What exactly are you referring to? The risk of radiation leakage? The risk of cooking food in them? The danger posed to those underneath a falling microwave oven?
I never cook or reheat food in plastic containers, but that's not due to the microwave oven but how plastics behave when heated. What are these people you're referring to talking about when they talk about safety?
risk of cooking food in them, Also some people were saying how it takes the nutrients out or something like that.