Microplastics in Food: How They Get There and How to Minimize Exposure

A credit card's worth of plastic every week -- how microplastics ended up in your groceries

Plastic production barely existed before 1950. That year, global output sat at roughly 2 million tonnes. By 2015, that number had exploded to 380 million tonnes annually, and of all the plastic ever manufactured, only about 9% has been recycled. The rest sits in landfills, floats in oceans, or breaks apart into fragments smaller than a sesame seed.

Those fragments are microplastics -- plastic particles under 5 millimeters. Some are manufactured small on purpose (the microbeads that used to be common in face scrubs, for instance). Most form when larger plastic objects splinter under sunlight, waves, and wind. A plastic bag in the ocean does not disappear. It erodes, the same way rock does, except faster -- breaking into millions of invisible pieces that persist for centuries.

About 8 million tonnes of plastic enter the oceans annually, and 40% of all plastic produced goes toward packaging -- the wraps, bottles, trays, and containers that touch our food every day. That packaging does not stay inert. It sheds. And what it sheds ends up in what we eat.

Estimates of how much plastic Americans consume vary widely. One analysis based on 15% of the average American caloric intake put it at 39,000 to 52,000 microplastic particles per year from food, water, and air combined. Other researchers have calculated the number much higher -- up to 1.5 million particles per day, depending on diet and methodology. The discrepancy matters because it reveals how little standardization exists in microplastic measurement. Different labs use different filters, different size cutoffs, and different counting techniques. The number is not zero, and given rising plastic production, it is probably increasing.

Your salt, your water bottle, and your tap -- three routes you use daily

If you had to rank the foods most consistently contaminated with microplastics, salt and water would be near the top. Not because they are uniquely vulnerable, but because we consume them in such quantity that even low contamination per serving adds up fast.

Sea salt and table salt

A study published in Scientific Reports examined 17 salt brands from 8 countries across 4 continents. Microplastics turned up in 16 of the 17 brands, at concentrations ranging from 1 to 10 particles per kilogram. The most common polymers were polypropylene (40%) and polyethylene (33.3%) -- the same plastics used in food containers and grocery bags.

Chinese researchers found even higher numbers: 550 to 681 particles per kilogram in sea salt, with lake salt at 43 to 364 and rock salt at 7 to 204. A separate global analysis by Kwon et al. reported 5,400 particles per kilogram in table salt. These numbers spread across a wide range because detection methods differ -- the Nature study only captured particles larger than 149 micrometers, while newer techniques catch much smaller fragments.

One finding runs counter to intuition: terrestrial salts like Himalayan salt tend to have higher contamination than marine salts. The contamination comes not just from the water source but from processing, grinding, and packaging. A disposable plastic spice grinder can release up to 7,628 particles when grinding just 0.1 grams of salt. The grinder itself becomes the biggest contamination source.

Bottled water

Mason et al. tested 259 bottled water samples from around the world and found an average of 325 particles per liter when counting particles down to 6.5 micrometers. A German study found that returnable plastic bottles contained 118 particles per liter -- roughly 8 times more than disposable bottles, likely from repeated mechanical stress on the plastic during washing and refilling.

When researchers at Columbia University used newer detection methods capable of identifying nanoplastics (particles smaller than 1 micrometer), the numbers jumped dramatically. One study found an average of 240,000 plastic particles per liter of bottled water, with 90% being nanoplastics invisible to older detection methods. Each twist of a plastic bottle cap can produce up to 500 additional microplastic particles from abrasion alone.

Tap water

Tap water contains microplastics too, though generally at lower concentrations. A Hong Kong study measured 2.181 particles per liter in tap water -- substantially less than bottled water. Several scientific reviews have confirmed that people consume more microplastics from bottled water in single-use plastic bottles than from tap water. Filtered tap water in a non-plastic container cuts this exposure route substantially.

Every time you open a package, the package opens back

Salt and water get the headlines, but food packaging may be the more significant daily source of microplastic exposure. Lisa Zimmermann and her team at the Food Packaging Forum published a systematic review in NPJ Science of Food demonstrating that food packaging is a direct source of the micro- and nanoplastics measured in food. Their finding was specific: the number of microplastics in a beverage increases with each bottle opening, because the mechanical stress of twisting a cap grinds plastic against plastic.

