Dear Colleagues,

The production of plastics is constantly increasing, and this trajectory is set to persist until 2050. Microplastics (particles smaller than 5 mm) and nanoplastics (particles smaller than 1000 nanometers) are generated by the weathering and breakdown of plastic objects, car tires, clothing, paint coatings, and leakage of preproduction pellets and powders. The ubiquity of microplastics in the global biosphere raises increasing concerns about their implications for human health. Microplastics and nanoplastics (MNPs) enter the human body through ingestion, inhalation, and skin exposure, where they interact with tissues and organs. MNPs have been found in selected human tissues, such as the placenta, lungs, and liver, as well as breast milk, urine, and blood. Like particulate air pollution, MNPs can cross the cell membrane and trigger oxidative stress and inflammation, eventually increasing the risk of developing inflammation-based disorders, including chronic inflammation and cancer.

In addition, MNPs can lead to microbial dysbiosis by altering the microbial composition and immune system homeostasis, disrupting mucus layers, and increasing intestinal permeability. However, major knowledge gaps are still present. Indeed, owing to their persistence, wide size range, and complex nature, MNPs may exhibit distinct specific properties with a different and broader toxicity profile compared to those of other ambient particles. Therefore, technological advancements are urgently needed, together with new studies to evaluate the impact of MNPs on human health.

This Special Issue aims to bring together cutting-edge studies that further our understanding of the complex interplay between MNPs and health issues. We welcome multidisciplinary contributions, involving scientists from environmental and medical sectors as well as polymer researchers.

Dr. Amedeo Amedei and Dr. Cinzia Parolini
Guest Editors