Ecological and health risk assessment of heavy metal pollution of sediments from artisanal mining in North Central Nigeria.

Abstract

Artisanal and small-scale mining activities (ASMA) are common in many countries, especially within the rural areas, for socio-economic reasons. However, mining activities-induced heavy metal environmental pollution has now become a global ecological and public health problem requiring urgent targeted responses by all relevant stakeholders. The present study evaluated the ecological and health risk implications of ASMA-induced heavy metals pollution of 42 different sediments in North Central Nigeria using standard procedures. There was heavy metals pollution of sediments within the study areas in the order: Fe > Cr > As > Zn > Pb > Cd. Iron concentrations were significantly (p < 0.05) higher than those of other metals. Only Cd concentrations (3.29 ± 0.74 mg/kg) exceeded the FAO permissible sediment levels (1.00 mg/kg), indicating potential health risks. Cumulatively, site 4 (Niger State) was the most polluted site (Metal pollution index = 42.69) with site 7 (Kwara State) being the least (Metal pollution index = 9.07). However, Cd followed by As were the primary toxic pollutants. Based on the principal component analysis results, Cd and Zn concentrations were of anthropogenic origin while the Pb and Cr concentrations were lithogenic in origin. Only Fe (7.3340) and As (7.4630) individually as well as all the heavy metals cumulatively (15.3534) posed lifelong non-carcinogenic risk to adults exposed to heavy metal-laden sediments within the study areas. Nevertheless, the dermal and inhalational exposure routes posed no carcinogenic and non-carcinogenic health risks to adults. The relevant stakeholders should strive to improve the current mining practices with modern technology in order to reduce its heavy metals-induced environmental pollution and associated health risks within the study areas.