Complete and utter crud Will, they are taking the royal pee or just don't know themselves. Microwaves are intant (ish) will be gone by the time you open the door.
Microwaves will not be in the food, they purely excite the water in the cells, and therefore heat it up.. nothing scary about it!
What is less understood however is the effect on dairy products as apparently that can cause cancerous type chemicals to be produced in the microwave process. I DO NOT know if this is true however, so I'll let you research it yourself. But once again.. microwaves or radiation will NOT be present in the food when you eat it.
Quit using the microwave and start doing stir fry's and using the oven

Much nicer way to cook, and much tastier... microwave food is complete crap, and I have no idea why you even bother, unless you've been caught short as such.
Oh and there is a scare mongering thing about frying food as well where it alledgely causes cancerous chemicals to be created somehow.... once again do some research.
The only thing I would say, is look at the number of people in westernised countries dying from cancer and those in other 'less packaged' food orientated countries. Our lifestyle (for whatever reason), food habits, cars , whatever cause us to get cancer somehow. Perhaps it's just genetic... who knows....