Humans are exposed to micro-and-nano plastics (MNPs) through various routes, but the adverse health effects of MNPs on different organ systems are not yet fully understood.
This review aims to provide an overview of the potential impacts of MNPs on various organ systems and identify knowledge gaps in current research.
The summarized results suggest that exposure to MNPs can lead to health effects through oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disrupted microbial metabolic pathways, abnormal organ development, and carcinogenicity. There is limited human data on the health effects of MNPs, despite evidence from animal and cellular studies. Most of the published research has focused on specific types of MNPs to assess their toxicity, while other types of plastic particles commonly found in the environment remain unstudied. Future studies should investigate MNPs exposure by considering realistic concentrations, dose-dependent effects, individual susceptibility, and confounding factors.
Introduction
The industrial benefits of plastics are widespread; production is expected to quadruple by 2050.1 However, their widespread distribution and presence in various environmental niches (air, water, or land) make humans vulnerable
to exposure through multiple routes (Domenech and Marcos, 2021).
Plastic materials are broken down through oxidation, hydrolytic degradation, photodegradation, mechanical degradation and biodegradation, producing various forms and sizes of debris, leading to the term “microplastic”2 and,
more recently: plastic nanoparticles (≤100 nm),
nanoplastic (100–1000 nm), microplastics (1 μm < 1000 μm), mesoplastics (0.5–5 cm), macroplastics (5–50 cm), and megaplastics (>50 cm).3,4
Microplastics (MPs) are added to commercial products
(primary MPs), including cleaning products and
fertilisers, or are produced through the degradation of larger plastic materials (secondary MPs).5 Nanoplastics (NPs),
a subset of MPs, are typically generated either by the fragmentation of MPs or released from other sources such as plastic materials used in electronics, paints, adhesives
etc.6,7
Secondary MPs and NPs are generally produced by the breakdown of macroplastics via shear forces,8
accounting for about 70–80% of total plastic released into the natural environment,
while primary MPs account for 15–30%.9 MPs are present in different forms, such as microfibers from textiles (diapers, fleeces, and disposable masks),
fragments, plastic pellets and nurdles from
industry, foam, and microbeads.10,11
Humans are exposed to MNPs through ingestion, inhalation and skin contact,12,13
Ref
. 2023 Dec 6;99:104901. doi: 10.1016/j.ebiom.2023.104901
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