• Caution about clinical issues
• Many of the countermeasures listed in the table on REMM have an unfavorable risk-to-benefit ratio when used to treat persons having low levels of internal contamination.
• Most authorities do not recommend treatment of internal contamination when the body burden is less than one annual limit of intake (ALI)¹.
• Treatment is strongly recommended when the body burden exceeds 10 ALI.
• For internal contamination levels greater than 1 ALI and less than 10 ALI, clinical judgment dictates treatment of internal contamination.
• Except for potassium iodine, DTPA, and Prussian blue, none of the countermeasures listed in REMM are FDA approved for decorporation, even if they have other uses that are FDA approved. If used, all off-label medications must be used with extreme caution. Use of FDA approved medications also requires clinical expertise, and knowledgeable specialists should be consulted when possible.
• Comments about conceptual issues
• According to NCRP, ALI is an operational quantity defined originally by ICRP as the level of intake of radionuclide activity that would irradiate a person to the annual limit set by the ICRP for occupational (workplace) exposure².
• Per NCRP, this number is usually considered to be 0.05 Sv (5 rem) effective dose and 0.5 Sv (50 rem) equivalent dose to any exposed tissue. This equivalent dose is thought to be below the threshold at which deterministic health effects occur and simultaneously low enough to limit the incidence of any stochastic health effects.
• The ALI concept assumes low level continuous uptake, as could happen with an occupational exposure. The ALI concept was developed to protect workers, not members of the general public.
• ALI was never intended for use as a measure of intake for persons internally contaminated as a result of radiological or nuclear incidents and certainly not for members of the public during events such as accidents or terrorist incidents, when intake might occur over a very short period of time.
• Nevertheless, the ALI concept has been used by some clinicians when considering when to initiate countermeasures for individual members of the public who have been internally contaminated with radioactive materials as a result of a terrorist incident or unintentional event (e.g., transportation accident).
• The NCRP is currently developing new formulae to replace the ALI as a management guideline for treatment of internal contamination after non-occupational radiation events. This new guidance will update that in NCRP Report No. 65, Management of Persons Accidentally Contaminated with Radionuclides

¹Marcus, CS. Administration of decorporation drugs to treat internal radionuclide contamination: medical emergency response to radiologic incidents. RSO Magazine, 2004;9(5):9-15. (PDF - 34 KB)
² Limits for Intakes of Radionuclides by Workers, International Commission on Radiological Protection (ICRP), Publication 30, Part 1, Annals of the ICRP 2, No.3/4, Elsevier Science, New York)

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