Right, I was really focusing on the bread itself, given the discussion was about the wrapping, rather than previous poisoning of ingredients (unless I'm mistaken, plastic wrapping would not help against ergotism). I'm sure people also get poisoned with chemicals they might put on the crops as well...
Bacillus Cereus is the major modern issue, and it largely comes from soggy bread/rice/pasta, so plastic is a significant factor.
I completely agree with you that we should, in general, phase out plastic as much as we can, but we have to be realistic about the benefits and drawbacks. I don't think it's anything that couldn't be replaced with oiled paper, but plastic is used for some good and bad reasons.