Microplastics in the Human Body: What Can They Do to Our Health?
Microplastics have been detected in human blood, brain tissue, and several other organs. But does their presence mean they cause disease? Discover what science currently tells us about their potential health effects, associated risks, and practical ways to reduce exposure.
Microplastics are present almost everywhere: in the water we drink, the food we eat, the air we breathe, and even household dust.
In recent years, researchers have identified plastic particles in various human tissues, raising concerns about their potential health effects.
However, one important question requires careful consideration: Does the presence of microplastics in the human body necessarily mean they are causing disease?
The answer is not yet definitive.
Although experimental studies have identified several potentially harmful biological mechanisms, research in humans is still investigating the magnitude of these risks and their relationship with disease development.
What Are Microplastics?
Microplastics are plastic particles smaller than 5 millimeters. They may be intentionally manufactured at microscopic sizes or result from the fragmentation of larger plastic objects, including bottles, packaging, synthetic textiles, and tires.
Even smaller particles are known as nanoplastics, although the precise size thresholds used to define them vary across studies.
Commonly investigated polymers include:
Polyethylene (PE)
Polypropylene (PP)
Polystyrene (PS)
Polyethylene terephthalate (PET)
Polyvinyl chloride (PVC)
In addition to the particles themselves, plastic materials may contain chemical additives, including plasticizers, stabilizers, and flame retardants, which also raise toxicological concerns.
How Do Microplastics Enter the Human Body?
Human exposure occurs primarily through two pathways: ingestion and inhalation.
Ingestion may occur through drinking water, food, and particles released from packaging or containers used for storing and preparing meals.
Inhalation involves airborne particles, particularly in indoor environments, where synthetic textiles, plastic products, and household dust may contribute to exposure.
Skin contact is another potential pathway under investigation, although its contribution to systemic exposure appears smaller than that of ingestion and inhalation.
Importantly, the amount of microplastics detected in food or the environment does not necessarily correspond to the amount absorbed by the human body.
Have Microplastics Been Found in Human Organs?
Yes. Studies have reported particles identified as microplastics or nanoplastics in human blood, lungs, placenta, atherosclerotic plaques, and other tissues.
Recent investigations have also reported their presence in human brain tissue.
These findings suggest that certain particles may cross biological barriers and reach different parts of the body.
However, current methods for collecting, identifying, and quantifying microplastics still have important limitations, including the possibility of sample contamination during laboratory analysis.
Detecting plastic particles in an organ does not necessarily mean they are causing disease in that organ.
This distinction is essential when interpreting scientific findings.
What Biological Effects Can Microplastics Produce?
Studies conducted primarily in cell cultures and animal models have identified several mechanisms through which microplastics may interfere with normal biological processes.
1. Inflammation
Certain particles can stimulate immune cells, increasing the production of inflammatory mediators.
Persistent exposure could potentially contribute to prolonged inflammatory responses, depending on particle characteristics and exposure levels.
2. Oxidative Stress
Microplastics may promote the generation of reactive oxygen species, particularly under experimental conditions.
When the production of these molecules exceeds cellular antioxidant defenses, damage to proteins, lipids, and other cellular structures may occur.
3. Intestinal Barrier and Gut Microbiota Alterations
Preclinical studies suggest that exposure to certain microplastics may modify the composition of the gut microbiota and impair the integrity of the intestinal epithelial barrier.
These changes could influence inflammatory and metabolic processes, although their clinical significance in humans remains uncertain.
4. Endothelial Dysfunction
The endothelium is the layer of cells lining the inside of blood vessels.
Experimental research suggests that certain plastic particles may interfere with endothelial function, potentially contributing to vascular inflammation and dysfunction.
5. Potential Endocrine Effects
Some chemical additives used in plastic manufacturing may interfere with hormonal signaling.
It is important to distinguish the biological effects of plastic particles from those associated with chemicals used in plastic products, such as certain bisphenols and phthalates.
6. Genotoxicity and Cellular Toxicity
Experimental studies have investigated whether certain plastic particles can cause DNA damage, alter cell proliferation, and promote cell death.
These mechanisms are relevant to understanding potential long-term effects, including processes involved in carcinogenesis.
These findings demonstrate biological plausibility, but they do not establish that typical environmental exposure produces all these effects in humans.
Can Microplastics Cause Cardiovascular Disease?
Cardiovascular health is one of the areas in which particularly relevant clinical findings have emerged.
A study published in 2024 in The New England Journal of Medicine identified microplastics and nanoplastics in atherosclerotic plaques removed from patients undergoing carotid endarterectomy.
