Arsenic and porphyrins

BACKGROUND: To evaluate the possible effect of inorganic arsenic (iAs) and of its species on the urinary excretion of porphyrin homologues. METHODS: Total porphyrins and their homologues (copro, penta, hexa, hepta, uroporphyrins) and arsenic species (trivalent and pentavalent As; monomethyl arsonic acid; dimethyl arsenic acid; arsenobetaine) were measured respectively by HPLC and HPLC-ICP MS in urine from 86 art glass workers exposed to iAs and from 54 controls. RESULTS: A significant increase in the excretion of penta and uroporphyrins was demonstrated for workers exposed to As; As3 was the species best correlated with urinary porphyrin excretion. CONCLUSIONS: The increase of urinary excretion for some porphyrin homologues appears to be consistent with the inhibition by As of URO-decarboxylase in the heme biosynthesis pathway. The determination of urinary porphyrin homologues could be useful to assess, on a group basis, some early effects of arsenic and to demonstrate possible individual susceptibility to the element.