Q: Can I prevent radioactive iodine intake by eating iodized salt? A: Iodine in iodized salt exists in the form of potassium iodate (KIO3), which is converted into iodine ions in the human gastrointestinal tract and blood to be absorbed and utilized by the thyroid gland, and the iodine content of iodized salt is set at 30 mg/kg in China. Based on the daily consumption of 10 grams of iodized salt per capita, 0.3 mg of iodine can be obtained. In contrast, iodine in the form of potassium iodide (KI) is present in iodine tablets, with an iodine content of 100 mg per tablet. Based on 30 mg of iodine per kg of iodized salt, adults need to consume about 3 kg of iodized salt at a time to achieve the preventive effect, which is far beyond the limit of salt intake that humans can tolerate. Therefore, prevention of radioactive iodine intake through consumption of iodized salt is not possible. Q: What are the side effects of excessive iodine intake on the human body? A: Excessive iodine intake can disrupt the normal function of the thyroid gland, leading to both hyperthyroidism and hypothyroidism. Exposure of pregnant women to high levels of iodine can lead to neonatal goiter and hypothyroidism. The incidence of hypothyroidism increases significantly with increasing iodine intake in both children and adults. It has also been shown that iodine supplementation in iodine-deficient areas can lead to elevated serum thyroid stimulating hormone (TSH) for a period of time. Most current reports indicate that iodine excess increases the prevalence of autoimmune thyroid disease. In addition, acute iodine toxicity can lead to abdominal cramps, diarrhea with blood in the stool, gastroduodenal ulcers, facial and neck edema, hemolytic anemia, metabolic acidosis, hepatic steatosis, and renal failure. Q: Some people say that applying iodine to the thyroid area can prevent radioactive iodine radiation, is this possible? A: Measures such as applying iodine to the thyroid gland to prevent radioactive iodine are not scientific. Q: Under what circumstances should I take stable iodine? What is the dosage? A: After a nuclear or radiation emergency, it is possible for a person to ingest radioactive iodine and concentrate it in the thyroid gland, exposing this organ to larger doses; taking stable iodine at this time will reduce the absorption of radioactive iodine by the thyroid gland. If stable iodine is taken at the same time as radioactive iodine inhalation, 90% of the deposition of radioactive iodine in the thyroid gland can be blocked. Taking stable iodine within a few hours of radioactive iodine inhalation can still reduce the amount of radioactive iodine absorbed by the thyroid by about half. The recommended dose for adults is 100 mg of iodine, for pregnant women and children between the ages of 3 and 12, the dose is 50 mg, and for children under the age of 3, the dose is 25 mg. Q: Who should be more careful when taking stabilized iodine? For newborns within the first month of life, the dose of stable iodine should be kept to the lowest effective level. Stabilized iodine should be used with caution or not for some people, for example, people with nodules in the thyroid gland, people with a cured proptosis goiter, people who have been treated with radioactive iodine, people with chronic inflammatory thyroid disease, people with unilateral thyroidectomy, people with subclinical hypothyroidism, people who are allergic to iodine, people with certain skin diseases (acne, eczema, psoriasis), etc. Q: How do iodine tablets (KI) protect against radiation? Physiologically, the main source of iodine in the body is the uptake by the thyroid gland, which relies on iodine to produce thyroid hormones; KI is stable iodine, which saturates the thyroid gland with iodine and thus prevents the intake of radioactive iodine. Iodine tablets do not protect against radioactivity from outside the body and radioactivity other than iodine that is absorbed by the body, so iodine thyroid blockade will be used in most cases in combination with other protective measures (e.g., concealment indoors, closed doors and windows). In order to take full advantage of the effect of iodine thyroid blockade with stabilized iodine, it is necessary to take stabilized iodine tablets before or as soon as possible after exposure. Even a few hours after the accident, the absorption of 50% iodine by the thyroid gland can still be prevented by taking them. To prevent inhalation of radioactive iodine isotopes, one tablet dose of stabilized iodine is usually sufficient to provide 24-hour continuous protection to the thyroid gland in the event of an incoming smoke cloud containing radioactive iodine isotopes. However, in a long-term continuous release situation, there is a risk of repeated exposure.