According to everything i can find the chance of the plasticizers getting into your food is slim to none. This is an old article but seems to say the same as the other things I read.
https://www.huffingtonpost.com/2011/11/30/microwaving-with-plastic-wrap-safety_n_1121271.html
While Huffington Post offers a vomitous volume on all things political...as do far too many others nowadays....I would not think of any them as an authority on health and wellness. NIH, FDA, CDC, and other agencies...perhaps. And - frankly....a lot of the internet today has suspect objectivity. In other words, WHO paid for the article to be written? What was the vested interest?
Polymeric materials, including re and post reacted polyols, monomers, epoxies, methyl-methacrylates ( acrylics as a group..),vinyl and poly-esters, urethanes, PVCs, and HDPEs all materials that I have worked with in a number of manufacturing and field applications.
There are reasons that plastics are marked with specific symbols is to give us an idea about their safety for food containment
under specific conditions. In other words - one plastic that can contain acidic materials....may not be safe for heating any foods in. So...Lets look at some real world plastics/plasticizer issues. But the numbering system is not a complete story.
How about this: we are currently reading and hearing about "micro plastics" in bottled water. This is NOT water that has been heated, or exposed to microwave radiation. It has been filtered ( at best...buyer beware, read the label, etc...)
Your car's dash. If left in a sunny, hot environment, it will - with time - dull, become hard and brittle, ...and crack. Why? Plasticizer migration. Glass and porcelain are as inert as possible.
SO - the more flexible the plastic, the higher the percentage of plasticizers. Heat, UV and IR can all accelerate greatly the plasticizer migration out of molecular bond. Since we know that heat can accelerate the migration....WHY would you want to use plastics in a microwave oven?
We each pick our "poisons".....Some folks still believe that cigarettes will not hurt them. It's just the chemicals in the tobacco......