EPA legal limit
No federal limit
Maximum Contaminant Level
EWG health guideline
0.5 ppt
Science-based, stricter target
Health effects
PFDA bioaccumulates primarily in the liver. Animal studies show liver toxicity, immune suppression, reproductive harm, and developmental effects. Its long biological half-life means exposure builds up over years. PFDA is associated with similar health outcomes to PFOA and PFOS at corresponding exposure levels.
Where it comes from
Legacy use in industrial processes similar to PFOA. Found near fluoropolymer manufacturing sites and in water contaminated by PFAS-containing firefighting foam. Less prevalent than PFOA and PFOS in drinking water but detected across multiple states.
How it's regulated
No federal EPA MCL. Not individually regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. EWG health guideline: 0.5 ppt, based on bioaccumulation potential and toxicity profile analogous to other long-chain PFAS.
How to filter pfda
Not all filters address pfda. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.
Frequently asked questions
What is pfda?
PFDA is a ten-carbon long-chain carboxylic acid PFAS. Like PFOA and PFOS, its long carbon chain causes it to bioaccumulate in living organisms. It is detected less widely than shorter-chain PFAS in drinking water (5.8 million people across 19 states in UCMR5) but is of elevated concern when detected due to its bioaccumulative properties.
What are the health effects of pfda?
PFDA bioaccumulates primarily in the liver. Animal studies show liver toxicity, immune suppression, reproductive harm, and developmental effects. Its long biological half-life means exposure builds up over years. PFDA is associated with similar health outcomes to PFOA and PFOS at corresponding exposure levels.
Is pfda regulated in drinking water?
No federal EPA MCL. Not individually regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. EWG health guideline: 0.5 ppt, based on bioaccumulation potential and toxicity profile analogous to other long-chain PFAS.
Where does pfda come from?
Legacy use in industrial processes similar to PFOA. Found near fluoropolymer manufacturing sites and in water contaminated by PFAS-containing firefighting foam. Less prevalent than PFOA and PFOS in drinking water but detected across multiple states.
How do I remove pfda from tap water?
The most effective methods for removing pfda are: Reverse osmosis (RO), NSF 58 certified RO system, Activated carbon block filter. Look for NSF-certified systems—independent certification confirms removal claims have been verified.
Is pfda in your water?
Enter your ZIP code to see the measured level in your specific utility.