Most of us are walking around with an array of poorly understood chemicals in our bloodstreams and livers -- an unintended consequence of the great 20th century heyday of chemical innovation. They're so stable they've been dubbed "forever chemicals". That means that even if we stop producing them today, some might still course through people's veins centuries from now. We're barely regulating them, even though their harms have become better-known.
The United States Environmental Protection Agency (EPA) took a small step forward last week by proposing limits on drinking water exposure to PFOA and PFOS -- two members of this large class of thousands of chemicals known as PFAS (per- and polyfluoroalky substances). The new EPA limits are a good start, but they don't get to the root of the problem: Although drugs are tested rigorously for safety before being released to the public, with chemical compounds the burden of proof is on consumers to prove they are unsafe -- after companies have already released them into the environment.
The nomenclature is confusing, because PFOS is a single compound, but PFAS refers to a class of thousands, all of which share a powerful fluorine-carbon bond -- the key to their persistence. Harvard public health professor Joseph Allen made a big leap for clarity and awareness in 2018 when he coined the term "forever chemicals" to describe the whole class, referencing that stubborn F-C bond.
PFOA, also known as C8, became infamous after the 2019 release of the film Dark Water, which was based on a true story about a rash of cancers and other unusual health problems in Parkersburg, West Virginia, in the 1990s. A determined lawyer found the water was contaminated with PFOA dumped by a DuPont facility manufacturing Teflon.
People might not have been as eager to buy Teflon cookware had we known that it was not just affecting people in Parkersburg but also contributing to PFOA accumulation in the environment worldwide, and in our bodies.
Many other PFAS compounds are getting into water through the use of firefighting foam. Others get into our bodies through food packaging, where they're used to repel water or grease. Harvard scientists also found PFAS chemicals in compostable food containers used in their own canteen.
Then there's personal care products, including cosmetics and dental floss. PFAS can also be absorbed from eating freshwater fish. They're often not listed on ingredients lists because they are among the "inert" ingredients, but it now appears their inertness is what makes them so damaging. We can even pick them up from household dust.
Earlier this year, a group of scientists studied toilet paper and found several PFAS compounds, including one called 6:2 diPAP, which is not well understood. That's worrisome because Americans flush away about 19 billion tonnes of toilet paper a year, and after going through wastewater treatment, the chemical-laced end product can end up in compost being spread on farmland.
Chemists know of hundreds of PFAS that are manufactured, but thousands have now turned up in environmental sampling, said Angela Slitt, a toxicologist in the College of Pharmacy at the University of Rhode Island. It's not clear where many come from. Nobody is sure how they got into toilet paper.
In pharmacology, she said, a drug is designed to clear the body after you stop taking it. PFAS are not a drug, but the extent to which many of them linger in the body is alarming. At least 98% of Americans have PFAS in our blood, and many PFAS tend to accumulate in the liver. Autopsies have revealed that PFAS can lodge in the brain and lungs as well.
New PFOS and PFOA have been voluntarily phased out of production in the US. The proposed EPA rules would put the burden on municipal water suppliers to keep these substances out of drinking water. Reassuringly, levels of these are decreasing in people's bloodstreams.
Nonetheless, scientists see the frequency of other PFAS levels rising in blood, said Prof Slitt, so the overall levels could be about the same. If one of these chemicals is banned, industry can just turn to substitutes -- "and we often know even less about them", she said.
Right now, the law makes it too easy for chemical companies to continue to release inadequately tested substances. "It's only after a problem has been created that the burden of proof is on the affected community or the affected individual," said Elsie Sunderland, a professor of environmental chemistry at the Harvard School of Public Health.
Various studies have linked PFAS exposure to elevated cholesterol, thyroid disfunction, reduced fertility in both men and women and poor antibody response to vaccines in children. Other studies show preliminary evidence linking them to certain cancers, weight gain and severe Covid-19.
Safe limits aren't obvious. Different states and countries have decided on varying levels depending on the specific disease of concern, said Prof Sunderland, and how much of a buffer they want to put between a dangerous dose and what people end up getting.
The WSJ reported that chemical firms want to keep making forever chemicals for essential purposes, including manufacture of semiconductors and electric vehicles.
It shouldn't be that hard to make exceptions for truly essential uses as long as companies follow rules to keep workers and surrounding communities safe and to keep consumers well informed.
Even when there's a lifesaving benefit, as with firefighting foams, firefighters and soldiers were not always informed of the risks. Many used the foams in training and safety drills and didn't clean them up afterwards, not knowing they were causing a serious, long-term water contamination problem for their own bases and surrounding communities.
In films about environmental contamination, the drama usually surrounds deadly cancers and dead farm animals, but there are slower ways chemical exposure can cause harm. Scientists are also seeing a possible connection with the gradual build-up of microplastics and rising obesity rates. It's also likely some change in our environment is behind a dramatic rise in colon cancer in young people.
We don't yet know all the long-term effects of those 12,000 PFAS compounds, but we should have more freedom to identify and avoid them. Bloomberg
Faye Flam is a Bloomberg Opinion columnist covering science.