The contamination is not limited to bottles. Ripping plastic wrap from packaged meat contaminates the food. Steeping a tea bag in hot water releases plastic particles -- one study found that a single nylon tea bag at brewing temperature released 11.6 billion microplastics into a single cup. Chicken and turkey packed in polystyrene trays contained 4.0 to 18.7 microplastic particles per kilogram.

Heat accelerates the process. Migration of plastic particles into food increases when packaging is heated, washed for reuse, exposed to sunlight, or subjected to mechanical stress. This is why microwaving leftovers in a plastic takeout container is a particularly effective way to dose yourself with microplastics. The label "microwave-safe" on a container means the container will not melt -- it does not mean the plastic will not degrade into your food.

The contamination extends beyond the packaging itself. EWG scientist Samantha Romanick found that food workers' personal protective equipment -- hair nets, aprons, and gloves -- sheds particles that get into food during production. Conveyor belts, plastic tubing, and processing equipment all contribute. The more stages of processing a food goes through, the more opportunities for plastic to work its way in.

A separate investigation by the Food Packaging Forum found that more than 3,600 chemicals leach into consumer products during food manufacturing, processing, packaging, and storage. Of those, 79 are known to cause cancer, genetic mutations, or endocrine and reproductive issues. The plastic particle is only part of the equation. The chemicals embedded in that plastic -- and adsorbed onto its surface from the environment -- may pose a greater risk than the particle itself.

Food item	Microplastic level	Primary source
Bottled water (with nanoplastics)	240,000 particles/L	Bottle, cap, packaging
Tea (nylon tea bag)	11.6 billion particles/cup	Tea bag material
Sea salt	550-681 particles/kg	Ocean contamination + processing
Table salt (global avg)	Up to 5,400 particles/kg	Processing and packaging
Honey	40-660 fibers/kg	Environmental contamination
Beer	12-109 fragments/L	Processing and packaging
Chicken in PS trays	4.0-18.7 particles/kg	Polystyrene packaging
Tap water	~2.2 particles/L	Water treatment infrastructure

The body burden: what microplastics do once they are inside you

Microplastics have been found in nearly every organ researchers have checked. They have been detected in human blood, lung tissue, liver, placenta, testes, breast milk, and brain tissue. Whether they are there is no longer in question. What they do after they arrive is.

Most of what you swallow passes through. According to a review published in the journal Life, more than 90% of ingested microplastics are excreted in feces. Particles larger than 150 micrometers generally cannot cross the intestinal lining. The ones that get absorbed are smaller, and the smallest fraction -- particles under 1.5 micrometers -- can penetrate deep into organs, cross the placenta, and breach the blood-brain barrier. Your gut lining works like a net with a specific mesh size. Bigger particles bounce off, but nanoplastics slip through the gaps.

A systematic review of 30 human studies found moderate-certainty evidence linking microplastic exposure to elevated inflammatory biomarkers (CRP, IL-6, TNF-alpha) and endocrine markers including altered thyroid hormones and cortisol. This goes beyond detection. The plastic appears to trigger measurable biological responses. The same review, though, rated evidence for links to specific diseases -- diabetes, cardiovascular disease, neurocognitive decline -- as low certainty. Researchers can see the body reacting. They cannot yet draw a clean line from that reaction to a specific diagnosis.

The most striking single finding came from a March 2024 study in the New England Journal of Medicine. Researchers examining carotid artery tissue found that patients with detectable microplastics or nanoplastics in their arterial plaques were twice as likely to have a heart attack, stroke, or die from any cause over the following three years compared to patients without detectable particles. Association, not causation -- but a twofold increase in mortality is hard to dismiss as noise.

