Résumé
Inorganic arsenic is a ubiquitous metalloid, with well-known toxic properties for human health. In many regions of the world, human arsenic exposure is identified as a public health problem because of its presence in drinking water and certain food. Even at relatively low levels, regular consumption of contaminated water is considered to increase the risk of cancers in different organs, such as urinary bladder, skin, and lung, probably also liver, kidney and prostate. More recently, multiple other chronic diseases have been associated with environmental arsenic exposure, such as diabetes, cardiovascular diseases, as well as impaired immune function and child development. The WHO guideline water arsenic concentration is 10 µg L-1. Certain plants, rice in particular, is known to easily take up arsenic from the soil. In the south regions of Bolivia, concentrations above 100 µg L-1 have been found in traditional wells or tube-wells used by the population on a daily basis without having a clear knowledge of the situation. This arsenic originates from leaching of arsenic in sediments and volcanic rocks of geogenic origin (Muñoz et al, Ramos OE et al). Preliminary results of an ongoing cross sectional study have confirmed the human exposure in some villages south from Poopó Lake. Concentration between 10 and 150 µg/L were observed in tap water, traditional wells and tube-wells. The concentrations in collected urines samples, a marker of the total exposure through drinking water and food, confirmed exposure in the low to medium range, known to be associated with increased risk of adverse health effects. The lack of knowledge by medical staffs of the region and the absence of overt symptoms will be discussed.