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The Remance gold mine, in Veraguas, Panama, has been widely affected by mining activity, whose last exploitation period was between 1989 and 1999, by the company Minera Remance S.A. Previous studies have reported that stream sediments are severely polluted; terrace sediments represented a serious ecological risk and stream sediments a high ecological risk represented by the presence of high concentrations of potentially toxic elements (PTEs. In addition, the study also showed that soil health, evaluated through the DHA (dehydrogenase activity) factor, is more affected in the terrace sediments and stream sediments than in the soils. The carcinogenic and non-carcinogenic risk assessment was exceeded for children into a recreational setting in areas of major mining activity; for adults, the carcinogenic risk is also exceeded mainly by the ingestion route. The area is inhabited by peasants, who carry out their daily activities, such as recreation and subsistence agriculture, reason why it is necessary to carry out bioaccessibility studies on these materials to properly assess the real risks for this population.The objective of this study has been to determine the oral bioaccessibility of PTEs in terrace sediments and stream sediments to evaluate the health risks that these materials represent in case of accidental ingestion in a recreational setting. The following PTEs were analysed: were determined in the pseudo-total fraction by ICP-OES: Cu, As, Zn, Sb and Ba. The oral bioaccessibility test was performed by the UBM method and the concentrations of the PTEs in the gastric and gastrointestinal phase were determined by ICP-OES. The percentage of bioaccessibility (% BAF) for the PTEs, and the carcinogenic and non-carcinogenic risks by ingestion in all fractions were evaluated for children and adults in a recreational setting.The results show that terrace sediments have higher total concentration of PTEs than stream sediments, while the oral bioaccessibility is higher in stream sediments than in terrace sediments and is higher in the gastric phase than in the gastrointestinal phase. The order of oral bioavailability was as follows: Cu>Zn>Ba>As>Sb.As for the non-carcinogenic risk by ingestion, the maximum permissible limit (HI=1) is exceeded for the sum of the studied PTEs in the pseudo-total fraction of stream sediments and terrace sediments in a recreational setting for children, but not in the gastric and gastrointestinal fractions. The maximum permissible limit for carcinogenic risk (1x10-5) is exceeded by As for adults and children in all stream and terrace sediments in the pseudototal fraction, and for children in the gastro and gastrointestinal fraction in the stream sediments of “El Toro” stream and terrace sediments of “Veneno” stream below one of the mine tailings accumulations. Therefore, recreational activity in these streams is not recommended.Keywords: bioaccesibility, potentially toxic elements, ingestion, stream sediments, terrace sediments, gold mine, Panama

The Remance gold mine, in Veraguas (central Panama), had its last mining operation in 1999, using the cyanidation process for Au separation. As a result of this activity, three waste tailings were exposed to the weather, in addition to mine dumps and the open pit mining areas. Currently the area is inhabited by peasants who develop subsistence agriculture and livestock. Therefore, the objective of this study has been to evaluate the environmental and human health risks that this area represents. The total concentrations of potentially toxic elements (PTEs) such as As, Cu, Zn, Ba, Sb and Hg were determined in mining process areas, surrounding soils and edible and inedible plants in the area; in addition to the cyanide species and the enzymatic activity by dehydrogenase (DHA) in soils. The accumulated contamination index (PLI) and potential ecological risk (RI) were calculated, the carcinogenic (CR) and non-carcinogenic (HQ) risk to human health represented by soils and edible plants was estimated.Regarding the degree of contamination, it is observed that the contamination is considerable in the tailings and the sediments of the pithead, and it spreads to the surroundings mainly in the sediments of the streams and their terraces, and, to a lesser degree, to the soils around it, showing that the main route of dissemination is through runoff; the same trend is followed by the potential ecological risk, being extreme in the sediments of the pithead, serious in the tailings and terrace sediments, high in the stream sediments and medium in the surrounding soils. The enzymatic activity by DHA tells us that the health of the surrounding soils is better than that of the stream sediments and terrace sediments, but less than in other sites affected by mining activity in Spain. Cyanide species are linked to DHA and this in turn is favoured by organic matter (OM). On the other hand, it was observed that cyanide elutes from the tailing’s piles in a complex cyanide way, favouring the transport of PTEs associated with it to the stream sediments.Regarding the risks to human health in soils, As and Cu concentrations exceed the limits for non-carcinogenic and carcinogenic risk in both children and adults, with the residential scenario being the worst scenario, and for adults also the agricultural scenario. In edible plants such as rice, corn, cassava and tea leaves, Sb exceeds the limit for non-carcinogenic risk, and Cu and As for carcinogenic risk. Due to the potential ecological and human health risks that the area represents, actions must be taken to reduce them.Keywords: potentially toxic elements (PTEs), gold mine, risk assessment, edible plants, human health.

The inadequate treatment of waste materials in mine tailings, the closure stage not carried out correctly, carries risks due to the residues of potentially toxic elements (PTEs) that it may contain. In Panama, environmental regulations are recent, and even so the regulations are not strictly enforced, leaving a problem for the adjacent communities. Such is the case of the Remance Gold Mine, in Veraguas, Panama; this area has been exploited intermittently for over a hundred years, by different companies; the last period of exploitation was between 1989 and 1999, through a cyanidation process to extract the precious metal. Currently three tailing dams with mining waste are exposed to climatic conditions such as rain and wind, in addition to this, within the mine area and its surroundings live peasants who carry out subsistence activities such as agriculture and livestock. The purpose of this study was to evaluate the remaining potentially toxic elements and the persistence of cyanide in the tailings, and whether the remaining quantity represents a risk to human health and the environment, according to current environmental regulations in Panama and America. For this purpose, samples have been taken from the tailings and adjacent areas that could be directly related to the cyanidation process, geochemical analysis such as pH, CEC, conductivity, organic matter, potentially toxic elements and total cyanide have been carried out. The most concerning aspects of the results obtained here have been the contents of Ba (between 55 and 610 mg kg-1), Zn (between 12 and 153 mg kg-1), Sb (between 0.6 and 25.5 mg kg-1) and Hg (between 0.1 and 3.2 mg kg-1), which, according to the criteria of land use quality standards in Panama and American countries, correspond to values above the permissible limits for agricultural and residential land use. Meanwhile the levels of As (between 17.3 and 5030 mg kg-1) and Cu (between 5.4 and 403 mg kg-1) are higher than the legally established values for industrial land use. Far more significant are the values for total cyanide (between 1.4 and 518 mg kg-1), revealing the persistence of this chemical over time. These cyanide values are far higher than those reported in the literature for solid tailings from an abandoned gold mine and the values for gold mine tailings in the Americas, thus representing a serious threat to the environment.