| Metabolism of Inorganic Arsenic in Children with Chronic High Arsenic Exposure in Northern Argentina Gabriela Concha, Barbro Nermell, and Marie Vahter Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden Abstract
This study concerns the metabolism of inorganic arsenic (As) in children in three villages in northern Argentina: San Antonio de los Cobres and Taco Pozo, each with about 200 µg As/l in the drinking water, and Rosario de Lerma, with 0.65 µg As/l. Findings show that the concentrations of As in the blood and urine of the children in the two As-rich villages were on average 9 and 380 µg/l, respectively, the highest ever recorded for children. The concentrations were about 10 and 30 times higher for blood and urine, respectively, than in Rosario de Lerma. Total As in urine was only slightly higher than the sum of metabolites of inorganic As (U-Asmet) , i.e., inorganic As, methylarsonic acid (MMA) , and dimethylarsinic acid (DMA) ; this shows that inorganic As was the main form of As ingested. In contrast to previous studies on urinary metabolites of inorganic As in various population groups, the children and women in the present study excreted very little MMA. Thus, there seems to be a polymorphism for the enzymes (methyltransferases) involved in the methylation of As. Interestingly, the children had a significantly higher percentage of inorganic As in urine than the women, about 50% versus 32%. Also, the percentage of inorganic As in the children is considerably higher than in previous studies on children (about 13% in the two studies available) and adults (about 15-25%) in other population groups. This may indicate that children are more sensitive to As-induced toxicity than adults, as the methylated metabolites bind less to tissue constituents than inorganic As. In the children, the percentage inorganic arsenic in urine decreased, and the percentage of DMA increased with increasing U-Asmet, indicating an induction of As methylation with increasing exposure. Key words: age, biotransformation, blood, drinking water, exposure, methylation, urine. Environ Health Perspect 106:355-359 (1998) . [Online 15 May 1998] http://ehpnet1.niehs.nih.gov/docs/1998/106p355-359concha/ abstract.html Address correspondence to M. Vahter, Institute of Environmental Medicine, Karolinska Institutet, Box 210, 171 77 Stockholm, Sweden. We acknowledge Ricardo Maderna, CIGEBA, National University of la Plata ; the staff of the hospital in San Antonio de los Cobres, in particular Gerardo Vogler, Director of the hospital ; Gloria de Telechea, Hugo Telechea, and Alfredo Corrado of the hospital in Rosario de Lerma ; and Luis Alberto Verón of the El Quebrachal Hospital, Salta Province. This project was financed by the Commission of the European Community, contracts CT 93 0305 and PL 9324313. Received 10 November 1997 ; accepted 10 March 1998.
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