Center for Research on Ingredient Safety

Updated: April 16, 2024

Science evolves as research and evidence grow to help us determine the safety of an ingredient, contaminant, or technology. However, headlines around ingredient safety are often faster than the research concluding an ingredient's harm or safety profile.

We may not immediately know if a compound or process is safe, but we can provide context and background in our new series called "Real-time Science."

In this update, we look at the new regulations established by the U.S. Environmental Protection Agency on several PFAS compounds in our public water supply.

What are PFAS compounds?

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of human-made chemicals of more than 15,000 compounds of which approximately 600 are currently in use.

PFAS compounds possess strong carbon-fluorine bonds, making them highly resistant to environmental degradation, which means that once released, they can be persistent environmental contaminants.

Researchers have also connected legacy PFAS ingredients with adverse health outcomes in animal studies, often at doses well above those encountered by people and by associations in epidemiology studies. However, more research is needed to evaluate the long-term safety of newer PFAS ingredients.

What types of products contain PFAS ingredients?

While legacy PFAS ingredients have been phased out of production, newer PFAS ingredients remain in use, and we can find them in various industrial, commercial, and consumer products:

• Firefighting foams: PFAS have been widely used in firefighting foams to extinguish fires involving flammable liquids, such as gasoline, oil, and jet fuel.

• Stain-resistant coatings: PFAS are used in coatings on carpets, furniture, and clothing to make them resistant to water, grease, and stains.

• Non-stick cookware: PFAS have been used in producing non-stick coatings for cookware.

• Food packaging: PFAS are used in some food packaging materials to prevent grease from soaking through.

• Water-resistant clothing and shoes: PFAS are used in some outdoor clothing, such as rain jackets, to make them water-resistant.

• Personal care products: PFAS are sometimes used in personal care products, such as dental floss or makeup, to make them water-resistant.

• Cleaning products: PFAS are sometimes used in cleaning products to improve performance.

• Electronics: PFAS are used in some electronic products, such as semiconductors, to improve their performance.

Are PFAS, PFOS, and PFOA compounds the same chemical? Are the terms interchangeable?

PFAS, PFOS, and PFOA compounds are not interchangeable terms.

While there are more than 9,000 Perfluoroalkyl and polyfluoroalkyl substances (PFAS), there are two legacy PFAS compounds in particular that are highly studied: perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).

So, PFOS and PFOA describe two PFAS compounds, just as apples and oranges describe two fruits.

What are legacy PFAS ingredients?

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are two examples of legacy PFAS ingredients, meaning manufacturers have largely phased out these two ingredients from our everyday products, and they have been studied more in-depth than other PFAS compounds.

Additionally, we have used these ingredients widely for decades. Due to their resistance to degradation, we can find them in our environment and bodies.  

Have we studied the other 15,000+ PFAS ingredients?

While PFAS chemicals are in the same family, they are not the same compounds, and each compound needs to be evaluated independently.

Therefore, we have not studied the vast majority of known PFAS ingredients.

Are PFAS harmful to human health?

It's believed most people are exposed to PFAS at relatively low levels, and at low levels of exposure, it's uncertain if there are any adverse health outcomes (1,2).

However, we need more research on emerging PFAS ingredients. We also need more data to understand better how PFAS ingredients may affect our bodies, especially when exposed to more than one PFAS ingredient at a time (1).

At exposure levels that exceed typical human exposure (e.g., in occupational settings) epidemiological studies suggest legacy PFOS and PFOA may adversely impact human health in the following ways:

• Developmental and reproductive problems

• Liver damage

• Kidney disease

• Thyroid disease

• Increased risk of certain cancers

• Immune system dysfunction

It’s noteworthy that these effects were seen in high-exposure settings or through epidemiological studies, which can have a number of confounding factors. Confounding factors are unmeasured variables that influence the interpretation of results when attempting to establish cause and effect. Additionally, these types of studies typically show correlation not causation, which is an important distinction (1,2,3).

How are we exposed to PFAS compounds?

