What are "forever chemicals," and why do they end up in fish?
PFAS — per- and polyfluoroalkyl substances — are a family of thousands of synthetic chemicals prized for repelling water, grease, and stains. The same near-indestructible bond that makes them useful means they essentially never break down in nature. They wash off products and out of industrial sites, travel through stormwater and groundwater, and accumulate as they move up the food chain.
They don't break down
The carbon–fluorine bond is one of the strongest in chemistry. PFAS persist in water, soil, and bodies for years to decades — hence the nickname "forever chemicals."
They build up in living things
Long-chain PFAS like PFOS bind to proteins in blood and the liver. Predatory fish concentrate them from water and prey — so a fish's tissue is a sensitive record of what's in the water.
They affect our health
Regulators link PFAS exposure to immune, liver, thyroid, developmental, and cancer effects. In 2023 the WHO's cancer agency classified PFOA as carcinogenic to humans.
Thirteen catfish. Fourteen forever chemicals.
In April 2024 the Good Samaritan Institute collected 13 catfish at the Mosquito Control Ditch #10 stormwater outfall (240 Osprey Ln, Santa Rosa Beach) and sent their combined livers — a single composite sample — to Pace Analytical, a nationally accredited lab. Using the EPA's draft Method 1633, the lab detected 14 distinct PFAS compounds. These are the headline numbers — every figure here is taken directly from the lab's Report of Analysis.
Read this honestly: liver, not fillet
This is a composite of catfish livers — the organ that concentrates PFAS far more than the fillet most people eat. Because the livers of 13 fish were pooled, the result reflects the local population, not a single outlier. That makes it a powerful early-warning bioindicator of contamination in the bay — but it is not a direct measure of what's on your dinner plate. The honest takeaway: PFAS are clearly present and accumulating in this watershed's food web, and fillet-level testing plus a source investigation are the logical next steps. We flag this caveat on every benchmark comparison below.
Explore every detection
Each bar is a PFAS compound the lab measured above its detection limit. Tap any bar for what the chemical is, where it comes from, and its exact reported value. PFOS so dominates that a log scale helps reveal the smaller, trace-level detections.
A profile dominated by PFOS
More than two-thirds of the total PFAS burden is a single legacy compound — PFOS — the most bioaccumulative member of the family and the one most commonly found in freshwater fish nationwide. Sulfonic-acid PFAS (PFSAs) make up about 71% of the total; carboxylic acids (PFCAs) account for the rest. This "PFOS-led" fingerprint is typical of older contamination from firefighting foam, metal plating, and stain-resistant treatments.
Every compound the lab screened
All PFAS analytes from the catfish-liver analysis — detections and non-detections alike. Sort any column, search by name, or filter to just the detections. Reporting Limit (RL) and Method Detection Limit (MDL) show how sensitive the test was for each compound.
| Compound ▼ | Class ▲▼ | Result ▲▼ | RL ▲▼ | MDL ▲▼ | CAS No. ▲▼ |
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How does this compare?
There is no federal limit for PFAS in fish tissue, but several states and national studies give us yardsticks. Here's where this sample's PFOS lands against them — with the essential reminder that those yardsticks are built on fillet/muscle data, while our sample is PFOS-concentrating liver.
PFOS in the catfish liver vs. fish-tissue reference points
Liver ≠ fillet — directional onlyMichigan "Do Not Eat" trigger
Michigan's 2024 PFOS threshold for a "Do Not Eat" fish advisory (fillet). Our liver value sits above it.
U.S. freshwater fillet median
Median total PFAS in 500+ U.S. freshwater fish fillets (2013–2015 EPA monitoring data, analyzed 2023).
Channel-catfish muscle (national)
PFOS in channel-catfish muscle in EPA's multi-species fish dataset — a like-species, fillet-basis reference point.
EPA drinking-water limit (PFOS)
The enforceable PFOS limit for drinking water, for scale. Water and fish-tissue units differ — this is context, not a tissue comparison.
Why we won't say "the catfish exceeds the Do-Not-Eat level"
Liver tissue routinely carries several times more PFAS than fillet from the same fish. A clean apples-to-apples comparison needs a fillet sample. What this liver result does establish is that PFAS are present and bioaccumulating in the watershed at levels that warrant follow-up fillet testing and a hunt for the source.
