Urinary arsenic speciation profile in ethnic group of the Atacama desert (Chile) exposed to variable arsenic levels in drinking water

Abstract

Ethnic groups from the Atacama Desert (known as Atacameños) have been exposed to natural arsenic pollution for over 5000 years. This work presents an integral study that characterizes arsenic species in water used for human consumption. It also describes the metabolism and arsenic elimination through urine in a chronically exposed population in northern Chile. In this region, water contained total arsenic concentrations up to 1250 μg L⁻¹, which was almost exclusively As(V). It is also important that this water was ingested directly from natural water sources without any treatment. The ingested arsenic was extensively methylated. In urine 93% of the arsenic was found as methylated arsenic species, such as monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. The original ingested inorganic species [As(V)], represent less than 1% of the total urinary arsenic. Methylation activity among individuals can be assessed by measuring primary [inorganic As/methylated As] and secondary methylation [MMA/DMA] indexes. Both methylation indexes were 0.06, indicating a high biological converting capability of As(V) into MMA and then MMA into DMA, compared with the control population and other arsenic exposed populations previously reported.

Keywords:

• Arsenic in urine
• arsenic methylation index
• arsenic speciation
• Atacama Desert
• arsenic exposure

Funding

The authors appreciate the support of Red Doctoral Redoc.CTA, MINEDUC project UCO 1202 and the 480 international collaboration program of project Fondecyt N1121128 for the financial support of Professor Dulasiri Amarasiriwardena visit to the University of Concepcion. The authors acknowledge partial financial support from the Fulbright-Chile Commission and the Fulbright Council (USA), Grant AIA-FY2001. We also thank the support of the National Commission for Scientific and Technological Research (CONICYT), Project Fondecyt N°1121128, The Associative Research Program (Grant PIA ACT-130).