Health risks attributable to radiation

Draft document: Health risks attributable to radiation
Submitted by Lynn Howard Ehrle, Chairman, International Science Oversight Board
Commenting on behalf of the organisation

In the Matter of the Committee 1 Task Group Report: Principal Conclusions and Proposals Since several Committee members are co-authors on low-dose risk assessment papers and since all of these members have signed on to summary statements that seriously understate the risk, their obvious bias in their list of conclusions and proposals is easily detected. a. U.S. Natl. Cancer Institute: C Land and E Ron b. UNSCEAR 2000 consultants or national delegates: R Cox, E Ron, K Sankaranarayanan, J Preston and A Kellerer c. PNAS 25 Nov 2003 low dose cancer risk paper: E Ron, C Land, D Preston, J Preston and J Little d. BEIR VII: R Cox, A Kellerer, K Sankaranarayanan and R Ullrich Lines 184-186: The following summary statements relate largely to the health effects of radiation in the dose range up to a few tens of mSv for the purposes of radiation protection. Comment: The phrase "up to a few tens of mSv" is imprecise and the paper makes no estimate of the low-dose range, thus leaving the impression that any dose above30-40 mSv should be considered a high dose. UNSCEAR 2000 submits "a low dose might be considered to be any exposure up to about 200 mGy" (v. II, Annex G, p.79). Lines 188-190: For cancer and hereditary disease at low doses/dose rates the use of a simle proportionate a scientifically plausible assumption. Comment: The European Committee on Radiation Risk (Health Effects of Ionising Radiation Exposure at Low Doses for Radiation Protection Purposes, 2003) concludes, "there are good reasons for assuming that effects in the low dose range from zero dose to about 10 mSv are likely to follow some kind of supralinear or fractional exponent function...the emphasis on initial radiation damage processes implicit in the ICRP system is only valid for high doses delivered externally." UNSCEAR 2000 concludes, "a strictly linear dose response should not be expected in all circumstances" (v. II, Annex G, p. 160). Lines 192-196: A dose and dose-rate effectiveness factor (DDREF) of 2 recommended in Publication 60 should be retained for radiological protection purposes. Comment: ICRP Publication 60 was published in 1991. Its conclusions are outdated and obsolete in light of other authoritative studies over the past 15 years. For example, more recent Life Span Study data (D Pierce, Y Shimizu, D Preston, M Vaeth, K Mabuchi-- Report 12, Part 1, Radiat Res 1996;152:1-27) estimate a fatal cancer risk factor of 0.12 per Sv, more than double the ICRP 60 estimate of 0.05. The underlying premise of a DDREF factor is that "human dose-response for acute exposure is likely to have a concave-upward shape, except at extremely high doses...readers are reminded that when RERF analysts examined all the A-bomb 1956-1985 data (Y Shimizu, H Kato, W Schull, D Preston, S Fujita, D Pierce--Life Span Study Report 11, Part 1), they found the dose- response to be either linear or supra-linear" (John Gofman, Radiation-Induced Cancer from Low- Dose Exposure, 1990, Chap. 22). Lines 218-219: Cancer risk following in-utero exposure is judged to be no greater than that following exposure in early childhood. Comment: Alice Stewart's Oxford Survey of Childhood Cancers (Brit Med J 1958;1:1495-1508) demonstrated that an in-utero X ray of a 10-20 mGy dose to a pregnant woman resulted in a 40% excess incidence of cancer and leaukemia in the child before age 10. This study was confirmed by MacMahon (J Natl Cancer Inst 1962;28:1173-1191) and Doll and Wakeford (Brit J Radiol 1997;79:130-139). There are no studies demonstrating this level of excess cancer incidence in infants whose mothers have not been exposed. Lines 232-236: Dose responses for radiation-induced tissue reactions (deterministic effects) in adults and children are, in general, judged to have true threshold doses which result in the absence of risk at low doses. Comment: "The existence of any threshold, even at the lowest dose, has been thoroughly discounted. UNSCEAR 2000 notes, Cells are able to repair both single- and doouble-strand breaks in DNA over a period of a few hours, but this repair can be imperfect, resulting in long-term cellular damage and mutation...error-free repair is not anticipated... breakage of both strands of the duplex may be achieved by the traversal of a single ionizing track and does not require multiple-track action" (v. II, Annex G, p. 80.) Lines 244-245: Risks of non-cancer disease at low doses remain uncertain and no specific judgment is possible. Comment: The ECRR Report examines data relating to populations exposed to low level internal radiation from fission products released from Chernobyl, following Hiroshima, and also following exposures to depleted urnium (DU) particles in the war zones of Iraq and Kosovo. Tables 12.3, 12.4, and 12.5 reference studies that document a variety of non-cancer effects. Unfortunately, Committee 1 and the ICRP has ignored these and other studies and the whole subject of internal emitters. The C1 Foundation Document (FD-C-1) commits sins of scientific omission and comission and should be rejected. The Comments section does not represent peer review by independent investigators and there is no assurance they will be taken into account when the finaldocument is codified. Many papers and books by independent scientists don't even appear on ICRP reference lists, let alone find their way into the drafts. As noted in my previous Comment, the revolving door is alive and well at ICRP. Same names, same faces.