Cooked meat diaper: toxic?
According to the USDA:


  If packaging is accidentally cooked in a conventional oven, is the
  food safe to eat?
  
  Plastic packaging materials should not be used at all in conventional
  ovens. They may catch on fire or melt, causing chemical migration into
  foods. Sometimes these materials are inadvertently cooked with a
  product. For example, giblets may be accidentally cooked inside the
  turkey in their packaging or a beef roast may be cooked with the
  absorbent pad from the fresh meat packaging underneath.
  
  The giblet bag and the absorbent pad are clearly not intended to be
  cooked, however if this happens and the packaging materials remain
  unaltered (that is, do not melt or come apart) the cooked meat will
  not pose an imminent health hazard. If the packaging materials have
  melted or changed shape in some other way do not use the product.


Who are they kidding? Of course, they are altered. With deep regrets, I threw my roast away. (More info here.)