There is not a specific report on Halloween kidnappings. Dept of Justice estimates 114,600 non-family abductions attempted each yr
http://www.chacha.com/question/how-many-kids-get-kidnapped-on-halloween-in-the-us
---------
Don't let your kids go without an ADULT present.
------------
In 2008, candy was found with metal shavings and metal blades embedded in it. The candy was Pokémon Valentine's Daylollipops purchased from a Dollar General store in Polk County, Florida. The candy was determined to have been manufactured in China and not tampered with within the United States. The lollipops were pulled from the shelves after a mother reported a blade in her child's lollipop and after several more lollipops with metal shavings in them were confiscated from a local elementary school. [4]
In 2008, some cold medicine was discovered in cases of Smarties that were handed out to children in Ontario, Canada. [5]
----------------
I think some places offer to "x-ray" the candy. This might be a good idea before letting your kids eat from what they have collected.