The use of medicinal plants by the Brazilian population is a traditional practice and is often the main resource used in primary healthcare. The therapeutic use of these plants involves several steps in the supply chain: origin, harvest, drying, storage, form of preparation by the user and use. The aim of this documental study of exploratory nature was to survey the scientific literature about the problems associated with each of those steps and discuss the issues related to the lack of studies to prove the pharmacological efficacy and the absence of toxicological risks, as well as the autodiagnosis practice. The 20 plants most commercialized in a large market of Rio de Janeiro City in August 2007 were the basis for the documental survey of the present study. Of these, six had proven toxic properties depending on their preparation and use: arnica (Solidago chilensis Meyen), aroeira (Shinus terebinthifolius Raddi.), rue (Ruta graveolens L.), "babosa" (Aloe vera L.), comfrey (Symphytum officinale L.) and pennyroyal (Mentha pulegium Lam. & DC.). The National Agency for Sanitary Surveillance shows contraindications for: "boldo-do-Chile" (Peumus boldus Molina), "chapéu-de-couro" (Echinodorus macrophyllus Micheli), lemon balm (Lippia alba N.E.Br.), "erva-de-bicho" (Polygonum spp.), "espinheira-santa" (Maytenus spp.), "picão" (Bidens pilosa L.), pennyroyal (Mentha pulegium Lam.) and plantain (Plantago major L.). "Abajerú", arnica, "boldo-do-Chile", comfrey, "erva-de-bicho" and "espinheira-santa" were reported to show identification problems in the harvest and in the commercialization compared to morphologically similar plants. Cultivated and wild plants showed variability in active principles influenced by environmental and genetic factors: "chapéu-de-couro" (Echinodorus macrophyllus Micheli), lemon balm (Lippia alba N.E.Br.) and "erva-de-bicho" (Polygonum spp.). Contamination and compromising of the preservation of active principles due to inadequate drying and storage was reported for guaco (Mikania glomerata Sprengel), camomile (Chamomilla recutita L.), lemon balm, "chapéu-de-couro" and "boldo-do-Chile" (Peumus boldus Molina). All stages of the supply chain of medicinal plants constitute challenges to ensure the proper species identification, availability, quality, safety, and efficacy of their use.
popular medicine; toxicity; supply chain of medicinal plants