cigars. Small cigars and cigarillos are disproportionately used by lower income and less educated people, young people, African Americans, Hispanics, LGBT people, and men. Usage of flavored cigarillos has grown explosively, with sales in U.S. convenience stores up 50% between 2008 and 2015, after tripling between 1997 and 2007. Among adult and youth cigar users, about 40 percent use flavored cigarillos. The most popular flavors for cigarillos are fruit (38.8 percent), sweet or candy (21.2 percent), and wine (17.0 percent). Flavored cigarillos are popular with lower income and younger people in part because they are inexpensive and are promoted by tobacco companies as affordable alternatives to cigarettes. Unlike cigarettes, cigarillos can be sold in small packs of one or two each for around 99¢ for two. In many jurisdictions, cigarillos and other cigars are taxed at lower rates than cigarettes, making them more appealing to low-income populations, including youth, young adults, and the unemployed. Electronic cigarettes E-liquid, the nicotine-containing liquid used in electronic cigarettes, is usually flavored. E-liquids come in a myriad of flavors, including mint, spice, fruit, and candy ones. A 2017 survey of internet e-cigarette retailers found 15,586 unique flavors of e-liquid and counting, up from the 7,764 found in a 2014 analysis. In surveys of regular e-cigarette users, the most popular e-liquid flavors are largely tobacco, mint and fruit, although candy and dessert flavors are also common. Mango is the most popular JUUL flavor. Fruit flavored e-liquid is the most commonly marketed e-liquid flavor on social media. Flavored e-liquids form a major part of the appeal for using e-cigarettes, especially for youth, for whom flavoring is cited as a major reason for using e-cigarettes. Some e-liquid flavorings are toxic. Cinnamaldehyde is a highly cytotoxic material in vitro used in cinnamon-flavored e-liquids. Cinnamaldehyde have been identified as cytotoxic at the amount of about 400 times less than those allowed for use by the US Environmental Protection Agency. A 2018 in vitro study found that exposing lung cells to liquid or vapor containing cinnamaldehyde causes significant and rapid damage to their cilia and mitochondria. This led the authors of the study to conclude that "inhalational exposures of cinnamaldehyde may increase the risk of respiratory infections in e-cigarette users." Some e-liquids containing cinnamaldehyde stimulate TRPA1, which might induce effects on the lung. E-liquids contain possibly toxic aldehydes and reactive oxygen species (ROS). Many flavors are known aldehydes, such as anisaldehyde,