U.S. Department of Health and Human Services (DHHS) comments on Draft ICRP Background Document on The Representative Individual Please send comments and questions to Sam Keith, Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road, NE, Mail stop F-32, Atlanta, GA 30022, USA, Tel. 770-488-3322, Fax 770-488-4178, e-mail skeith@cdc.gov. NOTE: DHHS may wish to submit additional comments later for consideration. GENERAL COMMENTS. This background document is useful in appreciating the focus of the ICRP 2005 recommendations. *Adding a glossary would help both the reader and the authors assure consistency of use. SPECIFIC COMMENTS. Pg v, abstract, para 1. Sentence 1 should address stakeholders as a relevant stakeholder in addition to the operating managers and regulators that are included in the text. Pg v, abstract, para 1. The last sentence does not address optimization as an important aspect of meeting the Commission’s goal of protecting the public. Despite optimization being mentioned elsewhere in the text, one can interpret the message of this sentence as saying the Commission’s background document on optimization is irrelevant and that meeting only the dose constraint satisfies the Commission’s goal. Optimization is finally addressed in paragraph S20. Pg 2, para (7). The last sentence is not clearly written. Pg 2, para (8). The next to last sentence states that “in medical exposure, … the source and exposure to individuals is usually obvious.” Since exposure by a radioactive patient (the source) to other members of the public is rarely obvious, they this exposure does not appear to be within the scope of medical exposures as described in this paragraph. It appears that such exposure is of a type that this document will want to address. Para S6. The last sentence addresses uncertainty, but it is not clear that uncertainty in measurements and other relevant inputs to dose assessments has been integrated into the uncertainty assessment addressed in the text. Para S8. In this section as well as in Appendix A, 1 year was selected for the 0-<6 year age category. Recommend providing the rationale for using 5 years in sentence 4. Para S10. This sentence appears to be in conflict with the message in the optimization document in which optimization is states as a required addition to dose constraint (see Figure 1 in the optimization document). Para S11. Recommend changing bullet (1) to read, “the dose must account for all completed pathways. Recommend changing bullet (3) to read, “dose coefficients and habit data (see Appendix A) must be applied according to specific age categories.” Para A.4. An alternative approach would be to identify the age at which the median dose coefficient would occur for each age group and isotope. If the current method (e.g., using ratios of median age to highest age in the group), then the ratio for the lowest:median ages should also be assessed. Para A.8. Recommend assessing ages other than the median age aginst the distal ages to determine a central age to wse for each group. If the 1 year and 10 year ages are to be used, then: (1) Tables A2 through A5 should each contain a column for comparing the 6 year:10 year values. The absence of the “10 year:6 year” column precludes evaluating the suitability of selecting 10 years as the appropriate age for this report. (2) An easier to appreciate comparison would be to use the age group ratios of 3 mo:1 year, 1 year:5 year, 6 year:10 year, and 10 year:15 year” so that one can directly see whether the 1 year and 10 year ages selected are actually central to the data.