How Invisible Microplastics Threaten Your Health

By Dr. John Neustadt

The modern economy relies on plastic. Toys, car parts, bags, shoes, food packaging, agricultural equipment, medical devices, personal care products, clothing, electrical and plumbing supplies, all contain or are entirely plastic. In the US alone, over one million people work in plastics manufacturing to produce 130 billion pounds of plastic. Plastics contribute half a billion dollars to the US economy.¹ Simply put, there’s no way to avoid plastics. 

While plastics have revolutionized life, they’ve become one of history’s most significant environmental hazards. For example, plastic bags never fully break down. They merely become smaller plastic particles as they decompose, where they can enter the food chain.

The smallest plastic particles are known as microplastics, and Americans are exposed to between 39,000 and 52,000 microplastic particles each year through their diet alone. This exposure mainly occurs through consuming food and beverages, with significant sources including seafood, drinking water, and processed foods; however, when factoring in breathing in microplastics from the air, the exposure jumps to 74,000 and 121,000 microplastic particles annually.^2,3 Microplastics are so ubiquitous that studies around the world have detected them in sugar, beer, and salt.^4-6

Microplastics definition

Microplastics are plastic fragments less than 5 millimeters in size—about the width of a standard pencil eraser. However, many microplastics are much smaller, sometimes even microscopic. To put this into perspective, the smallest microplastics can be as tiny as a grain of sand. In contrast, nanoplastics, an even smaller category, can be the size of a human red blood cell. 

Microplastics can originate from various sources, but they generally fall into two main categories: primary and secondary microplastics.

• • Primary microplastics are intentionally small plastics designed for specific applications, such as microbeads in exfoliating skincare products or industrial abrasives used in sandblasting.
  • Secondary microplastics are more common in the environment, including particles created when tires wear down due to driving and microfibers that degrade from plastic bottles, plastic bags, fishing nets, and clothing.⁷

Bioaccumulation

Once microplastics enter the environment, they can become part of the food chain.  

Fish, shellfish, birds, and land animals often mistake microplastics for food. When they ingest them, the microplastics can block their digestive tracts, reduce nutrient absorption, and introduce toxic chemicals. They can also become stored in their bodies. Thus, we consume those microplastics while eating chicken, beef, and seafood.

Additionally, when irrigation water contains microplastics, they can be absorbed by plants through their roots and leaves. When we consume fruits and vegetables, we inadvertently ingest microplastics as well. A study evaluated fruits and vegetables from Italy for their microplastics content. The fruit samples revealed a median of 223,000 microplastics, whereas the vegetable samples contained 97,800.⁸ Furthermore, research in India discovered microplastics in potatoes, bananas, and grapes.⁹

Bottled water also contains microplastics. In the United States, bottled water contains 240,000 micro- and nano-plastic particles per liter. Ninety percent of the plastic comprises the tiniest particles, known as nanoplastics, while the remaining 10% includes microplastic particles.¹⁰

Notably, technology used in most research is not sensitive enough to detect nanoplastics. Therefore, only the amount of microplastics is reported by most researchers, meaning the total amount of plastic contamination is likely much higher than what most studies detect. 

While it’s been estimated that people eliminate about 90% of microplastics in their stool, 10% stays in your body. These micro- and nano-plastics are even being passed to babies in the womb. One study discovered microplastics in placental tissue, raising concerns about fetal development. Other research has detected microplastics in human intestines, lungs, tonsils, testes, kidneys, brain, liver, and circulating in the blood.^11-14

In blood samples from 20 healthy adults, 90% contained microplastics.¹⁴ Fecal samples in infants determined that ingestion of microplastics was responsible for the presence of poly(ethylene terephthalate), abbreviated in their stool. This dangerous chemical was 10 times higher in fecal samples from infants than adults.¹⁵ Another study detected microplastics in 77% of blood samples from 22 healthy adults.¹⁶

A problem that’s getting worse

It’s a problem that’s getting worse. Two studies, conducted eight years apart, examined micro- and nanoplastics in the brains and livers of deceased people. Compared to brain and liver samples evaluated in 2016, those analyzed in 2024 had significantly more microplastics. Additionally, the amount of plastic particles in the brains of people diagnosed with dementia was higher than in people without dementia. Plastic particles were also detected in the walls of brain blood vessels and immune cells.¹⁷

Health risks

Once inside the body, they induce cellular toxicity and affect multiple organ systems. Some plastics contain harmful additives such as phthalates and bisphenol A (BPA), which are powerful hormone disruptors. Some plastics, like black plastic kitchen utensils (e.g., spatulas, forks, and spoons) can contain flame retardant because they are often made with recycled electronic plastics. These chemicals, called polybrominated diphenyl ethers (PBDEs) can leach into food during cooking, leading to ingestion and subsequent accumulation in the body. Chronic exposure to BFRs has been linked to neurotoxicity, endocrine disruption, and carcinogenicity.^{18, 19}

Plastics can also often contain toxic metals, like antimony, arsenic, cadmium, and mercury.²⁰ Introducing these toxic chemicals into the body damages cellular signaling and creates a cascade of dangerous effects.²¹ Microplastics also disrupt the microbiome, reduce healthy gut bacteria, and contribute to dysbiosis, which is one way microplastics cause inflammation.²²

Multiple research reviews concluded that microplastic exposure is highly correlated with reproductive damage (e.g., decreased sperm quality), reduced immunity, chronic inflammation, causes genetic damage, and harms respiratory health.^{23, 24}Microplastics have also been implicated in neurotoxicity, development of antibiotic resistance, and blood clots.^{25, 26}

Ways to reduce exposure

• • Use glass or stainless steel containers instead of plastic.
  • Drink filtered tap water instead of bottled water. 
  • Eat a high-fiber diet, which can trap microplastics and help eliminate them in the stool.
  • Avoid plastic-packaged food when possible. When plastic contacts food, chemicals from the plastic, such as BPA, toxic metals, flame retardants, and more enter the food. Twenty-five percent of more than 3500 food contact chemicals were found in humans.27 
  • Ventilate and clean indoor spaces regularly to reduce airborne microplastics.
  • Choose natural fiber clothing (cotton, wool) over synthetic fabrics (polyester, nylon).

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