Microplastics and Human Health: A Review of Possible Risk and Clinical Consequences

Abstract

In 2023, annual worldwide plastic production rose to 400.3 million metric tons, resulting in widespread nano- and microplastic (NMP) pollution and significant risks to human health. NMPs are defined as plastics that measure 1 nm to 5 mm in size. NMP exposure can happen through ingestion, inhalation and dermal contact, and have been detected in brain, lung, blood and placental human tissues. This review will provide relevant scientific evidence about exposure pathways and biological impacts of NMPs, including cytotoxicity, genotoxicity and inflammation reported in in vitro studies, as well as neurological, reproductive, and skeletal impacts observed in retrospective in vivo evidence. The main route of human exposure to NMPs is through the ingestion of contaminated food and water. Thus, humans have been reported to ingest upwards of 5 g of microplastics each week. Humans can also be exposed through inhalation and dermal contact, followed by either inhalation or dermal absorption into the tissues or body. There are numerous issues and gaps within the literature that hinder risk assessment attempts including, but not limited to, methodological inconsistencies, underreported or unpublished long-term study outcomes, and ethical challenges in experimental research and studies. The path forward includes the need for standardized protocols, diverse in vitro human models, ethical and longitudinal in vivo methods, and interdisciplinary collaboration and research. The promotion of biodegradable plastics and public education campaigns can also help reduce NMP exposure. The review demonstrates the urgent need for integrated research approaches to better understand and reduce NMP risks to human health, along with safer materials and informed policy intervention