Chemical Safety of Unpolished Nigerian Rice

Abstract

Levels of arsenic (As), lead (Pb), cadmium (Cd), calcium (Ca), chromium (Cr), potassium (K), sodium (Na), and zinc (Zn) in locally cultivated rice consumed in Ondo and Ekiti States of Nigeria were investigated. The rice samples were obtained from six different rice-producing towns; Akure, Ondo, Ado, Igbemo, Ikole and Erinjiyan. The estimated dietary intake (EDI) of these elements were determined and compared with the provisional tolerable daily intake (PTDI) and dietary reference intake (DRI) values for toxic and essential elements respectively. The measured mean levels of Pb, As, Cr, Cd, Zn, Na, Ca and K were 0.047 ± 0.007, 0.041 ± 0.004, 0.570 ± 0.032, 0.026 ± 0.003, 7.856 ± 0.659, 42.15 ± 0.191, 337.11 ± 0.315, and 2650.09 ± 0.337 µg/g respectively while the average EDI were 00.101 ± 0.042 µg/day, 0.088 ± 0.14µg/day, 1.234 ± 0.045 µg/day, 0.057 ± 0.002 µg/day, 0.017 ± 0.071 mg/day, 0.091 ± 0.013 mg/day, 0.73 ± 0.018 mg/day and 5.742 ± 0.337 mg/day respectively. The EDIs were not significantly higher than the reference values for the elements except Cr. Also the rice samples were not rich enough in sodium, calcium and potassium compared to the dietary reference intakes for these elements. It is recommended that rice diets should be supplemented with other food items such as meat, fruits and vegetables.