As I said, peanut butter producers are pretty careful about screening their peanuts. Handily, most Aspergillus molds fluoresce under UV, so they’ll pass the peanuts under a black light and kick out any that glow too much.
That said, if you do get cancer from your peanut butter, it’ll probably be years before anyone finds it, and you’ll have forgotten all about this incident by then, so it’ll just seem like one of those things, you know? So don’t worry.
According to this site: http://www.organizeyourlife.org/Expiration.htm that’s pretty damn old even for peanut butter. My bet is that you’ll live though. I’d be careful about eating others peoples stuff out of the company fridge. There are those that have had food stolen before and put something laced with feces in the fridge for the thieving party to enjoy.
According to this article from Slate, in most cases, expiration dates on food are pretty meaningless. They’re not mandated in any way, and mostly are just the date before which the manufacturers promise that it’ll taste the way it ought to, not the date after which it’ll make you violently ill.
That said, 2003 is pretty damned old. Does nobody ever clean out the fridge in your workplace? Where I’ve worked, everything in the fridge got tossed on a weekly or monthly schedule.
When cleaning up for accreditation (hospital) last month, I tossed a box of baking soda out of the main fridge, it had a coupon on the back that expired Dec 1999. I have no way of knowing if this was a really old box of baking soda that had been sitting in the fridge that long, or if it first had been in a store room for years or something.
Curious, I peeled the box open to see what it looked like. A light grey brick. It made a satisfying thunk when it went into the garbage pail, and then crumbled only slightly. So things could be in a work fridge for decades.
I just checked the jar I finished yesterday morning, and it expired October of 2006! I just looked in the mirror, and I’ve got severe myopia, thinning hair and an addiction to Have I got News for You! I also recall feeding some to some mice a while back, and they all died. :eek:
(Just stay away from mouse traps and you’ll probably be fine)