Analysis of Health Risk Due to the Presence of Radioactivity and Chemical Elements in Groundwater, Aldama Municipality, Chihuahua, Mexico

There exist potential health risks due to the presence of some elements in groundwater. This study presents measurements of gross alpha and beta activity and chemical concentrations (fluorides and nitrates) in 25 water wells in Aldama municipality, Chihuahua, Mexico. Total alpha and beta emitter analyses were performed at the Academic Unit of Nuclear Studies at the Autonomous University of Zacatecas. Radioactive elements were concentrated by total evaporation. All samples were measured with a Wallac-Oy 1411 liquid scintillate with a pulse separation option (Pulse Shape Analysis) for 6 h. Fluorine and nitrate analyses were performed at the Faculty of Engineering of the Autonomous University of Chihuahua by flow injection-hydride generation collection-atomic absorption spectrometry. Exposure levels were calculated for each well and found to exceed maximum limits allowed under Mexican law in terms of 1) gross alpha and beta activity; and 2) fluoride and nitrate concentrations. Gross alpha activity in two wells exceeded the reference value of 0.56 Bq·L-1. Fluorides and nitrates were found in 40% and 48% of water wells, respectively. Fluoride values were higher than 1.5 mg·L-1, and the exposure doses for adults and children exceeded the reference value of 0.06 mg·kg-1·d-1. Children are the most vulnerable, since their intake doses are near or above of 0.12 mg·kg-1·d-1 of the minimum level of risk for the development of skeletal fluorosis or bone fractures. On the other hand, while nitrate concentrations in water wells exceeded the drinking water limit of 10 mg·L-1, this does not represent a serious health risk, since the calculated exposure doses for adults and children are below the chronic reference level of 1.6 mg·kg-1·d-1established by the USEPA.