The claim: Food heated in a microwave oven becomes radioactive and when you eat or drink it, the radiation damages genes in cells in your body, causing cancer.
The facts: Microwaves are a form of radiation but they are not known to cause cancer. Microwaves are a type of low energy radiation called 'non-ionising' radiation, which is different from the high energy radiation in X-rays, which can damage DNA. Also while microwave ovens use microwave radiation to heat food, this does not mean they make food radioactive.