389 observed that the forming elements of rocks such as Cu, Fe and Zn in high concentrations have low mobility equivalent to the tailings under study, especially iron and zinc. Low certified concentrations of bioaccessible Pb and As from the BGS102 reference material yielded data with the highest variability (RSD≈20%) of gastric and gastrointestinal bioaccessibility. On the other hand, when tailings under studies contained higher total and bioaccessible concentrations RSD was reduced to values below 10%.Regarding the variable of pH control, as a critical factor to obtain reproducibility of the method in the laboratory using the UBM method, in this study with and without the device, it was possible to implement it with RSD close to 20%, equivalent to international studies (Wragg, J. et al, 2009). 3.3 CONCLUSION The efficacy of the MABIOMET used in the laboratory was validated by obtaining the average bioaccessible concentration of Pb for the gastric stage and the average bioaccessible concentration of As for the gastrointestinal stage within the certified confidence limit for the BGS 102 reference material. Additionally, the confidence limits determined are consistent with the certified data, with a relative standard deviation of less than 20%. The application of the device to representative samples of tailings from Andacollo to analyse the bioaccessibility of lead and arsenic, yielded an average repeatability of 4%, measured as RSD%, obtained for the 5 tailings including both stages of the process. Finally, for the set of elements analyzed (As, Cu, Fe, Pb and Zn) in the 5 abandoned tailings, the average standard deviation for both stages of the UBM process for the representative samples was less than 20%. These results allow for the validation phase of MABIOMET technology in the field and laboratory, in a relevant environment, demonstrating its competitive commercial advantages, such as cost savings and reduced monitoring times in large areas through representative and statistically significant composite samples. This allows for the quantification of specific risks to human health and the adoption of rapid preventive measures. Furthermore, it enables the generation of realistic risk classifications at mining sites, rather than overestimates based on total or reference concentrations that do not consider the specific characteristics of each tailing (Ma, L, et al 2022). In this way, MABIOMET technology allows scientific advances in risk assessment to be placed at the forefront, with an emphasis on human health, as it quantifies the bioaccessibility of carcinogenic and mutagenic metals and metalloids, elements present in mining sites and tailings (Shentu et al, 2023). Bioaccessibility is the environmental variable directly related to relative bioavailability (Ruby et al., 1999), which is multifactorial, as it depends on the geochemistry of the site, particle size (Ma J, et al, 2019), the metal under study, its chemical speciation, pH, presence of carbonates, Fe/Mn oxides, and organic matter present (Tang et al; 2022). For this reason, it is necessary to carry out permanent monitoring with experimental in situ tests and refine risk studies, avoiding their overestimation, as is currently the case when using total concentrations, especially in the case of arsenic and lead ( Xie, K., et al, 2023 and Wragg, et al, 2009).
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