M. Vahter et al., A UNIQUE METABOLISM OF INORGANIC ARSENIC IN NATIVE ANDEAN WOMEN, European journal of pharmacology. Environmental toxicology and pharmacology section, 293(4), 1995, pp. 455-462
The metabolism of inorganic arsenic (As) in native women in four Andea
n villages in north-western Argentina with elevated levels of As in th
e drinking water (2.5, 14, 31, and 200 mu g/l, respectively) has been
investigated. Collected foods contained 9-427 mu g As/kg wet weight, w
ith the highest concentrations in soup. Total As concentrations in blo
od were markedly elevated (median 7.6 mu g/l) only in the village with
the highest concentration in the drinking water. Group median concent
rations of metabolites of inorganic As (inorganic As, methylarsonic ac
id (MMA) and dimethylarsinic acid (DMA)) in the urine varied between 1
4 and 256 mu g/l. Urinary concentrations of total As were only slightl
y higher (18-258 mu g/l), indicating that inorganic As was the main fo
rm of As ingested. In contrast to all other populations studied so far
, arsenic was excreted in the urine mainly as inorganic As and DMA. Th
ere was very little MMA in the urine (overall median 2.2%, range 0.0-1
1%), which should be compared to 10-20% of the urinary arsenic in all
other populations studied. This may indicate the existence of genetic
polymorphism in the control of the methyltransferase activity involved
in the methylation of As. Furthermore, the percentage of DMA in the u
rine was significantly higher in the village with 200 mu g As/l in the
water, indicating an induction of the formation of DMA. Such an effec
t has not been observed in other studies on human subjects with elevat
ed exposure to arsenic.