Microplastics have been detected in virtually every organ and tissue researchers have examined in the human body, from blood and lungs to the brain and placenta. While there’s no single number for the total count of particles inside a person at any given time, studies have measured concentrations in specific tissues: roughly 1.6 micrograms per milliliter of blood, a median of about 2 particles per gram of lung tissue, and concentrations in the brain that appear higher than in any other organ tested so far.
What’s Circulating in Your Blood
A 2022 study analyzing blood from 22 healthy volunteers found a mean concentration of 1.6 micrograms of plastic per milliliter of whole blood. That may sound tiny, but it means plastic particles are continuously moving through your cardiovascular system, reaching every organ. The study detected particles 700 nanometers and larger, so smaller fragments likely went uncounted.
A follow-up study of 20 blood donors identified 24 different polymer types in the blood of 18 participants (90%). The most common was polyethylene, the plastic used in grocery bags and food packaging, making up 32% of particles found. Ethylene propylene diene rubber accounted for 14%, and ethylene-vinyl acetate (common in shoe soles and adhesives) made up 12%. The sheer variety of plastics circulating in the bloodstream reflects how many different sources contribute to the body’s plastic burden.
Where Microplastics Accumulate in the Body
Once plastic particles enter the bloodstream, they don’t stay there. They settle into organs, and some tissues appear to collect more than others.
Lung tissue from surgical patients showed a median concentration of about 2.19 particles per gram, with 12 different plastic types identified across 108 particles. People with lung disease had significantly higher concentrations, averaging 4.31 particles per gram compared to 0.47 in control samples. This makes sense: your lungs are a direct entry point for airborne plastic fibers shed from synthetic clothing, carpets, and dust.
The brain, however, may be the biggest accumulator. Research from the University of New Mexico found plastic concentrations in the frontal cortex that were higher than in the liver, kidney, placenta, or testes. Even more striking, brain plastic levels appear to have increased by 50% over just eight years, based on comparisons of archived tissue samples. The most common polymer was polyethylene, and electron microscopy revealed clusters of sharp plastic shards measuring 200 nanometers or smaller embedded in brain tissue. People who had been diagnosed with dementia had up to 10 times more plastic in their brains than those without the condition, though researchers are still working to understand whether that’s a cause or a consequence.
Microplastics Before Birth
Plastic exposure begins before you’re born. A study of 10 placentas from healthy pregnancies in Ottawa found plastic particles in every single one, averaging about 1 particle per gram of tissue. The particles ranged from 2 to 60 micrometers in size, with polyethylene, polypropylene, polystyrene, and PVC being the most common types. These are the same plastics found in food containers, packaging film, and pipes, suggesting that a mother’s dietary and environmental exposures transfer directly to the placenta.
How Much Plastic You Take In
You may have heard the claim that people eat a credit card’s worth of plastic every week (about 5 grams). That figure, which circulated widely in news coverage, has since been challenged. A peer-reviewed analysis found that the original calculation contained severe errors and overestimated intake by several orders of magnitude. A more conservative estimate puts the median adult intake at roughly 4.1 micrograms per week, which is thousands of times less than a credit card.
That said, the lower estimate still means you’re steadily ingesting plastic particles through food, water, and air. Stool samples confirm this: a pilot study found a median of 3.5 microplastic particles per gram of stool in the 50 to 500 micrometer size range, with up to nine different plastic types detected. This tells us that a portion of ingested microplastics passes through the digestive tract, but it also confirms that some fraction is absorbed into the body rather than excreted.
Why the Numbers Keep Changing
One reason there’s no definitive answer to “how many microplastics are in a human body” is that detection technology keeps improving. Early studies could only identify particles above 500 micrometers. Newer techniques detect particles down to 700 nanometers, and the smallest fragments found in brain tissue measured 200 nanometers or less. Each time researchers look at smaller size ranges, they find dramatically more particles. The plastics we can currently measure likely represent a fraction of what’s actually present.
Concentrations also vary significantly between individuals, influenced by diet, occupation, geography, and the types of packaging and textiles in your daily environment. Someone who drinks primarily from plastic bottles, microwaves food in plastic containers, and lives near heavy traffic will almost certainly carry a higher burden than someone who doesn’t. The field is still young enough that population-wide averages remain rough, but the direction is consistent: every study that looks for microplastics in human tissue finds them, and concentrations appear to be rising over time.