PFAS

Information for Clinicians

Key Points• Communities around the United States have been concerned about possible
health effects from PFAS exposure and have been looking to healthcare
providers for counseling and support related to PFAS exposure.
• Ingestion of contaminated food and water is a main route of PFAS exposure.
• Health effects potentially associated with PFAS exposure include increases incholesterol levels, decreases in birth weight, lower antibody response to vaccines,
kidney and testicular cancer, pregnancy-induced hypertension, preeclampsia, andchanges in liver enzymes.
• An exposure history can help clinicians determine the duration, magnitude, and routes ofpatients’ PFAS exposures and reveal opportunities for exposure reduction.
• In deciding whether to order PFAS testing, clinicians can consider− an individual’s exposure history,− results of PFAS testing from the patient’s water supply, food sources, or other exposure routes,
and− whether results can inform exposure reduction and health promotion.
• PFAS blood testing results do not provide information for treatment or predict future health problems.
• Patients and clinicians can discuss the potential risks and benefits of using PFAS blood testing
results to guide clinical management. Considerations include− factors unique to the patient, including the patient’s risk for disease,− whether health screening beyond the usual standards of care is appropriate, and− the potential for unnecessary further testing and treatment related to false positives fromadditional screening tests.
• No approved medical treatments are available to reduce PFAS in the body.
• ATSDR will continue to review the science and periodically update this information.

Properties of PFAS
Per- and polyfluoroalkyl substances (PFAS) are a family of thousands of synthetic chemicals that all contain apartially or fully fluorinated carbon chain. Their chemical properties allow them to reduce friction and resist oil
and water. As a result, they have been widely used in industry and consumer products since the 1940s. Major
applications include surfactants used in industrial processes and firefighting foams, and protectants for paper
packaging products, carpets, and textiles that enhance water, grease, and soil repellency.

Last updated 1/18/2024

PFAS are widespread and persistent in the environment. The carbon-fluorine bonds are strong, so thesecompounds do not fully break down in the environment or human body. In humans, properties of the mostwell-studied PFAS include the following:• Absorption: Absorbed in the intestines and lungs; limited dermal absorption• Distribution: Bind to serum proteins; to a lesser extent, also bind to tissue proteins (e.g., liver, kidneys,
and brain)• Metabolism: Most not metabolized; some metabolized to other PFAS
• Elimination: Mainly in urine (clearance rate can vary by sex and kidney function); also, through defecation,
menstruation, breastfeeding, and placental transfer• Half-life: A few days to 8 years or more, depending on the specific PFAS

Human Exposure to PFAS
Epidemiology
Nearly all people in the United States have measurable amounts of PFAS in their blood. Researchers often
use people’s blood PFAS levels as a proxy for exposure. Since 1999, the National Health and Nutrition
Examination Survey (NHANES) has been measuring certain PFAS (e.g., PFOS, PFOA, PFHxS, and PFNA) inblood samples from people living in the United States. The data show declining levels of three prevalent PFAS(PFOA, PFOS, and PFHxS), in part because the U.S. Environmental Protection Agency (EPA) enlisted major
manufacturers to phase out production and reduce facility emissions of PFOA, PFOS, PFHxS, and PFNA.
Population blood levels of substitute PFAS (e.g., GenX) are not well studied. Blood levels of these shorterchain PFAS do not necessarily reflect total cumulative exposure because they tend to have relatively shorthalf-lives.
Geometric Mean PFAS Blood Levels in the United States
35

PFNA

15
10
5

18
20

16

17
-

20

20

15
-

14
20

20

13
-

12
20

20

10

11
20

20

08

09
20

20

06

07
-

20

20

05
20

20

04

0

03
-

Some communities can have higher
geometric mean levels of blood PFAS
than NHANES.

PFHxS

20

20

* Nanograms per milliliter (ng/mL) isequivalent to micrograms per liter (µg/L)
and to parts per billion (ppb).

PFOA

00

• PFNA: 0.411 ng/mL, with 95% of thegeneral population ≤1.40 ng/mL.

