For PFAS, is environmental persistence on its own enough to trigger regulation?

California is on the verge of setting a precedent for chemical-control policy in the US. For the first time, an agency in the state plans to treat a large group of commercial substances as a class for the purpose of regulation.

The molecules in question are per- and polyfluoroalkyl substances (PFAS). Many are toxic, but not all. Of the PFAS studied thus far, some exhibit the same types of toxicity, such as liver or thyroid problems, while others work through different biological pathways to cause harm. What these compounds have in common is that they are extremely persistent in the environment, giving rise to the nickname “forever chemicals.”

And California will contend in a rule it intends to finalize by July 1 that persistence alone is enough to trigger regulation of PFAS.

The chemical industry is strongly resisting California’s argument. Chemical manufacturers oppose the use of persistence as grounds for regulation, even though the state’s upcoming action wouldn’t immediately—and might not ever—lead to regulation that affects the sales or use of PFAS.

California’s planned regulation likely won’t grab big headlines. State regulators intend to deem carpets and rugs treated with PFAS-based stain-resistant coatings as having “a hazard trait that can harm people or the environment.”

That hazardous trait is persistence, California says.

If the rule is finalized, California’s Department of Toxic Substances Control (DTSC) will become the world’s first agency to use persistence as the primary rationale for regulating a class of chemicals, scientists from the department say in a recent paper (Environ. Health Perspect. 2021, DOI: 10.1289/EHP7431). In the past, governments have relied on compounds’ similar toxicities to regulate them as a class. Examples are chlorinated dioxins and furans, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons.

California wouldn’t be the first government entity to lump all PFAS together for possible restrictions. In Denmark and in the states of Maine, New York, and Washington, lawmakers have banned PFAS as a class from paper and cardboard food packaging or other materials that come in contact with food. In a related move, the US Congress, as part of the fiscal 2020 defense spending bill, prohibited the use of PFAS in packaging used for prepared military foods called “meals ready to eat.”

But laws enacted by elected officials generally are less vulnerable to lawsuits than are regulations issued by government agencies.

In fact, as the California DTSC finalizes its action, US chemical manufacturers are pledging to challenge any attempt to control PFAS as a single category.

“Although the grouping of some substances within the class based on similar physical, chemical, and biological properties may be possible, a proposal to regulate all PFAS as a single class is neither scientifically accurate nor appropriate,” the American Chemistry Council (ACC) says in a statement provided to C&EN. The organization is the largest lobbying association of the US chemical industry.

The ACC also takes issue with the DTSC conclusion about the hazard of PFAS.

“Persistence does not indicate a hazard,” the ACC says. The industry group points out that the ability of PFAS to resist degradation is the property that makes them effective in a variety of applications.

Replacement compounds for PFAS “would likely require the intrinsic qualities of persistence as well,” the ACC says. That should factor into any risk analysis of these compounds, the industry group says.

“Many PFAS are not biologically available and will not enter the food chain,” the ACC adds.

However, in their paper, the DTSC scientists point to previously published investigations that determined that about 85% of all PFAS can degrade or metabolize into perfluoroalkyl acids, which are biologically active. This subset of PFAS, which includes the widespread contaminants perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), is toxic as well as persistent.

The authors say they are particularly concerned with the PFAS used most widely in consumer goods. These PFAS consist of polymers with fluorinated side chains that can cleave off the polymeric backbone. They can enter landfills from discarded products such as rugs and carpets with stain-resistant treatments, releasing perfluoroalkyl acids for decades or centuries. The perfluoroalkyl acids can enter the environment via leachates from landfills or leaks in their liners. And the release can be controlled only by regulating the PFAS that form the acids, the authors argue.

Many researchers from around the world have joined the DTSC scientists in arguing that all PFAS should be treated as a single class for regulation. In a paper published last year, scientists point to these chemicals’ long-term persistence, their potential to accumulate in organisms, and their known or potential hazards to health (Environ. Sci. Technol. Lett. 2020, DOI: 10.1021/acs.estlett.0c00255).

This idea of taking action against all PFAS in a particular application is spreading.

US state lawmakers, like those in Maine, New York, and Washington, are increasingly introducing bills that incorporate the concept of controlling all PFAS in specific products, says Sarah Doll, national director of Safer States. This network of environmental health coalitions and organizations tracks state chemical policies.

Previously, state legislators have targeted specific PFAS, such as PFOS and PFOA, she says. But chemical producers have responded by switching from targeted PFAS to novel PFAS. These new molecules are generally less studied than the chemicals they replace, even though the replacements and their antecedents may share the same toxic characteristics and all are persistent, Doll says.

The policy trend to address PFAS as a class “is a movement that is beginning to gather some steam” despite industry pushback, says Linda Birnbaum, a toxicologist who retired as director of both the US National Institute of Environmental Health Sciences and the National Toxicology Program in 2019. She is a coauthor of the 2020 paper asserting that PFAS should be regulated as a class.

The pending California regulation is different from laws that ban specific products containing PFAS. The move, authorized under the state’s 2008 Green Chemistry Initiative, would not directly restrict any product or chemical.

The DTSC cannot regulate PFAS as commercial chemicals, department spokesperson Sanford Nax says. Nor can the department regulate all PFAS-containing consumer products in one fell swoop.

Under California law, “DTSC can only regulate product-chemical combinations,” Nax explains. This means the department must select specific products or groups of products containing targeted chemicals.

That’s why California’s planned regulation would deem PFAS-treated rugs and carpets as a “priority product” under the DTSC’s 2013 Safer Consumer Products Regulations. That classification, in turn, would trigger a chain of actions.

First, manufacturers of floor coverings sold in California would have to compare the use of PFAS in their products with potential alternatives. The producers must determine if there is a way to make their rugs and carpets safer under the state’s standards.

Next, after analyzing alternatives, each company would face choices for making its products safer. A firm could select another chemical for imparting stain resistance to its rugs or carpets. Or it could come up with a different product design. Or it could decide to retain its current product-chemical combination.

Finally, after companies choose their actions, the DTSC would determine whether regulation of PFAS-treated rugs and carpets is needed to protect public health and the environment. The department has an array of choices for doing this, such as banning sales of certain products, instituting disposal requirements for products, requiring companies to provide consumers with information, and opting for no regulation.

Although the department is focusing only on rugs and carpets right now, DTSC officials are “concerned about the use of PFAS in any consumer products that can lead to human and ecological exposures to these chemicals,” Nax says.

The California agency expects to classify more products containing PFAS as “priority products,” Nax says. One group consists of treatments containing PFAS, such as fabric-protecting sprays for use on upholstery, carpets, clothing, and shoes. Another is food packaging that contains PFAS and is made from paper, paperboard, or molded plant fiber.

Time will tell if this novel argument on PFAS persistence spreads beyond the Golden State.