Radioactive iodine is a form of iodine that emits radiation. It is commonly used in medical treatments, particularly for conditions related to the thyroid gland, such as hyperthyroidism and certain types of thyroid cancer. When ingested, it targets thyroid cells, helping to destroy overactive or cancerous tissue. This substance is produced in nuclear reactors and can also occur naturally in trace amounts. Due to its radioactive properties, it must be handled with care to minimize exposure. In medical applications, it is administered in controlled doses to ensure safety and effectiveness in treatment.