Questions and Answers: Drinking Water Health Advisories for PFOA, PFOS, GenX Chemicals and PFBS
1. What is a drinking water health advisory?
A health advisory provides information on a contaminant that can cause negative human health effects and is known or anticipated to occur in drinking water. EPA's health advisories are non-enforceable and non-regulatory. They provide technical information to drinking water system operators, as well as federal, state, Tribal, and local officials, on the health effects, analytical methods, and treatment technologies associated with drinking water contaminants. The health advisory documents include the derivation of the health advisory values which are the concentrations of such drinking water contaminants at or below which adverse health effects are not anticipated to occur over specific exposure durations, such as one day, 10 days, or a lifetime.
EPA’s health advisories offer information that may be used to protect people from adverse health effects resulting from exposure throughout their lives or during a sensitive life stage to contaminants in drinking water.
2. What are PFAS? What are PFOA, PFOS, GenX chemicals, and PFBS?
Per- and poly-fluoroalkyl substances (PFAS) are a large and diverse group of chemicals used in many commercial applications due to their unique properties, such as resistance to high and low temperatures, resistance to degradation, and nonstick characteristics. Although PFAS have been manufactured and used broadly in commerce since the 1940s, concern over potential adverse effects on human health grew in the early 2000s with the detection of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in human blood. Since that time, hundreds of different PFAS have been found in water, soil, and air. Many PFAS are made up of long chains of carbon-fluorine bonds, such as PFOA and PFOS, and many PFAS are environmentally persistent, bioaccumulative, and remain in human bodies for a long time.
Most uses of PFOA and PFOS were voluntarily phased out by U.S. manufacturers in the mid-2000s, although there are a limited number of ongoing uses, and these chemicals remain in the environment due to their persistence and lack of degradation. In addition, some newer PFAS in use break down into PFOA and PFOS.
PFAS made up of fewer carbon atoms, such as hexafluoropropylene oxide (HFPO) dimer acid and its ammonium salt (together referred to as “GenX chemicals”) and perfluorobutane sulfonic acid and its related compound potassium perfluorobutane sulfonate (together referred to as “PFBS”), were developed to replace PFOA and PFOS, respectively, and are used to make various consumer products and in industrial applications because they confer the similar desired properties and characteristics but generally are more quickly eliminated from the human body than PFOA and PFOS. They are still persistent in the environment.
3. What health effects are the basis for these health advisories?
The 2022 interim updated health advisories for PFOA and PFOS are based on human epidemiology studies in populations exposed to these chemicals. Based on those studies and EPA’s draft analyses, the levels at which negative health effects could occur are much lower than previously understood when EPA issued the 2016 health advisories for PFOA and PFOS (70 parts per trillion or ppt).
Human studies have found associations between PFOA and/or PFOS exposure and several types of health effects including the liver, the immune system, the cardiovascular system, human development (e.g., decreased birth weight), and cancer. The most sensitive non-cancer effect from the best available science that is the basis for the interim updated health advisories for PFOA and PFOS is suppression of vaccine response (decreased serum antibody concentrations) in children. (If you have questions about PFOA, PFOS, GenX chemicals, or PFBS and COVID-19 vaccines please refer to question 13).
The 2022 health advisories for GenX chemicals and PFBS are based on animal toxicity studies following oral exposure to these chemicals. GenX chemicals have been linked to health effects on the liver, the kidney, the immune system, and developmental effects, as well as cancer. The most sensitive non-cancer effect and the basis for the GenX chemicals health advisory is a liver effect (constellation of liver lesions). There is suggestive evidence of carcinogenic potential of oral exposure to GenX chemicals, but there are not sufficient data to calculate a cancer risk concentration in water for GenX chemicals at this time. Animal studies following oral exposure to PFBS have shown health effects on the thyroid, reproductive organs and tissues, developing fetus, and kidney. The most sensitive non-cancer effect and the basis for the PFBS health advisory is a thyroid effect (decreased serum total thyroxine). There are no known studies evaluating potential cancer effects of PFBS so the potential for cancer effects after PFBS exposure could not be evaluated.
