Pollution and health risk assessment of drinking water sources within artisanal and small-scale gold mining areas: a case of Asankrangwa District in Ghana

Abstract

Artisanal and small-scale gold mining (ASGM) is common in many developing countries; while it contributes to their socio-economic development, it also causes environmental pollution. This study examined the impact of ASGM activities on the quality of drinking water sources in the Asankrangwa District in Ghana, in terms of water quality index, heavy metal pollution index models, and human health risks. The results of physicochemical parameters indicate that 40.0% of all water sources are unsuitable for consumption. Heavy metal pollution indices indicated that 45.0% of the water sources were extremely polluted, and 25.0% were moderately polluted. For instance, cadmium (Cd) concentrations across all water sources reached levels up to 23 times the WHO limit (3.0 × 10^-3 mg/L). Additionally, mercury (Hg) concentrations in 75.0% of the water sources (2.0 × 10^-3-7.2 × 10^-1 mg/L) exceed the maximum contaminant limit (2.0 × 10^-3 mg/L) by approximately 361 times. Streams, in particular, exhibit higher Hg levels than groundwaters. Analysis revealed that 90% of the water sources pose a significant carcinogenic health risk upon consumption, with lifetime cancer risk values exceeding 1.0 × 10^-4. The findings revealed that the pollution level is reduced and water quality improved 5 km from the ASGM sites; however, the water sources require treatment to render them suitable for consumption.