Radiopharmaceuticals in breast milk

As assessment has been made of the radiological hazards to an infant following the administration of a radiopharmaceutical to a breast feeding mother. Feeding should be discontinued after administration of most I-131 and I-125 compounds, Ga-67 citrate or Se-78 methionine, and for iodinated compounds where it was possible to resume feeding, a thyroid-blocking agent should be administered. For Tc-99m compounds, pertechnetate had the greatest excretion in milk and interruptions of 12hr and 4hr were considered appropriate for pertechnetate and MAA respectively. Other Tc-99m compounds, Cr-51 EDTA and In-111 leucocytes did not justify an interruption just on the grounds of their associated excretion in milk. The ingestion hazard could be minimized by reducing the administered activity, and in some cases, by the substitution of a radiopharmaceutical with lower breast milk excretion. For Tc-99m lung and brain scans, the absorbed dose due to radiation emitted by the mother (i.e. when cuddling) was less than the ingested dose, but for a Tc-99m bone scan the emitted dose was greater. In all three cases, the emitted dose did not exceed 0 x 5 mGy for the infant in close contact to the mother for one-third of the time. For In-111 leucocytes, the emitted dose was about 2mGy, and it was concluded that close contact should be restricted to feeding times during the first 3 days after injection. 36 references, 2 figures, 5 tables