4. What is a lifetime health advisory?
EPA’s lifetime health advisories identify levels to protect all people, including sensitive populations and life stages, from adverse health effects resulting from exposure throughout their lives to PFOA, PFOS, GenX chemicals, or PFBS in drinking water. The health advisory levels were calculated to offer a margin of protection against adverse health effects. EPA’s lifetime health advisories also take into account other potential sources of exposure to these PFOA, PFOS, GenX chemicals, and PFBS beyond drinking water (for example, food, air, consumer products, etc.), which provides an additional layer of protection.
5. What are the 2022 interim updated health advisory levels for PFOA, PFOS, and the health advisories for GenX chemicals, and PFBS?
EPA’s 2022 lifetime health advisory levels, measured in parts per trillion (ppt), offer protection for people from adverse health effects resulting from exposure throughout their lives to these individual PFAS in drinking water:
- Interim updated health advisory for PFOA = 0.004 ppt
- Interim updated health advisory for PFOS = 0.02 ppt
- Health advisory for GenX chemicals = 10 ppt
- Health advisory for PFBS = 2,000 ppt
6. My water has measurable levels of PFOA, PFOS, GenX chemicals, and/or PFBS in it at levels above the health advisory:
Should I be concerned about my health? EPA’s 2022 lifetime health advisory levels represent the concentration of individual PFAS (PFOA, PFOS, GenX Chemicals, and PFBS) in drinking water at or below which adverse health effects are not anticipated to occur over a lifetime. It is important to note that lifetime health advisories are calculated to offer a margin of protection that also takes into account exposure through other sources beyond drinking water. If you are concerned about potential health effects from exposure to these PFAS above the health advisory level, EPA encourages you to contact your doctor or health care professional.
Should I stop breastfeeding my infant? The World Health Organization, U.S. Surgeon General, and the American Academy of Pediatrics, among others, believe the advantages of breastfeeding greatly outweigh the potential risks in nearly every circumstance. EPA encourages women and people who are currently pregnant, nursing, or bottle feeding an infant with formula to consult with their physician regarding concerns related to breastfeeding and potential exposure to chemicals such as PFOA, PFOS, GenX chemicals, and PFBS. For more information about PFAS and breastfeeding, visit the CDC’s (Agency for Toxic Substances and Disease Registry) webpage on PFAS and Breastfeeding.
Does bathing/showering with my tap water present a health risk? Studies have shown that only a small amount of PFAS can get into your body through skin. Hence, neither bathing nor showering are likely to be primary routes of PFOA, PFOS, GenX chemicals, or PFBS exposure. While EPA’s health advisories are primarily focused on drinking water ingestion, not exposure through skin or breathing, they account for a margin of safety for other potential exposure routes, such as through skin (dermal), breathing (inhalation), diet, consumer products, etc.
Can PFOA, PFOS, GenX chemicals, or PFBS be boiled out of my water? No. These chemicals cannot be removed by heating or boiling water.
Should I drink bottled water? At this time, EPA is not recommending bottled water for communities based solely on concentrations of these chemicals in drinking water that exceed the health advisory levels. If you are concerned about PFOA, PFOS, GenX chemicals, or PFBS in your tap water, you can contact your local water utility to see whether they can provide any specific recommendations for your community. EPA notes that the U.S. Food and Drug Administration (FDA) has not established standards for PFOA, PFOS, GenX chemicals, or PFBS in bottled water at this time. If you have questions about bottled water, please contact the FDA.
We know that the lower the levels of PFOA and PFOS, the lower the risk. Communities and water systems that detect any levels of PFOA or PFOS or that measure Gen X chemicals or PFBS at levels higher than the health advisory levels can inform their customers and consider taking actions to reduce levels in their drinking water by installing treatment technologies or obtaining an alternative-source of drinking water that has been tested and confirmed to not be contaminated by these PFAS, if available.
