Exposure Assessment of Some Heavy Metals (Arsenic, Lead, Cadmium, Mercury, Copper and Zinc) in Locally Produced Rice Sold in Accra Metropolis

Abstract

Rice is the second-most consumed cereal in Ghana. However, human activities such as mining and excessive use of agro-chemicals in some farming areas have the potential to pollute rice with heavy metals, and compromise food safety. The objective of this study was to assess the levels and risk of heavy metals in locally produced rice sold in Accra Metropolis. Also, the quantity and consumption pattern of rice in Accra was also surveyed using structured questionnaire. A total of 385 consumers who consented participated in the survey. Information collected included sex, age, and body weight as well as frequency and quantity of rice consumed. Children’s consumption information was collected from parents or caregivers. Thirty samples of local rice (uncooked) were sampled from markets and analyzed for heavy metals (arsenic, lead, cadmium, mercury, copper, and zinc) using ICP-MS. Exposure assessment was conducted using the U.S. EPA method. The estimated intake, carcinogenic and non-carcinogenic risk were determined. Survey results showed participants weighed between 60 and 69 kg, consumed an average of 496.36 grams of rice per week and 221.67 grams of rice per day. Children consumed averagely 58.33 grams of rice per day and 142.43 grams of rice per week and they weighed between 21 and 30 kg. Concentration of heavy metals in all the rice samples were below the upper limit permitted by Codex. However, the consumption of local rice was found to be associated with carcinogenic and non-carcinogenic hazards in both adults and children from the outcome of the risk assessment. Exposure to arsenic, lead, and cadmium were of primary concern for the children whilst for the adults, it was arsenic and lead. The health risk of exposure to heavy metals should be publicized and education intensified in order to protect public health.