Quantification of Heavy Metals in Some Locally Produced Rice (Oryza Sativa) from the Northern Region of Nigeria.

Abstract

Rice is one of the major staples grown in the northern parts of Nigeria. It has earned itself an important position of a commomly consumed staple by the national populace. Consumption of rice contaminated with heavy metals can pre-dispose individuals to serious health complications. This study determined the levels of some heavy metals (Cd, Cr, As, Pb and Hg) in locally produced rice samples from the northern region of Nigeria. Ten rice samples were obtained from various locations in Benue, Borno, Kaduna and Nasarawa states. The results showed that lead (Pb) ranged from 0.311 – 0.525 mg/kg in the samples. Average lead (Pb) concentration was 0.260 mg/kg. However, Cd, Cr, As and Hg were not detectable at 0.001mg/kg. A calculation of weekly intake of rice by an average Nigerian revealed that weekly consumption of lead (Pb) in this locally produced rice exceeded the 0.025mg/kg WHO/FAO (2002; 2001) provisional tolerable weekly intake of lead (Pb). This is of public health importance as individuals who consume this locally produced rice are at greater risk of lead (Pb) toxicity.                                                                                                                     

Key words: heavy metals, contamination, food, health, toxicity, rice.