Individuals who are concerned about PFOA, PFOS, GenX chemicals, or PFBS in their wells or in their homes may consider in-home water treatment filters that are certified to lower the levels in water. Learn more about these filters. If you are concerned about potential health effects from exposure to PFOA, PFOS, GenX chemicals, or PFBS above the health advisory level, contact your doctor or health care professional.
7. What are the lowest levels that PFOA, PFOS, GenX chemicals and PFBS can be reliably quantified in water, and how do those levels compare to the health advisories?
Based on current methods, the 2022 interim health advisory levels for PFOA and PFOS are below the level of both detection (determining whether or not a substance is present) and quantitation (the ability to reliably determine how much of a substance is present). This means that it is possible for PFOA or PFOS to be present in drinking water at levels that exceed health advisories even if testing indicates no level of these chemicals.
Based on current methods, the 2022 health advisory levels for GenX chemicals and PFBS are above both the detection and quantitation levels, and therefore can be reliably quantified using specified analytical methods in appropriate laboratory settings. Please refer to the table for more information.
In EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5), the agency established minimum reporting levels (MRLs) for the UCMR 5 contaminants, including 29 PFAS chemicals. EPA establishes MRLs to ensure consistency in the quality of the information reported to the agency. The MRL is the minimum quantitation level that, with 95 percent confidence, can be achieved by capable analysts at 75 percent or more of the laboratories using a specified analytical method (recognizing that individual laboratories may be able to quantify at lower levels). The UCMR 5 MRLs for PFOA, PFOS, GenX chemicals, and PFBS and the health advisories are summarized in the table:
Minimum Reporting Level (ppt)
2022 Lifetime Health Advisory Level (ppt)
8. Is EPA going to establish a national drinking water regulation for PFOA, PFOS and additional PFAS?
In March 2023, EPA proposed a National Primary Drinking Water Regulation for six PFAS, including PFOA and PFOS as individual contaminants, and PFHxS, PFBS, PFNA, and GenX Chemicals as a mixture of contaminants. The proposal includes both non-enforceable Maximum Contaminant Level Goals (MCLGs) and enforceable standards, or Maximum Contaminant Levels (MCLs). If finalized, the proposal would require public water systems to monitor for these contaminants in drinking water, notify consumers if levels are found in exceedance of the MCLs, and take steps to treat drinking water to the MCLs. After EPA has considered public comments on the proposed National Primary Drinking Water Regulation, EPA anticipates finalizing the regulation by the end of 2023.
9. Why has EPA maintained the 2022 interim health advisories for PFOA and PFOS now that the PFAS National Primary Drinking Water Regulation has been proposed?
EPA’s 2022 interim Health Advisories for PFOA and PFOS remain EPA’s non-regulatory health guidance for PFAS in drinking water until EPA’s proposed National Primary Drinking Water Regulation (NPDWR) is finalized. After EPA has considered public comments and issues a final NPDWR, EPA will decide whether to update or remove the interim health advisories.
Health advisories are not regulatory and are not legally enforceable. Health advisories reflects EPA’s assessment of health risks of a contaminant and provide technical information for states, tribes, and water systems that they may consider when addressing contamination in drinking water. MCLGs are developed to support a National Primary Drinking Water Regulation and are non-enforceable health goals set at the level at or below which there are no known or anticipated adverse effects on the health of persons and which allows an adequate margin of safety. MCLs are enforceable standards that are generally set as close as feasible to the MCLG taking into consideration the ability to quantify and treat to remove a contaminant, as well as considering and the costs and benefits of the MCL.
10. Why did EPA issue interim updated health advisories in 2022 based on draft health assessments for PFOA and PFOS instead of waiting until those assessments are final?
