Plastic and Microplastic Pollution: From Ocean Smog to Planetary Boundary Threats
Plastics and microplastics (MPs) are emerging pollutants which have become a global environmental issue. They are abundant in oceanic and terrestrial environments, undergoing bioaccumulation and trophic transfer and potentially harming the entirety of mankind. Microplastics in the environment may be transferred to humans via different pathways, such as dietary intake and inhalation. This chapter summarizes the occurrences of MPs in seawaters, sediments, freshwaters, bivalves, and atmospheric fallouts. Generally, the spatial distribution of plastics and MPs in seawaters suggested that higher levels were found in areas which are closer to lands. Similarly, high levels of MPs in freshwaters, sediments, and aquatic organisms were associated with intensified human activities. The occurrences of MPs in bivalves from around the globe suggested a potential human exposure via dietary intake. Moreover, trophic transfer of MPs under controlled conditions suggested that MPs can be transferred to organisms at higher trophic levels. Plastics and MPs were found in atmospheric fallouts from urban, suburban, and remote mountain sites, suggesting the potential for long-range atmospheric transport of MPs. This chapter provides the reader with a snapshot of the plastic and MP pollution in the global oceans and planetary boundaries. Future studies are desirable for examining the exposure pathways, mechanisms of toxicity, and possible health effects.