PFOS

25

20

• PFHxS: 1.08 ng/mL, with 95% of thegeneral population ≤3.70 ng/mL, and

30

99
-

• PFOA: 1.42 ng/mL, with 95% of thegeneral population ≤3.77 ng/mL,

Geometric Mean Blood PFAS Level(nanograms per milliter, ng/mL)• PFOS: 4.25 ng/mL*, with 95% of thegeneral population ≤14.6 ng/mL,

19

In 2017-2018, NHANES reported
geometric mean blood levels of

NHANES Cycle

PFAS Information for Clinicians • 2

Exposure Sources and Routes
Communities with documented PFAS contamination in drinking water supplies or food are often nearfacilities that have manufactured, used, or handled PFAS; these include some factories, airports, militarybases, wastewater treatment plants, farms where sewage sludge was used for fertilizer, landfills, orincinerators. Other PFAS exposure sources include PFAS-containing consumer products and workplaces that
manufacture, use, or handle PFAS.
Routes of exposure to PFAS include ingestion, placental transfer, and inhalation. Dermal absorption of PFAS
is limited and does not appear to be a significant route of exposure for the general population. For more
information on occupational exposures, please visit the National Institute for Occupational Safety and Health(NIOSH) PFAS webpage.

Ingestion
Ingestion of contaminated food and water is a main route of PFAS exposure. In communities affected by
PFAS-contaminated drinking water, water can be the main source of exposure. For other communities, therelative contribution of exposure sources can vary.
Ingestion of PFAS can occur through• drinking water from PFAS-contaminated municipal sources or private wells,• eating food (e.g., meat, dairy, and vegetables) produced near places where PFAS were used or made,• eating fish caught from water contaminated by PFAS (PFOS, in particular),• eating food from some types of grease-resistant paper or packaging (e.g., popcorn bags, fast foodcontainers, pizza boxes, and candy wrappers), and• swallowing contaminated soil.
Ingestion of residue and dust from PFAS-containing consumer products is another way people are exposed
to PFAS. Research has suggested that exposure to PFOA and PFOS from today’s consumer products isgenerally lower than exposures from PFAS-contaminated drinking water. Some products that might contain
PFAS include• stain resistant carpets, upholstery, and other fabrics,• water resistant clothing,• cleaning products,• personal care products and cosmetics (e.g., shampoo, dental floss, nail polish, and eye makeup), and• paints, varnishes, and sealants.
Children can have higher PFAS exposures through ingestion than adults. Children eat and drink more relative
to their body weight and can ingest dust or dirt containing PFAS through mouthing objects and hand tomouth behaviors. Children can also be exposed by• drinking formula mixed with PFAS-contaminated water, and• drinking breastmilk from persons exposed to PFAS.

Placental Transfer
Some PFAS cross the placenta and enter umbilical cord blood. The permeability of the placental barrier varies
for different PFAS.

PFAS Information for Clinicians • 3

Inhalation
Most PFAS are not volatile, so inhalation is not a typical exposure route for the general population. People
living near facilities that incinerate PFAS and PFAS-containing materials can be exposed to PFAS throughinhalation.
In the workplace, handling of PFAS and PFAS-containing materials and breathing associated dust, aerosols,
or fumes can also result in exposure to PFAS through inhalation. Inhalation is not a typical route of exposurefor the general population but can occur with use of some PFAS-containing consumer products.

Drinking Water Standards, Regulations, and Health Advisories
Federal and state PFAS drinking water standards as well as health advisories for PFAS may differ and can be
expected to change over time. In general, PFAS drinking water standards, regulations, and health advisories
are not intended for use in assessing an individual patient’s health risks, but following these can help reduce
drinking water exposures to PFAS.

Health Effects
Pathophysiology
The pathophysiology of PFAS toxicity is an area of active research. Many studies of populations haveexamined possible relationships between levels of PFAS in blood and rates of harmful health effects (seesection below), but research has not yet confirmed mechanisms for each health effect. Complicating
this challenge is that PFAS are sometimes examined as a class and other times examined as individualcompounds.

