ARSENIC LEVELS IN RURAL DUST OF A SETTLEMENT SURROUNDED BY AGRICULTURAL FIELDS IN A SEMIARID REGION OF NORTHWESTERN MEXICO

Arsenic is one of the ten chemical substances that represent a potential risk to human health. This element can be incorporated into the environment by diverse anthropogenic activities such as mining, agriculture, waste disposal, livestock, etc. Prolonged exposure or high concentrations of arsenic may pose a potential high risk to human health. The El Poblado Miguel Alemán (EPMA) is a dusty, mostly unpaved, rapidly growing, and a high degree of marginalization human settlement in northwestern Mexico. The EPMA is surrounded by the agricultural fields of La Costa de Hermosillo (LCH), which have been productive since the decade of 1940´s. Some agricultural fields have been abandoned due to a saltwater intrusion as a result of an overexploitation of groundwater. Therefore, active and abandoned fields can serve as potential source of contaminants, mainly due to the semi-arid environmental conditions of the region that favors erosion and re-suspension of dust, with final destination into rural areas. This is the first investigation that explores the arsenic concentrations in road dust, backyard soils, and schoolyard soils of the EPMA. The arsenic concentrations were determined using a portable X ray fluorescence in two particle size fractions (44 to 20, and <20 μm). The minimum and maximum arsenic concentrations in road dust samples for the analyzed fractions are 12.3-28.3 and 17.4-64.6 μg/kg, respectively. The results for backyard soils are 15.6-22.5 and 21.1-35.9 μg/kg, respectively. As concentrations in schoolyard soils are 14.9-20.9 and 22.5-28.9 μg/kg, respectively. Preliminary arsenic concentration in the studied samples exceeded the maximum permissible limit (22 μg/kg) for residential and rural soils according to the Mexican regulation (NOM-147). Therefore, dust re-suspension may be exposing the population to potentially harmful concentrations of arsenic.