoming clear that these more modern chemicals "are linked to disorders like pregnancy-induced diabetes. We’re only beginning to recognise the greater issue that could be at play.”

The EPA’s new drinking water advice tries to target both existing and novel PFAS. It focuses on perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), two of the oldest and most widespread PFASs. According to the advise, the threshold for safe drinking water has been lowered from 70 ppt to 0.004 ppt and 0.02 ppt. Those concentrations reflect the effects of constant, chronic exposure across a whole lifespan.

Hexa­fluoropropylene oxide dimer acid and HFPO ammonium salt, together known as GenX compounds, and perfluorobutane sulfonic acid, or PFBS, were both included for the first time in the EPA's health alert. To ensure public health, the government has established a 10 parts per trillion (ppt) limit for GenX chemicals in drinking water and a 2,000 ppt limit for PFBS. The FDA reports that the newer compounds have the same environmental persistence as the older ones.

Taking the Risks

The National Academies study addressed this burden in part by outlining testing standards for doctors to employ in identifying patients with elevated PFAS levels in their bodies.

The paper presents the first clinical recommendations on how to measure a person’s illness risk. A person with a PFAS blood content of less than 2 nanograms per millilitre doesn’t have to worry. Patients with blood concentrations between 2 and 20 ng/mL, on the other hand, need to be screened for illnesses including abnormal amounts of fat in the blood, which may lead to cardiac issues. Such screening is particularly crucial for persons more sensitive to the consequences of PFAS exposure, such children, pregnant people and those who are immunocompromised. The paper suggests regular testing for cancer, thyroid issues, and ulcerative colitis for anybody with a test result above 20 ng/mL.

“For over 20 years, we’ve been able to quantify PFAS in people’s blood, but there was no advice to explain what [those data] mean,” says National Academies study coauthor Jane Hoppin, who directs the Center for Human Health and the Environment at North Carolina State University in Raleigh. This "for the first time" provides "ranges, some recommendations for what may be levels of worry, and what sorts of health follow-up would be needed."

CITATIONS

V. Obsekov, L.G. Kahn and L. Trasande. Leveraging systematic reviews to explore disease burden and costs of per‑ and polyfluoroalkyl substance exposures in the United States. Exposure and Health. Published online July 26, 2022. Doi: 10.1007/s12403-022-00496-y.

National Academies of Sciences, Engineering, and Medicine. PFAS Exposure, Testing, and Clinical Follow-Up. The National Academies Press, 2022. doi: 10.17226/26156.

J.J. Shearer. Serum concentrations of per-and polyfluoroalkyl substances and risk of renal cell carcinoma. Journal of the National Cancer Institute. September 18, 2020. doi.org/10.1093/jnci/djaa143.

A.M. Temkin. Application of the key characteristics of carcinogens to per and polyfluoroalkyl substances. International Journal of Environmental Research and Public Health. March 4, 2020. doi.org/10.3390/jerph17051668.

Environmental Protection Agency. Questions and Answers: Drinking water health advisories for PFOA, PFOS, GenX chemicals and PFBS. July 18, 2022.