Consistent with EPA’s mission and responsibility to protect public health, EPA issued the June 2022 interim health advisories for PFOA and PFOS to inform the public of new scientific information on these chemicals’ health effects.
EPA conducted extensive evaluations of human epidemiological and experimental animal study data to support the development of the proposed PFAS National Primary Drinking Water Regulation. In November 2021, EPA released draft updated health effects analyses for PFOA and PFOS to the Science Advisory Board (SAB) for review. EPA evaluated over 400 peer-reviewed studies published since 2016 and used new approaches, tools, and models to identify and evaluate the information. Based on the new data and draft analyses presented in the 2021 health effects analyses that underwent SAB review, the levels at which negative health effects could occur are much lower than previously understood when EPA issued the 2016 Health Advisories for PFOA and PFOS (70 ppt).
In light of this new information, including peer-reviewed scientific studies, EPA also announced in November 2021 that the agency would move quickly to update the 2016 Health Advisories for PFOA and PFOS to reflect the new science and draft EPA analyses. To deliver on this commitment, in June 2022, EPA issued interim updated health advisories based on the draft 2021 analyses. The 2022 interim health advisories replaced the 2016 health advisories for PFOA and PFOS.
In March 2023, as part of the proposed National Primary Drinking Water Regulation (NPDWR), EPA released for public comment the draft updated toxicological assessments for PFOA and PFOS, which support the derivation of draft MCLGs included in the proposed rule. The 2023 draft updated toxicological assessments for PFOA and PFOS reflect changes made in response to Science Advisory Board peer-review feedback. The updated health effects data, from a review of the publicly available scientific studies, further support the finding that several adverse negative health effects can result from exposure to very low levels of PFOA or PFOS. As part of the proposed NPDWR, the proposed MCLGs for both chemicals are zero, based on agency policy for chemicals that have been classified as likely human carcinogens. EPA will consider public comments on the proposed NPDWR, including on the draft updated toxicological assessments. EPA anticipates finalizing the regulation by the end of 2023.
11. How can I find out if there is PFOA, PFOS, GenX chemicals, or PFBS in my drinking water?
If you are concerned about PFOA, PFOS, GenX chemicals, or PFBS in your drinking water, you can contact your local water utility to learn more about your drinking water and to see whether they have monitoring data or can provide any specific recommendations for your community.
If you own a home drinking water well, you can learn more about how to protect and maintain your well for all contaminants of concern. Read about home drinking water wellsand about PFAS in home drinking water wells.
12. If the health advisory levels for PFOA and PFOS are so low that we can't detect PFAS down to the health advisory levels, how will I know if there are health risks from drinking water in which these contaminates are not detected?
The lower the levels of PFOA and PFOS, the lower the risk. This means that while PFOA and PFOS may be present in drinking water in trace concentrations that cannot be reliably measured, water provided by these systems that test but do not detect PFOA or PFOS is of lower risk than if they are found.
Public water systems that find PFOA or PFOS in their drinking water can take steps to inform customers, undertake additional sampling to assess the level, scope, and source of contamination, and examine steps to limit exposure. While water systems may not be able to eliminate all risks from PFOA and PFOS, they can successfully reduce those risks.
13. The 2022 interim updated lifetime health advisories for PFOA and PFOS indicate that the most sensitive non-cancer effect, on which those health advisories are based, is suppression of vaccine response in children. Does this mean that vaccines for COVID-19 may be less effective for me or my child?
The studies that were the basis for the 2022 health advisory levels investigated the impacts of PFOA and PFOS exposure on children’s response to the tetanus and the diphtheria vaccines. It is important to note that these studies did not measure infection or illness rates, only response to vaccinations. The available studies suggest that PFOA or PFOS exposure at specific life stages and dose levels may affect the ability of children or adults to respond to vaccines, in general. However, the scientific literature review did not include studies that assessed the impact of these chemical exposures on response specifically to vaccines against COVID-19 infection or illness rates.
