There is a proper method to do it. It all depends on what chemical interactions happen. I forget which minerals it's supposed to be, but one is with iron and the other is with something else. Nitrated salts interact with one while regular curing interacts with the other. Both lead to a nice red colour.

When done properly it is safe and will not get consumed by bad bacteria. Botulism comes from unsanitary curing environments and has been blown way out of proportion by corporations that needed an argument to keep nitrated curing going.