Unlike inorganic arsenic, inorganic trivalent antimony (Sb) is not methylated in vivo. It is excreted in the bile after conjugation with glutathione and also in urine. A significant proportion of that excreted in bile undergoes an enterohepatic circulation. In workers exposed to pentavalent Sb, the urinary Sb excretion is related to the intensity of exposure. It has been estimated that after eight hours exposure to 500 micrograms Sb/m3, the increase of urinary Sb concentration at the end of the shift amounts on average to 35 micrograms/g creatinine.