Radiopharmaceuticals and Breast-Feeding

["Barry Siegel" <siegelb@mirlink.wustl.edu>]

A new version of 10 CFR 35.75 (the "Patient Release Rule") becomes effective
on 29 May 1997 in USNRC-regulated medical facilities.  Among other things, the
rule requires (1) that instructions be given to a breast-feeding woman who
receives a radiopharmaceutical, if the total effective dose equivalent (TEDE)
to her infant could exceed 100 mrem and (2) that a record be kept to document
that the patient received instructions if the TEDE to infant from continued
breast-feeding could exceed 500 mrem.  

In Regulatory Guide 8.39, NRC has provided a table of activities of certain
radionuclides administered to a breast-feeding woman above which instructions
would be required and above which a record is required.  The table also gives
a recommended duration of interruption of breast-feeding with the typical
administered activities of the radiopharmaceuticals.  Unfortunately, several
important radiopharmaceuticals are not listed in this table (and are not found
in review articles on radiopharmaceuticals and breast-feeding) and the NRC
recommendation for calculating the infant dose in such cases is conservative
to a fault (assume that 50% of the dose is excreted in breast milk and
ingested).

Does anyone have data/recommendations regarding the maternal administered
activity for the following radiopharmaceuticals that (1) would likely cause an
infant TEDE of 100 mrem and (2) would likely cause an  infant TEDE of 500 mrem
if breast-feeding were not interrupted, as well as the recommended duration of
interruption of breast-feeding after a usual dose of the drug?

F-18 fluorodeoxyglucose
Cr-51 red cells
Co-57 cyanocobalamin
In-111 DTPA (for radionuclide cisternography)
In-111 octtreotide
In-111 monoclonal antibodies
I-125 human serum albumin
I-131 MIBG

[I recognize that not all of these are regulated by NRC, but the underlying
radiation safety principles would be worth upholding even without a
regulation; hence, the desire for data if available.]

Barry A. Siegel, M.D.
Division of Nuclear Medicine
Mallinckrodt Institute of Radiology
510 S. Kingshighway Blvd.
St. Louis, MO 63110
PHONE:  (314) 362-2809
FAX:  (314) 362-2806
INTERNET:  siegelb@mirlink.wustl.edu