Monitored — not federally regulated
NMeFOSAA
N-methyl perfluorooctane sulfonamido acetic acid
A PFOS precursor — it doesn't have an EPA limit of its own, but it converts to PFOS in the human body. Detection in drinking water indicates ongoing exposure to PFOS-related chemistry.
01Health effects
Linked outcomes
- · Liver toxicity
- · Elevated cholesterol
- · Immune effects
- · Developmental toxicity
Organs affected
Liver, immune system
Effects above are summarized from EPA, NIH/NTP, ATSDR, and IARC documentation. Not a clinical or medical claim — see our sourcing standards.
02Where it comes from
Metabolite of N-methyl PFOS-based compounds used historically in food packaging, carpet treatments, and 3M's Scotchgard products.
03Regulatory status
Not federally regulated. Transforms into PFOS in the body, so detection effectively contributes to PFOS exposure.
04What you can do
If NMeFOSAA was detected in your water supply, two filter technologies reliably remove it at the tap:
- RO (reverse osmosis) under-sink systems — 90–99.9% removal across all PFAS chain lengths. Look for NSF/ANSI 58 certification.
- GAC (granular activated carbon) block filters — effective for long-chain PFAS; less reliable for short-chain compounds. Look for NSF/ANSI 53 with NSF P473.
See our certified-filter picks or read the in-depth PFAS removal guide.
Related compounds
Other monitored compounds
- PFBS →
Perfluorobutane sulfonic acid
Introduced as a shorter-chain PFOS replacement after 3M phased out PFOS in 2002. The shorter chain clears the body faster but is harder to filter out of water.
- PFHxA →
Perfluorohexanoic acid
One of the most frequently detected PFAS in US drinking water and a common degradation product of fluorotelomer chemistry used in food packaging and stain protection. Its short chain length makes it especially hard to remove with activated carbon filters.
- PFBA →
Perfluorobutanoic acid
Very short half-life in the body (3–4 days) compared to PFOA (years), but still persistent in the environment. Often the final breakdown product when longer-chain PFAS degrade.
- PFDA →
Perfluorodecanoic acid
A long-chain PFAS with an estimated human half-life of 7–12 years — among the most persistent compounds in the body of any monitored PFAS. Frequently detected in human blood samples even decades after primary uses ended.