While e-cigarettes are not considered as risky as regular cigarettes, researchers may have found a link between flavorings and a bad effect on the heart. In laboratory dishes, scientists grew cells that normally line the healthy human blood vessels. They then exposed cells to six different e-cigarette flavorings, testing if the flavors caused any effects. This method eliminated the possibility that nicotine caused any adverse effects. They also analyzed the effects of bathing those cells in blood taken from people right after they had an e-cigarette. Finally, they did a comparison of the cells' exposure to blood from nonsmokers and people who smoked a regular cigarette.