PFOA (Perfluorooctanoic Acid)

What is PFOA (Perfluorooctanoic Acid)?

PFOA (perfluorooctanoic acid) is a man-made PFAS "forever chemical" that labs measure in blood serum, usually in ng/mL.

PFAS are a large group of synthetic chemicals. EPA says there are thousands of them, used in nonstick coatings, stain-resistant fabrics and carpets, grease-resistant food packaging, and firefighting foam (EPA, updated September 2026; ATSDR, July 2025). The "forever" label comes from chemistry. NIEHS notes that the carbon-fluorine bond is one of the strongest, so these chemicals don't degrade easily (NIEHS, March 2026). PFOA is the best studied member of the family, and the other nine PFAS pages in this glossary start from the same basics, so this page owns them once. Labs measure PFOA in serum, the liquid part of blood. CDC says that measuring PFAS in serum lets scientists estimate how much has entered people's bodies, and that a measurable amount "does not imply that the levels of PFAS cause an adverse health effect" (CDC, 2017, foundational). PFOA leaves slowly. In 26 retired fluorochemical workers, the mean serum half-life was 3.8 years (95% CI 3.1 to 4.4) (Olsen et al., 2007). Among 106 people in Ronneby, Sweden, after their contaminated drinking water was replaced, the median was 2.7 years (95% CI 2.5 to 2.9) (Li et al., 2018). So one result is a snapshot of a number that moves over years, not days. People take in PFOA mostly by mouth. IARC's Q&A says the general population is exposed mainly through food and drinking water, and possibly through consumer products. Workers are thought to breathe it in, and at contaminated sites drinking water is the main source. ATSDR adds that food packaging such as popcorn bags, fast-food containers, and pizza boxes may contribute, and that in communities with contaminated water, the water can be the main source (ATSDR, November 2024). Levels in the US population have fallen. The standardized geometric mean serum PFOA in NHANES dropped from 4.5 ng/mL in 1999-2000 to 1.4 ng/mL in 2017-2018 (Pan et al., 2024). ATSDR credits the decline in part to EPA enlisting major manufacturers to phase out production. The PFOS (Perfluorooctane Sulfonate) page covers the 3M phase-out and the NASEM clinical guidance. In November 2023, an IARC working group (meeting of 7 to 14 November, published in The Lancet Oncology on November 30, 2023) classified PFOA as carcinogenic to humans (Group 1). The basis was limited evidence in humans for renal cell carcinoma and testicular cancer, sufficient evidence in experimental animals, and strong mechanistic evidence. PFOS went into Group 2B, possibly carcinogenic. Read the label for what it is. IARC states that its classification "indicates the strength of the evidence that a substance or agent can cause cancer" and "does not indicate the level of cancer risk associated with exposure at different levels or in different scenarios." It says nothing about any one person's number. EPA's April 2024 toxicity assessment likewise describes PFOA as "likely to be carcinogenic to humans via the oral route of exposure." The EPA drinking-water rule is a separate matter. On April 10, 2024, EPA announced a National Primary Drinking Water Regulation with an enforceable limit (MCL) of 4.0 parts per trillion (ng/L) for PFOA and a non-enforceable health-based goal (MCLG) of zero. It applies to public water systems. As of October 2026 the 2024 rule remains in effect. In May 2026 EPA proposed to keep the 4.0 ng/L limits for PFOA and PFOS while letting qualifying systems request an extension of the compliance date from April 26, 2029 to April 26, 2031, and to rescind the limits for PFHxS, PFNA, HFPO-DA, and the Hazard Index. Comments closed July 20, 2026, and neither proposal was final in the sources available. The D.C. Circuit denied EPA's request to vacate part of the rule without full review, heard argument in American Water Works Association v. EPA on September 18, 2026, and had not issued a decision in the coverage available at the time of writing. A water limit and a blood level are different things. The limit is a number about water, in ng/L. Your report prints a serum number, usually in ng/mL, which is a unit 1,000 times larger, and no published conversion turns one into the other. ATSDR's clinician page says it has not developed health-based screening based on PFAS blood levels. The best-known human data on PFOA come from the Mid-Ohio Valley near DuPont's Parkersburg, West Virginia, plant. In a class-action case settled in 2005, the C8 Science Panel, three epidemiologists working from 2004 to 2012, drew on data from about 69,000 exposed residents. In 2012 the panel reported "probable links" between PFOA and six conditions: kidney cancer, testicular cancer, pregnancy-induced hypertension, thyroid disease, high cholesterol, and ulcerative colitis. Its wording matters: a probable link means that, "based upon the weight of the available scientific evidence, it is more likely than not that there is a link between exposure to PFOA and a particular Human Disease" (as quoted by Steenland et al., 2020). It is a finding about a studied community, not a statement about you. A 2020 review found the evidence "supportive but not definitive" for kidney and testicular cancers, consistent for cholesterol, and weaker for thyroid disease. A 2025 review argues the kidney cancer and thyroid links are not supported by later studies. If a PFOA result sits in your records, Longetic keeps it with the date, the units, and the lab's own notes. What it means for you is a conversation for your doctor.

