A narrative review of microplastics in the indoor and outdoor environment, human effects, and ecological risks

Due to their widespread identification in all environmental compartments, Microplastics (MPs) are emerging pollutants that have garnered growing scientific and public attention over the last decades. Early research on MPs and their effects was limited to studies of terrestrial and aquatic ecosystems, but more recent studies have included MPs in the air. There is now considerable concern about the effects of MPs on pristine environments and urban air quality. A literature search was conducted in Science Direct and Google Scholar using the following keywords: microplastics, indoor environment, outdoor environment, human effects, and ecological risks. Finally, eligible studies were selected for the review. Textiles, such as clothes, carpets, and curtains, are the main indoor sources of MPs. As well as the primary sources of MPs outdoors, there are landfills, urban and home dust, and synthetic particles. According to current theories, human exposure to MPs occurs through dermal contact, ingestion, and inhalation. Recent research has demonstrated that inhalation is the principal mechanism of human exposure to MPs. Early toxicological research suggests that MPs may lead to inflammation and oxidative stress. However, there is growing concern about the possible leaching of hazardous chemicals used as plastic additives. Nevertheless, MP exposure and risk assessment in humans is still in its infancy, and more research on the presence of MPs in various indoor and outdoor environments is required to provide the knowledge base needed for regulations to protect human health and the environment from MPs.