Just wondering what makes them go "bad" if it's powder... Not saying I use them, I do throw away but just curious

Maybe it's a conspiracy.... DUN DUN DUN
Alina Riley 2/22/09- My Baby Bunny

M/C at 5 weeks 6/30/10
Missed M/C at 10w1d, 10/18/10, D&C 10/19/10
12/25/10 +BFP, Stick baby, Stick!
1/31/11 diagnosed compound heterozygous for MTHFR
2/5/11 subchorianic hematoma found put on one weeks bed rest
3/13/11 ITS A BOY!

Re: Why do formula cans "expire" after opened for 1 week?
Damn, guess I could have looked.. I've been going over what my sis in law and DH have been saying... they must be confused then! This is GREAT news! lol
I found a long drawn out report on the FDA's website. It was looking into NICU baby deaths from a certain bacteria, E sep (or something like that). They basically said it's non-sterile and has traces of the bacteria in it already in the powder form. I'm guessing leaving it open could cause more to grow. So it's probably because it's non-sterile and anything to do with infants they are probably on the conservitive side. They also said the expiration date guarantees that the nutritional value will be as listed on the package if consumed by that date. Adding air may lessen the nutritional value.
"It should be noted that powdered infant formula are not sterile products"
ps. take this at face value.