Sticking your hand into a microwave oven to grab food immediately after turning it off is generally not recommended, but the risk of cancer is not a significant concern in this scenario. Microwaves emit non-ionizing radiation, which is different from ionizing radiation (such as X-rays or gamma rays) that is known to increase the risk of cancer. Non-ionizing radiation, like that produced by microwaves, does not have enough energy to directly damage DNA or cause cancer.
However, putting your hand inside a microwave oven immediately after use can still be dangerous due to the residual heat. Microwaves heat food by generating microwaves that cause water molecules to vibrate, creating heat. This heat is absorbed by the food, but the walls and other surfaces inside the microwave can also become hot during the cooking process.
When you turn off the microwave, the heat does not dissipate immediately. The surfaces of the microwave, as well as the food inside, may remain hot for a period of time. Reaching into the microwave immediately after use can lead to burns or scalds from the residual heat.
To avoid burns or injuries, it's best to use oven mitts or other protective coverings when handling hot items from the microwave. Give the microwave and the food a few moments to cool down before attempting to retrieve the food. It's important to prioritize safety and take precautions to prevent accidents or injuries in the kitchen.