METABOLISM OF ARSENIC AFTER ACUTE OCCUPATIONAL ARSINE INTOXICATION

Among the elements of toxicological relevance, inorganic arsenic (As) probably exhibits the most complex metabolism, and we deemed it intere sting to identify and quantify the different As species excreted after an occupational acute intoxication with arsine. For this purpose tota l Ar and five As species were determined using an hybrid analytical me thod coupling liquid chromatography with inductively coupled plasma ma ss spectrometry. The highest urinary elimination of total As was obser ved in the first 5 d after admission. The As species mostly excreted w ere monomethylarsonate (MMA), dimethylarsinate (DMA), Ar3+ arsenobetai ne (AsB), and to a lesser extent As5+. The amount of AsB excreted in u rine by the subject does not appear to be completely justified by AsB intake through food. Arsenic is excreted mainly via the urine with a c learance of 7.8 ml/h/kg and follows a triphasic model with periods of 28 h, 59 h, and 9 d, respectively. The evidence that DMA excretion cul minates after a few days, when the excretion of the inorganic form is substantially reduced (while that of MMA is still elevated), seems to confirm the existence of two successive methylating enzyme activities. Furthermore, the elimination rate of As from blood follows a three-ph ase model and the half-lives of different species vary from about 27 t o 86 h with the following gradient As5+ < MMA < As3+ < DMA < AsB.