Health Effects Associated with PFAS
The Agency for Toxic Substances and Disease Registry (ATSDR)’s 2021 Toxicological Profile for
Perfluoroalkyls provides a comprehensive review of toxicological information for 12 different PFAS. ATSDR
evaluated the available epidemiological data and found that the preponderance of the evidence suggested
associations between exposure to individual PFAS and certain health effects.
Additionally, ATSDR and the National Institute of Environmental Health Sciences (NIEHS) funded the
National Academies of Science, Engineering, and Medicine (The National Academies or NASEM) to provide
an objective review of the current evidence regarding human health effects of PFAS. In its 2022 report
Guidance on PFAS Testing and Health Outcomes, NASEM categorized the strength of evidence for various
health effects for PFAS as a class. In addition to the health effects listed by ATSDR, NASEM also foundepidemiologically-based associations with additional health effects.
Some animal and human studies find positive associations between PFAS exposure and a much wider rangeof health effects. For example, they identify associations with serum uric acid concentrations, reproductive
health, diabetes, kidney effects, asthma, and neurobehavioral outcomes. Results of animal studies do notalways correlate with human health effects because of physiologic differences between species. Inconsistentfindings among human studies and study design limitations are some reasons why other potential healtheffects are not identified as associated with PFAS.

PFAS Information for Clinicians • 4

Health Effect

ATSDR Review of Associations(PFAS Associated with
Health Effects)*

NASEM Category of
Association†

NASEM and ATSDR Health Effects
Increases in cholesterollevelsEvidence of an association (PFOA,PFOS, PFNA, PFDA)

Sufficient evidence of an
association

Small decreases in birthweight (<0.7-ounce
decrease per 1 ng/mL
blood PFOA/PFOS
increase)
Lower antibody response
to vaccines

Evidence of an association (PFOA,
PFOS)

Sufficient evidence of an
association

Evidence of an association (PFOA,PFOS, PFHxS, PFDA)

Sufficient evidence of an
association

Kidney and testicularcancerEvidence of an association (PFOA)

Sufficient evidence for kidneycancer / Limited or suggestive
evidence for testicular cancer

Pregnancy-induced
hypertension or
preeclampsia

Evidence of an association (PFOA,
PFOS)

Limited or suggestive evidenceof an association

Changes in liver enzymes

Evidence of an association (PFOA,PFOS, PFHxS)

Limited or suggestive evidenceof an association

Additional Health Effects Considered
No consistent evidence of an
Thyroid disease andassociation
dysfunction

Limited or suggestive evidenceof an association

Breast cancer

No consistent evidence of an
association

Limited or suggestive evidenceof an association

Ulcerative colitis

No consistent evidence of an
association

Limited or suggestive evidenceof an association

ATSDR and NASEM use different language to describe the strength of an association.
Many newer PFAS have properties, such as a shorter half-life, that limit the ability to use blood levels as a proxy forlong-term exposure. This makes it more challenging to study whether exposure to these PFAS could cause healtheffects.
* ATSDR’s approach took into consideration the consistency of the findings across studies, the quality of thestudies, dose-response, and plausibility. Although the data may provide evidence for an association, it does notalways imply that the observed effect is biologically relevant because the magnitude of the change may be within
the normal limits or not indicative of an adverse health effect. Causal relationships have not been established forthese health effects.
†

NASEM reviewed associations with PFAS as a class rather than by specific PFAS.

PFAS Information for Clinicians • 5Factors Impacting the Risk of Health Effects
The risk of health effects associated with environmental exposures, including PFAS, depends on exposure
factors (e.g., dose, frequency, route, and duration), individual factors (e.g., sensitivity to exposure and chronic
disease burden), and other determinants of health (e.g., access to safer water and quality healthcare).

Clinical Evaluation and Management
When patients have concerns about PFAS or other environmental exposures, clinicians can help addressthese concerns by actively listening and providing practical advice. Clinicians play an important role in helping
patients identify and reduce exposures and in promoting standard age-appropriate preventive care measuresfor physical health, mental health, and wellness (e.g., Bright Futures and U.S. Preventive Services Task Forcerecommendations).
No approved medical treatments are available to remove PFAS from the body. Based on information fromboth a patient’s PFAS exposure history and the patient’s health history, clinicians can collaborate with patientsto develop individualized care plans.

