Arsenic and trace metals in hair, nails and blood of villagers from the vicinity of a gold mine in Tanzania

Abstract

Tanzania has had mining on a large scale since 1998. The North Mara Gold Mine is located in Tarime District in the north-western part of Tanzania. Recent studies in the North Mara area have indicated that mining activities release trace elements to the surrounding environment, potentially exposing the local population. The aim of the study was to clarify whether villagers living in the vicinity of the North Mara Gold Mine were exposed to trace elements at levels sufficiently high to be detected and quantified in hair, nails and/or blood. Influence of age, gender and smoking habits were investigated as well as potential relationships between trace element concentrations in hair and nails. Samples of hair, nail and blood were collected from 63 subjects from the villages Nyangoto, Kewanja, Matongo, Nyarwana, Nyakunguru, Weigita and Nkerege, as well as from a reference group from Dar es Salaam. Concentrations of arsenic (As), antimony (Sb), cadmium (Cd), lead (Pb), zinc (Zn), manganese (Mn), molybdenum (Mo), copper (Cu) and thorium (Th) were quantified in all tissues by inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of As, Mn and Th in hair and nails were higher in villagers from Tarime District compared to the reference group and normal ranges found in previous studies. There was no suspected exposure to Sb, Cd and Cu as the concentration in both hair and nails were within normal ranges, but the concentration of Zn in hair and nails indicated that some subjects suffer from Zn deficiency. The high and low concentrations of As and Zn respectively, may potentially lead to health impairments associated with As toxicity and Zn deficiency. The trace element concentrations in blood were not higher than normal ranges found in non-exposed populations elsewhere. Gender and age influenced the concentration of As, Pb, Cu and Th in hair, but not in nails. The concentration of As in men was significantly influenced by age and smoking for hair and nails respectively. Accumulation of trace elements did however appear to be more strongly affected by the village of habituation than any other factor. Correlation between matched hair and nail samples were found for the elements As, Cd, Zn and Th. There is a clear need to clarify possible health impairments associated with the elevated As concentrations observed as well as accurately identify sources of exposure.