Microplastics & Chronic Disease – County Explorer

How predicted microplastic exposure connects with health, geography, and inequality across the U.S.

Scope: U.S. counties Unit: ecological Key caveat: not causal

This tool visualizes how wastewater, geography, and chronic disease data come together to show where microplastics may be more common – and what those patterns really mean. It’s not a toxicology study or risk calculator. Instead, it helps explore how infrastructure and inequality shape both exposure and health.

Wastewater + Geography + Population

Predicted Microplastics (µg/L)

Compare with Chronic Disease Rates

Microplastics & Health in the U.S. - what we can actually see

Microplastics are in headlines, bottles, and panic threads. National measurement is not. This project uses a transparent exposure proxy and real health data so you can explore the big picture yourself.

Scope: U.S. counties Unit: ecological Caution: not causal
How the numbers were built

What we measured

Why a proxy - there is no national grid of measured microplastic concentrations. We predict county exposure using variables that move microplastics through systems: wastewater design flow, treated population, treatment level, impervious cover, and distance to coast.

What the value means - Predicted microplastics is in µg/L equivalent. It is a model estimate trained where raster measurements existed, then applied to all counties.

Uncertainty - each county has a 95 percent prediction interval. We mark wide when the interval is large and OOR when inputs fall outside the training range. Treat those as provisional.

Units and definitions

  • Predicted microplastics - µg/L equivalent
  • Alzheimer’s mortality - crude deaths per 100k, mean 1999 to 2020
  • CHD, diabetes, asthma - crude prevalence percent
  • SES index - z-score mean of poverty, low education, unemployment
  • Design flow - wastewater capacity in million gallons per day
  • Distance to coast - km from county centroid

What the map shows

The color ramp shows the selected layer. Start with predicted microplastics. Click a county to open its profile with exposure, confidence, SES context, and disease metrics.

  • Legend uses quantiles for the current layer. Compare colors within a layer, not across different layers.
  • Low confidence can be faded and outlined with the toggle.
  • Compare line shows county vs state and U.S. medians.
Tiles and labels are visible under polygons so you can read real geography.
Search for a county or press Enter to jump to the first match.

What we found

  • Across counties, higher predicted exposure aligns with lower Alzheimer’s, CHD, diabetes, and asthma.
  • After adding socioeconomic structure, most exposure effects shrink. Alzheimer’s and CHD stay modestly negative.
  • The pattern is driven by where exposure is high - large coastal and urban systems with better care access and different age structure.
  • Geography and inequality dominate the map. The microplastics coefficient is mostly a shadow of those forces.

What this does not mean

Not proof that microplastics are safe. Not individual risk. Not a reason to ignore plastic pollution.

It means that in national county data, urbanization beats exposure as an explanation for differences we see.

How to think about it

Why geospatial nuance matters - counties bundle people together. States differ in reporting, demographics, climate, and care systems. Spatial autocorrelation means neighbors look alike. If you ignore those facts, you can read patterns as exposure effects when they are really geography.

What a better test would look like - individual level design with measured microplastic biomarkers, age-adjusted outcomes, smoking and PM2.5 controls, and spatial or multilevel modeling. Until then, treat predictive exposure surfaces as screening tools that guide where measurement would be most useful.

Future upgrades

  • Age-adjusted Alzheimer’s rates
  • PM2.5 and smoking
  • Within-state comparisons
  • Spatial lag or error models
  • External validation where microplastics are measured

Microplastics & Chronic Disease - County Explorer

Standalone viewer - double-click to open. No server required (internet needed for the basemap tiles).

Data sources

  • CDC PLACES Data Portal (2024). Chronic Disease Prevalence by County. Centers for Disease Control and Prevention.
  • CDC WONDER (1999 to 2020). Underlying Cause of Death: Alzheimer’s Disease (ICD-10 G30). Centers for Disease Control and Prevention.
  • U.S. Census Bureau (2023). American Community Survey 5-Year Estimates.
  • Alzheimer’s Association (2023). County-Level Prevalence Estimates of Alzheimer’s Dementia.
  • U.S. Environmental Protection Agency. (2023). Clean Watersheds Needs Survey (CWNS) Data Portal. https://www.epa.gov/cwns/clean-watersheds-needs-survey-cwns-database
  • United States Census Bureau. (2023). American Community Survey (ACS) 5-Year Estimates. https://data.census.gov
  • U.S. Centers for Disease Control and Prevention (CDC). (2024). PLACES: Local Data for Better Health, County Data 2024 Release. https://chronicdata.cdc.gov/500-Cities-Places/PLACES-County-Data-2024-Release/
  • U.S. Centers for Disease Control and Prevention (CDC). (2023). Underlying Cause of Death, 1999 to 2020 (ICD-10 G30: Alzheimer’s disease). https://wonder.cdc.gov/ucd-icd10.html
  • U.S. Environmental Protection Agency (EPA). (2024). Environmental Justice Screen (EJSCREEN) Dataset. https://www.epa.gov/ejscreen
  • U.S. Geological Survey (USGS). (2024). National Land Cover Database (NLCD) 2021 and 2024 Fractional Impervious Surface and Land Cover. https://www.usgs.gov/centers/eros/science/national-land-cover-database
  • Natural Earth. (2024). Coastline - 1:50m Vector Data. https://www.naturalearthdata.com/downloads/50m-physical-vectors/50m-coastline/
  • County Health Rankings & Roadmaps (CHR&R). (2024). Analytic Data 2023 to 2024. https://www.countyhealthrankings.org/
  • U.S. Environmental Protection Agency (EPA). (2022). Microplastics in Drinking Water: State of the Science and Future Research Needs. Report No. 830-R-22-001.
  • Rochman, C. M., et al. (2019). Policy: Classify plastic waste as hazardous. Science, 339(6230), 867 to 868.
  • Prata, J. C., et al. (2020). Environmental exposure to microplastics: an overview on possible human health effects. Science of the Total Environment, 702, 134455.

Built for DATA 467: Data Science Applications, University of Arizona. Instructor: Dr. Haverland. AI assistance by ChatGPT for integration and documentation. Citations and data provenance verified manually.