Herbal or medicinal plant products in various forms have been available for many hundreds of years for treatment of diseases in both Eastern and Western cultures . A survey indicated that about 70-80% of the world populations, particularly in the developing countries, rely on -nonconventional medicine mainly from herbal sources in their primary healthcare reported by WHO .Chinese Herbal Medicines and their manufactured products recorded in the Chinese Pharmacopoeia have been approved for safe use and have been widely consumed for thousands of years as home remedies or for prevention and treatment of diseases in China Such increase in popularityhas also brought concerns and fears over the adverse effects of herbal medicines, thus the quality, efficacy and safety of the products from herbal and natural sources available in the market should have been proven. Therefore, contamination or adulteration of CHMs with heavy metals such as lead, mercury, cadmium or arsenic has attracted much attention, especially arsenic contamination through natural and anthropogenic pathways .
There are concerns that CHMs can accumulate As from growth environments and conditions, such as soil/plant uptake, irrigation water and from atmospheric deposition, and conditions during dryness, storage, transport and manufacturing processes China has a maximum contaminant concentration (Green Standard of Medicinal Plants and Preparations for Foreign Trade and Economy in China) for arsenic in CHMs of 2.0 mg/kg. Some investigations of total arsenic in CHMs from both domestic and foreign markets have illustrated that total arsenic concentrations in some CHMs samples exceeded this legislative standard .