Nanoplastics: How They Get Into Your Body

Nanoplastics: How They Get Into Your Bloodstream

Researchers have detected plastic particles in human blood.

Evidence suggests that the smaller the plastic particle, the more likely it is to cross biological barriers and enter the bloodstream.

Here's the current understanding:

Particles larger than about 150 micrometers (µm) are generally not absorbed through the gut. Most pass through the digestive system and are excreted.

Particles smaller than about 20 µm can be absorbed in small amounts through the intestinal lining.

Particles below about 1–10 µm appear much more capable of entering tissues and the bloodstream, although only a small fraction of what is ingested is thought to be absorbed.

Nanoplastics (typically defined as smaller than 1 µm, especially those under 100 nanometers (nm)) are considered the most likely to cross the intestinal barrier, enter the bloodstream, and potentially reach organs such as the liver, kidneys, brain, or placenta.

Several important notes:

The particles found vary widely in size, and many studies cannot accurately measure the very smallest ones. Detection methods are still improving, making it difficult to compare studies.

Finding particles in blood does not by itself demonstrate that they are causing disease.

How do they get into the bloodstream?

Small plastic particles may cross the gut through several mechanisms:

• Uptake by specialised intestinal cells involved in immune surveillance

• Passage between or through intestinal epithelial cells, particularly for the smallest particles

• Transport inside immune cells after being engulfed

The lungs may also provide a route of entry for inhaled microscopic plastic particles.

What does this mean for health?

Scientists have confirmed that microplastics and nanoplastics can be found in human blood and various tissues, but the health implications are still being actively studied. 

Laboratory and animal studies suggest very small particles can trigger inflammation, oxidative stress, or other cellular effects, but it is not yet clear what levels of real-world human exposure are sufficient to cause harm.

Summary:

>150 µm: Little to no absorption into the body.

~20 µm or smaller: Some particles can cross the gut.

1–10 µm: More likely to reach the bloodstream.

<1 µm (nanoplastics): Most likely to cross biological barriers and circulate through the body.

Nanoplastics are extremely small plastic particles—typically less than 1 micrometer (1 µm) in diameter. 

For comparison:

• A human hair is about 70–100 µm wide

• A red blood cell is about 7–8 µm across

Many nanoplastics are 10–1,000 nanometers (nm), making them tens to hundreds of times smaller than a blood cell.

Because of their size, nanoplastics behave differently from larger microplastics. They have a much higher surface area relative to their volume, making them more chemically reactive and potentially more able to interact with cells.

Where do nanoplastics come from?

They are produced in two main ways.

1. Breakdown of larger plastics (the main source)

Most nanoplastics form when larger plastic items gradually fragment through:

• Sunlight (UV radiation)

• Heat

• Mechanical wear (friction, abrasion)

• Ocean waves

• Wind

• Microbial activity

For example:

A discarded plastic bottle slowly breaks into microplastics, then into nanoplastics over years.

Car tyres shed particles while driving, and those particles continue to fragment.

Synthetic clothing releases fibres during washing that can eventually degrade into even smaller particles.

2. Manufactured nanoplastics

Some are intentionally produced for industrial or research applications, though these are thought to contribute much less to environmental exposure than fragmented plastics.

Where are they found?

Researchers have found evidence of nanoplastics or strong indications of their presence in:

• Drinking water (both tap and bottled)

• Seafood

• Salt

• Fruits and vegetables

• Indoor and outdoor air

• Household dust

Because they are so small, they are difficult to measure accurately, so their true abundance is still uncertain.

How do people get exposed?

The main exposure routes are thought to be:

Eating: Food and beverages can contain plastic particles.

Drinking: Water, especially if stored or packaged in plastic, may contain micro- and nanoplastics.

Breathing: Indoor air often contains tiny fibers shed from carpets, furniture, curtains, and clothing.

Possibly through medical devices: Certain medical procedures involving plastic equipment may introduce plastic particles, though this is generally a much smaller source for most people.

