Microplastic Ingestion Risk Calculator

This tool treats dietary microplastic exposure as an additive burden: every intake pathway carries a published mean particle concentration, and the daily total is the sum of servings or liters multiplied by that concentration. The coefficients used here are roughly 94 particles per liter of bottled water against 5.5 per liter of treated tap water, about 90 particles per shellfish serving, 15 per finfish serving, and 0.6 particles per gram of sea salt. Bivalves dominate because they are filter feeders eaten whole with the digestive tract intact, whereas a filleted fish delivers muscle tissue where far fewer particles lodge. Microplastic is conventionally any plastic fragment below 5 mm across; anything under 1 micrometer is classed separately as nanoplastic. The practical caveat is that particle counts are not doses. Detection floors govern the numbers: most published surveys identify particles by infrared or Raman spectroscopy with practical limits near 20 to 50 micrometers, so the smallest and most biologically mobile fragments are systematically missed. The annual mass figure here assumes about 15 micrograms per particle, an average that collapses an enormously skewed size distribution into one number. The weekly bands of 500, 1000 and 2000 particles are ordering heuristics for comparing personal habits, not regulatory limits. No health-based guidance value for microplastic intake exists in any jurisdiction, and the 2019 World Health Organization assessment concluded the evidence base was too thin to set one.

The word microplastics entered the scientific literature in 2004, when Richard Thompson and colleagues at the University of Plymouth published Lost at Sea: Where Is All the Plastic? in Science, showing accumulating fragments in United Kingdom sediments and in archived Continuous Plankton Recorder samples reaching back to the 1960s. A 2008 workshop convened by the United States National Oceanic and Atmospheric Administration in Tacoma, Washington settled on the 5 mm upper bound that the field still uses. For roughly a decade the research question was environmental contamination rather than human intake. Attention shifted to ingestion after 2017. Surveys of tap water and then of bottled water, including a 2018 study led by Sherri Mason at the State University of New York at Fredonia covering 259 bottles from 11 brands, reported plastic particles in the large majority of samples and established the bottled-versus-tap gap this calculator encodes. A 2019 report commissioned by WWF from the University of Newcastle popularized the widely quoted figure of about 5 grams of plastic a week, and a 2019 paper by Kieran Cox and coauthors in Environmental Science and Technology summed food categories to 39,000 to 52,000 particles a year, or 74,000 to 121,000 once inhalation was included. Detection has kept improving: a 2024 study from Columbia University using stimulated Raman scattering microscopy reported nanoplastic counts in bottled water orders of magnitude above earlier estimates, a reminder that these numbers track method sensitivity as much as exposure.