How Microplastics Enter the Human Body
Microplastics are tiny plastic particles, typically less than 5 millimeters, that are ubiquitous in our environment. We are primarily exposed to these particles through three main pathways: ingestion, inhalation, and dermal contact.
- Ingestion: This is considered the primary route of exposure. We consume microplastics through contaminated food and water, with studies finding them in bottled water, seafood, sea salt, beer, and even produce. The particles can originate from degrading packaging or be absorbed by plants from contaminated soil.
- Inhalation: Airborne microplastics, especially synthetic fibers from clothing and dust, can be breathed in. Particles inhaled can lodge in the lungs or be cleared by the body's natural defense mechanisms and then swallowed, entering the digestive tract.
- Dermal Contact: While considered a less significant route, microplastics in cosmetics and personal care products can come into contact with the skin. Research suggests small nanoparticles might penetrate through hair follicles or injured skin.
The Body's Excretion Mechanisms for Microplastics
The human body does have natural mechanisms to eliminate some foreign particles, including microplastics. For larger particles, the process is relatively straightforward.
- Gut Elimination: Much of the microplastic that is ingested, especially larger pieces, does not get absorbed and simply passes through the digestive tract. These particles are then expelled from the body in feces. The efficiency of this process is supported by a high-fiber diet, which aids in waste removal.
- Liver and Spleen Clearance: For microplastics that do make it into the bloodstream, the reticuloendothelial system—primarily involving phagocytic cells (like macrophages) in the liver and spleen—can help remove them from circulation. These particles are then sometimes eliminated via biliary excretion into the digestive tract.
- Respiratory Clearance: The lungs have a clearance system called the mucociliary escalator. Inhaled particles can get trapped in mucus and are moved upwards to the throat, where they are swallowed and enter the gastrointestinal tract to be excreted.
What Happens to Microplastics That Aren't Flushed Out?
While larger microplastics are mostly excreted, smaller particles, particularly nanoplastics, can pose a more serious problem. These tiny particles, below 200 nanometers, are small enough to breach biological barriers, including the intestinal lining, placenta, and potentially the blood-brain barrier.
Bioaccumulation and Health Implications
Once inside the bloodstream, these particles can accumulate in various organs and tissues where they are harder to excrete. This is known as bioaccumulation. Studies have detected microplastics in the liver, kidneys, spleen, lungs, heart, brain, and placenta. This accumulation is linked to several health concerns:
- Inflammation: The immune system recognizes these particles as foreign invaders, triggering an inflammatory response that can lead to chronic inflammation in various organs.
- Oxidative Stress: Microplastics can generate reactive oxygen species (ROS), causing oxidative stress that damages cells and DNA.
- Gut Microbiome Disruption: Microplastics in the gastrointestinal tract can cause gut dysbiosis, an imbalance of gut bacteria, which can affect metabolism and immune function.
- Hormonal Disruption: Plastic particles can act as carriers for toxic chemical additives like Bisphenol A (BPA) and phthalates, which are known endocrine disruptors. These can interfere with hormone regulation.
Comparing Excretion of Larger vs. Smaller Plastic Particles
| Characteristic | Larger Microplastics (>200 nm) | Smaller Nanoplastics (<200 nm) |
|---|---|---|
| Primary Excretion Route | Fecal elimination via the digestive tract | Accumulation in organs and tissues |
| Barrier Penetration | Limited; generally does not penetrate intestinal or cellular barriers | Can breach biological barriers like the gut-blood and blood-brain barriers |
| Accumulation | Minimal, mostly passing through the body with waste | Significant, building up in organs such as the liver, spleen, and brain |
| Known Health Impacts | May cause gastrointestinal irritation and microbiome disruption | Systemic effects, including chronic inflammation, oxidative stress, and potential neurological, reproductive, and cardiovascular issues |
Supporting the Body's Defenses and Reducing Exposure
Because the body has limited capabilities to remove deeply embedded particles, the best strategy involves reducing intake and supporting natural detoxification pathways.
- Reduce Plastic Sources: Avoid plastic water bottles by using stainless steel or glass alternatives. Use glass or ceramic containers for food storage instead of plastic, especially when heating.
- Improve Water Quality: Use a high-quality water filtration system, such as reverse osmosis, to reduce microplastics in drinking water. Boiling hard water has also been shown to help clump microplastics for easier filtration.
- Boost Fiber Intake: A diet rich in fiber from fruits, vegetables, and whole grains promotes regular bowel movements, helping to bind and excrete microplastics from the gut.
- Enhance Antioxidants: Consuming antioxidant-rich foods and supplements (like glutathione) can combat the oxidative stress caused by microplastics and support liver function.
- Support Natural Cleansing: Staying well-hydrated is key for kidney function. Some complementary health practitioners also suggest saunas to promote sweating, though its effectiveness for microplastic removal is still being researched.
- Address Indoor Air Quality: Use HEPA air filters in your home to capture airborne microplastics from synthetic fabrics and dust. Choosing natural fiber clothing over synthetics can also help.
Current Limitations in Detoxification Science
It's important to acknowledge that research into microplastic toxicity and removal is still in its early stages. Scientists are working to understand the long-term effects and potential solutions. There is currently no proven medical procedure or treatment, like chelation therapy, for effectively removing microplastics that have accumulated deep in the body's tissues. However, some research is exploring experimental methods like therapeutic apheresis, a blood filtration process, for removing MNP-like particles from the bloodstream, though its clinical efficacy is not yet established.
Conclusion
While the body can effectively flush out many of the larger microplastic particles it encounters, its ability to eliminate the smallest nanoplastics is limited. These minuscule particles can cross vital biological barriers and accumulate in organs, where they are difficult to remove and can cause inflammation and other adverse health effects. Given that complete removal is not possible, the most effective strategy for managing microplastic exposure is prevention. By reducing plastic use, improving air and water quality, and supporting the body's natural detoxification processes with a healthy lifestyle, individuals can help mitigate the silent and pervasive threat that microplastics pose to long-term health.
