用微波爐叮食物真係會致癌的??

This is totally NOT true. Microwave heated food is completely safe for consumption.
Microwave heating is attributed to the absorption of electromagnetic energy by water molecules in the food. These water molecules vibrate vigorously and friction between the vibrating molecules produces heat. Thus the food is cooked.
Hence, the energy deposited on the food from microwave is just heat energy, which is no different from the heat energy absorbed by the food when it is cooked in an ordinary oven.
What people say that microwave cooked food would induce cancer is because of the use of unsuitable containers. Some plastic container would release toxic materials under high temperature. This toxic materials are carcinogenic (i.e. cancer causing). If such container is used to carry the food and heated in a microwave oven, surely the release of toxic materials from the container will contaminate the food, the consumption of which is definitely bad to health.
This is the saying why the use of wrapping paper that is suitable for microwave cooking is safe to health, since such paper could stand high temperature and would not disintegrate or release any toxic substance.