Are Brazil Nuts radioactive? You bet!
I tested a bag of them using gamma spectroscopy and found clear peaks for Radium 226 and Lead 214, as well as probable peaks for Bismuth 214. In the end, the radioactivity of Brazil nuts isn’t something to worry about. In an entire 24 hour period I only few a few hundred gamma rays from each peak. The radioactivity was just too low to be of worry.
Like most nuts, Brazil nuts are quite good for you and typically get a “glowing” review from health care professionals. =)