Why do we fear poisoned Halloween candy?

On October 31, 1983, advice columnist Abigail Van Buren—better known as “Dear Abby”—published a Halloween-themed column titled “A Night of Treats, not Tricks.” In that column, she wanted to “remind [readers] that,” among other things, “[s]omebody’s child will become violently ill or die after eating poisoned candy or an apple containing a razor blade.” Twelve years later, advice columnist Ann Landers (who, by the way, was Dear Abby’s sister) also wrote a Halloween article—“Twisted minds make Halloween a dangerous time”—echoing that concern. “In recent years, there have been reports of people with twisted minds putting razor blades and poison in taffy apples and Halloween candy,” Landers wrote. “It is no longer safe to let your child eat treats that come from strangers.”

Although there have been reports of razor blades and other foreign objects embedded in Halloween candy (or apples—although anyone giving out an apple on Halloween is already suspect), these dangers are almost always obvious with the most cursory glance....