WASHINGTON (AP) — The Food and Drug Administration on Thursday said it has sent warning letters to dozens of retailers selling fruit- and candy-flavored disposable e-cigarettes, including the current best-selling brand, Elf Bar. It’s the latest attempt by regulators to crack down on illegal disposable vapes that have poured into U.S. stores in recent years. Last month, the FDA issued orders allowing customs officials to seize shipments of Elf Bar, Esco Bar and two other brands at U.S. ports.