Food & Environment · The Healthy Aging Project

PFAS: Understanding Forever Chemicals

A clear guide to PFAS groups, sources, health concerns and practical ways to reduce exposure.

PFAS: The “Forever Chemicals” in Our Everyday Lives

What they are, which ones concern scientists, and what we can do about them

A coating that repels rain, a wrapper that resists grease, a foam that extinguishes a fuel fire: PFAS have been useful precisely because they resist conditions that break down many other chemicals. That durability has also created a worldwide pollution problem.

PFAS stands for per- and polyfluoroalkyl substances. They are manufactured chemicals, widely used since the 1940s. Their strong carbon–fluorine bonds help explain why many persist for extremely long periods. Some PFAS change into other persistent PFAS rather than disappearing completely. “Forever” is a nickname, not a claim that every molecule lasts eternally. [1,2]

How many groups are there?

There is no single, universally fixed number of PFAS groups. Different classifications serve different purposes. The family contains thousands of substances—more than 10,000 under widely used broad definitions—and counts depend on the definition and database.

A useful starting point is two broad categories: non-polymeric and polymeric PFAS. Polymers are large molecules built from repeating units. Each category contains several subgroups. [2,3]

Broad category	Important subgroup	Examples or uses

Non-polymeric | Perfluoroalkyl carboxylic acids | PFOA and PFNA

Non-polymeric	Perfluoroalkyl sulfonic acids	PFOS and PFHxS

Non-polymeric | Other acids, including ether acids | HFPO-DA, associated with GenX technology

Non-polymeric	Precursors that can transform into persistent acids	Certain fluorotelomer substances

Polymeric | Fluoropolymers | PTFE, used in some non-stick coatings

Polymeric	Side-chain fluorinated polymers	Some water- and stain-resistant textile treatments

Polymeric | Perfluoropolyethers | Certain specialist lubricants and industrial applications

This is an introductory map, not a complete classification. PFAS can also be described as long-chain, short-chain or ultrashort-chain. These labels overlap with the categories above; they are not additional separate families. [2,3]

Which is the most toxic?

Science cannot reliably name one PFAS as the most toxic of the entire family. Most have far less health information than PFOA and PFOS. Toxicity also depends on the effect being measured, the dose, the exposure route and how long the substance remains in the body.

PFOA deserves particular attention: the International Agency for Research on Cancer classifies it as carcinogenic to humans, Group 1. PFOS is classified as possibly carcinogenic to humans, Group 2B.

These categories describe the strength of evidence that a substance can cause cancer. They do not rank overall toxicity, describe the risk from a particular dose, or mean everyone exposed will develop cancer. [4]

Other important PFAS include PFNA and PFHxS. The European Food Safety Authority assesses these together with PFOA and PFOS when evaluating dietary exposure. Its assessment identified reduced immune response to vaccination as the most sensitive health effect. [5]

Studies associate exposure to particular PFAS with higher cholesterol, changes in liver enzymes, reduced vaccine antibody responses, and some pregnancy and birth outcomes. PFOA exposure is also associated with kidney and testicular cancer. These findings cannot automatically be applied equally to every PFAS. [6]

Short-chain replacements should not automatically be considered harmless. Some move readily through soil into groundwater and can be difficult to capture during water treatment. [7]

Where do PFAS come from?

PFAS enter the environment during manufacturing, product use and waste disposal. Sources include factories, firefighting foams, landfills and contaminated wastewater.

They have been used in some:

Water-repellent clothing and stain-resistant furnishings.
Grease-resistant food packaging.
Non-stick cookware coatings.
Cosmetics and personal-care products.
Electronics, industrial equipment and specialist lubricants.

Not every product in these categories contains PFAS. Contamination can spread through water, soil and air, eventually reaching food and drinking-water sources. [1,2,5]

How do they enter our bodies?

Eating contaminated food and drinking contaminated water are major routes. Where a water supply is polluted, drinking water can become the dominant source. Food can acquire PFAS from contaminated water, soil or animal feed, as well as some processing and packaging materials.

Swallowing household dust and workplace exposure can also contribute. People who manufacture or handle PFAS, including some firefighters, may face additional exposure. [5,8]

A plant-based or organic diet cannot guarantee protection: environmental contamination can reach crops too. The practical response is to investigate sources and vary the diet, rather than assume a particular food label makes food PFAS-free. [5]

How can we get rid of them?

There are three different challenges: removing PFAS from water, reducing levels in the body, and dealing with environmental pollution.

1. Reduce exposure through drinking water

Ask the water supplier whether PFAS have been tested, which substances were measured, and what the results showed. Clear water and good taste do not establish its PFAS content.

Boiling does not remove PFAS. It can concentrate them as water evaporates. [9]

Activated carbon, reverse osmosis and ion-exchange systems can reduce PFAS, but performance varies. Check the exact model’s independently certified PFAS-reduction claim. An NSF/ANSI 53 or 58 mark alone is insufficient: the certification must specifically cover the PFAS reduction claimed.

Replace cartridges on schedule. Certification for PFOA and PFOS does not establish removal of every PFAS, or guarantee zero contamination. Where drinking water is affected, use appropriately treated water for cooking and drinks too. [10]

2. Reduce avoidable sources at home

When replacing products, look for a clear statement that no PFAS are intentionally added. “PFOA-free” only addresses PFOA; other PFAS may still be present.

Choose untreated fabrics where stain resistance is unnecessary, and use reusable food containers to reduce reliance on disposable grease-resistant packaging. These choices can reduce avoidable uses, but they cannot eliminate environmental exposure.

For cookware, stainless steel and cast iron avoid a fluoropolymer coating. However, PTFE is not the same substance as PFOA. Germany’s Federal Institute for Risk Assessment does not expect health harm from properly used PTFE cookware. Avoid overheating it, especially an empty pan. [11]

3. Allow levels in the body to decline

The body gradually eliminates some PFAS, but the speed differs greatly between chemicals and individuals. Some have half-lives measured in years. A half-life is the time needed for a level to fall by half under specified conditions—not the time needed to clear everything.

There is no approved medical treatment to remove PFAS from the body. Reducing continuing exposure is the main established strategy. A PFAS blood test can document measured levels, but cannot predict whether an individual will become ill. [12]

A randomized trial involving 285 Australian firefighters found that repeated blood or plasma donations reduced measured PFAS levels, with plasma donation producing larger reductions. It did not establish that these reductions prevent disease. Donation must meet medical eligibility requirements; it is not a do-it-yourself detox programme. [13]

4. Tackle pollution at its source

A filter captures or separates PFAS; it usually does not destroy them. Used filter media and concentrated wastewater still need proper management.

Industrial thermal destruction and controlled disposal methods are available, but their suitability depends on the waste, operating conditions and controls. Landfilling and underground injection contain waste rather than destroy the chemicals. EPA guidance acknowledges remaining uncertainties. Household burning is not a solution. [14]

The durable response combines fewer unnecessary PFAS uses, prevention of industrial releases, monitoring, effective water treatment and responsible waste management.

For readers, the priority is practical: find out what is in your drinking water, address confirmed contamination, and reduce avoidable sources. Prevention is more useful than an expensive promise to “detox”.

Sources

Evidence checked: 30 October 2026.

Before making changes: This website shares general educational information and personal experience, not individual medical advice. Consult a qualified healthcare professional before changing your diet, exercise routine or treatment, especially if you have a medical condition or take medication. Do not stop prescribed treatment without professional advice.

← Back to all articles