How Biomonitoring Reveals Chemical Risks and Protects Public Health
Every day, our bodies silently collect evidence. With each breath of air, sip of water, or bite of food, we encounter thousands of chemicals—some beneficial, some benign, and some potentially harmful.
How do scientists measure our exposure to these environmental chemicals and determine what levels might pose health risks? Enter the world of biomonitoring, a sophisticated scientific approach that analyzes our blood, urine, or tissues to measure chemical exposures directly within the human body.
Unlike environmental monitoring that tests air, water, or soil samples, biomonitoring provides the ultimate exposure metric—it reveals what actually enters our bodies through all routes and sources combined. As we navigate an increasingly chemical-reliant world with over 450,000 synthetic substances in use, biomonitoring has become an indispensable tool for protecting public health. Yet as this article reveals, transforming chemical measurements from our bodies into meaningful health protections involves extraordinary scientific detective work and innovative approaches to risk assessment 1 6 .
Biomonitoring can detect chemicals at concentrations as low as one drop in 20 Olympic-sized swimming pools.
Biomonitoring involves measuring environmental chemicals—whether the original compounds, their breakdown products (metabolites), or the molecular changes they cause—in human tissues and fluids. The most common samples come from blood and urine, though researchers also use human milk, hair, saliva, or even teeth in specialized studies. These measurements are called biomarkers of exposure1 4 .
Countries worldwide have established large-scale biomonitoring programs to track population exposures:
CDC's National Health and Nutrition Examination Survey (NHANES) - the gold standard since 1999
Canadian Health Measures Survey (CHMS) operating since 2007
HBM4EU initiative (2017-2022) and the upcoming European Biomonitoring Framework
This represents biomonitoring's greatest hurdle: What do these measurements mean for health? As one study bluntly stated: "The presence of a substance in the body does not necessarily mean that it is causing harm. In addition, absence of a substance... does not necessarily mean the individual was not exposed" 4 .
A 2022 review examining 126 studies found biomonitoring data interpretation for risk assessment remains inconsistent and often lacks critical elements needed for sound conclusions 3 .
Scientists have developed sophisticated methods to bridge the gap between biomonitoring data and health risk assessment:
| Method | How It Works | When Used | Example |
|---|---|---|---|
| Direct Comparison | Compares measured concentrations directly to health-based levels | When biomarker-health effect links are established | Blood lead levels vs. CDC reference value (3.5 μg/dL) |
| Reverse Dosimetry | Back-calculates external exposure from biomarker levels using toxicokinetic models | When source identification is needed | Triclosan risk assessment in Canada |
| Forward Dosimetry | Compares biomonitoring data to Biomonitoring Equivalents (BEs) derived from health guidance values | For widespread chemicals with established TDIs/RfDs | Selenium, silver, and zinc assessments in Canada |
These are concentrations of a chemical or metabolite in blood or urine that correspond to established health guidance values like Reference Doses (RfD) or Tolerable Daily Intakes (TDI).
Michigan has emerged as a living laboratory for biomonitoring application following widespread PFAS water contamination. The Michigan PFAS Exposure and Health Study (MiPEHS) exemplifies rigorous design:
Recruited adults and children from high-exposure zones (Parchment/Cooper Township, Rockford/Belmont) and low-exposure controls
Blood samples analyzed for 7 PFAS compounds; urine for other chemicals
Thyroid function, kidney markers, lipid profiles, vaccine response
Historical exposure modeling combined with current biomonitoring
Detailed questionnaires on diet, occupations, consumer products 5
| PFAS Compound | Parchment/Cooper Median (μg/L) | Rockford/Belmont Median (μg/L) | Control Median (μg/L) |
|---|---|---|---|
| PFOS | 9.8 | 7.2 | 4.9 |
| PFOA | 5.1 | 12.6 | 2.3 |
| PFHxS | 3.3 | 2.9 | 1.4 |
| PFNA | 0.8 | 1.1 | 0.5 |
Source: Michigan PFAS Exposure & Health Study (2023) 5
Confirmed drinking water as major exposure source
North Kent County Exposure Assessment found serum PFAS levels dropped 20-40% after water filtration installation
Revealed complex exposure patterns
Different communities showed distinct PFAS profiles reflecting contamination sources
Discovered immune impacts
PEAR study linked higher exposures to reduced COVID-19 vaccine response
Informed policy interventions
Data directly supported Michigan's PFAS drinking water standards (8-16 ppt for key compounds) 5
Modern biomonitoring relies on specialized "reagent solutions"—both technical and methodological:
| Tool Category | Key Solutions | Function | Innovation |
|---|---|---|---|
| Analytical | Isotope-Dilution Mass Spectrometry | Detects trace-level chemicals with high precision | Measures >500 chemicals at parts-per-trillion levels |
| Data Interpretation | Physiologically Based Toxicokinetic (PBTK) Models | Predict chemical distribution in tissues | Enables reverse dosimetry for exposure reconstruction |
| Guidance Values | Biomonitoring Equivalents (BEs) | Translates health guidance values (RfD, TDI) into biomarker concentrations | Standardized via (HB)²GV Dashboard |
| Study Design | Minimum Information Requirements (MIR-HBM) Guidelines | Ensures data quality and comparability | Harmonizes global studies via HBM Global Network |
| Mixture Methods | Relative Potency Factors | Assesses combined effects of chemical mixtures | Used in EU's PARC project for PFAS mixtures |
Biomonitoring science continues to evolve through key innovations:
Biomonitoring has transformed from a specialized occupational tool into the cornerstone of modern exposure science.
As programs expand globally—from Canada's Indigenous biomonitoring initiatives to the EU's PARC project—they generate increasingly sophisticated data to protect public health. The power of this approach is undeniable: when lead was removed from gasoline, blood lead levels in Canadians dropped over 70%—a decline precisely tracked through biomonitoring 4 .
Yet the ultimate promise of biomonitoring lies not just in measuring exposures but in preventing harm. By identifying highly exposed communities like Oscoda, Michigan firefighters, or pregnant individuals, interventions can be precisely targeted. By establishing Biomonitoring Equivalents, regulators worldwide gain health-based benchmarks. And by revealing unexpected exposures—like the ubiquity of certain phthalates—manufacturing practices can be reformed.
"Biomonitoring holds up a mirror to our chemical environment—and ourselves."
In that reflection, we see not only our exposures but the opportunity to build a healthier relationship with the chemical landscape we inhabit. The silent evidence in our blood, when interpreted wisely, speaks volumes about how to achieve that future.
Demonstrated effectiveness in tracking exposure reductions