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Per- and polyfluoroalkyl substances (PFAS) and Human Health

Penn State Extension looks at how people are exposed to PFAS, human health associations, and next steps if worried about risk in local communities.

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Updated:

August 28, 2025

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What are PFAS?

PFAS are a group of man-made chemicals that have been used for over 70 years in a wide variety of business and consumer products. Thousands of different PFAS compounds have been manufactured. Many are considered 'forever chemicals' because they decay very slowly. These PFAS persist in the soil, air, and water and are commonly found in the blood and tissues of living things, including humans. People once thought PFAS were harmless, but a growing body of scientific evidence now indicates exposure to certain PFAS compounds may cause adverse health effects.

How are people exposed to PFAS?

According to EPA[1], there are numerous ways people are exposed to PFAS, including eating contaminated food, breathing contaminated dust, and drinking contaminated water. Common sources include aqueous film-forming foams that were once used to extinguish liquid fires, certain industrial discharges, and contaminated biosolids. While many PFAS chemicals such as PFOA and PFOS have been phased out due to human health concerns, others are still used in a variety of product categories including*:

Food packaging
Cleaning products
Nonstick cookware
Wood and metal finishing coatings
Clothing with water-resistant coatings
Cross country and downhill ski wax
Fabrics and carpets with stain or water repellent coatings
Personal care products including some shampoos, dental floss, and cosmetics

* Not all products in these categories will contain PFAS

How do you know if you have been exposed to PFAS?

Because PFAS have been used in so many products for such a long time, nearly all of us have been exposed to them, and most of us have some PFAS in our blood. Unfortunately, doctors can't yet use PFAS blood levels to estimate the probability that someone will develop a related health problem. If you live in a location where high levels of PFAS have been detected in drinking water, or you work in an occupation that puts you in regular contact with PFAS-containing products, you may be at risk for higher PFAS exposure and perhaps health risks

What are the human health risks from PFAS exposure?

Numerous human and animal studies have found evidence suggesting PFAS may be harmful to human health, but more research is ongoing to clarify the risk and determine what PFAS chemicals are most harmful, what exposure levels and durations trigger health impacts, which populations may be most vulnerable, and ways we can mitigate these effects. In 2021, the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) completed a comprehensive review of PFAS studies in humans. They examined these studies for scientific evidence of health impacts for 12 PFAS compounds, including two that are now regulated in Pennsylvania's public water supplies, PFOA and PFOS.^[2] They concluded enough quality evidence has been gathered to "suggest associations between (human) exposure to individual PFAS and certain health effects," but not enough data to establish "causal relationships" such as those that exist regarding the well-studied health outcomes from breathing cigarette smoke or drinking water that contains lead. Their report also summarized findings from a similar evaluation of existing PFAS health research conducted by the National Academies of Science, Engineering, and Medicine (NASEM).

Table 1. List of human health conditions the Agency for Toxic Substances and Disease Registry* (ATSDR)* and the National Academies of Science, Engineering, and Medicine** (NASEM) concluded are likely related to PFAS exposure.
Health Condition	Strength of evidence supporting a linkage to PFAS exposure* ATSDR Conclusions	Strength of evidence supporting a linkage to PFAS exposure* NASEM Conclusions**
Increased Cholesterol Levels	Evidence of an association for PFOA, PFOS, PFNA, PFDA	Sufficient evidence of association
Lower birth weights	Evidence of an association for PFOA, PFOS	Sufficient evidence of association
Lower antibodies from vaccinations	Evidence of an association for PFOA, PFOS, PFHxS, PFDA	Sufficient evidence of association
Cancer of kidneys	Evidence of an association for PFOA	Sufficient evidence of association
Cancer of testicles	Evidence of an association for PFOA	Suggestive evidence
Gestational hypertension and preeclampsia	Evidence of an association for PFOA, PFOS	Suggestive evidence
Effects on liver enzymes	Evidence of an association for PFOA, PFOS, PFHxS	Suggestive evidence
Cancer of breast	No consistent evidence of an association	Suggestive evidence
Thyroid disease	No consistent evidence of an association	Suggestive evidence
Ulcerative colitis (IBD)	No consistent evidence of association	Suggestive evidence

*ATSDR and NASEM used different words to describe the strength of evidence in their evidence categories. ATSDR uses the term "Evidence of an association" to describe health conditions where the evidence gives high confidence that PFAS are associated with the health condition. NASEM uses the term "Sufficient evidence" to describe a similarly high level of confidence of a health association, and the term "Suggestive evidence" to describe health conditions where the data provides only moderate confidence of an association. While ATSDR and NASEM agree on the strength of evidence for most health conditions, there are a few they categorize differently, which may frustrate people who want clear answers on PFAS health risks. More research is needed and is ongoing.

**NASEM looked at PFAS as a class of chemicals instead of trying to tease out health associations for individual PFAS chemicals, as ATSDR did for their analysis.

How long do PFAS remain in our bodies?

Medical researchers are still working on this question. Guidance from ATSDR reports that not all PFAS act the same once they are in our bodies. Some pass through us in a matter of days to weeks, but others can take decades before they are eliminated. While it's good news that PFAS we unknowingly ingest or inhale won’t necessarily be in our bodies forever, minimizing future exposure is still important.

What should I do if high levels of PFAS were detected in my community?

Current evidence suggests linkages between PFAS exposure and several negative human health conditions, but the medical community is still gathering and evaluating health data and formulating public health guidance. For these reasons, you should be reasonably concerned but not overly alarmed if PFAS has been found in your community. Learning more is a good next step. Determine the resources in your community (air, water, food, or something else) that are impacted by PFAS and determine how you can lower your exposure.

If the PFAS were detected in drinking water that came from a public water supply, you should contact the water provider for more information. If the PFAS is affecting nearby private wells, and your household water comes from a private well, you may want to get your water tested. Contact your local township, city, or borough for more information on testing options, or contact your county Penn State Extension office.

What if I already think I have been exposed to PFAS?

If you think you may have been exposed to high levels of PFAS and you would like to explore the implications on your health, the Pennsylvania Division of Environmental Health Epidemiology (DEHE) recommends that you discuss any health issues or concerns specific to PFAS exposure with a healthcare provider. Specifically, you can review the following and discuss with your primary care physician: