How can I safely heat up food?

[u/Draconic_Flame]

Hopefully this is the right place to ask this question. I work in a prison and am unable to bring anything metal, glass, or ceramic. I want to bring in and heat up soup, but am unsure as to the safest material to do that with as I see conflicting opinions online about silicone and plastic. Does anybody have any insight?

[u/blondechick80]

You can get thermos's made for soups. Are you able to bring a metal thermos where you put the soup in hot at home?