Typical reference context

There is no clinical reference interval for PFOA in serum. The numbers above come from different bodies, matrices, and purposes. The NHANES figures describe how values were distributed across Americans, and a population distribution is not a health threshold. For clinician guidance on PFAS blood results, which works from a sum of seven PFAS rather than PFOA alone, see PFOS (Perfluorooctane Sulfonate).

What changed recently

November 2023: IARC Monographs Volume 135 classified PFOA as Group 1 and PFOS as Group 2B.

April 2024: EPA announced the PFAS drinking-water rule (PFOA MCL 4.0 ng/L) and finalized its PFOA toxicity assessment, which describes PFOA as likely to be carcinogenic to humans by the oral route. In May 2024 EPA also designated PFOA and PFOS as hazardous substances under the federal Superfund law (CERCLA). On August 18, 2026, the D.C. Circuit upheld that designation in Chamber of Commerce v. EPA.

2025 to 2026: On May 14, 2025, EPA said it would keep the PFOA and PFOS limits, push their compliance date to 2031, and rescind four others. On January 12, 2026, the D.C. Circuit denied EPA's request to summarily vacate four of the six limits. EPA published the two proposed rules on May 20, 2026. Oral argument on the 2024 rule took place September 18, 2026. As of October 2026, all provisions of the 2024 rule remain in effect.

August 2026: CDC first published NHANES 2021-2023 PFAS laboratory data, which includes linear and branched PFOA for 2,551 participants. Summary statistics weren't available in the sources reviewed for this page.

Tests often checked alongside this

PFOA is usually reported in a PFAS panel with the other family members, and your report may list linear, branched, and total forms separately, as NHANES does. See PFOS (Perfluorooctane Sulfonate), PFHxS (Perfluorohexane Sulfonate), PFNA (Perfluorononanoic Acid), PFDA (Perfluorodecanoic Acid), PFUnDA (Perfluoroundecanoic Acid), PFHpA (Perfluoroheptanoic Acid), PFBS (Perfluorobutane Sulfonate), Me-PFOSA-AcOH, and Et-PFOSA-AcOH for what each one owns. Your doctor may also order routine tests such as a lipid panel or kidney and liver tests for their own reasons. None of them is a PFOA test.

What can affect this marker

Where you live and work shape the exposure that sits behind a result. Published sources name food and drinking water as the main routes for the general population, packaging and consumer products as possible contributors, inhalation for some workers such as those in chemical manufacturing or firefighting, and drinking water as the main source near contaminated sites (IARC, December 2023; ATSDR, November 2024; EPA, July 2026). Time matters too. With a half-life measured in years, a result reflects slow processes, and the same person's number can look different from one draw to the next without any change in what they did that week. Labs also differ in method and detection limit, so compare values only with their units and notes in view.

What to ask your doctor

• Why was this PFAS panel ordered for me, and how will you use the result?
• Which PFAS does the panel include, and does the PFOA figure combine linear and branched forms?
• Would my water utility's own PFAS report be useful to bring to this conversation?
• ATSDR says PFAS blood results don't predict future health problems. What would follow-up look like under the guidance you use?

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