Clinical Presentation
PFAS toxicity is not associated with characteristic signs or symptoms. Patients with concerns about PFAS
can present with a known exposure and be asymptomatic; they may have signs, symptoms, or a diagnosis of
a disease or health issue (e.g., high cholesterol); or they may live in a community with exposure concerns but
not know if they were exposed.

Exposure History
The goals of an exposure history are to• identify current and past PFAS exposures,• assess the duration, magnitude, and routes of exposure,• help patients understand how they have been exposed, and• determine if current exposures can be reduced.

A PFAS exposure history asks about the following:• Documented PFAS contamination in the home, workplace, or community.
• Water, dietary, and consumer product exposure from
9 contaminated drinking water (public water supplies or private well),
9 fish from contaminated water,
9 food wrapped or contained in grease-resistant paper or packaging, and
9 PFAS-containing consumer products (see “Exposure Sources and Routes”
section).
• Proximity to places that may manufacture, handle, or use PFAS, such as
9 farms where sewage sludge was
9 factories,
used for fertilizer,
9 airports,
9 military bases,
9 wastewater treatment plants,

9 landfills, and9 incinerators.

PFAS Information for Clinicians • 6

• Occupational or recreational exposures to
9 fluorochemical manufacturing processes,
9 firefighting foams,
9 ski wax, and9 other PFAS-containing materials.
• Past exposures.
• PFAS testing and results (e.g., drinking water or blood test results).
• Prenatal and infancy/childhood exposures including
9 transplacental exposures and9 breastmilk from a person exposed to PFAS or formula mixed with PFAS-contaminated water.
For any identified exposure, it is helpful to seek more detailed information about the route, dose,
duration, and frequency of the exposure.
For more information, see ATSDR’s educational materials on Taking an Exposure History.

Exposure Reduction
An exposure history can inform how to reduce exposure, which is a central goal with any toxic exposure. At
this time, it is not possible to eliminate all sources of PFAS exposure. With PFAS, the patient’s exposure might
have come from contaminated drinking water or from other sources in their diet, home, or workplace. Local
health departments may have information about area PFAS contamination concerns and can often provide
additional resources and risk reduction strategies.

Exposure Source
Drinking water

Example Exposure Reduction Strategies to Consider• Install a water filtration system or use a pitcher type filter shown to
reduce PFAS levels.*• Use an alternative water source tested for PFAS for drinking, foodpreparation (including infant formula), cooking, brushing teeth, or otheractivities that can result in ingestion of water.

Fish, meat, eggs, or dairy

Food from contaminated fields
or gardens
Dust in the home

Consumer products
Workplace• Test private well water. Consult local health or environmental agencies
for guidance on how to get a private well tested, how to interpret
results, and whether retesting is warranted. Consider installing a homewater treatment system if needed.
• Limit or avoid fish, meat, eggs, or dairy known to be contaminated with
PFAS. Use local health advisories and EPA's fish advisory list to guidechoices.
• Consume a wide variety of foods.
• For gardens, consider raised beds with alternate sources of soil andwater.
• Clean surfaces and floors frequently if soil around home iscontaminated or if household members have occupational exposure to
PFAS.
• When possible, choose products without PFAS (see “Exposure Routes
and Sources” section).
• Consult with an occupational and environmental medicine specialist.

PFAS Information for Clinicians • 7

* If monitored, maintained, and used properly, a water filter can reduce PFAS levels. How much PFAS are removed
by filtration is determined by the PFAS contaminant levels, the type of filter, and how well the filter is maintained.
The global public health organization NSF International has developed a test method to verify a water filter’sability to reduce PFOA and PFOS to below the health advisory levels set by the EPA or individual states. See NSF
International’s list of approved devices.

For additional steps to reduce exposure, see EPA’s Meaningful and Achievable Steps You Can Take to ReduceYour Risk.

