SSKI (i.e., the "saturated solution of KI" rather than tablets) may be used in radioiodine-contamination emergencies (i.e., nuclear accidents) to "block" the thyroid's uptake of radioiodine, at a dose of two drops of SSKI per day for an adult. This is not the same as blocking the thyroid's release of thyroid hormone, for which the adult dose is different (and is actually higher by a factor of 7 or 8), and for which KI anti-radiation pills (not a common medical treatment form of KI) are not usually available in pharmacies, or normally used in hospitals, or by physicians. Although the two forms of potassium iodide are completely interchangeable, normally in practice the SSKI solution, which is the historical medical form of high dose iodine, is generally used for all medical purposes save for radioiodine prophylaxis. For protection of the thyroid against radioiodine (iodine-131) contamination, the convenient standard 130 mg KI pill is used, if available. As noted, the equivalent two drops of SSKI (equaling the dose of one KI pill) may be used for this purpose, if the pills are not available.