Fig. 1

Urine from 93 kindergarten children analyzed by enzyme-linked immunosorbent assay (ELISA) and by chromatography–mass spectrometry (GC–MS). a Free and total cotinine levels determined by GC–MS and immunoreactive (IR)-cotinine levels in the urine of kindergarten children according to the amount of tobacco smoked by their father (0, 1–9, 10–19 and 20 cigarettes per day; n = 39, 8, 28 and 14, respectively). *P < 0.05 by Scheffe's test after analysis of variance (ANOVA) using logarithmic analysis. ^†† P < 0.01, by Kruskal–Wallis test. Spearman’s rank correlation coefficients are 0.20 (P = 0.06), 0.26 (P = 0.02), and 0.41 (P < 0.01) for free cotinine, total cotinine and IR-cotinine, respectively. b Free and total cotinine levels determined by GC–MS and IR-cotinine levels in the urine of kindergarten children according to the amount of tobacco smoked by their mother (0, 1–9, 10–19 and 20 cigarettes per day; n = 79, 6, 6, 1, respectively). *P < 0.05 by Scheffe’s test after ANOVA using logarithmic analysis, ^† P < 0.05, ^†† P < 0.01, by the Kruskal–Wallis test. Spearman’s rank correlation coefficients are 0.33 (P = 0.002), 0.37 (P < 0.001), and 0.47 (P < 0.001) for free cotinine, total cotinine and IR-cotinine, respectively