Emerging mercury mitigation solutions for artisanal small-scale gold mining communities evaluated through a multicriteria decision analysis approach

Abstract

Over 15 million people are involved in artisanal small-scale gold mining (ASGM) globally. Often, ASGM includes smelters that use mercury to extract gold. If mishandled, these actions may cause adverse health effects for smelters and their surrounding communities. There are multiple tools to reduce health risks while maintaining a sustainable economic profit, but each method has trade-offs, such as cost, efficiency, and potential health impacts that are not widely understood. Multicriteria decision analysis (MCDA) is a powerful tool in assessing multiple perspectives and factors that affect stakeholder decisions and can be used to inform smelters and community members on reducing exposure to mercury. Here, MCDA was used to determine the ranks of alternatives to reduce exposure to mercury based on socio-economic, ecological, and human health criteria. Stochastic processes were used to evaluate 12 alternatives, including mitigation strategies (i.e., chelation therapy techniques, retorts, water filters) as well as mercury-free mining substitutes. In this model, the borax method ranked first 72% of the time, followed by the gravity method (19%), a multicapture system retort (7%), and low-cost retorts (≤ 1%). While MCDA is an excellent tool, results tend to be generalized across a heterogenous landscape. More localized factors such as incorrect soil chemistry could cause performance challenges for options like mercury-free mining substitutes. To aid more localized decision-making, a decision tree model was developed to aid stakeholders to explore which alternatives are suitable based on context-specific factors using “Take-the-best” decision heuristics. This work can assist researchers and stakeholders involved with ASGM to identify which options are scalable for their region as well as to mitigate adverse effects of exposure to mercury.