# PFAS in NHANES: What U.S. Blood Levels Show Over Time > Nearly everyone has detectable PFAS. Legacy compounds fell hard after phase-downs—replacements did not erase exposure. *Published 2026-07-10 · Updated 2026-07-10 · By Elena Voss* In short CDC **NHANES** has measured serum PFAS since 1999–2000: nearly all Americans have detectable levels. Legacy **PFOS fell >85%** and **PFOA >70%** by 2018–2019 after phase-downs. NASEM tiers (~98% ≥2 ng/mL; ~9% ≥20 ng/mL in 2017–2018) guide clinical follow-up intensity—not panic. PFAS debates need a population yardstick. NHANES supplies that yardstick: who has what in serum, how levels moved after industrial phase-downs, and how clinical guidance maps percentiles onto follow-up intensity. *This article is informational and editorial only. It is not medical advice, diagnosis, or a treatment plan. Numbers and literature ranges cited here are not personal prescriptions. Consult a qualified clinician before changing medications, supplements, diet, equipment, or management of a diagnosed condition. Seek urgent care for emergencies.* ## What does NHANES actually measure for PFAS? NHANES is a nationally representative biomonitoring program reporting serum PFAS in multi-year cycles, typically for ages 12 and older in many tables. Results live in CDC’s National Report on Human Exposure to Environmental Chemicals. Near-universal detection is the headline ATSDR fact. That means background exposure is systemic—water, food packaging, products, and legacy environmental reservoirs—not a rare occupational oddity. ## How did population levels change after phase-downs? Legacy long-chain compounds show steep declines: PFOS down more than 85 percent and PFOA more than 70 percent from 1999–2000 to 2018–2019. Those are among the clearest public-health success metrics in environmental chemistry. Success is incomplete. Replacement chemistries, contaminated sites, AFFF history, and consumer products keep PFAS relevant. Newer NHANES analytes can show high detection even as classic compounds fall. Key reference points MetricFigure / note NHANES PFAS start1999–2000 Near-universal detectionATSDR: nearly all U.S. PFOS change to 2018–19>85% decline PFOA change to 2018–19>70% decline ≥2 ng/mL (2017–18 map)~98% ≥20 ng/mL (2017–18 map)~9% ## How do NASEM tiers connect population data to clinics? NASEM 2022 guidance links serum sum categories to graded clinical evaluation. ATSDR’s clinician pages translate those tiers into practical prompts—more intensive assessment as levels climb, including cancer-oriented symptom checks in higher tiers for specified ages. The 98 percent and 9 percent population fractions above 2 and 20 ng/mL (2017–2018 mapping) explain why most people land in some follow-up band while only a minority hit the highest tier. ## What should individuals do with this information? Benchmark labs to NHANES, reduce high-leverage exposures (contaminated water filtration, product choices), and avoid equating detectability with imminent disease. Occupational and community hotspots deserve targeted investigation. Track updates as new NHANES cycles publish. Do not freeze 2010s numbers forever. Primary sources—ATSDR, CDC tables, NASEM—beat secondary social summaries. Sources: [ATSDR PFAS facts and stats](https://www.atsdr.cdc.gov/pfas/data-research/facts-stats/index.html); [CDC Exposure Report data tables](https://www.cdc.gov/exposurereport/data_tables.html); [NASEM 2022 PFAS clinical guidance](https://nap.nationalacademies.org/catalog/26156/guidance-on-pfas-exposure-testing-and-clinical-follow-up). Readers should dual-source primary literature, translate slogans into exposure units and effect sizes, and rank interventions by expected value under uncertainty. Cheap reversible steps often outrank extreme protocols. Opportunity cost is real: hours spent on unvalidated tests are hours not spent on sleep, training, protein adequacy, and primary care. Sex, life stage, comorbidities, medications, and geography change interpretation. Prefer falsifiable claims with named endpoints over multi-disease cure lists. Update beliefs when stronger trials appear rather than freezing identity around a single paper or influencer narrative. Measured curiosity beats both panic and complacency. Further reading should prioritize primary sources and consensus documents over secondary social summaries. When evidence is mixed, state both the signal and the limits in the same paragraph. When evidence is strong, still avoid overclaiming universality across populations. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. Context, dose, endpoint, and population must travel together; slogans that drop any of those four are not finished claims. ## Sources 1. [ATSDR PFAS facts and stats](https://www.atsdr.cdc.gov/pfas/data-research/facts-stats/index.html) 2. [CDC Exposure Report data tables](https://www.cdc.gov/exposurereport/data_tables.html) 3. [NASEM 2022 PFAS clinical guidance](https://nap.nationalacademies.org/catalog/26156/guidance-on-pfas-exposure-testing-and-clinical-follow-up) --- Source: https://healthcanon.com/environmental-health/pfas-nhanes-biomonitoring-levels Index: https://healthcanon.com/llms.txt · Full text: https://healthcanon.com/llms-full.txt