You have to have a good handle on what you're putting in. It must be a nightmare to analyze some of this older stuff. Fire may be one of the oldest forces known to humankind, but what it does to a mixture of hazardous chemicals and metals is, in many ways, still not completely understood. Metals and chemicals change forms and interact in fire. For instance, operators may feed one form of chromium into the incinerator, but it could change to a more toxic form in the flames.
Incineration can even create compounds that scientists have yet to identify.
I'm not going to give incineration blanket approval, but I think it can have acceptable risk if it's done properly. The technology doesn't yet exist to continuously monitor everything coming out of an incinerator stack. The EPA and private companies are working on such a monitor but have not yet created one. And it's kind of like rocket science trying to hook onto this dirty old stack. We just haven't gotten it to work yet.