Microwaves are used for communications, radar, intrusion alarms, door openers, and medical therapy, but they are most commonly used for cooking. Metal reflects microwave radiation, but dry nonmetallic surfaces allow microwaves to pass through with little or no heating effect. Organic materials, however, are extremely heat conductive. Because microwaves can penetrate organic materials, including tissues, thermal burns and other effects may result from microwave exposure.
Microwave ovens are very safe when kept in good working condition and used properly.
They do not serve as a source of exposure to harmful microwaves. Even though microwave ovens are not a source of harmful radiation exposure, they should be properly used and maintained. Do not use a microwave oven if it is damaged. Ensure that microwave ovens are clearly labeled for laboratory use or food preparation only. Microwave ovens should only be repaired by trained personnel.