Microplastics and the Human Body: 

Pathways of Absorption and Health Impacts

Main-author: Ioana Caprar,

Faculty of Environmental Science, Babes-Bolyai University, Cluj-Napoca, Romania;

Research Institute of Water and Environmental Engineering (IIAMA), Polytechnic University of Valencia, Spain

-to be continued-

-scratch of an ongoing project-

Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium totam rem aperiam eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo nemo enim ipsam voluptatem.

In recent years, microplastics—tiny plastic particles less than 5 millimeters in diameter—have emerged as a significant environmental and public health concern. Found in oceans, freshwater, soil, and even air, these microscopic fragments are increasingly being detected in the human body. As research expands, scientists are beginning to unravel the pathways through which microplastics enter our bodies and the potential impacts they may have on our health.

~  ~  ~  ~

Pathways of Microplastic Absorption in the Human Body

Microplastics can enter the human body through several primary routes:

1. Ingestion

One of the most common ways microplastics enter the human body is through food and water. These particles are present in:

• Seafood: Marine organisms ingest microplastics, which can then bioaccumulate up the food chain to humans.

• Bottled and tap water: Studies have found microplastic contamination in both bottled and tap water globally.

• Salt and other food products: Table salt, beer, honey, and even fruits and vegetables have been found to contain microplastics.

Once ingested, microplastics can pass through the gastrointestinal (GI) tract. While larger particles may be excreted, smaller ones—especially in the nanoplastic range (less than 1 micrometer)—can potentially penetrate the intestinal lining and enter the bloodstream.

2. Inhalation

Microplastics are also present in the air, particularly in urban environments and indoor settings. Fibers from synthetic textiles and dust particles containing microplastics can be inhaled and lodge in the lungs. Inhaled microplastics may remain in lung tissue or be transferred to other parts of the body via the circulatory system.

3. Dermal Absorption

Though less common, there is concern that microplastics in personal care products, such as exfoliants and cosmetics, might be absorbed through the skin. However, the evidence for dermal absorption is currently limited and under investigation.

~ ~ ~ ~ 

Potential Health Impacts of Microplastic Exposure

The health effects of microplastic exposure in humans are still not fully understood, but emerging evidence points to several areas of concern:

1. Inflammation and Immune Response

Microplastics can cause localized inflammation when they accumulate in organs or tissues. The immune system may recognize these particles as foreign bodies and trigger a response, potentially leading to chronic inflammation and tissue damage over time.

2. Chemical Toxicity

Plastics often contain additives such as phthalates, bisphenol A (BPA), flame retardants, and heavy metals. Additionally, microplastics can adsorb environmental pollutants like pesticides and polycyclic aromatic hydrocarbons (PAHs) on their surfaces. When ingested or inhaled, these chemicals can leach into the body, potentially disrupting hormonal functions, damaging organs, or contributing to cancer risk.

3. Oxidative Stress and Cellular Damage

Laboratory studies suggest that microplastics can induce oxidative stress, a condition characterized by excessive free radicals that damage cells and DNA. This process is linked to aging, cancer, and neurodegenerative diseases.

4. Gut Microbiome Disruption

Microplastics may interfere with the balance of bacteria in the gut, potentially impairing digestion, metabolism, and immune regulation. Animal studies have shown that plastic exposure can alter the composition of gut microbiota, although human studies are still limited.

5. Respiratory and Pulmonary Issues

Inhalation of microplastic fibers and particles has been associated with respiratory issues such as asthma, chronic coughing, and reduced lung function, especially in workers exposed to high concentrations of synthetic dust.

~ ~ ~ ~ 

Current Knowledge Gaps and Future Directions

Despite growing concern, many questions remain unanswered. Scientists are still working to quantify how much microplastic is actually absorbed into the human body, how long it persists, and which health outcomes are directly attributable to it. More longitudinal human studies and standardized detection methods are needed to draw firm conclusions.

Policymakers and public health agencies are beginning to respond by encouraging reduced plastic use, banning microbeads in cosmetics, and funding research into alternatives to traditional plastics.

~ ~ ~ ~ 

Conclusion

Microplastics have infiltrated every corner of the planet, including the human body. While our understanding of their health implications is still developing, the preliminary evidence suggests real risks, especially with long-term exposure. Reducing plastic pollution, improving waste management, and minimizing personal exposure are essential steps in safeguarding both environmental and human health. As research continues, it will be crucial to stay informed and advocate for policies that address the root of the microplastic crisis.

Ioana Caprar, 27.05.2025