The U.S. Environmental Protection Agency is preparing to release a draft regulation limiting two fluorinated chemicals, known by the abbreviations PFOA and PFOS, in drinking water. These chemicals are two types of PFAS, a broad class of substances often referred to as “forever chemicals” because they are very persistent in the environment.

PFAS are widely used in hundreds of products, from nonstick cookware coatings to food packaging, stain- and water-resistant clothing and firefighting foams. Studies show that high levels of PFAS exposure may lead to health effects that include reduced immune system function, increased cholesterol levels and elevated risk of kidney or testicular cancer.

Population-based screenings over the past 20 years show that most Americans have been exposed to PFAS and have detectable levels in their blood. The new regulation is designed to protect public health by setting an enforceable maximum standard limiting how much of the two target chemicals can be present in drinking water – one of the main human exposure pathways.

These three articles from The Conversation’s archives explain growing concerns about the health effects of exposure to PFAS and why many experts support national regulation of these chemicals.

1. Ubiquitous and persistent

PFAS are useful in many types of products because they provide resistance to water, grease and stains, and protect against fire. Studies have found that most products labeled stain- or water-resistant contained PFAS – even if those products are labeled as “nontoxic” or “green.”

“Once people are exposed to PFAS, the chemicals remain in their bodies for a long time – months to years, depending on the specific compound – and they can accumulate over time,” wrote Middlebury College environmental health scholar Kathryn Crawford. A 2021 review of PFAS toxicity studies in humans “concluded with a high degree of certainty that PFAS contribute to thyroid disease, elevated cholesterol, liver damage and kidney and testicular cancer.”

The review also found strong evidence that in utero PFAS exposure increases the chances that babies will be born at low birth weights and have reduced immune responses to vaccines. Other possible effects yet to be confirmed include “inflammatory bowel disease, reduced fertility, breast cancer and an increased likelihood of miscarriage and developing high blood pressure and preeclampsia during pregnancy.”

“Collectively, this is a formidable list of diseases and disorders,” Crawford observed.

Read more: What are PFAS? An environmental health scientist explains

2. Why national regulations are needed

Under the Safe Drinking Water Act, the Environmental Protection Agency has the authority to set enforceable national regulations for drinking water contaminants. It also can require state, local and tribal governments, which manage drinking water supplies, to monitor public water systems for the presence of contaminants.

Until now, however, the agency has not set binding standards limiting PFAS exposure, although it has issued nonbinding advisory guidelines. In 2009 the agency established a health advisory level for PFOA in drinking water of 400 parts per trillion. In 2016, it lowered this recommendation to 70 parts per trillion, and in 2022 it reduced this threshold to near-zero.

But many scientists have found fault with this approach. EPA’s one-at-a-time approach to assessing potentially harmful chemicals “isn’t working for PFAS, given the sheer number of them and the fact that manufacturers commonly replace toxic substances with ‘regrettable substitutes – similar, lesser-known chemicals that also threaten human health and the environment,” wrote North Carolina State University biologist Carol Kwiatkowski.

In 2020 Kwiatkowski and other scientists urged the EPA to manage the entire class of PFAS chemicals as a group, instead of one by one. “We also support an 'essential uses’ approach that would restrict their production and use only to products that are critical for health and proper functioning of society, such as medical devices and safety equipment. And we have recommended developing safer non-PFAS alternatives,” she wrote.

Read more: PFAS 'forever chemicals' are widespread and threaten human health – here's a strategy for protecting the public

3. Breaking down PFAS

PFAS chemicals are widely present in water, air, soil and fish around the world. Unlike with some other types of pollutants, there is no natural process that breaks down PFAS once they get into water or soil. Many scientists are working to develop ways of capturing these chemicals from the environment and breaking them down into harmless components.

There are ways to filter PFAS out of water, but that’s just the start. “Once PFAS is captured, then you have to dispose of PFAS-loaded activated carbons, and PFAS still moves around. If you bury contaminated materials in a landfill or elsewhere, PFAS will eventually leach out. That’s why finding ways to destroy it are essential,” wrote Michigan State University chemists A. Daniel Jones and Hui Li.

Incineration is the most common technique, they explained, but that typically requires heating the materials to around 1,500 degrees Celsius (2,730 degrees Fahrenheit), which is expensive and requires special incinerators. Various chemical processes offer alternatives, but the approaches that have been developed so far are hard to scale up. And converting PFAS into toxic byproducts is a significant concern.

“If there’s a lesson to be learned, it’s that we need to think through the full life cycle of products. How long do we really need chemicals to last?” Jones and Li wrote.

Read more: How to destroy a 'forever chemical' – scientists are discovering ways to eliminate PFAS, but this growing global health problem isn't going away soon

Editor’s note: This story is a roundup of articles from The Conversation’s archives.