PFAS Blood Testing
Systematic, community-wide blood testing can enable public health officials to investigate and respond tocommunity-wide exposures. Results from these tests can assess the types and blood levels of PFAS in thecommunity. (Blood PFAS is the accepted biomarker of exposure for PFAS studies, but some investigations
have also included urine testing.)
Clinicians can order PFAS blood levels through CLIA-certified*commercial clinical laboratories. Results (current levels of PFAS in the
blood) could reflect recent exposures or past exposures in the case of
PFAS with long half-lives.
In deciding whether to order PFAS testing, clinicians can consider• an individual’s exposure history,• results of PFAS testing from the patient’s water supply, foodsources, or other exposure routes, and• whether results can inform exposure reduction and healthpromotion.
Benefits of PFAS blood testing might include

ATSDR developed a PFAS
Blood Level Estimation Toolfor community members with
exposure to PFAS throughdrinking water—in particular,
for people who would likemore information about how
this exposure might affectblood PFAS levels. Estimatesfrom this tool might be helpfulwhen discussing potential
PFAS exposures with patients.

• information that could guide exposure reduction,• greater recognition of PFAS-associated health effects, and• possible psychological relief from knowing one’s PFAS blood level.
Limitations of PFAS blood testing include• PFAS blood test results do not identify sources of exposure,• only certain PFAS can be tested in blood and these PFAS might not represent the PFAS to which a patient
has been exposed,• results do not indicate whether a current illness can be attributed to PFAS exposure,• PFAS blood test results do not predict future health outcomes,• comparison of PFAS results across laboratories can be difficult (e.g., due to differences in assays used and
PFAS tested),• how long test results remain clinically meaningful is not known, and• neither the utility of repeat PFAS testing nor the optimum interval for testing is known.

* For quality assurance, Clinical Laboratory Improvement Amendments (CLIA) regulate laboratory testing and requireclinical laboratories to be certified by federal agencies before they can accept human samples

PFAS Information for Clinicians • 8

Clinical Management Based on PFAS Blood Levels
Patients and clinicians can discuss the potential risks and benefits of using PFAS blood testing results toguide clinical management. Considerations include• factors unique to the patient, including the patient’s risk for disease,• whether health screening beyond the usual standards of care is appropriate, and• the potential for unnecessary further testing and treatment related to false positives from additional
screening tests.
ATSDR has not developed health-based screening based on PFAS blood levels and encourages clinicians tofollow usual standards of care for health concerns.
For additional consideration, NASEM has proposed health screenings for patients exposed to PFAS basedon the sum of certain PFAS (MeFOSAA, PFHxS, PFDA, PFUnDA, PFOS, PFOA, and PFNA) levels.† Providers
who rely on NASEM thresholds for making decisions about further testing can consider that many people in
the U.S. will exceed NASEM’s proposed thresholds for additional screening. Application of suggested cutoff
levels based on PFAS blood testing could create changes in clinical care that differ from current preventive
care guidelines.

Pregnancy, Breastfeeding, and Children
Pregnancy – Exposure to PFAS can be associated with pregnancy-induced hypertension, preeclampsia,
and small decreases in birth weight. These conditions can occur in many pregnancies, independent of PFAS
exposure. Usual prenatal care, including monitoring a patient’s blood pressure closely, is appropriate.
Breastfeeding – PFAS can be found in human breast milk. Clinicians can assist patients in deciding
whether to breastfeed based on factors specific to the patient and the child. Due to the many benefits ofbreastfeeding, the Centers for Disease Control and Prevention (CDC) and American Academy of Pediatrics
recommend that most nursing people continue to breastfeed. More information on breastfeeding is available
at Breastfeeding: Why It Matters.
Children – Studies have reported that exposure to certain PFAS is associated with a slightly lower immune
response to some vaccines. The data do not suggest a need to reevaluate the usual immunization schedule(e.g., to repeat vaccinations).

† For additional consideration, NASEM has proposed using levels developed by the German Human Biomonitoring(HBM) Commission for PFOA and PFOS. The HBM Commission reviewed studies that did not include cancer as an
outcome. NASEM incorporated the European Food Safety Authority (EFSA) methodology that used the sum of PFOS,PFOA, PFHxS, and PFNA to define a risk level and added other PFAS measured by NHANES into the summation. For
patients with a sum of blood PFAS levels <2 ng/mL, NASEM recommends the usual standard of care. For blood PFAS
levels 2 to <20 ng/mL, they encourage exposure reduction and screening for dyslipidemia, hypertension in pregnancy,and breast cancer. For blood PFAS levels ≥20 ng/mL, they suggest adding the following tests at all well visits: thyroid
function testing with serum TSH for patients >18 years; an assessment for signs and symptoms of kidney cancer,
including urinalysis, for patients >45 years; and an assessment for signs and symptoms of testicular cancer andulcerative colitis in patients >15 years. NASEM estimated that for the U.S. population represented by NHANES in
2017–2018, 98% of people had PFAS levels ≥2 ng/mL; 9% had PFAS levels ≥20 ng/mL.