During follow-up, patients whose plaques contained these particles experienced a higher incidence of a combined outcome involving myocardial infarction, stroke, or death from any cause.
The study identified an important association. However, because it was observational, it cannot establish that microplastics caused the cardiovascular events.
Environmental, metabolic, and behavioral factors may also influence these outcomes.
Therefore, these findings justify further investigation but do not yet establish a definitive causal relationship.
Can Microplastics Affect Digestive, Respiratory, and Reproductive Health?
A 2024 systematic review in Environmental Science & Technology by Chartres and colleagues evaluated the potential effects of microplastic exposure on these three systems.
The researchers examined human observational studies and experimental animal studies.
The review concluded that microplastic exposure is suspected to adversely affect digestive, reproductive, and respiratory health, with varying levels of confidence in the available evidence.
Potential effects included:
Changes in sperm quality and reproductive function
Alterations in intestinal structure and inflammatory responses
Impaired pulmonary function and respiratory injury
Cellular changes associated with potentially carcinogenic processes
However, much of the evidence came from experimental studies.
These findings reinforce concerns about potential health risks, but they do not establish that all these effects occur in humans exposed to typical environmental concentrations.
Is There a Relationship Between Microplastics and Cancer?
The possible involvement of microplastics in cancer development and progression is an emerging area of research.
Experimental studies have identified mechanisms potentially relevant to carcinogenesis, including persistent inflammation, oxidative stress, DNA alterations, and changes in cell proliferation.
The systematic review by Chartres and colleagues also identified evidence suggesting possible links to biological processes involved in colon and lung cancer.
What Did a Study on Cervical Cancer Find?
A 2025 study in the Journal of Hazardous Materials by Xu and colleagues investigated microplastic contamination in cervical cancer tissues.
The researchers identified different types of plastic polymers, particularly polyethylene and polypropylene.
The study also reported higher microplastic levels associated with disease progression and changes in the metabolic profiles of tumor tissues.
Among the observed findings were alterations in metabolic pathways involving sugars and nucleotides.
These results raise hypotheses about possible interactions between plastic particles and the tumor microenvironment.
However, the study did not demonstrate that microplastics caused cervical cancer or were responsible for its progression.
Prospective studies and additional mechanistic investigations are necessary to clarify these relationships.
What Can We Conclude About Microplastics and Cancer?
Current evidence is insufficient to establish that typical environmental exposure to microplastics causes cancer in humans.
The findings are relevant to scientific research but do not yet allow researchers to quantify individual cancer risk or establish definitive causal relationships.
Can Microplastics Affect the Brain?
The detection of plastic particles in human brain tissue has raised new questions about their potential ability to cross the blood–brain barrier.
Experimental studies are investigating possible neuroinflammatory effects, cellular alterations, and mechanisms of neurotoxicity.
However, it has not been demonstrated that the presence of these particles causes dementia, Alzheimer's disease, or other neurodegenerative conditions.
Finding particles in tissue samples from individuals with a particular disease does not, by itself, establish a cause-and-effect relationship.
What Amount of Microplastics Is Toxic?
This is one of the most important questions — and one for which science does not yet have a definitive answer.
Currently, there is no universally established safe or toxic exposure threshold for microplastics in humans.
Potential toxicity depends on several factors:
Particle size, shape, and composition
Polymer type and chemical additives
Exposure concentration and duration
Route of exposure
Absorption, distribution, and elimination processes
Furthermore, many experimental studies use doses and exposure conditions that do not necessarily reflect everyday human exposure.
Consequently, laboratory findings cannot be directly translated into estimates of individual health risk.
Can Diet Help Reduce the Biological Effects of Microplastics?
A new area of scientific investigation is exploring whether certain dietary bioactive compounds can modulate biological responses associated with microplastic exposure.
A study published in 2026 in Nature Communications by Zhao and colleagues reported interesting findings in this field.
What Did the Researchers Investigate?
The study consisted of two phases.
In the first phase, 151 participants were evaluated to investigate associations between fecal microplastic concentrations and several blood, inflammatory, and metabolic markers.
The researchers observed associations between fecal microplastic levels and certain inflammatory and metabolic indicators.
In the second phase, they conducted a randomized, double-blind, placebo-controlled clinical trial lasting 28 days.
A total of 98 participants completed the intervention.
The researchers investigated a combination of polyphenols, bioactive compounds naturally present in many plant-based foods.
The formulation contained 43 phenolic compounds, including quercetin, ellagic acid, gallic acid, rutin, and cyanidin-3-glucoside, administered at a total daily dose of 465 mg.
What Were the Results?
