Determination of lead and mercury in medical herbal products marketed in Venezuela

The plants with medical purposes represent approximately 25% of the total of the medical prescriptions in industrialized countries, and close to 80% in developing countries. Few patients are aware of the potential interactions among the phytotherapeutic products, as well as the presence of toxic chemical elements. Health organizations are warning consumers not to use certain phytotherapeutic products because they could contain high levels of heavy metals. Studies carried out in United States of America, United Kingdom, India, Malaysian and Pakistan show the presence of cadmium, lead and mercury in this type of products. For this reason, in the present research, the presence of Hg and Pb in phytotherapeutic products marketed in Venezuela is investigated. The samples were analyzed by means of acid digestion (HNO3) in a microwave oven and then analyzed by atomic absorption spectroscopy (AAS). The results demonstrated that the found values were within the tolerable levels for medical herbs suggested by the World Health Organization (WHO). Additionally, the mercury and lead provisional tolerable weekly intake (PTWI) was evaluated and the results also demonstrated that they were lower than the human-reference values (300 μg/kg and 1500 μg/kg, respectively). In summary, the analyzed phytotherapeutic products marketed in Venezuela do not represent a public health problem. Nevertheless, the authors recommend to enhance this type of study to other herbal products marketed in Venezuela.