The global challenge of reducing mercury contamination from artisanal and small-scale gold mining (ASGM): evaluating solutions using generic theories of change

ASGM accounts for 37% of global anthropogenic mercury emissions, primarily affecting tropical regions with inadequate regulations. Mercury contamination poses serious health risks, including neurological and reproductive damage, particularly for miners, their families, and nearby communities. The global deposition of mercury from ASGM is substantial, with many areas receiving significant mercury deposition compared to other regions. The Amazon Basin, Indonesia, and the Congo Basin are among the most affected areas. Mercury is inextricably linked with ASGM, as it is used to extract gold from ore and alluvial sediments, resulting in a high proportion of mercury being released to the environment. Mercury contamination has been identified as a human health issue and a conservation issue. It can biomagnify and bioaccumulate in ecosystems, leading to elevated mercury concentrations in organisms at higher trophic levels. This has been observed in various animal taxa, including birds, bats, fish, and insects, which have shown altered reproductive organs, damaged tissues, and decreased animal size and reproductive output. The use of mercury in ASGM is a significant concern due to its informal and unregulated nature. Organized crime groups have been involved in ASGM, leading to human rights abuses, corruption, and violence. Vulnerable populations are both impacted by ASGM and may participate in ASGM activities due to its potential for lucrative livelihoods. Governments, environmental organizations, and human rights advocates have worked to develop interventions for mercury threat abatement from ASGM. These strategies range from local to national and global scales, including mercury-free ASGM technologies, monitoring contamination, ending the trade of mercury, and enforcing ASGM bans. However, these strategies are often complicated, expensive, and require long-term commitments, with uncertain impacts. A theory of change (ToC) is a powerful approach for assisting in the decision-making process for ASGM interventions. A ToC describes a causal chain of results, referred to as "Impact Pathways," which emerge from the activities and outputs of the intervention. This approach can help articulate assumptions about interventions, connections among actions, and desired outcomes, enabling a more effective approach to address the mercury contamination issue from ASGM. The Minamata Convention on Mercury is a global agreement aimed at reducing mercury emissions. Governments and civil society organizations have worked to develop interventions for mercury threat abatement from ASGM, including engagement with the Minamata Convention, support for existing national laws and policies, and engagement of indigenous people and local communities with governments to meet their legal obligations. By methodically articulating assumptions about interventions, connections among actions, and desired outcomes, it is possible to create a more effective approach to address the mercury contamination issue from ASGM.