Since 1970, lumps of plastic breakage into micro/nano pieces has been clearly shown a serious and large source of ocean pollution. To clarify in detail the course of this impact, thermoplastics were decomposed at natural conditions kinetically. And field surveys conducted on four thousand sand and water samples including these at deep-sea sites from around the world during the period, 2000 to 2015. All samples were found to contain styrene oligomers (SOs), that had been generated from drifting polystyrene (PS) degradation. Lumps of plastic not only break up into micro/nano-fragments but also degrade into their basic structure units of plastic. From 1950 to 2015, 4.2 billion metric tons (MT) of SOs were shown to be generated from drifting PS. The monomers are newly and highly significant source of pollution of marine ecosystem directly and global warming of planet and should be given the utmost serious attention.