Comments on Report: Assessment of Radiation Health Effects of the Resettlement of Enewetak Atoll

Page 1

Comments on Report: Assessment of Radiation Health Effects of the Resettlement of Enewetak Atoll Prepared by m School of Nuclear Engineering Georgia Institute of Technology The following lre l few brief consnentson this report byM. A. Bender and A. B. Brill dated October 12, 1979: 1. In general, this is an excellent report. 0 2. The report accepts the dose measurements of Robinson et al. (1979) without providing the reader with any of the pertinent information needed so that he can judge its adequacy. For example, there is no breakdown of the dose between that which is external and that which is internal. There is no indication whether internal dose values include a contribution from the actinide alpha-emittets, yet one would expect that some of the islands have appreciable quantities IIof239PU . It is not stated, but I assume their dose values are almost ‘ontribution from other radionuclides to be negligible. 3. It seems odd that values are given only for total body dose. lnce, l s stated above, the dose is mostly from 90 Sr + 90Y, 137CS and 239Pu$ one would expect the lxternal dose to be primarily beta-dose and x-ray emitter. One wonders if the beta bremstrahlung dose was lj--. zncluded with the total body dose. 4. What would their estimate be on the skin cancer induction from =.this skin dose. UNSCEAR gives a wide variation of skin cancer.,coefficient of 2 x 10 to 1.8 X 10 skin cancers per person rem. I doubt these values apply here, however, because some of the betaratfiation in this case has high energy and can penetrate ~ m into II

Page 2

tissue (i.e.$ far beyond the 0.007 cm penetration depth assumed by., Standards setting bodies in lstimating skin dose. AIsoS one should determine whether or not there are co-relations or synergistic relatxoh betweetibeta-radiation and UV as there are between UV-A and UV-B in the induction of skin cancer. One might suspect that skin cancer .. is the predominate mal.iiancy on the sun baked islands. -- 5. Since a large fraction of the radioactive contamination on the islands should be 90Sr + 90Y, and since 99 percent of Sr is deposited in the skeleton, why did the authors not discuss bone dose and radiation induced bone sarcoma and carcinoma as well as leukemia from II,.,. active bone marrow irradiation in the trabecular bone matrix? Published values of bone cancer coefficients range from2 x 10-6 to 2.2 x 10-4 cancers per person rem depending on age, radionuclide, type radiation, etc. o 6. Some of the comparisons of population exposure given do not add to the quality of the report. If natural background radiation in the 10,000 lethal cancers/y in the U.S., the objati’tiveshouldbe to reduce this background radiation - especially- that due to phosphate rock, etc. - and not use this as an excuse to permit more malignancies. One bad thing does not justify another! The comparison with lxposures to radiation workers in the U.S. weakens the report. I 7. It seems odd that these writers were able to use data from BEIR XII report. I have been trying unsuccessfully to get a copy of $his unpublished report for over a year. I guess the fact that this report is paid for by tax monies does not entitle university professors to a 6a In estimating the genetic risk, it is not stated whether or not the risk was reduced by a factor of 10 (as is often the practice) because the exposures are at low dose and low dose rate, i.e.: -- 3 (dose rate effect for spermatogonia) x 2 (2 sexes) D-a of Lyon et al. (Nature New Biol. 101, July 1972) suggest use of is factor of 10 may not be warranted at very low dose rates. 11 9. T/hen the authors suggested small doses of radiation might even be beneficial genetically, they might have added also that influenza 0“

Page 3

might be beneficial genetically because it tends to remove the weaker members of a population. 10. The report would have been improved if a Table 3 had been added gi$~ng the estimated genetic damage. The overall genetic risk was cant rem. This upper value is greater than the upper value of cancer - risk so the reader should be given the final lstimates of genetic - 11. The report is in error in stating there are no human exposure ata at low dose ranges, e.g. studies of in utero exposure and data on II ,. Hanford raiiacion workers are iow dose studies. 12. The report uses only the linear and linear quadratic models, yet much of the data on human population exposure conforms best with a cancer coefficients are a power of dose less than unity in a number of cases or the cancers induced per rem are greater at low doses than at high doses because of overkill at high doses, damage to the reticuloendythelial system, etc. o 13 It may not be a good assumption that the cancer risk on these islands is the same as that in the U.S. because the natural background radiation here is between 1/3 and 1/2 that in the U.S. and the Hanford IIradiation worker data suggest that about half the cancer per year in ~] the U.S. are the result of natural background radiation. M. I question that leukemia is one of the best understood canc~rs. The” lack of leukemia induction by radiation in Olmstead County’ of the Hanford worker data (Mancuso, Stewart, lnd Kneale) suggest that low chronic exposure to normal population (those not subjected to fire, blast, disease such an ankylosing spondylitis, etc.) die preferentially of forms of cancer other than leukemia. 15. There is a peculiar statement on page 28 to the lffect that the BE~R III relative risk model gives a cancer risk 2 to4 times the risk e-imates of UNSCEAR 1977 and so it seems l~;ear risk model instead. 16. Why was the life span of these islands U*S. life span is 70 years. reasonable to accept the chosen as 50 years? The