A rusted microwave oven can leak microwave radiation. Rust on the outer casing does not necessarily pose a threat to health but rust elsewhere can be more serious. Regularly disconnect the oven and check the inside walls and the door. Be aware that rust may not be immediately visible but may lie beneath the surface. Wiping a cloth over the surface can dislodge any loose coating material and show the rust beneath.
Arcing and rust
Arcing occurs when microwave rays reflect against metal and cause sparks during oven use. When sparks appear, check that none of the cooking utensils in the oven are metal. If they are not metal the interior coating of the oven may have corroded and exposed rust to the rays. This could be the cause of the arcing. At the first sign of sparks in a microwave, turn off the oven and disconnect from the mains.
Microwave radiation leakage
Rust on the inside of a microwave oven or on the door can cause microwave radiation to leak. The scientific community appears to agree that microwave radiation can affect biological cell processes within humans and cause problems such as cataracts, leukaemia and sterility. Exposure to microwaves can also lead to tissue damage such as blistering, necrosis and erythema. However, according to the Microwave Technologies Association, no evidence exists of a microwave oven ever causing harm.
Checking for radiation leaks
To confirm a radiation leak, put a mobile phone into a microwave oven and shut the door. Dial the phone's number. If the phone in the oven rings, microwaves are able to enter the oven. This suggests that radiation is also able to leak out, possibly through a patch of rust. Alternatively, place a fluorescent light bulb in front of a microwave oven that is on. Leaking radiation will cause the bulb to light up or flicker.
Clean the inside of a microwave oven after use with a damp hot cloth. If you fail to clean the interior of the oven, food and grease debris hardens and may cause rusting. Deal with stubborn stains as follows. Place a lemon slice in a bowl of hot water. Put the bowl in the oven and use a low setting on the microwave for a few minutes to create steam. Remove the stains with a damp hot cloth.