The gut is where the action concentrates. Research published in Frontiers in Cellular and Infection Microbiology found that microplastics increase intestinal permeability -- the condition sometimes called "leaky gut" -- allowing harmful particles to enter the bloodstream. Polyethylene microplastics increased harmful pathobionts while reducing butyrate production, a short-chain fatty acid that feeds the cells lining your colon. The microbiome disruption was linked to increased inflammation, which in turn exacerbates insulin resistance -- a known driver of type 2 diabetes.

Microplastics also act as delivery vehicles. Researchers call this the "Trojan Horse" effect: the large surface area and hydrophobic surface of plastic particles makes them effective carriers for endocrine-disrupting chemicals, heavy metals, and persistent organic pollutants. Among the chemicals hitching a ride, bisphenol A (BPA) mimics and disrupts natural hormones, altering fertility and fetal development. Phthalates change hormone functioning and increase cancer risk. Approximately 1,000 chemicals used in plastics are classified as endocrine disruptors.

An honest assessment of where the science stands: no established Acceptable Daily Intake or safe exposure threshold exists for microplastics in humans. Regulators do not yet know what dose causes harm, partly because no standardized method exists to measure the internal burden of microplastics in a human body. The particles are there. They correlate with inflammatory markers. The chemicals they carry are individually harmful. What is missing is definitive proof that particle X at dose Y causes disease Z -- and that kind of evidence takes large, long-running human studies that are only now getting funded.

12 swaps that actually cut your exposure

You cannot eliminate microplastics from your diet. They are in the soil, the water, and the air. But you can substantially reduce the amount you consume with targeted changes in how you store, prepare, and choose food. The following swaps are ranked roughly by impact based on the contamination data covered above.

The single biggest lever: stop heating food and drinks in plastic. Heat accelerates microplastic shedding more than any other factor researchers have identified.

Swap out	Swap in	Why it matters
Plastic water bottles	Filtered tap water in glass or steel	Bottled water contains up to 240,000 particles/L vs ~2/L in tap
Microwaving in plastic containers	Transfer to ceramic plate or glass dish	Heat causes plastic to shed particles into food
Nylon/plastic mesh tea bags	Loose leaf tea or paper tea bags	Single nylon tea bag releases 11.6 billion particles
Plastic cutting boards	Wood or bamboo cutting boards	Knife cuts release microplastic particles
Nonstick pans	Stainless steel or cast iron	Nonstick coating chips into food as pans wear
Plastic food storage	Glass, stainless steel, or ceramic	Eliminates leaching during storage, especially with leftovers
Plastic wrap	Beeswax wrap or aluminum foil	Direct contact with food transfers particles
Plastic spice grinders	Ceramic or metal grinder mechanisms	Plastic grinders release 7,628+ particles per use
Ultra-processed foods	Whole or minimally processed foods	More processing = more plastic contact = more contamination
Breaded/processed seafood	Wild-caught, unprocessed fish	Breaded shrimp had most MP; wild Alaskan seafood had least
Dishwashing plastics	Hand wash in warm (not hot) water	Dishwasher heat increases microplastic shedding
Unwashed rice	Rinsed rice before cooking	Washing removes plastic contaminants from surface

A few of these deserve extra context. The ultra-processed food finding comes from EWG research presented at the University of New Mexico's Microplastics Exposure and Human Health conference in February 2026. EWG scientist Samantha Romanick analyzed peer-reviewed studies using spectroscopic techniques and found a consistent pattern: the more industrial processing steps a food goes through, the more microplastics it accumulates.

The rice washing finding is straightforward. Researchers found that rinsing rice before cooking removed plastic contaminants regardless of what material the rice was packaged in. Instant cooked rice contained more particles than dry packaged varieties, likely from additional processing steps.

Beyond food preparation, your body has some capacity to deal with microplastics. Ohio State University researchers recommend probiotics to help the gut process waste including microplastics, high-fiber diets to promote elimination through regular bowel movements, and vitamins C and E as antioxidants to counter the oxidative stress that microplastics induce. A HEPA filter in your vacuum also helps reduce airborne microplastics that settle on food preparation surfaces.

When "plastic-free" is not plastic-free

Some of the steps people take to avoid microplastics do not work the way they expect. A few make things worse.

