Each October, as the days shorten and the air grows crisp, millions of Americans^[1] prepare for the beloved – and often sugar-fueled – tradition of Halloween. From jack-o’-lanterns glowing on porches to costumes ranging from the whimsical to the gory, Halloween is a time of playful scares, childhood memories and, of course, candy.

But as the wrappers pile up and the sugar rush hits, there’s something far more sinister...