環境および分析毒性学

Multielemental Analysis of Gold Ore Samples from Underground Artisanal Gold Mines in Tongo, Upper East Region of Ghana: Implications of Occupational Exposure

Abstract

Doyi I, Essumang D, Nyarku M, Gbeddy G, Ackah M, Ameho E and Owusu-Bentil N

Background: The presence of gold deposits discovered in rural areas in Ghana has attracted a lot of unemployed youth and smallscale mining ventures to the rural communities. The activities of illegal small-scale gold mining (locally referred to as “galamsey”) in the community is causing serious environmental havoc and destruction. The results of heavy element profiling of gold ores associated with the underground artisanal gold mining activities of the Tongo mines in the Upper East Region of Ghana have been reported in this paper. The analysis was made to assess the occupational exposure of the miners as well as to investigate the environmental impact of toxic heavy metals. Results: Gold ores from seven artisanal gold mines were sampled and analysed for heavy elemental content using Atomic Absorption Spectroscopy technique. The ranges of major elements detected were: Pb (14.16-37.00 mg/kg); Co (6.40-31.52 mg/kg); As (25.08-27.36 mg/kg); Hg (5.04-6.16 mg/kg); Ni (69.44-332.40 mg/kg); Mn (259.04-528.64 mg/kg) and Cd were Below Detectable Limits (BDL). The potential health risk assessment calculated for a lifetime of exposure for ingestion, inhalation and dermal contact were determined as the cumulative carcinogenic risk for children and adults. Risk assessment indicated that the carcinogenic risk is completely insignificant but the cumulative non-carcinogenic Hazard Index recorded alarming values of 4.55E+00 to 4.15E+01 and 8.53E-01 to 3.43E+01 for children and adults respectively. Conclusions: The investigations show that the concentrations of Pb, As and Ni which are known carcinogens presents no significant carcinogenic lifetime risk due to ingestion, inhalation and/or dermal contact but the non-carcinogenic risk, expressed as the Hazardous Index (HI), is not so benevolent; the cumulative index for all elements exceeding 1 and should be of concern, particularly in cases of the exposure of children. Capsule abstract: The concentrations of elements ranged from 5.04 mg/kg for Hg to 528.64 for Mn with highest Hazard Index being 4.55E+00 to 4.15E+01 and 8.53E-01 to 3.43E+01 for children.