People who are supposed to restrict their sodium intake for health reasons can use potassium chloride instead of sodium chloride (salt) for seasoning. Potassium chloride is sold in every grocery store as one or another brand of "NoSalt", "Diet Salt", etc. Some are a blend of sodium and potassium chlorides, others like this one are nearly pure potassium chloride and/or other potassium salts.
This is by and large a good thing. As a reader, Phil Karn, has pointed out, potassium is a necessary nutrient, and for people with high blood pressure displacing sodium with potassium is an important step towards reducing it.
But interestingly, naturally occurring potassium contains a small but measurable fraction of potassium-40, which is radioactive. I bought a container of it expecting it to register barely, if at all, on our Geiger counter. Instead it is really quite unmistakable: A plate with about 4 tablespoons spread out registers over 400 counts per minute. Of course, one normally wouldn't eat that much at a time: Using a few assumptions about how much people might eat, I would guesstimate that steady use might result it doubling the average amount of background radiation you're normally exposed to. This is not significant considering that just living in certain cities, near a granite building, etc, will more than double the average background level. Interestingly, I have learned from Phil Karn that Issac Asimov long ago made a similar calculation: That the radiation dose from potassium in the body is roughly equal to the radiation dose from the other natural sources put together. This website has an interesting speculation about the role of potassium's radioactivity.
If you're currently using a salt substitute, please don't stop because of this information! The risk from radiation is utterly insignificant compared to the risk from high blood pressure. Furthermore, the amount of potassium in your body is probably about the same from day to day regardless of whether you're eating salt substitute or not. This is because the body needs a certain amount, and generally gets more than it needs in food whether you are using salt substitute or not: The excess is excreted efficiently.
Nevertheless, I'm keeping it in our Hot Box just for fun. It's a great demonstration of the importance of location: Outside the Hot Box it's just a container of salt, inside the Hot Box it's a real conversation piece.
There is a lot of interesting information about the surprising places you can find radiation in this book.
Source: Grocery Store
Contributor: Theodore Gray
Acquired: 27 August, 2002
Text Updated: 11 August, 2007
Sample Group: Medical