I doubt this is what Apac Chemical Corporation intended as the usefulness of its product information on Citric Acid, but nevertheless product guides like these are extremely important to us trying to avoid hidden corn.
Listed below are a few of the notable mentions for uses for citric acid of which people might not be aware:
Water Softener Salts: Both Home and Commercial water softener salts contain citric acid. (if you have a water softener, you may want to stop drinking the water straight from the tap, and invest in a filtration system)
Cigarettes: Citric acid controls the burn rate of the paper so it doesn't burn faster than the tobacco. Its also used on the tobacco to "balance the flavors".
Canola Oil: Many corn allergics have repeatedly reported problems with Canola oil. Well this article lists Canola Oil specifically as containing citric acid. Its used as a de-gumming agent.
Seafood: Citric acid keeps it smelling fresh.