Human Health Risk Assessment of Heavy Metal Contamination in an Artisanal Gold Mining Community of Kogi State, Nigeria

Abstract

Artisanal and small-scale gold mining (ASGM) is known to improve the standard of living in the host communities and economic performance of countries involved. However, despite the positive impact on the economy, ASGM is a significant point source of uncontrolled mobilization of hazardous chemicals, notably heavy metals into the environmental media such as soil, air and water. This study assessed human health risk of exposure to heavy metals in soil around artisanal gold mining in Ike community of Kogi State. Twelve (12) soil samples obtained from the gold mining area were analysed for heavy metals (As, Cd, Ni, Pb and Zn) using Atomic Absorption Spectrometry (AAS). Measured concentrations of these metals were used to calculate health risk of children and adults using health risk assessment models. The results showed that mean values of heavy metal concentrations in the soil reflected low metal load (<1) with decreasing order of As>Pb>Zn>Ni>Cd. The results obtained from analysis of noncarcinogenic risk demonstrated that hazard index values of various heavy metals for three exposure pathways (ingestion, dermal and inhalational) were < 1 for children and adults populations. However, As recorded hazard index values > 1 for ingestion pathway for both populations. It was found that As recorded carcinogenic risk of 1.85E-03 for children and 9.86E-04 for adults and Cd recorded 4.67E-04 for children. These values exceeded the safety limit, ranging from 1E-06 to 1E-04, as stated by US Environmental Protection Agency. The study showed that As might pose carcinogenic and non-carcinogenic risks for both populations. Also, Cd might pose carcinogenic risk for children. Hence, As and Cd would be regarded as elements of serious concern in the study area.