PFDA (Perfluorodecanoic Acid)

What is PFDA (Perfluorodecanoic Acid)?

PFDA (perfluorodecanoic acid) is a 10-carbon PFAS that clears slowly: published human half-life estimates run from 4.5 to 12 years.

PFDA is a perfluoroalkyl carboxylic acid with a 10-carbon chain, which makes it one of the longer members of the PFAS family. What PFAS are, and why they're called forever chemicals, is covered on the PFOA (Perfluorooctanoic Acid) page. On a lab report you'll see it as PFDA, perfluorodecanoic acid, or PFDeA, the abbreviation CDC's NHANES files use. It sits in a sequence with PFNA (Perfluorononanoic Acid) one carbon shorter and PFUnDA (Perfluoroundecanoic Acid) one carbon longer. Chain length matters here because ATSDR's 2021 toxicological profile notes that elimination slows as the chain gets longer. The half-life deserves precision. ATSDR's 2021 table lists a single human study for PFDA. Zhang and colleagues (2013) estimated a mean half-life of 12 years in 66 adults over 50 and 4.5 years in 20 women under 50, as tabulated in ATSDR's 2021 profile. The geometric means were 7.1 and 4.0 years, well below the means, which points to a few very long individual estimates. The estimates rest on urinary clearance, and New Jersey's environmental agency notes that counting fecal elimination would shorten them. So the fair range is 4.5 to 12 years, drawn from 86 people, and it doesn't describe any one person. Rats clear PFDA in roughly 3 to 8 weeks (552 to 1,406 hours in the ATSDR table), so animal data can't be carried over to people. The same Zhang study gave PFNA 4.3 and 2.5 years for the same two groups, and PFUnDA the same 12 and 4.5 years as PFDA. A half-life of years has one practical consequence: a blood value reflects what has accumulated, not what happened last week. Where PFDA comes from is less settled than the generic "nonstick pans and water" story suggests. EPA's final IRIS toxicological review (July 2024) says PFDA has been used in stain- and grease-proof coatings on food packaging, furniture, upholstery, and carpet, and also in nano-sprays, outdoor textiles, ski wax, and leather. It names ingestion of food and drinking water as routes, along with inhalation and skin contact. It singles out people who install and treat carpets and professional ski waxers as having higher occupational exposure from airborne dust. The review also cites a modeling study (Gebbink and colleagues, 2015) in which direct dietary intake of PFDA made up 51.3 percent of exposure in its intermediate scenario. That's a model, not a measurement of any person. EPA also cites a global emissions inventory (Wang and colleagues, 2014) that counts PFDA formed when other chemicals break down, so some of the PFDA in people comes from precursors, not from PFDA itself. PFDA was rarely the PFAS that stood out in water-contaminated communities. In ATSDR's exposure assessments at 10 U.S. communities with known PFAS drinking water contamination (final report September 22, 2022), blood PFDA was statistically elevated at only one site, New Castle, Delaware, at 1.4 times NHANES 2017 to 2018 levels. The report doesn't explain why. In the general U.S. population, PFDA is detected in most people. NHANES measured it in 1,711 of 1,929 people aged 12 and older in 2017 to 2018 (about 89 percent at or above the 0.10 ng/mL detection limit). When the pre-pandemic data through March 2020 were added, 2,479 of 3,072 were at or above the limit (about 81 percent). The geometric mean fell from 0.355 µg/L in 2005 to 2006 to 0.154 µg/L in 2015 to 2016, then rose to 0.193 µg/L in 2017 to 2018. The detection limit was 0.2 to 0.3 ng/mL through 2007 to 2008 and 0.1 ng/mL from 2009 to 2010 on, so compare cycles with care. Finally, PFDA is in the NASEM sum. The National Academies' 2022 guidance for clinicians counts seven PFAS together: MeFOSAA, PFHxS, PFOA, PFDA, PFUnDA, PFOS, and PFNA. The 2 and 20 ng/mL bands apply to that sum, so a PFDA value alone can't be placed in a band. The framework, and who it's written for, is explained on the PFOS (Perfluorooctane Sulfonate) page.

Typical reference context

These numbers describe a population, a guidance framework for a sum, and a dose. None of them is a reference interval for PFDA in your blood. No clinical reference interval exists for PFDA alone, so the lab report is the only source for the limits that apply to your result.

What changed recently

The biggest PFDA-specific development is regulatory science. EPA released a draft IRIS toxicological review of PFDA for public comment and external peer review in spring 2023 and finalized it in July 2024. EPA concluded the evidence indicates PFDA is likely to cause liver, immune, developmental, male reproductive, and female reproductive effects. The immune finding rests mainly on decreased antibody responses in children, and the developmental finding includes decreased birth weight in human studies. EPA found inadequate information to assess carcinogenic potential. These are hazard conclusions for a population assessment, not statements about any person's result.

Human studies that single out PFDA are thin. Eklund and colleagues (2025, Journal of Exposure Science & Environmental Epidemiology) followed 997 Swedish adults from age 70 to 80 and found PFDA positively associated with eGFR, a kidney filtration estimate, in longitudinal and cross-sectional models. The authors say the direction varied across PFAS, that the picture is incompletely understood, and that results in an older group may not generalize. Most other new PFDA-only work is animal or cell research. A 2025 zebrafish study in Environmental Science & Technology (Wang and colleagues) reported immune suppression and found PFDA more immunotoxic than PFBA, PFOA, and PFNA in that model, which says little about people.

On the policy side, PFDA isn't among the PFAS covered by EPA's April 2024 drinking water rule, and EPA's page, as of May 18, 2026, still treats it as outside the rule. A drinking water limit and a blood level are different measurements in any case.

Tests often checked alongside this

PFDA is rarely ordered alone. Labs usually report it in a PFAS panel next to its chain-length neighbors PFNA (Perfluorononanoic Acid) and PFUnDA (Perfluoroundecanoic Acid), and next to PFOS (Perfluorooctane Sulfonate) and PFOA (Perfluorooctanoic Acid). Some panels add a sum, which is where the NASEM seven come from. Liver and kidney tests come up in the research summarized below, from EPA's liver conclusion to the Swedish kidney study, but whether any test is ordered with a PFAS panel is your doctor's call.

What to keep with each result

Write down the lab's name, the collection date, the unit, and the reporting limit printed on the report. Labs report PFAS in ng/mL or µg/L, which are the same unit, and a result below the reporting limit prints as a "<" value or ND, a point the PFUnDA (Perfluoroundecanoic Acid) page explains. Reporting limits differ between labs and methods, so two PFDA results from different labs aren't automatically comparable. Longetic keeps each report you upload searchable with those details beside it, so you can see your own values over time as each lab printed them.

What to ask your doctor

• Was PFDA reported on its own or as part of a panel with a sum, and which PFAS does that sum include?
• What reporting limit and method did this lab use, and does that match the lab that ran my earlier results?
• What prompted this test, and does published guidance such as the NASEM framework apply to my situation?
• Should I note work or household history, such as carpet installation or ski waxing, in my record next to this result?

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