Every primary source we cite, federal rules, the federal register, peer-reviewed toxicology, standards documents, state regulations. Organised by topic; deep-linked to the official publication wherever possible.
Finalised April 10, 2024; published 89 Fed. Reg. 32532 (April 26, 2024). First federally-enforceable Maximum Contaminant Levels for six PFAS: PFOA, PFOS, PFHxS, PFNA, HFPO-DA (GenX), and a Hazard Index for the mixture. Initial monitoring required by 2027; MCL compliance by 2029.
The standing UCMR authority. UCMR 5 was promulgated under this section, published at 87 Fed. Reg. 80415 (December 27, 2022). Covers 29 PFAS analytes plus lithium for every PWS serving ≥3,300 people. Sampling 2023–2025.
Updated lifetime drinking-water health advisories: PFOA 0.004 ng/L, PFOS 0.02 ng/L. Both were below the analytical detection limit of EPA Method 537.1; both were withdrawn when the 2024 MCLs were finalised. Cited for historical context only.
"Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry." Covers 18 long-chain PFAS including PFOA, PFOS, PFNA, PFHxS, HFPO-DA. The reference method for UCMR 5 and for finished-water compliance under the 2024 MCL.
"Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry." Companion to 537.1; adds ∼25 short-chain PFAS (PFBA, PFBS, etc.). A complete drinking-water PFAS test runs both methods.
Agency for Toxic Substances and Disease Registry. Authoritative review of human and animal toxicology for PFOA, PFOS, PFNA, PFHxS, and related compounds. Documents serum half-lives (PFOA ∼3.8 yr, PFOS ∼5.4 yr), placental transfer, lactational transfer, and the epidemiological associations with low birth weight, immune response, ulcerative colitis, kidney and testicular cancer.
EFSA Journal 2020;18(9):6223. Sets a Tolerable Weekly Intake of 4.4 ng/kg body weight per week for the sum of PFOA + PFOS + PFNA + PFHxS. Critical effect: reduced antibody response to childhood vaccination at age 1 (Faroe Islands cohort).
International Agency for Research on Cancer. PFOA classified Group 2B ("possibly carcinogenic to humans").
IARC re-evaluation. PFOA reclassified Group 1 ("carcinogenic to humans"). PFOS classified Group 2B for the first time. The most recent authoritative cancer classification for these compounds.
Steenland, Fletcher, Savitz. Six "Probable Link" reports for PFOA: kidney cancer, testicular cancer, ulcerative colitis, thyroid disease, pregnancy-induced hypertension, and hypercholesterolaemia. Settlement-funded independent science panel for the Leach v. DuPont class action.
The public-facing portal for UCMR 5 results. Quarterly summary publications and bulk-data downloads.
Smalling, K.L., et al. (2023). "Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications." Environment International 178, 108033. Found measurable PFAS in ∼45% of tap-water samples nationwide.
Environmental Working Group. Compiled from state DEP data, UCMR sampling, and DoD AFFF site inventory. Used for cross-referencing hotspot context in the brief; not used as a primary measurement source.
Standard covering point-of-use filters certified for health-effects contaminant reduction. The P473 protocol within NSF 53 is the specific test for PFOA and PFOS reduction.
Standard covering RO systems for residential point-of-use. The PFOA/PFOS reduction claim under standard 58 is the certification to require for RO units.
Michigan PFAS MCLs: PFNA 6 ng/L, PFOA 8 ng/L, PFOS 16 ng/L, PFHxS 51 ng/L, PFHxA 400,000 ng/L, GenX/HFPO-DA 370 ng/L, PFBS 420 ng/L.
PFNA 13 ng/L (adopted September 2018, first state-level enforceable PFAS MCL in the US), PFOA 14 ng/L and PFOS 13 ng/L (adopted June 2020).
PFOA 12 ng/L, PFOS 15 ng/L, PFHxS 18 ng/L, PFNA 11 ng/L.
The DuPont Washington Works class action that established the C8 Health Project and the C8 Science Panel through its 2005 settlement.
Bladen County Superior Court 17-CVS-580. Governs Chemours Fayetteville Works HFPO-DA (GenX) remediation across the Cape Fear River basin.
Every threshold cited on this site, every number in every brief, and every claim in every guide traces back to a publication on this list. If you find a citation we missed or an outdated reference, please email hello@howsafeismywater.com, corrections are logged publicly in our corrections log.
