Microplastics in Human Health

In the early twenty-first century, the discovery of microplastics—tiny plastic particles less than 5 mm—initiated a surge in research. Microplastics, characterized by their origin, shape, and monomeric units, have been detected across freshwater and marine environments, raising concerns about their impact on marine biota. Recent studies have uncovered microplastics in diverse sources, including food products and human consumables, yet the physiological effects on human health remain poorly understood. A considerable amount of plastic waste generated decades ago still resides in landfills. Its degradation, along with the production of plastic products, has led to the accumulation of microplastics (size <5 mm) and nanoplastics (size <1 μm) in our surroundings, including both the terrestrial as well as the aquatic environments. The atmosphere we reside in, the food and water that we consume, and the personal care products that we use have been categorized as the most common sources of exposure to microplastics by humans. These tiny contaminants come in variable shapes, sizes, and types and affect human health considerably. Despite the presence of biological barriers, these particles can navigate their way through the cells to enter the body and pose a threat at chemical, cellular, and organ levels, leading to severe conditions like alteration of gene expression, inflammation in the GI tract, and several other metabolic effects. Another fate of these microplastics could be their biodegradation inside the body, potentially via enzymatic digestion by the residing gut microflora and the intracellular mitochondrial enzymes. The chapter thoroughly explores the prevalence of microplastics in the surroundings, their types, their journey to translocate from the source to inside the human body, and the consequences of the same.