Student / Research Project

Estimating PFAS Contamination Risk in Freshwater Fish

This tool uses a predictive research model to estimate the possible risk of PFAS ("forever chemical") contamination in freshwater fish, based on location, elevation, date, and fish size. It is intended to support research and education around per- and polyfluoroalkyl substances (PFAS) in aquatic ecosystems.

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Disclaimer This tool is for research purposes only. It uses a predictive model that may have significant margins of error. It is not an official health advisory. Always refer to your local Department of Fish and Wildlife for official consumption guidelines.

Try the Predictor See How It Works

What This Project Does

PFAS are persistent synthetic chemicals that have been linked to industrial sites, airports, and military installations that historically used PFAS-containing firefighting foam (AFFF). These chemicals can enter waterways and bioaccumulate in fish over time. This project explores whether a simple set of location- and biology-based inputs can produce a useful, approximate risk estimate.

Scatter plot of PFAS data with a fitted upper-envelope curve of the form C/x — The fitted upper-envelope curve (purple), of the form C/x, plotted against the underlying sample data. The curve is set so that ~95% of points fall below it.

Full-range scatter plot of the underlying PFAS sample data — The same dataset shown across its full range, illustrating the rapid C/x-style decay that the upper-envelope model is fit to.

Left graph data: EPA, National Rivers and Streams Assessment 2018–19
Right graph data: EPA, 2022 National Lakes Assessment Fish Tissue Study
Military installation coordinates: US Military Bases (Kaggle, sourced from government data) and U.S. Bureau of Transportation Statistics

Run a Prediction

Enter the catch location, elevation, date, and fish length below. These values are passed into the getPFASUE() model described in the Methodology section.

Prediction Results

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Estimated PFAS Uptake Estimate (PFAS-UE) for this catch:

-- Risk

Estimated PFAS (ppb, 95% Upper Envelope)

Nearest Known Base

Fish Length Input

Model Inputs

Methodology

This site uses getPFASUE(), a 95th-percentile upper-envelope (quantile regression) formula. It is fit so that roughly 95% of actual sampled PFAS concentrations fall below the predicted curve — it estimates a statistical upper bound, not an average/expected concentration. It combines three inputs:

Proximity to Known Military Installations (D)

The site's latitude/longitude is compared against a reference list of ~750 U.S. military installation coordinates (military bases historically associated with PFAS-containing firefighting foam, AFFF). The distance in miles to the nearest installation is calculated using the haversine formula and used directly as an input to the formula.

Elevation (E)

Site elevation above sea level, in miles, is used directly as an input to the formula.

Fish Length (L)

PFAS is known to bioaccumulate over an organism's lifetime. Fish length is used here as a proxy for age/size and is passed directly into the formula.

All of this logic lives inside the getPFASUE() JavaScript function in the page source, clearly marked with comments. The catch date is still collected and the quantile constant (q) is still fixed at 0.95, but neither currently factors into the calculation in this version of the formula — that time-dependent term is commented out in the source rather than removed, in case it's reinstated later.

Limitations

This tool has significant limitations that anyone using it should understand.

Upper-bound estimate, not an average: This model predicts a 95th-percentile (upper envelope) value, meaning most actual measurements are expected to fall below the estimate, not near it. It should not be read as a typical/expected concentration.
Limited input variables: Real PFAS contamination depends on many additional factors not captured here, including local industrial activity, water chemistry, species-specific bioaccumulation rates, and site-specific hydrology.
Reference data limitations: The list of military installation coordinates is a static reference set and may not reflect every PFAS source, nor confirm that contamination actually occurred at any given site.
No ground-truth calibration: Outputs have not been cross-checked against state or federal fish consumption advisories.
Not a substitute for testing: Only laboratory analysis of actual fish tissue samples can determine real PFAS concentrations.
Not a health authority: This tool does not replace guidance from your state Department of Fish and Wildlife, Department of Health, or the EPA.