CHEMICAL AND TOXICOLOGICAL EVALUATION OF EDIBLE CLAY (ULO) SOURCED FROM SOUTHERN NIGERIA

Ukwueze Stanley Ejike* and Ochuba Chikodili Ogugua

ABSTRACT

The study was aimed at the pharmaco-chemical analysis and toxicological evaluation of three edible clay (ulo) samples from parts of southern Nigeria. The elemental constituents of the samples were determined by Atomic Absorption Spectroscopy (AAS) while the moisture and ash contents were determined using standard procedures. The acute toxicity assay was carried out according to Lorke’s method using albino mice. The chloroform, butanol and aqueous fractions of the methanol extract were assayed for the presence of phytochemicals. There was presence of calcium, magnesium, nickel, cobalt, chromium, manganese, iron, lead and cadmium in all three samples. The mean concentration of some of the elements varied significantly (p<0.05). The lead (Pb) content of the samples was within the standard approved limits except sample B whose content (0.84ppm) was above the specified limit (0.3ppm). Only sample B contained mercury. The mean moisture contents did not vary significantly among the samples (p=0.498) while the mean ash contents varied significantly among the samples (p=0.010). No deaths were recorded from the acute toxicity assay. Phytochemical screening showed the presence of reducing sugars and steroidal nucleus. In conclusion, edible clay was found to be mostly inorganic but contained some traces of organic deposits with low nutritive value. The high inorganic content, low moisture content and low toxicity might be indicative of its relative safety for human consumption as a source of some minerals but caution should be applied in its sourcing to avoid ingestion of heavy metals such as lead and mercury.

Keywords: Edible clay, toxicity, phytochemicals, minerals, heavy metals, pharmaco-chemical analysis.