Microplastics have transitioned from being merely an environmental issue to a significant public health concern. Recent data confirm their persistent presence within the human body and their interaction with key physiological processes. The discovery of microplastics in organs such as the brain, digestive system, respiratory system, and reproductive organs has shifted the debate to a critical point: this is no longer about external exposure but about intra-organic accumulation with potential health impacts.
Understanding Microplastics and Their Origins
Microplastics are defined as plastic fragments smaller than five millimeters, while even smaller particles, less than one micron, are classified as nanoplastics. These particles originate from the fragmentation of larger plastics and their direct release from everyday products or industrial processes. Their health significance lies in their ability to be ingested or inhaled, allowing direct contact with human tissues.
Global Recognition of the Issue
The World Health Organization (WHO) has acknowledged that human exposure to microplastics is now widespread, including through drinking water. The organization highlights that larger particles seem to be poorly absorbed, but warns that nanoparticles might behave differently, precisely the size range that is most challenging to measure and standardize.
Similarly, the Pan American Health Organization (PAHO) has classified this issue among the environmental determinants of health, emphasizing that plastic pollution disproportionately affects vulnerable populations, particularly those with limited access to clean water, sanitation, and healthcare services.
Microplastics in the Brain
One of the most striking discoveries is the detection of microplastics in human brain tissues. Recent studies have documented concentrations of microparticles and nanoplastics in the brain higher than those found in the liver or kidneys, organs traditionally associated with filtration processes. These findings are significant because they indicate that nanometer-sized particles can cross the blood-brain barrier. The importance of this discovery is reinforced by the observation of a temporal trend, with brain concentrations being higher in recent samples than in those collected several years ago. This increase suggests a cumulative phenomenon consistent with the sustained rise in plastic production and use, raising questions about the biological burden throughout life.
In a subgroup of individuals with dementia, brain levels of microplastics were even higher. Although the authors caution that no causal link can be established, this data is relevant as it raises a plausible hypothesis: alterations in the blood-brain barrier could facilitate the accumulation of these particles and amplify existing neurodegenerative processes.
Impact on the Digestive System
The digestive tract represents another critical point of interaction. The presence of microplastics in the gastrointestinal system could alter the gut microbiota and compromise the integrity of the epithelial barrier—processes closely linked to systemic inflammation and chronic diseases. Studies describe that the ingestion of microplastics is associated with dysbiosis, a reduction in tight junction proteins, and increased intestinal permeability. This pathophysiological effect facilitates the translocation of particles, bacteria, and metabolites into the systemic circulation, a mechanism that could link this exposure to metabolic, inflammatory, and liver disorders.
Respiratory Exposure to Microplastics
Inhalation has also emerged as a significant exposure route. Research has identified microplastics in ambient air and respirable particles, placing these pollutants on par with other inhaled factors known for their impact on lung health. In patients with asthma and chronic obstructive pulmonary disease (COPD), experimental exposure to microplastic fibers generated cellular responses different from those observed in healthy epithelium. This finding suggests that vulnerability is not homogeneous and that patients with pre-existing respiratory disease might react differently to the same environmental exposure.
Mechanistic Insights and Health Implications
From a mechanistic perspective, microplastics have been associated with oxidative stress, activation of inflammatory pathways, and endocrine disruptions. Although much of this evidence comes from experimental models, the described mechanisms coincide with well-characterized processes in cardiovascular, neurological, and metabolic diseases.
In the cardiovascular domain, the presence of nanoplastics in atherosclerotic plaques has been documented and associated with an increased risk of events. The significance of this discovery lies not in a demonstrated coincidence but in biological consistency: persistent particles in vascular tissues could act as cofactors in disease progression.
Reproductive Health Concerns
Regarding female reproductive health, new experimental evidence reinforces concerns. A study presented in Argentina showed that concentrations of microplastics comparable to those detected in human fluids affect oocyte maturation and embryonic development in experimental models. The relevance of these data lies in the fact that microplastics have already been identified in follicular fluid, blood, and placenta. This means that exposure occurs at critical stages of the reproductive cycle and development, even though infertility is a multifactorial phenomenon and cannot be attributed to a single factor.
Implications for Medical Practice
In medical practice, the body of data compels healthcare professionals to recognize microplastics and nanoplastics as an emerging environmental factor capable of interacting with chronic diseases and altering their course. The available evidence describes a consistent pattern: microplastics enter the body, distribute in tissues, activate biological responses, and accumulate over time. The challenge now is to transform these scientific data into useful knowledge for healthcare through rigorous research, health monitoring, and informed regulatory decisions.
Article originally published on Medscape in Spanish.
🔗 **Source:** https://francais.medscape.com/viewarticle/lactu-microplastiques-corps-humain-2026a10000yw