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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Proposed Rules
INWORKS study.59 This study included within its cohort over 308,000
nuclear industry workers from the United States, the United Kingdom, and France.60 The INWORKS studys authors stated that in summary, this study provides strong evidence of an association between protracted low dose radiation exposure and leukemia mortality. 61
NIOSH, in its comments, further stated that its researchers and others conducted meta-analyses of cancer risk from low-dose exposures in a variety of populations receiving protracted exposure to external ionizing radiation Jacob et al. 2009;
Daniels and Schubauer-Berigan 2011. These meta-analyses concluded that there is a small but significant excess risk of solid cancer and leukemia, respectively, at occupational doses received during a typical working lifetime Walsh 2011.62

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The NIOSH researchers and others also published two studies describing cancer risk among nuclear workers at four Department of Energy sites and the Portsmouth Naval Shipyard. According to the NIOSH comments, a pooled cohort study included nearly 120,000
nuclear workers from these five sites these workers were also included in the larger INWORKS study. The authors of the pooled cohort study found that the excess relative risk ERR was significantly associated with occupational radiation dose for all nonsmoking related cancers combined. 63
NIOSH stated that these findings suggest that the risk of these cancers rises by 0.7% and 2.0% respectively for every 10 millisieverts mSv; 1 rem increase in dose. 64 NIOSH, in its comments, stated that the LNT model presents a reasonable framework for protecting workers from excess risks associated with occupational exposure to ionizing radiation 65 and concluded with a recommendation that the NRC
retain the current radiation protection standards.66
Similarly, in its comments, EPA
recommended that the NRC deny the petitions. EPA stated the following:
59 K. Leuraud et al., Ionising Radiation and Risk of Death from Leukaemia and Lymphoma in Radiation-monitored Workers INWORKS: An International Cohort Study, Lancet Haematology, Vol. 2 June 2015.
60 Id., at 278.
61 Id., at 280.
62 NIOSH 2015, at 2.
63 Id., at 23.
64 Id., at 3. The NRCs general public and occupational dose limits are 1 mSv 0.1 rem and 0.05 Sv 5 rem, respectively. See 20.1201a1
occupational dose limit and 20.1301a1
public dose limit.
65 NIOSH 2015, at 3.
66 Id., at 6.

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Within limitations imposed by statistical power, the available and extensive epidemiological data are broadly consistent with a linear dose-response for radiation cancer risk at moderate and low doses.
Biophysical calculations and experiments demonstrate that a single track of ionizing radiation passing through a cell produces complex damage sites in DNA, unique to radiation, the repair of which is error-prone.
Thus, no threshold for radiation-induced mutations is expected, and, indeed, none has been observed.67

EPA, in its comments, referenced four epidemiological studies conducted after BEIR VII, including the INWORKS
study, two studies of residents along the Techa River in Russia who were exposed to radionuclides from the Mayak Plutonium Production Plant, and a study of children who had received computed tomography CT
scans.68 The EPA stated that these studies have shown increased risks of leukemia and other cancers at doses and dose rates below those which LNT
skeptics have maintained are harmlessor even beneficial. 69 EPA, in its comments, referenced the findings of the various domestic and international bodies, including the NAS
and concluded, given the continuing wide consensus on the use of LNT for regulatory purposes as well as the increasing scientific confirmation of the LNT model, it would be unacceptable to the EPA to ignore the recommendations of the NAS and other authoritative sources on this issue.70

EPA concluded that it could not endorse basing radiation protection on the petitioners proposals, which it characterized as poorly supported and highly speculative. 71
The ACMUI advises the NRC on policy and technical issues that arise in the regulation of the medical uses of radioactive material in diagnosis and therapy. The ACMUI is a committee authorized under the FACA, which regulates the formation and operation of advisory committees by Federal agencies. The ACMUI membership includes health care professionals from various disciplines, who comment on changes to NRC regulations and guidance; evaluate certain non-routine uses of radioactive material; provide technical assistance in licensing, inspection, and enforcement cases; and bring key issues to the attention of the Commission for appropriate action.
67 EPA, J. Edwards, Comments on Linear NoThreshold Model and Standards for Protection Against Radiation October 7, 2015, at 1.
68 Id.
69 Id.
70 Id., at 2.
71 Id.

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Subsequent to the filing and docketing of the petitions, the ACMUI formed a subcommittee to review and comment on the petitions. The ACMUI held a public teleconference meeting on October 28, 2015, to vote on the subcommittees draft report.72 The draft subcommittee report was approved by the ACMUI and issued as final on that same date.73 The ACMUI report stated that determining the correct doseresponse model for radiation carcinogenesis remains an unsettled scientific question. 74 Although the report acknowledged that there is a large, and growing, body of scientific literature as well as mechanistic considerations that question the accuracy of the LNT model, the ACMUI
determined that very large-scale epidemiological studies with long-term follow-up would be needed to actually quantify any such risks or benefits and that such studies may be logistically and financially prohibitive. 75
According to the ACMUI report, a mathematical extrapolation model remains the only practical approach to estimating the presumed excess cancer risk from low-dose radiation.
Therefore, the dose-response data derived from epidemiological studies of human cohorts, such as the 1945
Hiroshima and Nagasaki atomic bombing survivors exposed to highdose radiation, are largely consistent with an LNT model. 76 In making its recommendation, the ACMUI stated that it recommends that, for the time being and subject to reconsideration as additional scientific evidence becomes available, the NRC continue to base the formulation of radiation protection standards on the LNT model. 77
Conclusion Based upon the current state of science, the NRC concludes that the actual level of risk associated with low doses of radiation remains uncertain and some studies, such as the INWORKS study, show there is at least some risk from low doses of radiation.
Moreover, the current state of science does not provide compelling evidence of a threshold, as highlighted by the fact that no national or international authoritative scientific advisory bodies have concluded that such evidence exists. Therefore, based upon the stated 72 The meeting notice for the October 28, 2015, meeting was published in the Federal Register on September 8, 2015 80 FR 53896.
73 ACMUI, Final Report on the Hormesis/Linear No-Threshold Petitions October 28, 2015, at 1.
74 Id.
75 Id., at 12.
76 Id., at 2.
77 Id., at 1.

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