Abstract
Abstract
Artisanal and small-scale gold mining (ASGM) is both a major source of livelihood and of toxic metal environmental contamination in Ghana. While prior studies in the country have focused on mercury, less is known about the combined distribution and exposure risks of multiple toxic metals across environmental media and food systems. This study is the first multi-regional assessment of mercury, lead, arsenic, and cadmium across eleven ASGM sites in six regions of Ghana. A combination of field-based rapid screening (X-ray fluorescence [XRF], Jerome® mercury vapor analyzer) and laboratory analysis with inductively coupled plasma mass spectrometers (ICP-MS) and inductively coupled plasma-optical emission spectrometer (ICP-OES) was used to quantify contamination in soil, water, air, selected crops, and fish. Soil contamination in the Ashanti and Western regions exceeded international thresholds for lead, mercury, and arsenic, with arsenic levels in one site reaching 10,060 mg/kg. Overall, water contamination was less severe except for Asiakwa, and airborne mercury was mostly below national limits. Food system analysis suggested that soil–crop–dietary transfer may be an important exposure pathway. Several crops and fish samples surpassed WHO/FAO safety limits. Validation of portable XRF measurements against laboratory results showed strong correlations (r = 0.85–0.94), supporting the use of XRF in settings with limited resources. The novel contributions of this study include: the first integrated mapping of toxic metals across multiple media in Ghana’s ASGM areas; empirical evidence of food-chain bioaccumulation as a critical exposure route; and the demonstration of cost-effective, field tools for large-scale monitoring. These findings provide essential evidence for Ghana’s policy response under the Minamata Convention and highlight the need for region-specific mitigation strategies.