Arial Meehan, 9, center, dressed as a crazy cat lady, smiles as she walks down the street with other trick-or-treaters on Halloween 2018. | Natalie Kolb/MediaNews Group/Reading Eagle via Getty Images As is the custom, millions of children in the United States will be out in the streets this Halloween to trick-or-treat, decked out in costumes. Also as is custom, adults will fret about the mostly mythical dangers children may face. Once upon a time it was razor blades in apples; this year, it’s rainbow fentanyl in candy. But while fears of children receiving narcotic-spiked treats are un...