Miguel Ángel Salas-Luévano

Niveles de plomo en la población de alto riesgo y su entorno en San Ignacio, Fresnillo, Zacatecas, México

Objective. To determine the lead concentration in the blood of children and nursing or pregnant women from San Ignacio, Fresnillo, in Zacatecas, Mexico as well as in soil, plants, ash and lead-glazed pottery, in order to determine exposure due to a metal-recycling facility. Material and Methods. The study was carried out from December 2004 to April 2005. Lead in blood was measured with anodic stripping voltammetry, while dispersive energy X-ray fluorescence was used in the other matrices. Results. Based upon the criteria outlined in the Official Mexican Standards, 90% of the children was identified as category I, 5% as category II and another 5% as category III. The soil in the land near the facility contained from 73 to 84 238 ∝g/g, with an average of 4940 ∝g/g. Larger lead concentrations were found on sites located closer to the facility. San Ignacio’s soil contained, on average, 109 ∝g/g. High lead levels were found in glazed pottery and the concentration in agricultural crops was greater than 300 ∝g/g. Conclusions. Although the majority of children in San Ignacio have blood lead concentrations considered to be acceptable according to the Official Mexican Standards, several studies indicate that deleterious effects on children’s health exist even at low concentrations. The land around the metal recycling facility is contaminated with lead, and to that extent, the crops that are produced there, once ingested, are a source of contamination, which is compounded by the use of glazed pottery. Manzanares-Acuna E, Vega-Carrillo HR, Salas-Luevano MA, Hernandez-Davila VM, Letechipia-de Leon C, Banuelos-Valenzuela R. Niveles de plomo en la poblacion de alto riesgo y su entorno en San Ignacio, Fresnillo, Zacatecas, Mexico. Salud Publica Mex 2006;48:212-219.

Accumulation and phytostabilization of As, Pb and Cd in plants growing inside mine tailings reforested in Zacatecas, Mexico

The aim of this research was to identify plant species with potential to accumulate and stabilize arsenic (As), lead (Pb) and cadmium (Cd) in mine tailings reforested and naturally recolonized locations in a semiarid region of Zacatecas, Mexico. Plant shoots from 44 species and their rhizospheric soils were analyzed for As, Pb and Cd concentration using atomic absorption spectroscopy. Most represented plant families were Asteraceae, Poaceae, Fabaceae and Cactaceae. The highest concentrations in shoots were As, followed by Pb and Cd. Among herbaceous species, Bouteloua gracilis showed the highest bioconcentration factor (BCF) of As, while Plantago lanceolata showed the highest bioconcentration factor of Pb. The shrub species with highest concentration of As in the rhizospheric soil were Opuntia robusta, Melilotus alba, Baccharis neglecta and Arundo donax (near BCF to 1.0). Similar results were observed in trees Casuarina equisetifolia, Prosopis laevigata, Fraxinus uhdei and Eucalyptus globulus. In addition, Tillandsia recurvata showed a suitable indicator of atmospheric deposition to As. In general, the results suggest that these species can be effective for tailings reforestation with the possibility to enclose potentially toxic elements. Specially, C. equisetifolia which is abundant, having the potential for future applications in other contaminated sites with different types of mine tailings or abandoned mines from arid and semiarid zones.

Design of an explosive detection system using Monte Carlo method.

Regardless the motivation terrorism is the most important risk for the national security in many countries. Attacks with explosives are the most common method used by terrorists. Therefore several procedures to detect explosives are utilized; among these methods are the use of neutrons and photons. In this study the Monte Carlo method an explosive detection system using a 241AmBe neutron source was designed. In the design light water, paraffin, polyethylene, and graphite were used as moderators. In the work the explosive RDX was used and the induced gamma rays due to neutron capture in the explosive was estimated using NaI(Tl) and HPGe detectors. When light water is used as moderator and HPGe as the detector the system has the best performance allowing distinguishing between the explosive and urea. For the final design the Ambient dose equivalent for neutrons and photons were estimated along the radial and axial axis.