Arsenic, Cadmium and Lead content of rice sold in the Greater Accra Region

Thumbnail Image
JULY, 2016
Journal Title
Journal ISSN
Volume Title
Rice is an excellent staple crop which contains vitamins and minerals such as vitamins E & B and potassium needed for human growth and wellbeing. In recent times, majority of Ghanaians consume a lot of rice as compared to other local staple. However, heavy metal contamination of rice and other crops is threatening the quality of these crops and the health of consumers. Due to industrialization and other human activities, environmental pollution with chemicals is increasing and this has led to the contamination of agricultural produce. Heavy metal contamination has been associated with adverse effects such as damages to the nervous system, kidneys, liver, lungs and other vital organs in humans and animals. With dietary intake as one of the major routes of heavy metal exposure to human, there is the need to investigate the levels of these metals in our foods. This study intended at determining the concentrations of three heavy metals (arsenic, cadmium and lead) in rice sold on the Ghanaian market. Thirty two samples (16 unpolished rice, 16 polished rice (8 foreign rice and 8 local rice) were purchased from some of the markets in Accra; the capital city of Ghana. Samples were homogenized and digested for analysis using a microwave digester. The concentrations of the 3 elements (As, Cd & Pb) were analysed using Graphite Atomic Absorption Spectrophotometry. The method used was validated using a certified reference material. Results indicated that, for Arsenic concentration in rice samples, unpolished rice obtained concentrations which ranged from not detected to 0.2370 mg/kg with an average of 0.1212 mg/kg. Concentration of arsenic in polished rice ranged from 0.0531 to 0.1772 mg/kg with an average of 0.1032 mg/kg in foreign rice and 0.0297 to 0.1504 mg/kg with an average of 0.0843 mg/kg in local rice samples. Cadmium concentration ranged from not detected to 0.0628 mg/kg with an average of 0.0179 mg/kg in unpolished rice. Cadmium in polished rice ranged from 0.0012 to 0.0424 mg/kg with an average of 0.0128 mg/kg in foreign rice and 0.0025 to 0.0329 mg/kg with an average of 0.0099 mg/kg in local rice samples. Lead concentration in unpolished rice ranged from 0.0007 mg/kg to 0.1106 mg/kg with an average of 0.0239 mg/kg. Concentration of lead in polished rice samples ranged from 0.0027 to 0.1106 mg/kg with an average of 0.0308 mg/kg in local rice and 0.0007 to 0.0505 mg/kg with an average of 0.0171 mg/kg in foreign rice samples. It is recommended that agencies or institutions responsible for food regulation need to periodically determine the concentration of metals in both imported and local rice samples sold on our markets to elude the harmful effects of heavy metals on consumers.
Thesis submitted to the Department of Food Science and Technology in partial fulfilment of the requirements for the award of the degree of Master of Science in Food Quality Management,