Hi there, wow... fantastic job researching this. I work on the other end of the stick: dealing with the residual plastic pollution created by the disposal of these bags. We have been studying the general toxicity of the photodegradation of the bags and the air contamination released by the burning of the bags (which is the most often means of disposing them in villages in south east asia). I hadn't even thought of the pollution caused by their manufacture. If you're interested in pursuing this deeply, I highly recommend this journal article that examines the different ways plastics degrade into toxins. Google: "Plastic Degradation and Its Environmental Implications with Special Reference to Poly(ethylene terephthalate)" Meanwhile, I am just getting going on Steemit and will soon be posting lots on plastic and in particular, its transcension. :-)