Variation in heavy metals and microelements in South African medicinal plants obtained from street markets.

South African medicinal plants are traditionally harvested from a wide range of undisclosed locations by plant gatherers. Thus, there is a risk that plant material may be exposed to a variety of pollutants. The variation in five heavy metals (arsenic, cadmium, cobalt, nickel, and lead) and six essential elements (boron, copper, iron, manganese, molybdenum, and zinc) was determined in commonly used South African medicinal plants obtained from street markets. Elemental content was determined using inductively coupled plasma optical emission spectrophotometry. The reliability of the procedure was ensured by analysing a certified reference material. Medicinal plant samples contained arsenic and cadmium at levels exceeding the World Health Organization limits of 1 and 0.3 mg kg(-1) respectively. Lead and nickel were detected in all samples. Elevated iron and manganese levels were recorded in certain plant species. Multiple metal contamination of parts of medicinal plants gives grounds for concern. This study emphasizes the unsafe consequences of the South African practice of collecting medicinal plants from undisclosed locations and making these readily available to the public.

Toxicity of metal elements on germination and seedling growth of widely used medicinal plants belonging to Hyacinthaceae.

In South Africa, pollution of agricultural soils is on the increase primarily due to excessive application of fertilizers, sewage disposal and mining activities. This study was done to determine the effect of trace elements (Cu, Zn) and heavy metals (Cd, Pb, Hg) on germination and seedling development of Bowiea volubilis, Eucomis autumnalis and Merwilla natalensis. These medicinal plant species are highly recommended for cultivation in South Africa to reduce the pressure on wild populations. Copper and Zn at 1 mg L(-1) significantly (p < 0.05) reduced the percentage germination of E. autumnalis. Low concentrations (>or=1 mg L(-1)) of Cu and Zn negatively affected the roots of all three species. Mercury concentrations of 0.5 and 1 mg L(-1) significantly (p < 0.05) decreased the percentage germination of B. volubilis and E. autumnalis respectively. Cadmium and Hg at 2 mg L(-1) showed a detrimental effect on the root growth of B. volubilis. Concentrations of 0.5 mg L(-1) of all heavy metals tested significantly (p < 0.05) decreased shoot length of M. natalensis.