Microwave Cooking Does Not Cause Cancer: ARPANSA
Radiations are of several types and are grouped under the categories of ionizing and non- ionizing radiations.
Ionizing radiations could be harmful as the energy can get into the cells and change the chemical composition and working of the cells. Too much exposure to ionizing radiation can cause burns, radiation sickness, and cancer. Ionizing radiation can damage any cell in the body. But it all depends on how much radiation the cell gets.
Non-ionizing radiation does not carry enough energy to change cells chemically. The radiation from the microwave oven is non-ionizing. Other examples of such radiation are UV rays from the sun, electromagnetic fields, radiowaves, and radiation waves from household electrical appliances etc.
Microwaves are non-ionizing radiations and are a part of the electromagnetic radiation spectrum. They are very high frequency radio waves. Infrared radiation, ultraviolet light and X-rays are also electromagnetic radiations, but have shorter wavelengths than microwaves.
Metallic materials reflect microwaves whereas most non-metallic materials such as glass and plastics are partially transparent to microwaves. Food and even people, absorb microwave energy. An electronic device called a magnetron is used to produce microwaves. These microwaves then pass into the oven cavity where they are reflected around the oven walls and absorbed by the food placed in the oven. Microwaves penetrate the food or liquid and agitate the water molecules in the food to cause molecular friction, thereby producing heat. This results in a rapid rise in temperature.
Extensive researches have provided no substantiated evidence that microwave exposure, at any level, could either cause or promote cancer. Microwaves generated in microwave ovens do not exist once the electrical power to the magnetron is turned off. They do not remain in the food once the power is turned off. Going by this logic they cannot make the food or the oven, radioactive. Therefore the food cooked in a microwave oven cannot be straight away labeled as a radiation hazard.
All microwave ovens have at least two safety interlock switches which stop the generation of microwaves immediately when the door is opened. The design of microwave ovens is such that the microwaves should be contained within the oven, but it is still possible for some leakage to occur around the doors of certain microwave ovens.
There are tests which assess the level of microwave leakage and according to the Australian/New Zealand Standard for Household appliances, 'the microwave leakage at any point 50 millimetres or more from the external surface of the appliance shall not exceed 50 watts per square metre'. The experts view the recommended limit as conservative and feel that leakage levels moderately above the limit will have no adverse effects on health.
However, organizations providing testing services say that the microwave oven leakage in excess of the recommendations is rare and an oven in good condition and used appropriately is safe.
Studies are looking at the possible link between microwave ovens and cancer. Some studies suggest that there may be a link but other studies haven't been able to prove this at all. Microwaves produce a magnetic field while they are in use. But this doesn't tend to last long as we tend to cook for very short periods. The emission stops once the door is opened.
Most experts say that microwave ovens don't give off enough energy to change or damage the genetic material (DNA) in cells. So they definitely cannot cause cancer.
Although microwaves are safe to use, cooking in them can affect the nutritional value of some foods, viz., loss of vitamins from fruit and vegetables. But nutrients are lost when heating foods irrespective of the cooking method employed - boiling, grilling, frying or even steaming. It is the extent of cooking and water loss from the food that are the major determinants of the nutrient content of a food.
Vitamins are extremely heat sensitive and water soluble. Cooking food on very high temperature for a long time such as in baking, frying or draining away the water used during cooking are reasons for major nutrient losses.
The best way to keep as many nutrients as possible in the food is to use as little water as you can and not overcook them. Therefore as long as we do not overcook the food, microwave cooking can actually be quite healthy since it uses only a little water and cooks or warms the food in just a few minutes.
Reference: The Australian Radiation Protection and Nuclear Safety Agency, 2011 updates on radiation emissions from microwave ovens. Cancer Research UK, London.