Definition of Emerging Microplastic Syndrome Based on Clinical and Epidemiological Evidence: A Narrative Review

Microplastics and nanoplastics (MNPs) are pervasive contaminants infiltrating water, food, and human tissues. The sharp rise in plastic production—with over half manufactured between 2003 and 2022—has heightened concerns about their health impacts. Methods included: (1) a literature review of clinical studies on MNPs focusing on human health and (2) analysis of Standardized Mortality Rates (SMRs) for 44 groups of diseases in Italy (2003–2022, Italian National Institute of Statistics, ISTAT data). The outcomes suggest that MNPs have been connected to pathological alterations in a number of organ systems, such as the gastrointestinal tract (intestine, liver, and pancreas), breathing system, eyes, brain, and vascular structures. SMRs increased significantly in only eight of the 46 illness categories examined between 2003 and 2022. The analysis of clinical and epidemiological data allows us to identify a possible clinical assessment consisting of a 30-variable diagnostic questionnaire (Chicago Cluster Evaluation System, CCES), encompassing laboratory markers, clinical signs, and ultrasound findings. A binomial distribution model suggests that more than 8 positive responses may indicate a presumptive diagnosis of Microplastic Syndrome (MP-Sy). This framework reflects observed clinical/epidemiological patterns and provides a foundation for hypothesis-driven research. Prospective longitudinal studies are warranted to validate the proposed definition and its diagnostic utility. The aim of the present study is to propose a preliminary clinical framework for a potential MP-Sy integrating toxicological evidence with epidemiological data, define diagnostic criteria and assess their consistency with observed disease trends.