Which compound is effective at reducing the absorption of radiation targeting the thyroid?

Potassium Iodide is effective at reducing the absorption of radiation targeting the thyroid because it competes with radioactive iodine for uptake by the thyroid gland. When potassium iodide is administered, it saturates the thyroid with stable iodine, effectively blocking the absorption of radioactive iodine that might be released during a nuclear accident or other radiological emergency. This helps to protect the thyroid from the harmful effects of radiation, as the gland will preferentially uptake the non-radioactive iodine instead of the radioactive isotopes.

In contrast, sodium iodide, calcium iodide, and lithium iodide do not have the same effectiveness in saturating the thyroid gland in response to radiation exposure. They may not provide the same level of protection against radioactive iodine, making potassium iodide the specifically preferred choice for this purpose.