Survey of Heavy Metal Pollution in Four Chinese Crude Drugs and Their Cultivated Soils

A two-year survey on the residues of heavy metals in four Chinese crude drugs and their cultivated soils was conducted. Targeted heavy metals were copper (Cu), arsenic (As), lead (Pb), nickel (Ni), and cadmium (Cd). Herbs surveyed include White Peony Root (Radix Paeoniae Alba), Turmeric Root Tuber (Radix Curcumae), Thunberg Fritillary Bulb (Bulbus Fritillariae Thumbergii), and Tuber of Dwarf Lilyturf (Radix Ophiopogonis). Concentrations of all heavy metals were under the permitted levels except cadmium, which exceeded the permitted level in some samples of Thunberg Fritillary Bulb, White Peony Root, and Turmeric Root Tuber. Concentration coefficients were less than 1.0 for all heavy metals except cadmium. The concentration coefficient of cadmium in Turmeric Root Tuber was 14.0. Lower pH and high Zn concentration in the soil may facilitate the transfer of cadmium from cultivated soil into the herbs.