Total and inorganic arsenic contents in rhizomes of three herbal spices cultivated in Thailand

Parts of plants can accumulate arsenic at different concentrations. Several concerns have been raised regarding the arsenic levels since inorganic arsenic is found in almost food and known as a human carcinogen. Arsenic is present in several forms with different toxicities. Inorganic arsenic species [As(III) and As(V)] are the most toxic form found in food. In this study, total and inorganic arsenic contents were determined in the rhizomes of three spices in the family Zingiberaceae cultivated in Thailand; Alpinia galanga, Curcuma zedoaria and Zingiber cassumunar which were collected from different parts of Thailand between January 2011 and March 2012. Total arsenic (expressed in ng/g, dry wt) in the three spices were 92.4±9.19 (ranged from 74.7 to 107), 89.8±17.5 (55 to 127), and 107±19.5 (73.6 to 145), respectively, while inorganic arsenic were 48.8±6.99 (39.3 to 65.1), 38.7±4.71 (24.4 to 44.6), and 71.2±11.6 (52.7 to 92.1), respectively. Percentages of inorganic arsenic relative to total arsenic were found to be 53.2±8.18 (38.9 to 69.6), 44.5±9.95 (28.5 to72.8), and 67.4±7.46 (54.6 to 83.1), respectively. This study will be used for risk assessment of Thai people from dietary exposure of inorganic arsenic.