Secretion of 99Tcm in breast milk after intravenous injection of marked macroaggregated albumin.

A nursing mother received 99Tcm-macroaggregated albumin intravenously for a lung scan. Milk was pumped out at the times when feeding normally took place for three days and the activity was determined. The 99Tcm concentration diminished almost exponentially with an effective half-life of about 4 h. The radiation dose (26-0.001 muGy) was estimated to be so small that the risk to the child may be regarded as negligible.