Dietary Exposure to Mercury of the Adult Population in Mugusu Artisanal Gold Mining Village, Tanzania: A Total Diet Approach

Abstract

Gold extraction by artisan miners in different parts of Tanzania is widely done by mercury amalgamation technique. To the people living in and around the mining cites there is a potential for exposure to contamination through consumption of Hg contaminated food stuffs. Current studies on estimates of dietary human exposure to mercury in these areas have been limited to contributions of Hg contaminated fish consumption centrally to WHO recommendation on the use of Total Diet Studies. In this study dietary Hg intake of people at Mugusu gold mining village was determined by using a total diet study approach. Results indicate that 37 types of foods are consumed in this Village. Rice, maize, tubers and fish were the most consumed food categories with an average daily consumption of 134, 270, 113 and 97 g per person per day, respectively. The fish category contained the highest average content of total Hg (0.16 g g-1 wet weight). The calculated average dietary intake of Hg was 41.05 g/day, which is 2.6 times higher than the daily intake recommended by FAO/WHO (15.5 g/day) for protection of the foetus and young children. It is therefore concluded that the current total dietary intake of Hg in the studied area is at risk level to young children born to women living in this village. It is therefore recommended that, mercury intake in artisanal gold mining settlements should be monitored regularly.

Heavy Metals Contamination in Agricultural Soil and Rice in Tanzania: A Review

“…Machiwa [20] reported that many agricultural fields located near mining site in Geita and Tarime districts are contaminated with heavy metals. In Tanzania, major gold mines are located in Geita, Musoma, Kahama, Tarime, Chunya and Mpanda [21] which are also main food crops producing areas. Therefore, food crops cultivated near these gold mines are vulnerable to contamination with heavy metals.…”

“…Mining activities contribute to the increase of levels of heavy metals in the agricultural soils [22] High level of Hg in agricultural soils in Mugusu gold mining in Geita District is influenced by mining activities [21] Deposition of industrial waste on the agricultural soils leads to the increase of heavy metals on the agricultural soils [1] Lake Victoria basin wetlands in Tanzania are highly contaminated with heavy metals through runoff from industrial waste disposal [1] Phosphate fertilizers produced in Tanzania consists of Hg, Cd, As, Pb, Cu and Ni, these may increase levels of these heavy metals to the soils [30] Application of phosphate fertilizers increased levels of As, Cd and Pb on paddy soils of North of Iran [31] …”

“…These levels were associated with the effects of industrialization in that basin. Furthermore, Tungaraza et al [21] reported average level of Hg (0.026 mg/Kg) in rice grown in Mugusu mining area in Tanzania. These data on heavy metal contamination in rice are essential for food safety control organs to be able to perform risk assessments which inform food safety managers on strategies to prevent contamination in rice.…”

“…Other food crops may also be contaminated with heavy metals when grown on contaminated soils [21]. Lugwisha and Othman [16] reported the concentration of Cd of 0.09 mg/Kg in both onions and tomatoes collected in Lushoto district in Tanzania to be above the Codex Alimentarius Commission limit of 0.05 mg/Kg.…”

“…Tungaraza et al [21] reported the estimated daily intake (EDI) for Hg in rice grown around Mugusu artisanal gold mining areas in Tanzania to be 4.0 µg/day / person of 68 Kg weight which is equivalent to 0.06 µg/ Kg body weights/day. Although this value is lower when compared with the TDI for Hg set by the JECFA which is 0.57µg/Kg Bw/day [50], the growing rice consumption patterns in Tanzania can lead to higher intakes.…”