What PFAS exposure does to health
These are the health effects U.S. agencies (EPA, ATSDR) associate with the PFAS family at sufficient exposure. The catfish itself isn't the only concern — the same chemicals reach people through drinking water, other foods, and consumer products.
Heart & cholesterol
Linked to increased cholesterol and pregnancy-induced high blood pressure.
Liver damage
Associated with elevated liver enzymes and altered liver function.
Immune & thyroid
Reduced vaccine response in children; disrupted thyroid hormones.
Development & cancer
Lower birth weights; kidney and testicular cancer associations.
PFOA — Group 1
"Carcinogenic to humans" — the agency's highest certainty class. Detected here at 0.96 µg/kg.
PFOS — Group 2B
"Possibly carcinogenic to humans." It's the dominant compound in this sample at 66.1 µg/kg.
Verified Health associations per U.S. EPA and ATSDR toxicological profiles; cancer classifications per IARC Monographs Vol. 135 (Nov 2023). These describe the PFAS family and named compounds in general — not a clinical assessment of risk from this specific fish.
Two of the chemicals in this fish are about to lose federal protection
In May 2026 the EPA proposed rescinding drinking-water regulatory determinations for several PFAS — including PFNA and PFHxS, both detected in this catfish (PFNA is the second-highest result here). The public comment window is open now.
Public comment is open until July 20, 2026
The EPA is also proposing to extend PFOA/PFOS compliance deadlines to 2031. For a coastal special district working on stormwater and source-water protection, this is the moment to put watershed evidence — like this analysis — on the record. A virtual public hearing is set for July 7, 2026.
Verified EPA proposed rules, Federal Register, May 2026 (PFAS Rescission Rule; PFOA/PFOS Compliance Extension Rule). Status as of late June 2026 — confirm current docket dates before filing.
How the test was done
Credible numbers depend on a credible chain of custody. Here's exactly how the sample was collected, analyzed, and quality-checked — drawn from the lab's full Report of Analysis, which you can download below.
Sample & method
The fish were taken at a stormwater outfall — Mosquito Control Ditch #10 — which channels runoff into the watershed. That makes the site a logical place to look for a PFAS source. EPA Method 1633 is the agency's draft single-laboratory–validated procedure for 40 PFAS in water, soil, biosolids, and tissue, using isotope-dilution liquid chromatography–tandem mass spectrometry — the current gold standard for PFAS quantitation.
Laboratory & accreditation
Pace Analytical Services, LLC — a nationally accredited environmental laboratory network. Sample preparation (grinding) was performed at Pace's Green Bay, WI facility; PFAS analysis at Pace's Minneapolis, MN laboratory. The receiving lab (Pace West Columbia, SC, formerly Shealy Environmental) holds Florida certification #E87605/E87653.
Accreditation includes TNI/NELAP, DoD ELAP (A2LA #2926.01), ISO/IEC 17025, and a Federal Fish & Wildlife permit for biological-tissue handling — the credentials that make the results defensible in a regulatory setting.
Quality control — did the numbers hold up?
Method blanks were clean for every key detection (PFOS, PFNA, PFDA and the rest read below their reporting limits in the blank) — so the compounds found in the fish came from the fish, not the lab. Samples were analyzed within method hold times, and isotope-labeled surrogates were carried through to track recovery.
A few quality flags appear in the report and are disclosed here for transparency: some fluorotelomer-sulfonate surrogates fell outside control limits (S0), and two analytes that were not detected had control-sample recoveries outside limits (L1/L2). None of these affect the primary PFOS/PFNA/PFDA detections that drive this story.
Read the source — and the science
Everything on this page traces back to the primary lab report. Download the full 31-page Report of Analysis, and follow the references behind every benchmark and health claim.
Full Report of Analysis
The complete, unaltered Pace Analytical report — case narrative, certifications, full analytical results, quality-control data, and chain of custody.
Download the PDFPrimary sources
Clean water is a community project.
The Good Samaritan Institute commissioned this analysis to put real watershed data in front of the people and agencies who can act on it. Share it, test further, and add your voice while the federal comment window is open.