PFAS and breast cancer: what the NIH study means for you

I have been writing about forever chemicals for a while now, and I will admit this one stopped me cold. A study published this month in the Journal of Clinical Oncology found that two of the most common PFAS chemicals, PFOA and PFOS, are tied to significantly higher rates of the most aggressive type of breast cancer. Not overall breast cancer. The worst kind.

The study was large, well-designed, and peer-reviewed. Let me break down what it found and what you can do about it.

What the NIH researchers found

The research came out of the Sister Study, which is one of the biggest breast cancer studies in the country. It enrolled 50,884 women across the U.S. and Puerto Rico between 2003 and 2009. Every woman in the study had a sister who had been diagnosed with breast cancer, but none of the participants had it themselves when they joined.

Alexandra White, Ph.D., an NIH Stadtman Investigator, led the study. Her team, with first author Che-Jung Chang, Ph.D., measured 17 different PFAS chemicals in blood samples that had been collected years before any diagnosis. They then compared 1,609 women who went on to develop breast cancer with 2,269 who did not.

Two chemicals jumped off the page:

• PFOA (perfluorooctanoic acid): Women with the highest exposure had a 67% higher rate of ER-negative breast cancer compared to those with the lowest levels.
• PFOS (perfluorooctanesulfonic acid): Women with the highest exposure had a 93% higher rate. Nearly double.

The team also ran a meta-analysis combining earlier research, and the results held up. The study was published in the Journal of Clinical Oncology (DOI: 10.1200/JCO-26-00318) in November 2026.

Why ER-negative breast cancer is the concerning part

I had to look this up myself when I first read the study, so let me save you the search. Not all breast cancers behave the same way. ER-negative tumors do not have estrogen receptors, which means the hormone therapies that work on most breast cancers, like tamoxifen, do not work on these. Doctors have fewer tools. Patients have fewer options.

ER-negative breast cancers also tend to grow faster and have fewer known risk factors. The fact that PFAS showed up linked to this particular subtype, and not to breast cancer in general, caught the researchers’ attention. It suggests these chemicals may be doing something that has nothing to do with hormones, possibly affecting gene activity or immune function. The researchers noted these possibilities but said they did not test those mechanisms directly.

If you want to understand more about how PFAS mess with your body’s systems, I have written about PFAS and thyroid disease, PFAS and female fertility, and PFAS and male fertility.

So should you panic?

No. But you should pay attention.

The numbers here are comparisons between groups of women, not a forecast for any one person. A 67% or 93% increase sounds scary, and I am not going to pretend otherwise. But ER-negative breast cancer is less common than ER-positive, so the absolute risk for any individual is still relatively low. What makes this study hard to brush off is the consistency across nearly 4,000 women.

Here is the part I keep coming back to. First author Che-Jung Chang noted that exposure to these chemicals is “still potentially modifiable.” That means you can actually do something about it. You cannot undo past exposure, but you can stop adding to the pile.

PFOA and PFOS are not gone

I know what you might be thinking: “Didn’t they ban those chemicals?” Sort of. Most major manufacturers phased out PFOA and PFOS between roughly 2006 and 2015. But “phased out” and “gone” are very different words when you are talking about chemicals that never break down.

PFOA and PFOS are still in drinking water, soil, and the blood of nearly every person who has been tested. The EPA found them in water systems serving nearly 200 million Americans.

And the replacement chemicals that companies switched to? The NIH researchers pointed out that we barely have any safety data on those either.

What you can do to lower your PFAS exposure

You cannot flush PFAS out of your body overnight. These chemicals stick around for years. But every bit of new exposure you cut off matters, and over time your levels will come down. Here is what I did, and what I tell friends to try first.

1. Test and filter your water

Drinking water is the single biggest source of PFAS for most families. The National Institute of Environmental Health Sciences says contaminated water and food are the most common ways these chemicals get into our bodies.

Before you buy a filter, find out what is actually in your tap water. The Tap Score Professional PFAS Water Test is an EPA-certified lab test that measures dozens of individual PFAS compounds. It is not cheap, but knowing your actual numbers beats guessing.

