[reg45]

The radioactive material could also be in the steel of the can.

[Buckeye McFrog]

The radioactive material could also be in the steel of the can.

Very true. About 20 yrs. ago a bunch of steel café tables had to be recalled because they were emitting high doses. Turns out they were Made in Mexico from scrap that included a source isotope from a medical x-ray machine. A delivery of these to the cafeteria actually triggered the alarms at Los Alamos.