Bakelite to microplastics contamination: A comprehensive review on microplastics sources, distribution and their characteristic existence in environment

Polymers used as a commodity are prevalent as plastic products in day-to-day life globally. Mass production and mishandling of plastic waste turns out to produce contaminants in micro and nano size ranges. The life span of microplastics (MPs) constitutes a larger threat due to its existence in all spheres of earth. Their footprint and lifetime in environmental conditions is galactic, thus it is necessary to conduct a literature study and review on substantial sources, their distribution mechanisms and transformation process. MPs are formed under natural conditions by physical, chemical and biological forces. In this context, a comprehensive review on origin, deterioration, dispersion, sorption, motility, and settlement of MPs across ecosystems is evaluated. Major findings of review showed MPs have emerged in daily human food intake of about 0 to 1674 numbers/kg in salts and 52 particles/fish respectively. This review identifies that environmental concentration of MPs increases rapidly with one or more sources identified every year. This review enhances understanding of widespread distribution of MPs and potential health threats to human due to their abundance and size. Further, the number of research on plastic alternative products and additives for mitigating plastic pollution is less. Thus, this review also emphasizes the key aspects of focus to conduct research towards evidence based human health studies of MPs and developing effective strategies in mitigating plastics.