Once you have your results, get a filter rated for PFAS. Reverse osmosis is the gold standard and typically removes over 90% of PFAS. I like the AquaTru Countertop Reverse Osmosis System because it sits on the counter and you do not need a plumber to install it. It is NSF-certified for PFAS reduction.

If that is more than you want to spend right now, a good pitcher filter can still make a big difference. The Clearly Filtered Water Pitcher is independently tested to remove over 99% of PFOA and PFOS. Our full PFAS-free water filtration guide covers more options at different price points.

2. Ditch the nonstick pans

This one is personal for me because I held onto my nonstick pans way too long. Traditional PTFE nonstick coatings are part of the PFAS family, and when you heat them past medium, they can release trace PFAS into your food and kitchen air.

The fix is simple: switch to something that never had PFAS in it. The Lodge Pre-Seasoned Cast Iron Skillet is my go-to. It is cheap, will outlast you, and once it is seasoned properly, eggs slide right off. If cast iron feels too heavy, stainless steel works well too. I have more details in our stainless steel cookware guide and our nonstick cookware breakdown.

3. Look at your personal care and household products

PFAS turn up in cosmetics, dental floss, stain treatments, waterproof jackets, food packaging, and more. You do not have to replace everything in your house this weekend. Start with the products that touch your skin or your food most often, and work from there. Our guide to verifying PFAS-free claims will help you figure out which labels to trust and which ones are just marketing.

4. Think about testing your own levels

If you live near a military base, an industrial site, or an area with known water contamination, a blood test can tell you where you stand. Even if you are just curious, it gives you a baseline to measure against later. Our PFAS blood testing guide walks through what to expect and how to get tested.

Where we go from here

This study is one of the clearest links between PFAS and cancer that I have seen. And PFOA and PFOS are just two chemicals out of thousands in the PFAS family. Most of those have never been tested for cancer risk at all.

We do know more than we did a year ago, though. Testing is easier to get. More companies are making PFAS-free products. And the PFAS Free Life Database makes it a lot faster to find safer options instead of spending your whole weekend reading ingredient labels.

Frequently asked questions

Does PFAS cause breast cancer?

The NIH study found a strong association between PFOA/PFOS blood levels and ER-negative breast cancer, but it is an observational study, not proof of direct causation. What it does show is a consistent, dose-dependent pattern: higher PFAS levels in the blood correlated with higher rates of aggressive breast cancer across nearly 4,000 women. The researchers confirmed the finding with a meta-analysis of prior studies.

What types of breast cancer are linked to PFAS?

The November 2026 NIH study linked PFOA and PFOS to estrogen receptor-negative (ER-negative) breast cancer, a more aggressive subtype with fewer treatment options. No clear connection was found between these chemicals and overall breast cancer risk or ER-positive subtypes.

How can I reduce my PFAS exposure?

Start with your water: test it and install a filter certified for PFAS removal (reverse osmosis or activated carbon block). Replace nonstick cookware with cast iron, stainless steel, or ceramic. Check personal care products and food packaging for PFAS, and use the PFAS Free Life Database to find verified alternatives.

Are PFOA and PFOS still in use?

Most major manufacturers phased out PFOA and PFOS between 2006 and 2015, but these chemicals persist in the environment for decades. They are still found in drinking water, soil, and blood samples worldwide. Replacement PFAS chemicals are in wide use, but their health effects are largely unstudied.

Should I get a blood test for PFAS?

A blood test can measure your current PFAS levels and give you a baseline. It is worth considering if you live near a known contamination site, work in an industry that uses PFAS, or have a family history of breast cancer. Talk to your doctor about whether a PFAS panel makes sense for you.

*Study reference: Chang CJ, White AJ, et al. “PFOA and PFOS and Incidence of Breast Cancer in the Sister Study.” Journal of Clinical Oncology, November 2026. DOI: 10.1200/JCO-26-00318. See also: NIH press release

PFAS Free Life Database*