Microplastics Inside the Human Body: What Current Evidence Shows

Introduction

Microplastics are small plastic particles millimeters in size. They are formed when larger plastic products break down or when small plastic particles are manufactured for use in products such as cosmetics and industrial materials. Over the past decade, researchers have detected microplastics in water, soil, food, and air.

More recently, scientists have found microplastics inside the human body. Studies have reported their presence in blood, lungs, placenta, and even breast milk. These findings have raised concerns about possible health effects. While research is still developing, current evidence provides insight into how microplastics enter the body, how they move within it, and what effects they may have.

This article explains what is currently known about the internal body effects of microplastics in a clear and balanced way.



How Microplastics Enter the Body

Microplastics mainly enter the human body through ingestion and inhalation.

Ingestion occurs when people consume food or water contaminated with plastic particles. Seafood, table salt, bottled water, and packaged foods have all been shown to contain small amounts of microplastics. These particles can enter the digestive system along with normal meals.

Inhalation is another pathway. Tiny plastic fibers are present in indoor and outdoor air. Synthetic clothing, carpets, and upholstery release fibers that can be inhaled. Once inhaled, some particles may remain in the respiratory tract.

Skin contact is considered a minor route. Current research suggests that most microplastics are too large to pass through intact skin, though very small particles may behave differently.



What Happens in the Digestive System

After ingestion, microplastics travel through the stomach and intestines. Many particles are likely excreted in stool. However, smaller particles, especially those in the micro- and nano-size range, may cross the intestinal barrier.

Laboratory studies suggest that very small plastic particles can pass through intestinal cells and enter the bloodstream. This process is not fully understood, and the amount that crosses into circulation appears to be small.

In the gut, microplastics may interact with the microbiome, which is the community of bacteria living in the intestines. Some animal studies have shown changes in gut bacteria after exposure to microplastics. These changes have been linked to inflammation and altered digestion. Human data are limited, but this area is under active investigation.



Presence in the Bloodstream

In 2022, researchers reported the detection of microplastics in human blood samples. This finding confirmed that some plastic particles can move beyond the digestive or respiratory systems and circulate in the body.

Once in the bloodstream, particles may travel to different organs. The body’s immune system may recognize them as foreign material. White blood cells can attempt to engulf and remove these particles, leading to localized immune responses.

The long-term effects of circulating microplastics are not yet known. The amount detected in studies so far has been small, and research is ongoing to understand whether these levels pose significant health risks.



Effects on the Respiratory System

Inhaled microplastics can deposit in the airways and lungs. Occupational studies in textile and plastic industries have shown that inhaling synthetic fibers over long periods can cause respiratory symptoms.

Short-term exposure may irritate airways. Long-term exposure could contribute to chronic inflammation. Some research has found plastic fibers embedded in lung tissue samples.

The lungs have defense mechanisms, including mucus and tiny hair-like structures called cilia, which help remove inhaled particles. However, very small particles may reach deeper lung regions and remain there.

Inflammation in lung tissue is one possible effect. Chronic inflammation is linked to conditions such as asthma and reduced lung function, but direct connections between environmental microplastics and these diseases require more evidence.



Immune System Response

The immune system plays a key role in responding to foreign particles. When microplastics enter tissues, immune cells may attempt to isolate or remove them.

Laboratory studies suggest that plastic particles can trigger inflammatory responses. Inflammation is a normal protective reaction, but if it becomes chronic, it may contribute to tissue damage.

Some plastics contain additives such as plasticizers, flame retardants, and stabilizers. These chemicals may leach out of particles inside the body. Certain additives are known to affect immune function and hormone balance. The combination of physical particle presence and chemical exposure may increase biological impact.

Human studies are still limited, and most evidence comes from laboratory and animal models.



Potential Effects on the Liver and Kidneys

The liver and kidneys help filter and remove foreign substances from the body. If microplastics enter the bloodstream, they may reach these organs.

Animal studies have shown that high doses of microplastics can accumulate in the liver and cause oxidative stress. Oxidative stress refers to an imbalance between harmful molecules and protective antioxidants. This imbalance can damage cells.

Kidney effects have also been observed in some animal models exposed to large amounts of microplastics. However, these exposure levels are often higher than typical environmental exposure in humans.

At present, there is no clear evidence that everyday environmental exposure causes liver or kidney disease in humans. More long-term studies are needed.



Microplastics and the Placenta

Researchers have detected microplastics in placental tissue. The placenta supports the developing fetus during pregnancy. The presence of plastic particles in this organ has raised concerns about potential effects on fetal development.

The placenta acts as a partial barrier, but it does not block all substances. Early studies suggest that microplastics can be present on both the maternal and fetal sides of the placenta.

It is not yet known whether these particles directly affect fetal health. This area of research is still in early stages. Scientists are working to understand possible risks and exposure levels.



Hormonal and Chemical Effects

Many plastics contain chemicals that can interfere with the endocrine system. These chemicals are sometimes called endocrine-disrupting chemicals.

Examples include bisphenols and certain phthalates. These substances can influence hormone regulation. Hormones control growth, metabolism, reproduction, and other important processes.

Microplastics may act as carriers for these chemicals. When particles are inside the body, additives may leach out and enter surrounding tissues.

The health impact depends on the type of chemical, dose, and duration of exposure. While individual exposure levels may be low, repeated exposure over time is a concern for researchers.



Inflammation and Oxidative Stress

Two common themes in microplastic research are inflammation and oxidative stress.

Inflammation is the body’s response to injury or foreign material. Short-term inflammation helps with healing. Long-term inflammation can contribute to chronic diseases.

Oxidative stress occurs when harmful molecules called free radicals exceed the body’s ability to neutralize them. This can damage proteins, DNA, and cell membranes.

Animal studies suggest that microplastics can increase markers of inflammation and oxidative stress in tissues. Whether typical human exposure produces similar effects is still under study.



Limitations of Current Research

Although research findings have raised concerns, there are important limitations.

First, measurement methods vary. Detecting very small plastic particles in human tissues is technically challenging. Different studies use different techniques, making comparisons difficult.

Second, many studies are based on animals or laboratory cell models. These experiments often use higher concentrations than those typically found in the environment.

Third, long-term human studies are limited. Chronic diseases develop over years or decades, and microplastic research is still relatively new.

These limitations mean that conclusions must be cautious and based on evidence rather than speculation.



Reducing Exposure

While research continues, individuals can take practical steps to reduce exposure.

Using glass or stainless steel containers instead of plastic for food storage may help. Avoiding heating food in plastic containers can reduce the release of particles and chemicals. Choosing natural fiber clothing may decrease indoor microplastic fibers.

Improving ventilation and regular cleaning can reduce airborne particles indoors. Supporting policies that reduce plastic waste can also lower environmental contamination.

These steps may not eliminate exposure entirely, but they can help reduce overall intake.



Conclusion

Microplastics are now part of the global environment and have been detected inside the human body. Research shows that small plastic particles can enter through food and air, reach the bloodstream, and interact with organs such as the lungs, liver, and placenta.

Possible internal effects include inflammation, oxidative stress, immune responses, and chemical exposure from plastic additives. However, most evidence comes from laboratory and animal studies. Clear conclusions about long-term health risks in humans require more research.

Understanding how microplastics move through and affect the body is an ongoing scientific effort. Clear communication, careful research, and practical exposure reduction can support public health as knowledge continues to grow.