Potassium Iodide

Potassium Iodide is a salt with the chemical formula KI. Chemically, it is not very different from other iodide salts, and shares the same crystalline structure common to other halogen salts, such as ordinary table salt Sodium Chloride, NaCl.

For years, people have been using potassium iodide in photography. The salt is used in a simple reaction with silver nitrate to form silver iodide, a vital component for high-speed photographic film. It has also been in use as an expectorant to treat coughs and lung congestion.

Potassium iodide is also added to most table salts today, in small amounts. Because the element iodine is a necessary requirement for important metabolic enzymes made by the thyroid gland, humans need some quantity of it in their diet to remain healthy. In coastal areas where marine foods are eaten regularly, iodine deficiency is uncommon, however in more remote inland areas or arid equatorial climates it is much more common and leads to the serious condition ‘goiter’. Since potassium iodide looks and even tastes similar to sodium chloride, it makes a great iodine supplement in table salt. When you purchase a salt that is advertised as ‘iodized’, that means it contains potassium iodide.

More recently, potassium iodide has found a more dramatic application for use in nuclear emergencies. Nuclear fallout raises the levels of radioactive iodine in the environment to dangerous amounts. Radioiodine builds up to toxic levels in the thyroid and can cause serious damage to the gland. Potassium iodide works by competitively inhibiting radioiodine from building up in the thyroid.

In recent years, the FDA has approved potassium iodide tablets for use as a last resort form of protection in a nuclear emergency. The ideal protection is to evacuate a potentially radioactive area altogether. Potassium iodide does not protect someone from the other dangerous effects of radiation poisoning, including DNA damage, which leads to cancers and other life threatening illnesses. However, if evacuation is not feasible, potassium iodide tablets can at least offer protection from thyroid damage, which is one of the more immediate effects from too much radiation.

Potassium iodide is made in a simple reaction between a potassium base with hydroiodic acid. It can also be made by treating an iodine rich brine or saltpeter with potassium carbonate.

Potassium iodide is available over the counter in most areas. Like any other medication, you should talk to your doctor or pharmacist before using it.