Anthropogenic activities performed in the Ecuadorian Amazon have released potentially toxic elements (PTEs) into the rivers, causing severe environmental pollution and increasing the risk of exposure to the residents of the surrounding areas. This study aims to carry out a human health risk assessment using deterministic and probabilistic methods to estimate the hazard index (HI) and total cancer risk (TCR) related to multi-pathway human exposure to PTEs in polluted rivers. Concentrations of Al, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in surface water and sediment samples from rivers on the Ecuadorian Amazon were considered to assess the potential adverse human health effects. As a result, deterministic and probabilistic estimations of cancer and non-cancer risk through exposure to surface waters and sediments were above the safety limit. A sensitivity analysis identified the concentration of PTEs and the exposure duration (ED) as the two most important variables for probabilistic health risk assessment. The highest risk for receptors was related to exposure to polluted sediments through incidental ingestion and dermal contact routes. According to the deterministic estimation, the human health risk through ingestion of water was above the threshold in specific locations. This study reveals the potential health risk to which the population is exposed. This information can be used as a baseline to develop public strategies to reduce anthropogenic pollution and exposure to PTEs in Ecuadorian Amazon rivers.

Consumption of food grown in contaminated soils may be a significant human exposure pathway to pollutants, including toxic elements. This study aimed to investigate the pollution level of trace elements in farmland soil and crops collected in orchards from Ponce Enriquez, one of the Ecuador’s most important gold mining areas. The concentration of arsenic (As), cadmium (Cd), chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) was analyzed in soil and crop samples (celery, chives, corn, herbs, lettuce, turnips, green beans, cassava, and carrots). In addition, a probabilistic human health risk assessment, in terms of hazard quotients (HQ) and cancer risk (CR), was conducted to assess the potential risk related to local crop ingestion. The contents of As, Cr, Cu, and Ni in soils exceeded the Ecuadorian quality guidelines for agricultural soils. The trace elements concentration in local crops was higher than the maximum permissible levels set by the Food and Agriculture Organization of the United Nations (FAO). The HQ and CR of local crop ingestion were several orders higher than the safe exposure threshold, mainly for lettuce, chives, and turnips. Our results revealed that inhabitants of the study area are exposed to developing carcinogenic and non-carcinogenic effects due to long-term food consumption with high trace elements. This study sheds light on the need to assess further the quality of agricultural soils and crops grown in mining areas with signs of contamination to guarantee consumer food safety.

Mining environmental liabilities (MEL) are of great concern because of potential risks to ecosystems and human health. In this research, the environmental risk (R_I) related to MEL existing in three artisanal and small-scale gold-mining areas of Ecuador was evaluated. For this purpose, data of 167 MEL including landfills, mining galleries, tailing deposits, and mineral processing plants from Macuchi, Tenguel–Ponce Enriquez, and Puyango mining areas, were analyzed. The risk assessment related to the presence of waste deposits was carried out based on the methodology proposed by the Spanish Geological Survey. Moreover, the procedure outlined in the Environmental Risk Assessment Guide of the Ministry of Environment of Peru for nonwaste deposits was applied. The highest R_I values were identified in Puyango and Tenguel–Ponce Enriquez. Thus, they were both categorized as priority control areas requiring intervention and rehabilitation plans. The MEL that require a high level of intervention include waste deposits and mine entrances associated with potentially toxic elements. Moreover, the point risk maps showed that rivers in the studied areas have a potential pollution risk. This study provides risk levels associated with MEL in mining areas from Ecuador. This information could be used for environmental management and pollution mitigation.

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Artisanal and small-scale gold mining is an important contributor to global human emissions of Hg. This study assesses the probabilistic human health risk for two receptors groups (residents and workers) of Portovelo mining area through exposure to Mercury (Hg) in the air at two sites: (a) the central urban area; and (b) El Pache sector. A preliminary risk assessment was performed using Hg concentrations from previous studies. The human health risk in the workplace scenario showed unacceptable levels of non-carcinogenic risk in rainy and dry seasons. Hazard Quotient (HQ) showed that 75% of the workers receptors were exposed to harmful effects on the nervous, digestive, respiratory, and immune systems. Regarding the residential scenario, no human health risk is presented. The study provides information on the levels of risk to the health of the inhabitants living in mining communities to improve public management strategies to minimize risks. La minería del oro artesanal y a pequeña escala contribuye de forma importante a las emisiones globales de Hg. El presente estudio evalúa el riesgo probabilístico para la salud humana de dos grupos de receptores (residentes y trabajadores) de la zona minera de Portovelo por exposición al mercurio (Hg) en el aire en dos sectores: (a) la zona urbana central; y (b) el sector de El Pache. Se realizó una evaluación preliminar del riesgo utilizando concentraciones de Hg de estudios anteriores. El riesgo para la salud humana en los lugares de trabajo mostró niveles inaceptables de riesgo no cancerígeno en las estaciones lluviosa y seca. El cociente de peligrosidad (HQ) mostró que el 75% de los trabajadores receptores estaban expuestos a efectos nocivos en el sistema nervioso, digestivo, respiratorio e inmunitario. En el escenario residencial, no se presenta ningún riesgo para la salud humana. El estudio proporciona información sobre los niveles de riesgo para la salud de los habitantes de las comunidades mineras con la finalidad de mejorar las estrategias de gestión pública para minimizar los riesgos.

Tailings are a significant concern due to their potential release of toxic elements into the environment, posing risks to ecosystems and human health. Therefore, understanding their polluting potential is crucial for effective mitigation strategies. This study evaluates the contaminating potential of eight tailing dams in the upper basin of the Puyango River in southern Ecuador. A physicochemical and mineralogical characterization of the tailings was conducted. The contents of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Se, V, and Zn were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The contamination index (IC) and the risk (R_I) to the environment and population were evaluated. As a result, it was found that As, Cu, Pb, Se, and Zn exceeded the maximum permissible limits in all the samples according to Ecuadorian regulations. Six of the eight tailing dams presented very high pollution levels (21.28 < IC < 298.61), indicating a severe contamination risk. As, Sb, and Se were the most significant contributors to the index, with 29%, 31%, and 20% contribution to the overall IC, respectively. However, the risk assessment indicated a low risk (R_I < 5) to both the population and the natural environment, mainly due to the distance between the tailing dams and the potential receptors. While the present risk associated with the studied tailing dams is low, there exists potential for long-term escalation.