Potassium Iodide (KI) is touted as an anti-radiation pill. It’s supposedly one thing we all need in the event of a radiation emergency — a must have for first responders. While this may be true in some cases, there’s still a lot of misinformation out there about what KI is and what it can be used for.
For starters, KI is a thyroid-blocking agent. KI fills your thyroid gland with “clean” (non-radioactive) iodine so your thyroid won’t absorb radioactive iodine in the atmosphere. But keep in mind that, according to the FDA, “It is not a general radioprotective agent” (http://www.fda.gov/cder/drugprepare/KI_Q&A.htm#Can%20KI%20be%20used).
Radioactive iodine is a byproduct of nuclear fission. Nuclear fission is the process by which nuclear power plants produce heat, and nuclear bombs use fission to make mushroom clouds. If radioactive iodine is not present, KI is useless. Radioactive iodine is not a byproduct of a dirty bomb, so KI would not be of use in the most likely nuclear situation we will face.
Regardless, if this type of emergency does occur, your local emergency management will determine whether or not to recommend that people in the area take KI. Of course, if this is recommended, it is the individual’s choice whether or not to take KI.
Further, there’s a whole host of considerations to make before you choose to take KI. A couple of links with good resources are http://www.fda.gov/cder/guidance/4825fnl.htm and http://www.fda.gov/cder/drugprepare/KI_Q&A.htm#Can%20KI%20be%20used.