In recent years, the infiltration of micro- and nanoplastics into the human body has shifted from a speculative concern to a pressing scientific reality. These microscopic plastic particles, pervasive in the environment, have raised profound questions about their ability to permeate biological barriers and influence human health on a molecular level. A groundbreaking review by Pan, Janjua, Thomas, and colleagues, published in Microplastics and Nanoplastics (2026), delivers an exhaustive, critical analysis of the extent to which these tiny plastic particles penetrate human tissues, posing new challenges and opening vast avenues for research.
Microplastics, generally defined as plastic particles less than 5 millimeters in size, and nanoplastics, which fall below 1 micrometer, have become ubiquitous in ecosystems, air, water supplies, and even the food chain. Due to their diminutive size, they are hypothesized to cross physical and biochemical barriers in the body that larger particles cannot. The review paper dives into the latest evidence concerning how these particles move beyond the gut epithelium after ingestion, permeate pulmonary tissues following inhalation, and even traverse the blood-brain barrier, disrupting delicate neurophysiological processes.
One of the central technical themes of the review is the characterization of the physicochemical properties that govern the interactions of micro- and nanoplastics with cell membranes and biological fluids. Surface charge, hydrophobicity, polymer composition, and particle shape critically influence the degree to which these plastics may adhere to cell surfaces or become internalized via endocytosis or passive diffusion. These complex mechanisms, the authors argue, are essential to understanding bioavailability and biodistribution because they vary widely depending on particle origin and environmental conditioning.
Equally vital is the elucidation of the immune system’s role in detecting and responding to these plastic particles. Macrophages and other immune cells have been demonstrated to engulf nanoplastics, which may provoke chronic inflammation or oxidative stress if clearance mechanisms falter. The review rigorously compiles data from in vitro studies indicating the generation of reactive oxygen species and pro-inflammatory cytokines triggered by nanoplastic exposure, potentially leading to cellular apoptosis or necrosis. These immune responses, if persistent, could culminate in tissue damage relevant to diseases such as asthma, atherosclerosis, or even cancer.
Crucially, the authors dissect the pharmacokinetics of micro- and nanoplastics, highlighting gaps in knowledge about their absorption, distribution, metabolism, and excretion (ADME) profiles. Animal models employed to mimic human exposure have revealed that nanoplastics can cross the intestinal barrier via disrupted tight junctions and enter the lymphatic system and systemic circulation. However, substantial uncertainty remains around the long-term bioaccumulation of these particles in organs such as the liver, kidneys, and brain, underscoring the need for more longitudinal studies employing advanced imaging and tracer techniques.
The biodegradation—or lack thereof—of these plastics inside the human body forms another cornerstone of the review. Unlike naturally occurring nanoparticles, micro- and nanoplastics are chemically inert and resistant to enzymatic breakdown, allowing them to persist and potentially interfere with normal cellular functions. This chemical resilience raises concerns about their capacity to act as vectors for co-pollutants, such as persistent organic pollutants or heavy metals, which might adsorb onto their surfaces and intensify toxicological effects within human tissues.
The impact of micro- and nanoplastics on the human microbiome is another emerging frontier explored in the review. Gut microbiota play an invaluable role in health and immunity, and preliminary studies suggest that ingestion of these particles may alter microbial diversity, impairing gut barrier integrity and influencing systemic inflammation. These findings, the authors emphasize, could have far-reaching implications for metabolic diseases, autoimmune conditions, and neurological disorders linked to gut-brain axis dysregulation.
Central to the discourse is a comparative evaluation of exposure routes. Inhalation emerges as a surprisingly efficient entry portal, with airborne nanoplastics small enough to penetrate alveolar sacs and gain access to the bloodstream. Occupational hazards in manufacturing and waste processing industries compound this risk, warranting urgent epidemiological surveillance. The review additionally flags the contamination of drinking water supplies and seafood, highlighting that dietary intake remains a primary human exposure pathway.
To transcend current knowledge limitations, the authors advocate for integrating multidisciplinary approaches, including analytical chemistry, toxicology, environmental science, and molecular biology. Recently developed high-sensitivity mass spectrometry and fluorescence tagging methods enable precise quantification of nanoplastics in biological matrices, propelling exposure assessment into a new era. In vitro organ-on-chip models further allow dynamic investigation of plastic particle interactions with human tissues under physiologically relevant conditions, circumventing some ethical and practical constraints of in vivo studies.
Risk assessment frameworks are meticulously scrutinized in the review, revealing an urgent need to redefine safety thresholds in light of micro- and nanoplastic pervasive exposure. Conventional toxicology primarily addresses chemical contaminants, yet the particulate nature of plastics introduces novel biological impacts that current regulatory paradigms insufficiently address. The authors urge policymakers to consider cumulative and synergistic effects, especially given the complex cocktail of environmental pollutants humans face simultaneously.
Importantly, the review also contemplates human variability in vulnerability to plastic particle permeation. Genetic predispositions, pre-existing illnesses, age, and nutritional status can modulate both particle uptake and physiological responses, complicating population-level risk predictions. Understanding these individual differences is pivotal for developing targeted interventions and protective measures, especially among at-risk groups such as children, pregnant women, and immunocompromised individuals.
Among the most compelling revelations relates to nanoplastics’ potential to breach the blood-brain barrier, a critical safeguard against neurotoxins. Experimental work evaluated in the paper demonstrates that certain nanoplastics can induce subtle disruptions in endothelial tight junctions and may accumulate in brain parenchyma, potentially perturbing neural function. This finding opens a Pandora’s box of questions about links between ubiquitous environmental plastics and neurodegenerative diseases, warranting urgent mechanistic and epidemiologic research.
The authors also explore the socio-economic and ethical dimensions surrounding micro- and nanoplastic pollution. The disproportionate exposure burden on marginalized communities, often residing near plastic manufacturing or waste sites, raises issues of environmental justice. Effective public health responses must incorporate social determinants and equitable access to clean environments while balancing industrial and consumer behavior reforms aimed at reducing plastic waste generation.
Ultimately, this comprehensive review challenges the scientific community, regulatory bodies, and the public to rethink the complex interface between micro/nanoplastics and human biology. It calls for pioneering research agendas and heightened global cooperation to understand, monitor, and mitigate the silent invasion of plastic particles inside the human body. The intricate biological ramifications stretch beyond toxicology—the issue implicates broader questions of how humanity measures, interacts with, and reshapes the material world in the Anthropocene era.
In conclusion, the seminal work by Pan et al. consolidates current insights and underscores critical knowledge gaps about micro- and nanoplastic permeation in humans. It serves as both an alarm and a roadmap, urging accelerated scientific inquiry that integrates cutting-edge technology with holistic perspectives on human health and planetary stewardship. The discoveries highlighted in this review are poised to transform environmental health sciences and stimulate viral discourse about one of the most insidious, invisible threats of modern living.
Subject of Research: The permeation and biological effects of micro- and nanoplastics in the human body.
Article Title: A critical review of micro- and nanoplastic permeation in the human body.
Article References:
Pan, Y., Janjua, T.I., Thomas, K.V. et al. A critical review of micro- and nanoplastic permeation in the human body. Microplastics & Nanoplastics (2026). https://doi.org/10.1186/s43591-026-00177-6
Image Credits: AI Generated
