Fig. 2
Blood Pb levels from various population structures. a and b Number of patients (a), or blood Pb concentrations (b) within various ethnic groups reported by patients themselves. c Box plot of Pb levels between Han, and other 43 ethnic minorities. Asterisks depict a statistically significant difference (p < 0.01) with Wilcoxon rank sum test. d and e Detailed geographical distribution of the Han Chinese (d), and other 43 minorities (e). Size of the symbols reflect the number of individuals. f and g Sample size (f), and blood Pb concentrations (g) indicated with heating map of Han Chinese patients receiving Pb test born in each region in China. h and i Sample size (h), and blood Pb concentrations (i) of other 43 ethnic minorities. Color corresponds to number of patients (f, h), or Pb levels (g, i)