Figure 1.

Comparison of DNA damage levels between vapers and nonusers, smokers and nonusers, and vapers and smokers. DNA damage levels were determined in genomic DNA of oral epithelial cells from healthy adult “exclusive” vapers (never smokers), cigarette smokers only, and nonusers by LA-QPCR, as described in the text. Panels (A–C) show the LA-QPCR results in the POLB gene whereas Panels (D–F) displays the respective results in the HPRT gene. Distribution of data within each group is shown by box and whisker plots whereby “lower” and “upper” edges of the boxes represent the first and third quartiles, respectively, and horizontal lines within the boxes indicate the second quartile. The “lower” and “upper” vertical lines extending from the boxes, also known as the “whiskers,” represent the lowest and highest data points, respectively, in the set (minimum and maximum values, respectively, excluding values outside the whiskers’ range). The five measures of box and whisker plots are all labeled within the graphs. All samples were assayed independently up to 2 times and results were averaged for each sample. DNA damage levels were compared between each two independent groups, as described in the text; p values are indicated for all comparisons.