The polyphenol intervention was associated with significant reductions in the plasma concentrations of three inflammatory cytokines:
Interleukin-1 beta (IL-1β)
Interleukin-6 (IL-6)
Interleukin-8 (IL-8)
Changes in gut microbiota composition and certain metabolic pathways were also observed, suggesting possible mechanisms involved in inflammatory response modulation.
However, the intervention did not demonstrate a significant reduction in fecal microplastic concentrations attributable to treatment.
These findings suggest that polyphenols may modulate certain biological responses associated with microplastic exposure, but they do not demonstrate that polyphenols eliminate microplastics from the body.
Should We Take Polyphenol Supplements?
Not specifically for microplastic exposure, based on the evidence currently available.
Although the findings are promising, the trial was short and primarily evaluated intermediate biological markers rather than disease prevention.
Moreover, results obtained with a specific formulation cannot automatically be generalized to other supplements or individual foods.
There is currently insufficient evidence to recommend polyphenol supplementation specifically to prevent or treat the potential health effects of microplastic exposure.
Nevertheless, a varied diet rich in fruits, vegetables, legumes, and other plant-based foods remains advisable because of its well-established nutritional benefits.
The study represents an important step forward, but larger, longer-term clinical trials are needed to determine the clinical significance of these findings.
How Can We Reduce Microplastic Exposure?
Despite the remaining scientific uncertainties, several practical measures may help reduce avoidable exposure.
1. Avoid heating food in unsuitable plastic containers. Whenever possible, use glass or microwave-safe ceramic containers.
2. Minimize prolonged contact between hot food and disposable plastic packaging. Heat may increase particle release under certain conditions.
3. Avoid repeatedly reusing single-use plastic containers. These products are not necessarily designed for prolonged or repeated use.
4. Choose drinking water from a safe source. Where tap water is potable, appropriate filtration may be an alternative to relying exclusively on bottled water. However, not all filters remove microplastics equally effectively, and microbiological safety remains the priority.
5. Reduce unnecessary plastic packaging. This is particularly relevant for hot foods and beverages.
6. Improve indoor ventilation and reduce household dust accumulation. Inhalation is another potential exposure pathway.
7. Do not eliminate healthy foods because of concerns about microplastics. Fruits, vegetables, whole grains, legumes, and other nutritious foods remain essential components of a healthy diet.
These are precautionary measures. It has not yet been demonstrated that adopting them directly reduces the incidence of diseases related to microplastic exposure.
What Can Science Currently Conclude?
The presence of microplastics in the environment and the human body has been documented in multiple scientific investigations.
Experimental studies have identified biologically plausible mechanisms of toxicity, while human studies have begun to identify associations with certain clinical outcomes.
The systematic review by Chartres and colleagues strengthened concerns regarding potential effects on digestive, respiratory, and reproductive health.
The study by Xu and colleagues expanded research on the presence of microplastics in tumor tissues, while the clinical trial by Zhao and colleagues provided new insights into the potential to modulate inflammatory responses through dietary bioactive compounds.
Nevertheless, important questions remain regarding exposure thresholds, cumulative exposure, long-term effects, and causal relationships.
The most appropriate approach is not alarmism, but prevention guided by the best available scientific evidence.
Reducing unnecessary exposure may be a reasonable precaution, without compromising dietary habits and health behaviors whose benefits are already well established.
As scientific research advances, additional studies will be essential to clarify the true impact of microplastics on human health.
Scientific References
Wright SL, Kelly FJ. Plastic and Human Health: A Micro Issue? Environmental Science & Technology. 2017;51(12):6634–6647.
Leslie HA, et al. Discovery and quantification of plastic particle pollution in human blood. Environment International. 2022;163:107199.
Marfella R, et al. Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine. 2024;390:900–910.
Chartres N, Cooper CB, Bland G, et al. Effects of Microplastic Exposure on Human Digestive, Reproductive, and Respiratory Health: A Rapid Systematic Review. Environmental Science & Technology. 2024;58:22843–22864.
Xu H, et al. Microplastic changes during the development of cervical cancer and its effects on the metabolomic profiles of cancer tissues. Journal of Hazardous Materials. 2025;483:136656.
Zhao L, Zheng J, Shen Y, et al. Composite polyphenols mitigate microplastic exposure-related immune disturbances: a two-phase population trial. Nature Communications. 2026;17:6132.
Landrigan PJ, et al. The Minderoo-Monaco Commission on Plastics and Human Health. Annals of Global Health. 2023;89(1):23.
Dr. Andrea Pereira, Physician, Specialist in Nutrology
This article is intended for educational purposes and does not replace individualized medical advice.
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