Microplastics are ubiquitous environmental contaminants leading to inevitable human
exposure. Even so, little is known about the effects of microplastics in human health.
Thus, in this work we review the evidence for potential negative effects of microplastics
in the human body, focusing on pathways of exposure and toxicity. Exposure may occur
by ingestion, inhalation and dermal contact due to the presence of microplastics in
products, foodstuff and air. In all biological systems, microplastic exposure may
cause particle toxicity, with oxidative stress, inflammatory lesions and increased
uptake or translocation. The inability of the immune system to remove synthetic particles
may lead to chronic inflammation and increase risk of neoplasia. Furthermore, microplastics
may release their constituents, adsorbed contaminants and pathogenic organisms. Nonetheless,
knowledge on microplastic toxicity is still limited and largely influenced by exposure
concentration, particle properties, adsorbed contaminants, tissues involved and individual
susceptibility, requiring further research.