On Thu, 16 Jul 2009 00:50:48 -0500, the infamous Don Foreman
scrawled the following:

The active ingredient is oxalic acid, which is also a pretty good rust
remover.

As regards use around food and with cookwa
http://growingtaste.com/oxalicacid.shtml

Oxalic acid is also a main ingredient in deck cleaners/brighteners.

--
Mistrust the man who finds everything good, the man who finds everything
evil, and still more the man who is indifferent to everything.
-- Johann K. Lavater