Four studies are first to support theory PFAS could hinder body’s ability to fight virus, but authors say more is research needed
By Tom Perkins
Higher levels of exposure to toxic PFAS “forever chemicals” may increase the likelihood of Covid-19 infection, more serious symptoms and death, a group of recent studies have found.
Public health advocates and researchers have feared since the coronavirus pandemic’s onset that PFAS, which are known to be immunotoxic, could hinder the body’s ability to fight Covid-19, and the four studies represent the first bit of research supporting the theory. However, the authors caution that more research is needed.
“There’s clear science and evidence that immunological response and PFAS are connected and associated – that’s why the Covid aspect is so important to pursue,” said Christel Nielsen, one of the study’s co-authors.
PFAS, or per-and polyfluoroalkyl substances, are a class of about 9,000 compounds most often used to make products water-, stain- and heat-resistant, and are called “forever chemicals” because they don’t naturally break down. They’re so effective that they’re used in thousands of applications across dozens of industries, but they’re also linked to cancer, decreased immunity, liver disease, kidney problems, birth defects and more.
PFAS are estimated to be in about 97% of Americans’ blood, and have been detected in all corners of the globe, including the Arctic. Some compounds can remain in the body for years or decades, depending on the quantity and chemical structure.
The chemicals are probably immunotoxic because they interfere with the body’s ability to create cells that turn into plasma cells. Plasma generates the antibodies that fight infection, and PFAS compounds appear to impact “key molecules” in that process, said Phillipe Grandjean, an environmental health professor at Harvard.
A study he co-authored found one widely-used compound, PFBA, seemed to be particularly problematic. PFAS that are commonly used to repel water and grease in food packaging, or used as stain and waterproofing agents in clothing, shoes and carpeting can turn into PFBA when they break down.
The study’s authors checked plasma samples from 323 Danish residents who had Covid and looked for five PFAS compounds known to be immunotoxic. The study found detectable PFBA in plasma showed “a clear association with a more severe” symptoms and death.
“If you had PFBA in your blood, then you were more likely to go to the hospital, and to stay longer, to get into intensive care and to die from the infection,” said Grandjean. More than 20 of those people who had PFBA in their blood had died.
“The likelihood of this happening accidentally is extremely small,” Grandjean said.
Industry has said “short-chain” compounds like PFBA are safe because they don’t stay in the blood for as long as many other PFAS, but the study casts doubt on that claim. While many PFAS accumulate in the blood, PFBA accumulates in the lungs, and appears to exacerbate symptoms because of that trait. It did so even when it was found at lower levels than other compounds.
“The unique retention of PFBA in lung tissue may offer a clue to” why PFBA seems to cause more serious disease, the study stated.
PFAS exposure has also been linked to obesity and diabetes, the authors noted, which can intensify Covid symptoms. The chemicals have endocrine-disrupting properties that seem to mimic, block, or otherwise interfere with hormones that affect immunity.
Two studies looked at whether exposure to high levels of PFAS increased the risk of infection.
Researchers in Sweden checked infection rates from the pandemic’s first year in Ronneby, a town of about 30,000 where one-third of the population was for decades exposed to highly contaminated drinking water, and the entire population has elevated blood levels.
The infection rate was about 19% higher than in a nearby town with water that didn’t have elevated PFAS levels. The study also found that people with lower PFAS blood levels were more likely to be infected, though contamination is so great in Ronneby that lower levels there are still higher than the general population.
The authors characterized their analysis as a “fast and easy” way to look for a public health correlation and determine whether more investigation is needed: “This is something that clearly warrants further research,” said Nielsen, a study co-author, who added that they are undertaking a second more in-depth study and looking into the chemicals’ impact on vaccine efficacy.
Chinese researchers with similar aim checked urine and blood samples from 160 residents in the Shanxi and Shandong provinces, two regions heavily polluted by PFAS. The study compared samples from 80 people who had either tested positive for Covid and 80 who had never been infected, and found “significantly higher risks of [Covid] infection in the subjects with increased urinary PFOS, PFOA,” two of the most toxic and widely used compounds.
An ecological study in Italy looked into morbidity rates among those exposed to high levels of the chemicals for 65 years in the Veneto region. An examination of a population of 200,000 found those exposed to high levels of PFAS had a 27% higher Covid mortality rate. The population was exposed to a mix of at least 12 compounds, which included PFBA.
The data “might plausibly suggest a general immunosuppressive effect of PFAS, it might be a quite specific effect of PFBA concentrating in the lungs and exacerbating Covid respiratory toxicity, or PFAS might lead to other conditions that predispose people with coronavirus infection to more severe disease”, the study’s authors wrote.
Co-author Annibale Biggeri called the issue “an injustice”, adding that PFAS can also increase the likelihood of a variant because the virus will stay in bodies for longer.
He said the studies findings should prompt public health officials to make special considerations for areas highly affected by PFAS. Researchers say there’s little that someone who has been exposed to high levels of the chemicals, or has high levels in their blood, can do beyond the usual precautions.
“The most important recommendation that we can give is to get vaccinated, pure and simple, for everyone, and perhaps particularly in a highly exposed area,” said Swedish study co-author Anna Joud.