Monthly Archives: October 2015

Radioactive “Lite Salt”

Filed under Radiation, Science

Do you enjoy potassium “lite salt”?

I know I do. I eat it on everything. It’s tastey and healthy, but did you know that it was radioactive? All natural potassium atoms comes in 3 different types, called isotopes (meaning equal members). Each has the same number of protons, which makes it potassium, but a different number of neutrons. Potassiunm 39 and 41 are stable, but poor potassium 40 simply isn’t. Over time, potassium 40 slowly decays into argon gas or calcium. In doing this, it emits beta particles and even gamma rays!

So, how radioactive is a can of “lite salt” from the store? I bought an 11oz (311g) can and did the math:

(note: 1Bq = 1 radioactive decay of an atom per second)

One can of “lite salt” contains 311g of salt.
One 1400mg serving contains 350mg of potassium, 25% per serving.

Thus, the mass of potassium in the can is:
k/srv = 350mg/1400mg = 25% of 311g = 77.75g

Now, the isotope K40 is naturally 0.0117% of potassium, so:
0.000117 * 77.75g = 9.097 milligrams of K40 per can.

The specific radioactivity of K40 is 265400Bq
Thus, the can of salt has an activity of:
0.009097g * 265400Bq/g = 2414.3Bq/can

A gamma occurs 10.66% of the time meaning that my “lite salt” can
emits around:
0.1066 y/bq* 2414.3Bq = 257.36438 photos/sec

So, it tastes great and emits ~257 gamma rays per second lol

Not too much to worry about, but really amazing!