The Centers for Disease Control (CDC) Agency for Toxic Substances and Disease Registry (ATSDR) has released a statement on the health effects of PFAS and COVID-19:
“CDC/ATSDR understands that many of the communities we are engaged with are concerned about how PFAS exposure may affect their risk of COVID-19 infection. We agree that this is an important question. CDC/ATSDR recognizes that exposure to high levels of PFAS may impact the immune system. There is evidence from human and animal studies that PFAS exposure may reduce antibody responses to vaccines (Grandjean et al., 2017, Looker et al., 2014), and may reduce infectious disease resistance (NTP, 2016). Because COVID-19 is a new public health concern, there is still much we don’t know. More research is needed to understand how PFAS exposure may affect illness from COVID-19.”
14. Is EPA working to develop laboratory methods able to reliably quantify PFOA and PFOS below 4ppt?
EPA continues to conduct research and follow advances in testing technology, methods, and techniques that may improve our ability to reliably quantify PFOA and PFOS at lower levels. EPA has published a list of laboratories that met the fifth Unregulated Contaminant Monitoring Rule (UCMR 5) laboratory approval program application and proficiency testing criteria for methods 533 and 537.1.
15. What treatment technologies exist to remove PFOA, PFOS, GenX chemicals, and PFBS from drinking water?
Activated carbon, anion exchange and high-pressure membranes have all been demonstrated to remove these chemicals from drinking water systems. These treatment technologies can be installed at a water system’s treatment plant and are also available as in-home filter options. Each of the four health advisory documents identifies the treatment technologies that have been demonstrated to remove the PFOA, PFOS, GenX chemicals, and PFBS and the factors that impact performance of the technologies. Learn more about these treatment technologies.
16. My state currently has a safety level for PFOA, PFOS, GenX chemicals, and/or PFBS that differs from EPA’s 2022 health advisory values. Why is this?
EPA’s 2022 health advisories reflect our analysis, described in the 2021 draft health effects support documents reviewed by the SAB, of the best available, peer-reviewed science and provide non-regulatory and non-enforceable information to assist federal, state, Tribal and local officials, and managers of public or community drinking water systems in protecting public health when spills or contamination situations occur. States have, and may continue to, issue different values based on their own analyses. For more information about the science and process EPA used to determine its 2022 health advisory values, refer to EPA’s Drinking Water Health Advisory Documents.
17. Besides drinking water, how else can people be exposed to PFOA, PFOS, GenX chemicals, and PFBS?
PFOA and PFOS were widely used to make carpets, clothing, fabrics for furniture, paper packaging for food, and other materials that are resistant to water, grease or stains. They were also used for firefighting at airfields and in a number of industrial processes. Many of these uses were phased out by U.S. manufacturers in the mid-2000s but some uses remain. GenX chemicals are replacements for PFOA, and PFBS is a replacement for PFOS.
An individual’s exposure to these PFAS can vary due to a number of factors. Most people have been exposed to these chemicals through consumer products but drinking water can be an additional source of exposure in communities where these chemicals have contaminated water supplies.
18. What funding is EPA making available to communities to address PFOA, PFOS, GenX chemicals, and PFBS in drinking water?
The Bipartisan Infrastructure Law (BIL) provides an unprecedented $9 billion specifically to invest in communities with drinking water impacted by PFAS and other emerging contaminants. This includes $4 billion to the Drinking Water State Revolving Fund (DWSRF) and $5 billion through EPA’s Emerging Contaminant in Small and Disadvantaged Communities Grant Program. States and communities can further leverage an additional nearly $12 billion in the DWSRF dedicated to making drinking water safer, and billions more through funds that Congress provides annually to fund DWSRF loans.
EPA will ensure that states, Tribes, and localities get their fair share of this federal water infrastructure investment – especially disadvantaged communities.
More information about the BIL and its emerging contaminant funding details can be found at Bipartisan Infrastructure Law.