There's a lot we don't know about the fluids used in electronic cigarettes. That doesn't necessarily mean the potentially dangerous "e-liquids" should be illegal, as state Sen. Kemp Hannon (R-Garden City) has proposed. Lots of dangerous substances are legal. But e-liquids should be regulated and childproof. In a recent report, Centers for Disease Control Director Thomas Frieden said the liquids "are a threat to small children because they are not required to be childproof, and they come in candy and fruit flavors that are appealing to children." In high concentrations, nicotine is a poison, and the e-liquids can include other potentially dangerous ingredients. The Food and Drug Administration says it will propose regulations on e-liquids. Those rules should require manufacturers to tell what's in the liquids, and protect children from them.