**3. Safety evaluation of bamboo charcoal**

#### **3.1. Basic properties of bamboo charcoal**

The true density, BET specific surface area and average pore diameter of Moso bamboo charcoals are 1.68 (g/cm<sup>3</sup> ), 138.70 (m2 /g), and 2.41 (nm), respectively. Moreover, the heavy metal element of bamboo charcoal for Br, Pb, Hg, Cr and Cd is analyzed using X-ray Fluorescent Analyzer of XGT-1000WR [39]. Br and Cr are not detected because their amounts are probably very low. Both Cd and Hg in the charcoal are closed to 0.5 ppm. The Pb in the charcoal is 2.9 ppm. That meets the Sanitation Standard for Edible Natural Colorants, Food Sanitation Standards (1989), Ministry of Health and Welfare in Taiwan at below 40 ppm [41].
