(S5) 2ed sentence: Does the Commission believe that there is no presumption that health effects result from doses below natural background? (S6) and (S7) There must be something I donft understand. How can the single source constraints in table S1 be equal to the dose limits given in (S7)? (S13) The difference between equivalent dose and dose equivalent is extremely important and useful. As suggested in ICRP Pub 74 (378) gIt therefore appears that the operational quantities provide a satisfactory basis for most measurements..h For example the determination of the dose equivalent at a point (H) as calculated by H = Q(L)D(L)dL when integrated over the tissue of interest results in the organ dose equivalent (ICRU, 1993). The effective dose (E) can then taken to be equal to the summation of the organ dose equivalents and wT . This approach produces an acceptable approximation to the formulation E = wTHT. Both of these approaches provide gradiation weighed doseh but the reader should be aware of which approach has been used . (S16) Table (S4) One change I would like to have seen in the tissue weighting factors was to change all the 0.12 values to 0.10. Two significant figures is not justified. These values were chosen in Pub 60 only because the bone marrow and lung values in Publication 26 were 0.12. The mistake we made in accepting this glogich was that it obscured the fact that the cancer coefficients had increased by factors of about 4.