Old pancake mix, cake or biscuit mix should be disposed of.

[okarol]

Old pancake mix, cake or biscuit mix should be disposed of. This warning especially applies to any person(s) with mold allergies. And immunosuppressed people should also heed the warning.

http://www.snopes.com/medical/toxins/pancake.asp

Check the expiration dates on packages like pancakes and cake mixes that contain yeast. Apparently, the mold that forms in old mixes can be toxic. Throw away ALL OUTDATED  pancake mix, brownie mixes, Bisquick, cake & cookie mixes, etc., you have in your home.

[Restorer]

Also (and I learned this the hard way not too long ago) check any old, opened packages of flour, corn meal, etc. for bugs... or you might end up making cornbread with extra protein!