Traditional medicinal plants in Nigeria--remedies or risks

Soil pollution due to increasing industrialization is a reality that is taking its toll on mankind today. Considering the population of people that use herbal remedies especially in developing countries and the discharge of industrial waste on surrounding herbal vegetation, it is imperative to determine the heavy metals contamination in some commonly used medicinal plants.

Representative samples of five medicinal plants Ageratum conyzoides, Aspilia africana, Alchornea cordifolia, Amaranthus brasiliensis and Chromolaena odorata were collected from Ikpoba-Okha L.G.A, Edo State Nigeria, around a paint company and another set of same plants were collected from a non-polluted source. Dried leaves and roots of collected plants were digested and analyzed using Atomic Absorption Spectrophotometer (AAS) for the presence of Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Zinc (Zn). Soil samples from polluted and non-polluted areas were also analyzed to ascertain the levels of these heavy metals in the environment.

Results show that the concentrations of these heavy metals in the leaves and roots of plants collected from polluted soil were significantly higher than those obtained from unpolluted soil. Correspondingly heavy metal concentrations were significantly higher in polluted than in unpolluted soil samples.

As part of continuing effort in the standardization of traditional remedies, environmental contamination control and abatement is evident. The source of medicinal plants/herbs should also be a cause for concern since the toxicity of medicinal plants is sometimes associated with environmental sources of the plants.