What Are PFAS?

PFAS stands for per- and polyfluoroalkyl substances. They are a large family of human-made chemicals built around chains of carbon atoms bonded to fluorine. Those carbon-fluorine bonds are extremely strong, which is why many PFAS resist heat, water, oil, and breakdown in the environment or the body.

This is the chemical group most people mean when they say “forever chemicals.”

Quick Reference

• Simple definition: A large family of human-made chemicals with strong carbon-fluorine bonds that resist breaking down

• Main concern: Persistence and bioaccumulation; some well-studied members linked to health effects

• Key distinction: Long-chain (older, more data, largely phased out) vs. short-chain (newer replacements, still persistent)

• Key action: Reduce contact with major sources where practical and stay informed about water quality and product changes

Why it Matters

Some PFAS are very persistent and can accumulate in people and the environment over time. A smaller number of well-studied ones have been linked to health effects, including changes in cholesterol, reduced vaccine response, developmental effects, and increased risk of certain cancers. The level of concern depends on the specific chemical, how much exposure occurs, and individual factors.

Because there are thousands of different PFAS, research is uneven. A few have extensive data behind them; many others have very little.

Where You Can Find Them

• Nonstick cookware — Traditional PTFE-based nonstick coatings (the classic “Teflon-style” surfaces). Many stainless-steel, cast-iron, and ceramic-coated pans avoid them; the concern is mainly with older or conventional nonstick lines.

• Grease-resistant food packaging — Paper wrappers, molded-fiber takeout bowls and trays, microwave popcorn bags, and some pizza boxes that were treated so oil wouldn’t soak through. Rigid plastic and plain Styrofoam containers are generally lower concern for this specific issue.

• Waterproof and stain-resistant textiles — Outdoor jackets, rain gear, stain-treated carpets, and some upholstery fabrics marketed as highly water- or stain-repellent.

• Certain cosmetics and personal-care products — Most often waterproof mascara, long-wear or transfer-resistant foundation, liquid lipsticks, and some eyeliners. Products that advertise long wear or waterproof performance are the ones most likely to have used PFAS for that effect. Everyday soaps, basic lotions, and non-waterproof makeup are far less common sources.

• Firefighting foams — Especially the aqueous film-forming foams historically used at airports, military bases, and some industrial fire-training sites.

• Industrial processes and manufacturing — Facilities that make or use PFAS can release them into air and water.

• Drinking water — In some communities near manufacturing plants, military bases, airports, or places where firefighting foam was heavily used.

• Household dust — PFAS can shed from treated products and settle in dust, which becomes another pathway for exposure, especially for young children.

These are the main everyday places people encounter them. The biggest practical reductions usually come from swapping older nonstick pans, cutting back on heavily packaged greasy foods, and paying attention to local drinking-water information if you live near a known source.

Why Greasy Takeout Containers Have Been a Problem

The issue isn’t every takeout container — it’s mainly the ones designed to hold oily or greasy food without soaking through.

For years, many paper and paperboard containers (wrappers, molded-fiber bowls, some pizza boxes, and microwave popcorn bags) were treated with PFAS coatings so grease and oil would bead up instead of seeping into the material. When hot, fatty food sits in those containers, small amounts of the chemicals can move into the food. That’s why greasy takeout and packaged foods became a noticeable source of exposure for some people.

Not all containers are the same:

• Paper and molded-fiber containers with a slick, grease-resistant finish were the most common place PFAS showed up. These are the ones that historically used the coatings.

• Styrofoam (expanded polystyrene) generally does not rely on PFAS for grease resistance. The material itself is already water- and grease-repellent in a different way.

• Rigid plastic takeout containers (the clear or opaque clamshells and tubs made from polypropylene or similar plastics) typically do not need or contain PFAS coatings.

• Reusable plastic storage containers like classic Tupperware-style boxes are also not a primary PFAS source in the same way. The bigger historical concern with some plastic food storage was other chemicals (such as certain plasticizers), not the forever-chemical coatings used on paper packaging.

In 2024 the FDA announced that manufacturers had stopped selling PFAS-containing grease-proofing agents for food packaging in the U.S. That removes the main new source, though older stock, some imported products, and residual environmental presence can still exist. Choosing plain plastic, aluminum, or untreated paper when you have the option still reduces contact with the older treated materials.

The Simple Explanation

PFAS are a large family of synthetic chemicals defined by the presence of carbon-fluorine bonds. The carbon-fluorine bond is one of the strongest in organic chemistry. That strength is what gives many PFAS their useful properties — resistance to heat, water, oil, and stains — and what also makes them extremely slow to break down in the environment or in living organisms.

There are thousands of individual PFAS compounds. They are often grouped by the length of their carbon chain. Long-chain PFAS (such as PFOA and PFOS) have more carbon atoms. These were widely used for decades, tend to stay in the human body longer, and have the most extensive health data. Production of the most common long-chain versions has been largely phased out in the United States and many other countries. Short-chain PFAS were introduced as replacements. They still resist environmental breakdown, but they generally move through soil and water differently and are cleared from the body faster than the older long-chain compounds.

Once released, many PFAS can travel long distances in water and air. They have been detected in remote environments far from where they were manufactured or used. In people, different PFAS are eliminated at different rates — some in a matter of months, others over years. Because the group is so large, toxicity and environmental behavior are not uniform; a relatively small number of well-studied compounds account for most of the current regulatory and health focus.

Long-Chain vs. Short-Chain PFAS

One of the most useful ways to understand the group is by chain length.

Long-chain PFAS (such as PFOA and PFOS) have longer carbon chains. These were widely used for decades. They tend to stay in the human body longer and have the most health data behind them. Production of the most common long-chain versions has been largely phased out in the United States and many other countries.

Short-chain PFAS were introduced as replacements. They still resist breaking down, but they generally move through the environment differently and leave the body faster than the older long-chain versions. Research on many short-chain compounds is still developing.

Common Misconceptions

• “PFAS is one chemical.” It is a large family of thousands of related substances.

• “All PFAS are equally toxic.” Research depth and hazard profiles vary widely.

• “If long-chain PFAS are phased out, the problem is solved.” Short-chain versions are still in use and still persistent, though they behave differently.

• “PFAS-free labels mean zero exposure.” The chemicals already released into the environment will take a long time to decline.

What You Can Do About It

Complete avoidance is not realistic for most people, but you can lower your exposure in practical ways:

• Choose stainless steel, cast iron, or ceramic cookware instead of older nonstick pans when possible.

• Cut back on greasy takeout and microwave popcorn in treated packaging.

• Look for clothing and gear that are not marketed as highly water- or stain-resistant if you don’t need that performance.

• If you live near a known contamination site or have private well water, check whether testing has been done and what the results show.

• Support and pay attention to stronger drinking-water standards and phase-outs of the most persistent PFAS in products.

Regulators in the U.S. and other countries have begun setting limits for some of the better-studied PFAS in drinking water and restricting their use in certain products. Those steps are still evolving.

PFAS are a large and varied group of chemicals, not a single substance. A small number of well-studied ones have clear health data behind them, while many others are still being researched. The most practical approach for most people is to reduce contact with the biggest everyday sources — older nonstick cookware, certain grease-resistant packaging, and heavily treated waterproof products — while staying aware of local drinking-water information. Small, consistent changes add up, and regulatory limits continue to tighten around the compounds we know the most about.

For the broader public explanation of the “forever chemicals” nickname and everyday context, see the related post on Forever Chemicals.