Microplastic toxicity is primarily caused by the particles themselves rather than sorbed chemicals
the verdict
INSUFFICIENT LEANING
refutedsupported
the weight of evidence
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Available reviews suggest that microplastics contribute to toxicity through mechanical stress and intrinsic particle properties alongside leachable additives and adsorbed contaminants, but the evidence only partially supports whether particles are the primary cause over sorbed chemicals.
Nanoplastics have emerged as widespread environmental contaminants with toxicological properties that differ from those of microplastics. While existing reviews often examine their effects on specific organisms, they rarely provide direct comparisons with microplastics. This review aims to comprehensively assess the toxic effects of nanoplastics on animals, with a comparative perspective highlighting their distinctions from microplastics. In mammals, nanoplastics cross the blood–brain barrier and induce oxidative stress, neuroinflammation, mitochondrial dysfunction, and synaptic disruption, with consequences ranging from cognitive impairment to Parkinson’s disease-like neurodegeneration. They also impair liver, kidney, intestinal, pancreatic, and reproductive function, with evidence of transgenerational toxicity. In aquatic organisms such as fish, crustaceans, bivalves, and aquatic invertebrates, nanoplastics compromise growth, immunity, reproduction, and metabolism, while in terrestrial invertebrates they cause gut toxicity, mitochondrial damage, immune suppression, and heritable defects. Across taxa, the dominant mechanisms involve oxidative stress, apoptosis, inflammation, and interference with metabolic and signaling pathways. Comparisons with microplastics reveal that while both particle types are harmful, nanoplastics generally exert stronger and more systemic effects due to higher bioavailability, cellular uptake, and molecular reactivity. Microplastics primarily impose mechanical stress, whereas nanoplastics disrupt cellular homeostasis at lower exposure levels, often acting at the subcellular level. Evidence also indicates size-, surface chemistry-, and concentration-dependent effects, with smaller and functionalized nanoplastics exhibiting heightened toxicity. Despite growing knowledge, significant gaps remain in cross-size comparative studies, long-term and multigenerational assessments, trophic transfer analyses, and investigations involving environmentally derived nanoplastics. Addressing these gaps is critical for advancing ecological risk assessment and developing mitigation strategies against plastic pollution.
To assess the impact of microplastics (MPs) on human health. The authors conducted a non-systematic review of articles published in English, Portuguese, French, and Spanish in the last decade in the following databases: PubMed, Google Scholar, EMBASE, and SciELO. The keywords used were: microplastics OR nanoplastics OR marine litter OR toxicology OR additives AND human health OR children OR adults. MPs are a group of emerging contaminants that have attracted scientific interest and societal attention in the last decade due to their ubiquitous detection in all environments. Humans can primarily be exposed to MPs and nanoplastics via oral and inhalation routes, but dermal contact cannot be overlooked, especially in young children. The possible toxic effects of plastic particles are due to their potential toxicity, often combined with that of leachable additives and adsorbed contaminants. Unless the plastic value chain is transformed over the next two decades, the risks to species, marine ecosystems, climate, health, economy, and communities will be unmanageable. However, along with these risks are the unique opportunities to help transition to a more sustainable world.
Data summary : MPs are a group of emerging contaminants that have attracted scientific interest and societal attention in the last decade due to their ubiquitous detection in all envi- ronments. Humans can primarily be exposed to MPs and nanoplastics via oral and inhalation routes, but dermal contact cannot be overlooked, especially in young children. The possible toxic effects of plastic particles are due to their potential toxicity, often combined with that of leachable additives and adsorbed contaminants.
19 Tire wear particles (TWPs), consisting of styrene butadiene rub- ber (SBR), are one of the most significant sources of MP worldwide, as are the road-marking paint particles created by the physical abrasion from vehicles and weathering.8 Transport (ambient wind flow), dispersion (local tur - bulence or disturbance), and deposition (downward air Impact
It is essential to clarify this issue for individuals with nor - mal barrier function and, more importantly, for those with compromised skin due to disease (e.g., eczema) or physical abrasion.58,89 Small particle size and skin stress conditions are criti - cal factors favoring penetration. The skin is protected by the stratum corneum, the outermost layer, which forms a barrier against injuries, chemicals, and microbial agents.73 Effects of MPs/NPs on the skin Human epithelial cells undergo oxidative stress from expo- sure to MPs and NPs, confirming the need to assess the effects of this exposure.
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