If you mentioned the poisons, then MMGW wouldn't be the argument and burning oil would be under much greater risk, and we can't have that because it would cost profits over the next few quarters to rectify. It is however noticed by those who care.
http://www.theguardian.com/environment/2009/apr/09/shipping-pollution
Apples & oranges, Henning.
The article mentioned the sulfur in the fuel. The PE plastic being used as an example in this thread doesn't contain sulfur.
The sulfur in fuel can be removed, and is removed in automobile gasoline, to avoid "poisoning" the catalytic converter.
Most diesel sold in the world, except possibly for marine application, is 10 to 50 PPM sulfur. In the USA, they started phasing out the marine diesel last year, at 500 ppm, replacing it with 10 ppm fuel.
The toxins from burning PE plastic at low temperature are mostly soot and aromatic hydrocarbons (benzene, napthalene, ect). This is avoided by burning it at higher temperature and more oxygen (air).
Chlorinated and flourinated plastics (PVC, PTFE) are a whole 'nother story- HF or HCl are formed (capture these in a scrubbing stack), also polyhalogenated aromatics. These last are very difficult to be rid of since they actually re-form as the gas cools- some of my undergrad research was on these compounds.
So, burning plastics is bad if they are halogenated. A proper facility can burn other plastics.
If one agrees with MMGW, one should reduce their burning of non-renewable hydrocarbons and products therefrom.
If you cite a reference, make it pertinent to the conversation.