A review of the secretion of radioactivity in human breast milk: data, quantitative analysis and recommendations

A general method is given to quantify the radioactivity ingested by a breast-fed infant following maternal radiopharmaceutical administration, and to derive the period to interrupt feeding which reduces the corresponding effective dose equivalent to below 1 mSv. Results are presented from applying the method to all available measurements of radioactivity secreted in breast milk. This review includes some hitherto unpublished data, takes more account of the scarcity of the available data, and has resulted in modifications to the guidance for interrupting breast feeding. Recommendations for interrupting feeding with mature milk have been expanded into four categories: (1) interruption not essential; (2) interruption for a fixed period of time; (3) interruption until measurements indicate feeding can be resumed; and (4) cease breast feeding. Changes to the earlier guidance are that 99Tcm-pertechnetate, (99Tcm) erythrocytes, 125I-OIH and 131I-OIH have been moved to the third category, and that recommendations have been included for 99Tcm-DMSA, 99Tcm-glucoheptonate, 99Tcm-HDP, 99Tcm-HMDP, 123I-iodide and 123I-OIH. Before recommendations (1) and (2) can be issued to a mother, quality control measurements must be made of the radiopharmaceutical administered. Recommendations (3) or (4) only should be issued to mothers secreting colostrum. If there are changes in the recommended dosimetry in the future, the calculated fractional ingested activities can be used as a basis to refine the recommendations.