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. ▲▼ |
|---|---|---|---|---|---|
| PFOSPerfluorooctane sulfonic acid | Sulfonic acid | 66.1 | 0.47 | 0.11 | 1763-23-1 |
| PFNAPerfluorononanoic acid | Carboxylic acid | 16.2 | 0.47 | 0.084 | 375-95-1 |
| PFDAPerfluorodecanoic acid | Carboxylic acid | 6.9 | 0.47 | 0.093 | 335-76-2 |
| PFUnAPerfluoroundecanoic acid | Carboxylic acid | 2 | 0.47 | 0.086 | 2058-94-8 |
| PFHxSPerfluorohexane sulfonic acid | Sulfonic acid | 1.2 | 0.47 | 0.1 | 355-46-4 |
| PFOAPerfluorooctanoic acid | Carboxylic acid | 0.96 | 0.47 | 0.062 | 335-67-1 |
| PFDoAPerfluorododecanoic acid | Carboxylic acid | 0.62 | 0.47 | 0.074 | 307-55-1 |
| PFHpSPerfluoroheptane sulfonic acid | Sulfonic acid | 0.61 | 0.47 | 0.078 | 375-92-8 |
| PFTrDAPerfluorotridecanoic acid | Carboxylic acid | 0.51 | 0.47 | 0.12 | 72629-94-8 |
| PFHpAPerfluoroheptanoic acid | Carboxylic acid | 0.45J | 0.47 | 0.096 | 375-85-9 |
| PFBSPerfluorobutane sulfonic acid | Sulfonic acid | 0.43J | 0.47 | 0.055 | 375-73-5 |
| PFPeAPerfluoropentanoic acid | Carboxylic acid | 0.29J | 0.94 | 0.17 | 2706-90-3 |
| PFTeDAPerfluorotetradecanoic acid | Carboxylic acid | 0.27J | 0.47 | 0.071 | 376-06-7 |
| PFDSPerfluorodecane sulfonic acid | Sulfonic acid | 0.18J | 0.47 | 0.11 | 335-77-3 |
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 PFOS threshold for a "Do Not Eat" fish advisory (fillet), lowered six-fold from 300 µg/kg in 2025. 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 may 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) — and extending PFOA/PFOS compliance deadlines to 2031. The public comment period closed July 20, 2026, and the EPA is reviewing comments before final action.
This data is on the record
Before the docket closed, the Good Samaritan Institute submitted this watershed dataset as a formal public comment to Docket EPA-HQ-OW-2025-0654 — putting independent Choctawhatchee Bay evidence in front of the agency as it weighs whether to finalize the rescission. A virtual public hearing was held July 7, 2026; the EPA has not yet announced final action.
Read the filed comment (PDF)docket under EPA review
Verified EPA proposed rules, Federal Register, May 2026 (PFAS Rescission Rule, FR Doc. 2026-10085; PFOA/PFOS Compliance Extension Rule). Comment period closed July 20, 2026; status as of late August 2026 — no final rule announced. Confirm against the live federal docket.
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.
Questions people ask about this finding
Were PFAS found in Choctawhatchee Bay catfish?
Yes. An independent lab detected 14 PFAS "forever chemicals" in a composite liver sample pooled from 13 catfish collected at a Santa Rosa Beach stormwater outfall, led by PFOS at 66.1 µg/kg — about 68% of the 96.7 µg/kg total.
Does this mean the catfish are unsafe to eat?
Not directly. The sample is pooled catfish liver, which concentrates PFAS far more than the fillet people eat, so it is an early-warning bioindicator of contamination — not a fish-consumption advisory. Fillet-level testing is the logical next step.
What is a safe level of PFAS in fish?
There is no federal limit for PFAS in fish tissue. For fillet, Michigan issues a "Do Not Eat" advisory at 50 µg/kg PFOS (lowered from 300 in 2025), and the U.S. freshwater fillet median is about 9.5 µg/kg. Those are fillet figures and are not directly comparable to this liver result.
Who did the testing and what method was used?
Pace Analytical Services, a nationally accredited environmental lab, using the EPA's draft Method 1633 (isotope-dilution LC-MS/MS). The analysis is documented in Report of Analysis Lot ZD17009, completed May 21, 2024.
Where were the fish collected?
At the Mosquito Control Ditch #10 stormwater outfall (240 Osprey Ln, Santa Rosa Beach, FL), which drains to the Choctawhatchee Bay watershed. The site was chosen as a sampling location; no specific facility or party is identified as a source.
What happens next and how can I help?
The next steps are fillet-level testing and a source study. This dataset was submitted to the EPA's PFAS drinking-water rulemaking (Docket EPA-HQ-OW-2025-0654) before the comment period closed on July 20, 2026; the EPA is reviewing comments and has not announced final action. You can help by sharing the data and supporting follow-up fillet testing.
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. The federal comment window has closed and this data is on the record — now the work is sharing it, funding fillet-level testing, and tracing the source.