The metabolism of arsenic in humans acutely intoxicated by As2O3. Its significance for the duration of BAL therapy.

The urinary excretion of inorganic arsenic and of its less toxic metabolites [monomethylarsonic acid (MMA) and dimethylarsinic acid (DM)] has been followed-up in five cases of acute oral intoxication by As2O3. In addition to supportive therapy all patients were given BAL. The proportion of the three species of urinary arsenic (inorganic, MMA, DMA) changes markedly with time. During the first 2 to 4 d after the intoxication, arsenic is excreted mainly as its unmetabolized inorganic form but this is rapidly followed-up by a progressive increase of the proportion excreted as MMA and DMA. The time at which the majority of arsenic is excreted as its organic metabolites depends on the severity of the intoxication but in all the cases, more than 95% of th excreted arsenic is in the organic form after 9 d, the dimethylated derivative being preponderant. Speciation of arsenicals in urine might be useful to determine the duration of BAL treatment.