The FDA will soon introduce new regulations on the sales on e-cigarettes. The rules will set an age limit for buying e-cigs (18 and up), ban their sale in vending machines, and require warning labels. Meanwhile, we don’t really know what sucking on these devices means for our health. Here’s Thomas Glynn, director of cancer science at the American Cancer Society: “Seven years is a nanosecond in scientific terms. We don’t even know what the long-term effects of inhaling heated propylene glycol are.” Take a look at what the new rules do and don’t do.