I've heard about this. Apparently the mixes will grow molds that become a toxin of sorts. If the person has an allergy, it can be fatal for them.
A lot of this can be prevented by putting the mixes into the freezer. Freezing prevents mold growth. I keep my flour in the freezer for this reason as well as not getting bugs in it. I mean my household flour, not my bakery flour
I heard about the college kid dying. This is why FIFO is imperative as well as date labeling your products when received.