Which method is not safe for thawing frozen food?

Thawing food safely is crucial for preventing the growth of pathogenic bacteria that can occur when food is not kept at safe temperatures. Thawing at room temperature is unsafe because it allows the outer layer of the food to reach a temperature conducive to bacterial growth while the inside remains frozen. As food thaws unevenly at room temperature, it could sit in the temperature danger zone (between 41°F and 135°F) for too long, increasing the risk of foodborne illness.

In contrast, thawing methods such as in the refrigerator, under cold running water, and in the microwave (when the food will be cooked immediately after) are considered safe. Thawing in the refrigerator maintains a consistently safe temperature, while cold running water can help bring the temperature of the food down quickly and safely. Using a microwave is safe as long as the food is cooked right afterward, preventing any prolonged exposure to temperatures that encourage bacterial growth.