I would like to concur with Dr. Newmans posting on the use of Iodine containing radiocontrast agents. While it is true they contain iodine, the iodine is covalently bound to benzene rings, and the manufactures' studies reinforce that virtually NO iodine is metabolically released into the plasma(less than 0.005%), but rather rapidly cleared renally with the molecule intact. Hence, it would be virtually impossible for the iodine in radiocontrast agents to be released and then enter milk. Virtually all of these radiocontrast agents look alike, they differ slightly in structure, but almost all have covalently bound iodine molecules in varying concentration. Their plasma half-lives are almost without exception less than one hour, and they seldom leave the plasma compartment. Their concentration in breast milk has been found to be less than 0.5% of the maternal dose. Further, their oral bioavailability is nil, and we commonly use these same agents orally in neonates as radiocontrast agents. Remember, after 5 half-lives, about 99% of all medications are completely cleared from the body. Regards Tom Hale, Ph.D.