Oral bioaccessibility of potentially toxic elements in stream- and terrace- sediments affected by mining activities, Remance gold mine (Panama)

Abstract

<p><strong>Abstract:</strong> 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.</p> <p>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.</p> <p>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.</p> <p>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<sup>-5</sup>) 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.</p> <p><strong>Keywords</strong>: bioaccesibility, potentially toxic elements, ingestion, stream sediments, terrace sediments, gold mine, Panama</p>