Why are scientists concerned?

Nanoplastics are of particular interest because they may be able to:

• Cross the intestinal lining

• Enter the bloodstream

• Be taken up by individual cells

Cross barriers that larger particles generally cannot, such as the placenta in some studies.

Laboratory studies have shown that nanoplastics can:

• Trigger inflammation

• Generate oxidative stress

• Alter cell function

• Affect immune responses

However, these studies often use concentrations or particle types that may not match typical human exposure. It is still unclear how these findings translate to everyday health risks.

Can you reduce exposure?

It's probably impossible to avoid nanoplastics entirely, but you can reduce exposure by:

• Filtering water (some filters remove more particles than others)

• Limiting the use of scratched or damaged plastic food containers, especially for hot foods

• Avoiding microwaving food in plastic unless the container is specifically designed for that purpose

• Ventilating your home and cleaning dust regularly, since indoor dust is a significant source of airborne plastic fibres

• Choosing natural-fibre textiles when practical, as synthetic fabrics shed plastic fibers over time

Overall, scientists are confident that nanoplastics are widespread in the environment and that humans are exposed to them. 

The biggest unanswered question is not whether they're present, but what levels and types of exposure, if any, lead to meaningful health effects over a lifetime. 

Ongoing research is focused on answering that question.

Where has nanoplastics been found in the human body so far?

Researchers have now detected microplastics and nanoplastics (MNPs) in a wide range of human tissues and fluids. 

Because nanoplastics (typically defined as particles smaller than 1 micrometer) are especially difficult to measure, many studies report them together with microplastics. 

Detection methods are still improving, so the evidence is stronger for some tissues than others.

Here are the places where they have been reported so far:

Body part or fluid | Evidence

Blood

Detected in circulating blood, suggesting particles can travel throughout the body.

Lungs

Found in lung tissue from living patients and in autopsy samples.

Brain

Recent studies have reported micro- and nanoplastics in human brain tissue, including the olfactory bulb and cerebral cortex.

Heart

Detected in heart tissue, including samples collected during cardiac surgery.

Liver

Reported in human liver tissue.

Kidneys

Found in kidney tissue in some studies.

Placenta

Detected on both the maternal and fetal sides of the placenta.

Amniotic fluid

Reported in samples from pregnancies.

Umbilical cord blood

Particles have been detected, suggesting fetal exposure is possible.

Breast milk

Found in samples from breastfeeding mothers.

Testes

Reported in human testicular tissue.

Semen

Microplastics have been detected in semen samples.

Ovarian follicular fluid

Found in fluid surrounding developing eggs.

Bone marrow

Detected in a small number of studies.

Arteries

Found in plaques removed from arteries during surgery.

Gastrointestinal tract

Detected in colon tissue and throughout the digestive system.

Stool (faeces)

Consistently detected, indicating ingestion and excretion.

Urine

Reported in several studies, though at generally lower levels than in stool.

 

Some human studies have found associations—for example, higher levels of plastic particles in arterial plaque have been linked with a greater risk of later cardiovascular events—but these studies do not establish that the plastics caused those outcomes. 

Much of the evidence for biological effects still comes from laboratory and animal studies, often using concentrations that may differ from typical human exposure.

What remains uncertain?

Scientists are still working to answer several key questions:

• How many nanoplastics accumulate in different organs over a lifetime

• Which types of plastics are most biologically active

• How long particles remain in the body before being cleared

• What exposure levels, if any, are sufficient to cause disease

Whether the plastics themselves, the chemicals they contain, or pollutants attached to them are responsible for any health effects.

In summary, researchers have found micro- and nanoplastics in numerous human tissues—including the blood, lungs, brain, placenta, reproductive tissues, heart, liver, kidneys, and digestive system. 

While this demonstrates that these particles can reach many parts of the body, the long-term health consequences remain an active area of research rather than a settled scientific conclusion.