Assessment of cyanide and some heavy metals concentration in consumable cassava flour 'lafun' across Osogbo metropolis, Nigeria

Introduction: Cassava, a naturally flourishing tuberous plant in Nigeria which has been source to varieties of food in its raw, semi-processed, and processed forms has helped reduced poverty and hunger. Cassava in its various food forms contains varying amount of elements like cyanide, copper, selenium, iron, lead, nickel, cadmium and zinc which are essential elements for man, animal and plants but become toxic if the homeostatic mechanisms maintaining their physiological limit are disrupted or their concentration is very high at certain levels. The significant concentration of heavy metals in cassava flour and prolong consumption can damage the health of man. This research work determined the concentration of cyanide and some metal toxicant in cassava flour from Osogbo metropolis. Methodology: Samples were collected across five markets in Osogbo metropolis and analyzed for cyanide, copper, selenium, iron, lead, nickel, cadmium and zinc. Cyanide concentration was determined using UV/visible spectrophotometer, cadmium and selenium using titrimetric methods, while lead, nickel and cadmium were determined using the atomic absorption spectrophotometer. Results: Across all the samples analyzed, the result showed that the ranges of concentration for cyanide was 0.03-0.09mg/kg, copper 0.35-0.62mg/kg, selenium 3.46-5.43mg/kg, iron 0.1-0.6mg/kg, lead 0.01-0.34mg/kg, nickel 0.20-0.49mg/kg, cadmium 0.01-0.05mg/kg, zinc 0.182-0.31mg/kg. The concentration of cyanide, copper, selenium, iron, nickel, cadmium, and zinc are within the NIS permissible limit. Conclusion: The concentration of lead (0.34mg/kg) was found higher in Akindeko market than the NIS permissible limit of 0.1mg/kg for edible cassava flour. Hence, this study clearly advises that there is need for citizen advocacy, continuous monitoring and supervision to improve the hygienic preparation and storage of cassava flour in order to protect man.