Microwave ovens do not make foods radioactive. Microwave ovens heat food by producing radiation which is absorbed by water molecules in the food. This makes the water molecules vibrate and produce heat, which cooks the food. Microwaves heat food. They do not make any changes to food that aren’t made in any other cooking method. So they do not make food any more likely to cause cancer. If you follow the instructions for use for a microwave oven there is no known harmful effect on humans. For more information on radiation emissions from microwave ovens please refer to the Australian Radiation Protection and Nuclear Safety Agencywebsite.