PFAS Information for Clinicians • 9Additional Expertise
For patients with PFAS exposure concerns, other professionals can help gather useful exposure information,
evaluate the patients, recommend exposure reduction methods, and develop a patient monitoring or
treatment plan. For example,• Board-certified clinicians specializing in occupational and environmental medicine, medical toxicology,
or pediatric environmental health can assist in evaluating and managing patients exposed or potentially
exposed to hazardous substances.
• Occupational health clinicians (often at work sites) have knowledge about workplace exposures andhealth issues and can provide context or guidance to workers and clinicians.
• State or local health/environmental departments have knowledge about documented environmental
contamination and associated health issues. They can help determine whether/how to assess health risks.
They can also assist with identifying water quality reports and how to get private wells tested.
ATSDR will continue to review the science and periodically update PFAS information for clinicians.

More Resources
Additional Information
ATSDR Toxicological Profile for PFAS
ATSDR PFAS and Your Health
ATSDR PFAS Blood Level Estimation Tool
ATSDR Minimal Risk Levels for PFAS
CDC’s Breastfeeding: Why it Matters
CDC National Report on Human Exposure to Environmental Chemicals
EPA’s Meaningful and Achievable Steps You Can Take to Reduce Your Risk
NASEM Guidance on PFAS Testing and Health Outcomes
National Institute for Occupational Safety and Health PFAS webpage
American Academy of Pediatrics’ Bright Futures in Clinical Practice
U.S. Preventive Services Task Force

Clinical Resources
American College of Medical Toxicology
American College of Occupational and Environmental Medicine
Pediatric Environmental Health Specialty Units

Abbreviations
AFFF

Aqueous film forming foam

ATSDR

Agency for Toxic Substances and Disease Registry

CDC

Centers for Disease Control and Prevention

CLIA

Clinical Laboratory Improvement Amendments

EFSA

European Food Safety Authority

PFAS Information for Clinicians • 10

EPA

U.S. Environmental Protection Agency

GenX[Not an abbreviation; this is a trade name for a type of PFAS]

HBM

Human Biomonitoring

MeFOSAA

2-(N-Methyl-perfluorooctane sulfonamido) acetic acid

NASEM

National Academies of Sciences, Engineering, and Medicine

NHANES

National Health and Nutrition Examination Survey

NIEHS

National Institute of Environmental Health Sciences

NIOSH

National Institute for Occupational Safety and Health

NSF

National Science Foundation

PFAS

Per- and polyfluoroalkyl substances

PFBS

Perfluorobutane sulfonic acid

PFDA

Perfluorodecanoic acid

PFHxS

Perfluorohexane sulfonic acid

PFNA

Perfluorononanoic acid

PFOA

Perfluorooctanoic acid

PFOS

Perfluorooctane sulfonic acid

PFUnDA

Perfluoroundecanoic acid

References[ATSDR] Agency for Toxic Substances and Disease Registry. 2021. Toxicological profile for perfluoroalkyls.
U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA [accessed 2023
May 4]. Available from: https://www.atsdr.cdc.gov/ToxProfiles/tp200.pdf[CDC] Centers for Disease Control and Prevention. 2023. National Report on Human Exposure to
Environmental Chemicals. Centers for Disease Control and Prevention, Atlanta, GA [accessed 2023 May 4].
Available from: https://www.cdc.gov/exposurereport/index.html[NASEM] National Academies of Sciences, Engineering, and Medicine. 2022. Guidance on PFAS Exposure,
Testing, and Clinical Follow-Up. Washington, DC: The National Academies Press. Available from:https://nap.nationalacademies.org/catalog/26156/guidance-on-pfas-exposure-testing-and-clinical-follow-up

PFAS Information for Clinicians • 11