Geothermal fluids and volcanic emissions are important sources of arsenic (As), resulting in elevated concentrations of As in ground-, surface-water and soil, which may adversely affect the environment. Arsenic originating from geothermal features and volcanic activities is common in Latin America forming a serious threat to the livelihoods of millions of people. This review attempts to provide a critical overview of the geochemistry of As originating from these sources in Latin America to understand what information exists about and what future research needs to be undertaken. This study evaluated 15 countries in Latin America. In total, 423 sites were characterized with As originating from geothermal sources, mostly related to present volcanic activity (0.001 < As<73 mg/L, mean: 36.5 mg/L) and the transboundary Guarani Aquifer System (0.001 < As<0.114 mg/L, mean: 0.06 m...