Parents are understandably wary about their children taking candy from strangers, but in modern times we have many more safeguards than people in the 19th century had. Halloween in Bradford, England, in 1858 saw at least 19 deaths, including children, from eating candy. The candy in this case was called peppermint humbugs, a popular confection that was locally made. After people started dying, an analysis found that each bite-sized candy contained twice as much arsenic as it required to kill someone! By then, it was too late for those who had ingested the candy.
However, this wasn't a case of intentional murder. The investigation uncovered a series of mistakes in the supply chain that involved greed, laziness, and inattention to detail. The incident led to reforms and new laws to keep those mistakes from ever happening again. Read about the case of the Bradford candy poisoning at Mental Floss. -via Strange Company
(Image credit: Willstewart)
Feeding a sample of the obviously not-quite-right formula to the family dog, then waiting a day, could have saved many lives.