The Hazardous Level of Heavy Metals in Different Medicinal Plants and Their Decoctions in Water: A Public Health Problem in Brazil

The determination of Cd, Co, Cr, Cu, Fe, Na, Zn, and Pb by inductively coupled plasma-optical emission spectrometry (ICP OES) was performed on dry matter and decoctions of the medicinal plants Cordia salicifolia, Chiococca alba (L.) Hitchc., and Echites peltata used as an appetite suppressant and diuretic in Brazil. The accuracy of the measurements was analyzed by the spike recovery test. Results showed that the concentration of these seven metals (Cd, Co, Cr, Cu, Fe, Na, and Zn) in dry plant samples is below the oral concentration of elemental impurities established by the United States Pharmacopoeia Convention (USP). However, there are no concentration limits for Fe, Na, and Zn established by the USP in drug substances and excipients. Levels higher than the recommended value by the USP were observed for Pb and the lowest for Cd, Co, Cr, and Cu, both in dried plant samples and their decoctions. In the decoctions prepared from these plants were found elements such as Cd, Co, Cr, Cu, Fe, Na, Zn, and Pb. In the decoction prepared from 40 g C. salicifolia leaves and 40 g C. alba wood, the content of Cd is above the oral daily exposure value set by the USP. Hazard index (HI) for decoctions prepared from these plants exceeded the threshold (1). Given the uncertainties associated with the estimates of toxicity values and exposure factors, futures researches should address the possible toxicity in humans. Uncontrolled selling and long-term ingestion of medicinal plants can cause toxicity and interfere with the effect of drugs. Limited knowledge on the interaction potential of medicinal plants poses a challenge and public health problem in Brazil and other countries.