PFAS are persistent in the environment, meaning they degrade over the course of decades rather than weeks or hours, leading to widespread soil, water, and wildlife contamination in areas with heavy PFAS use, such as military bases.

• Water contamination: PFAS can contaminate groundwater and surface water, posing a potential threat to aquatic ecosystems and potentially impacting the availability of safe drinking water for humans and animals.

• Soil contamination: PFAS can persist in soil for long periods, potentially contaminating agricultural land, which may affect soil health.

• Bioaccumulation: PFAS can accumulate in the tissues of fish and other animals, leading to higher concentrations of these chemicals in the food chain.

• Air pollution: PFAS can be released into the air during manufacturing, use, and disposal, potentially contributing to air pollution and affecting air quality.

• Products: There are many industrial, commercial, and consumer products containing PFAS ingredients.

What else do I need to know about PFAS ingredients?

Much of the available information comes from studying two legacy PFAS ingredients used by manufacturers that have been largely phased out of production: PFOS and PFOA.

While the data may sound alarming, and we need to act in ways that benefit our populations' health, it's important to remember that there are over 15,000 PFAS compounds, and not all will behave like PFOS and PFOA.

What regulations are related to PFAS ingredients and water systems?

We know water is a major source of PFAS contamination. Critically, we all drink water daily, so we have greater exposure to potential contaminants over a long duration, which can increase our risk of adverse health events to any contaminant, not just PFAS compounds.  

The U.S. Environmental Protection Agency (EPA) released regulations in April 2024 to limit the amount of specific PFAS and PFAS-related compounds allowed in public water systems. Public water systems have until 2029 to implement changes to ensure compliance.  

Below are the compounds and the maximum contaminant level allowed:

*The Hazard Index (HI) measures the overall risk of exposure to multiple chemicals at once. So, in order for it to be considered safe, the fractions of these compounds found in the water added together must earn a HI score less than or equal to 1 to be considered safe.  

Let’s break down these measurements for additional perspective.

When we talk about parts per trillion (ppt), we are talking about an exceedingly small amount. While a billion or trillion sounds like a larger quantity, it’s a much smaller quantity by a much larger magnitude.

For example:

1 part per million (ppm) = 0.000001 of 1
1 part per billion (ppb) = 0.000000001 of 1
1 part per trillion (ppt) = 0.000000000001 of 1

Changing the scale to money can help us visualize the scale.

1 ppm = 1¢ in $10,000
1 ppb = 1¢ in in $10,000,000
1 ppt = 1¢ in $10,000,000,000

If we were to visualize 4 ppt it’s the same as:

• 2 bricks from the Great Wall of China (500 billion bricks)

• 1.5 trees from the Amazon Rain Forest (390 billion trees)

• 0.8 stars in the night sky (200 billion stars)

Do the EPA regulations for PFAS chemicals impact well water systems?

Private well water systems do not need to follow the same standards as public water systems. However, funding to help ensure well water safety is available under legislation related to the regulation.

What should I look for in headlines related PFAS ingredients?

As PFAS ingredients continue to make headlines, it's important to critically evaluate the information presented in the media. To ensure an accurate assessment of human risks, we should ask ourselves the following questions when reading about PFAS:

• Does the study focus on human models or animal models?

• Is the study designed for human health or environmental purposes?

• Is the study about new PFAS compounds or legacy PFOA and PFOS compounds?

It's crucial to note that not every study is intended for human health assessment, and not all studies serve as the basis for regulatory decisions. Some studies may be conducted to determine if further investigation is necessary.

By asking these key questions, we can better understand the context and significance of PFAS-related news.

The good news.

It’s estimated that only 6%- 10% of public water facilities included in the new ruling will need to take corrective actions, meaning  that 90+% of our current public water systems test at or below the new requirements.

We can see firsthand how the recent regulatory and legislative update reinforces that science can help us continue to improve as a society. If you have any questions about foods and ingredients, please reach out to us on Twitter, send us an email, or submit your idea to us at go.msu.edu/cris-idea