Microwaves are high frequency radio waves (radiofrequency fields) and, like visible radiation (light), are part of the electromagnetic spectrum. Microwaves are used primarily for TV broadcasting, radar for air and sea navigational aids, and telecommunications including mobile phones. They are also used in industry for processing materials, in medicine for diathermy treatment and in kitchens for cooking food. When used according to manufacturers' instructions, microwave ovens are safe and convenient for heating and cooking a variety of foods. However, several precautions need to be taken, specifically with regards to potential exposure to microwaves, thermal burns and food handling. Microwave safety: The design of microwave ovens ensures that the microwaves are contained within the oven and can only be present when the oven is switched on and the door is shut. Leakage around and through the glass door is limited by design to a level well below that recommended by international standards. However, microwave leakage could still occur around damaged, dirty or modified microwave ovens. It is therefore important that the oven is maintained in good condition. Users should check that the door closes properly and that the safety interlock devices, fitted to the door to prevent microwaves from being generated while it is open, work correctly. The door seals should be kept clean and there should be no visible signs of damage to the seals or the outer casing of the oven. If any faults are found or parts of the oven are damaged, it should not be used until it has been repaired by an appropriately qualified service engineer. Microwave energy can be absorbed by the body and produce heat in exposed tissues. Organs with a poor blood supply and temperature control, such as the eye, or temperature-sensitive tissue like the testes, have a higher risk of heat damage. However, thermal damage would only occur from long exposures to very high power levels, well in excess of those measured around microwave ovens. Thermal safety: Burn injuries can result from handling hot items heated in a microwave oven, in the same way as items heated using conventional ovens or cooking surfaces. However, heating food in a microwave oven presents some peculiarities. Boiling water on a conventional stove allows steam to escape through bubbling action as the water begins to boil. In a microwave oven there may be no bubbles on the walls of the container and the water will super-heat and may suddenly boil. This sudden boiling may be triggered by a single bubble in the liquid or by the introduction of a foreign element such as a spoon. People have been severely burned by super-heated water. Another peculiarity of microwave cooking relates to the thermal response of specific foods. Certain items with non-porous surfaces (e.g. hotdogs) or composed of materials that heat at different rates (e.g. yolk and white of eggs) heat unevenly and may explode. This can happen if eggs or chestnuts are cooked in their shells. Food safety: Food safety is an important health issue. In a microwave oven, the rate of heating depends on the power rating of the oven and on the water content, density and amount of food being heated. Microwave energy does not penetrate well in thicker pieces of food, and may produce uneven cooking. This can lead to a health risk if parts of the food are not heated sufficiently to kill potentially dangerous micro-organisms. Because of the potential for uneven distribution of cooking, food heated in a microwave oven should rest for several minutes after cooking is completed to allow the heat to distribute throughout the food. Food cooked in a microwave oven is as safe, and has the same nutrient value, as food cooked in a conventional oven. The main difference between these two methods of cooking is that microwave energy penetrates deeper into the food and reduces the time for heat to be conducted throughout the food, thus reducing the overall cooking time. Only certain microwave ovens are designed to sterilize items (for example baby’s milk bottles). The user should follow the manufacturer's instructions for this type of application. Misconceptions: To dispel some misconceptions, it is important to realize that food cooked in a microwave oven does not become "radioactive". Nor does any microwave energy remain in the cavity or the food after the microwave oven is switched off. In this respect, microwaves act just like light; when the light bulb is turned off, no light remains. [Broken External Image]:http://www.bubblews.com/assets/images/news/208081451_1389270696.jpg Source
