Information in this record refers to the use of sodium chromate Cr 51 as a diagnostic agent. No information is available on the use of sodium chromate Cr 51 during breastfeeding. The manufacturer recommends withholding breastfeeding after a diagnostic dose of sodium chromate Cr 51, but does not provide a specific duration. The long biological and physical half-lives of chromium may preclude resumption of breastfeeding of the infant. Mothers concerned about the level of radioactivity in their milk could ask to have it tested at a nuclear medicine facility at their hospital and when the radioactivity is at background levels they may safely resume breastfeeding. A method for measuring milk radioactivity and determining the time when a mother can safely resume breastfeeding has been published.[1]