Glass bottles are not automatically cleaner. A study of bottled beverages found that soft drinks and beer stored in glass bottles had higher microplastic contamination than the same beverages in plastic bottles. The culprit: painted metal bottle caps, which shed particles into the liquid. The glass itself is fine. The closure is not.

"BPA-free" does not mean chemical-free. Products marketed as BPA-free can still contain other plastic substances or heavy metals that break down with UV exposure or heat. BPA was one of thousands of chemicals in plastics. Removing it does not remove the others.

Some "plastic-free" products are actually plastic. Laundry detergent sheets and strips that advertise themselves as plastic-free are made of polyvinyl alcohol (PVA), which is a type of plastic. The same goes for microfiber cleaning cloths -- they are made from synthetic polymer fibers that shed microplastics with every use.

Reverse osmosis filters can contribute to the problem. While RO systems are effective at removing microplastics from water, some units use nylon filters that release millions of nano-sized plastic particles of their own. The filter material itself becomes a contamination source.

The science is not settled on long-term harm. A systematic review grading evidence using the GRADE framework found that causal relationships between microplastic exposure and specific clinical diseases remain unestablished. The associations with inflammation and endocrine disruption are real and replicated, but the step from "associated with biomarker changes" to "causes disease X" has not been definitively made. This does not mean microplastics are safe -- it means the dose-response relationship has not been quantified. Given that no safe exposure threshold has been established, reducing exposure is a reasonable precautionary approach even while the science catches up.

Common belief	Reality
Glass bottles are microplastic-free	Metal caps and closures shed particles into contents
BPA-free plastic is safe	Other chemicals and heavy metals remain in BPA-free plastics
"Plastic-free" detergent sheets	Made of PVA, which is a type of plastic polymer
Microwave-safe containers do not leach	"Microwave-safe" means it will not melt, not that it will not shed
Himalayan salt is purer than sea salt	Terrestrial salts often have higher microplastic contamination
Microplastics definitively cause disease	Strong associations exist but causal proof is still emerging

Frequently Asked Questions

How many microplastics do I eat per day?

Estimates range from 39,000 to 52,000 particles per year (roughly 107-142 per day) based on a conservative analysis of the American diet, to much higher figures when nanoplastics and all food sources are included. The wide range reflects differences in detection methods rather than disagreement about whether exposure occurs. Diet composition matters: people who drink bottled water regularly, eat ultra-processed foods, and heat food in plastic containers are at the higher end.

Does boiling water remove microplastics?

Boiling water does not remove microplastics, but filtration does. Reverse osmosis systems and activated carbon filters can capture most microplastic particles, though some RO systems with nylon filter components may introduce their own nanoplastics. For tap water, a quality carbon block filter is a practical option. For bottled water, the most effective step is to stop using it and switch to filtered tap water in a non-plastic container.

Are microplastics worse in seafood than other foods?

Seafood gets disproportionate attention, but the actual microplastic load per serving is often lower than less obvious sources. Filter-feeding shellfish like mussels contain 0.2 to 0.70 particles per gram, which is small compared to the billions of particles released by a single plastic tea bag. Processing matters more than the food category: breaded shrimp had the most microplastic particles among 16 protein sources tested, while wild-caught Alaskan seafood had the least.

Can my body get rid of microplastics?

Your body excretes more than 90% of ingested microplastics through feces. The concern is with the smaller particles -- those under 150 micrometers that can cross the intestinal barrier, and especially nanoplastics under 1.5 micrometers that penetrate deep into organs. Supporting your body's elimination pathways through high-fiber diets, adequate hydration, and regular exercise may help with the larger particles, but there is currently no proven method to remove microplastics that have already entered tissues and organs.

Should I stop eating salt because of microplastics?

No. While 94% of salt products worldwide contain microplastics, the actual particle count per serving is low relative to other sources. The Nature study calculated that even at the highest contamination level they measured, a person would ingest a maximum of 37 plastic particles per year from salt alone. Switching to a ceramic or metal grinder and storing salt in a glass container makes a bigger difference than changing salt types.