For some reason the eraser in one of my grade school classes was a communal one you had to ask for it from the teacher. It was one of those squarish rectangular kind. While I had it in my possession, unfortunately I had an itch inside my nose, I used the edge to kind of scrape clean the inner circle of my nostril. It did a good job, and I returned it to the teacher right after.
as long as you don’t microwave food in plastic containers, i’m sure you will be ok. if you are eating pre-prepared frozen dinners, its the dinners that are killing you, not the microwave. i use it to freshen stale bread a bit, and that’s about it. i wouldn’t be cooking a meal with them.