[en] Energy development activities will be impacted by the Underground Injection Control Regulations that are formulated under Part C of the Safe Drinking Water Act. The thrust of Part C of the Act is to protect groundwater that now is or in the future might be used for drinking water. A new draft of the regulations, on which this analysis is based, is currently being considered. These regulations will be either another set of proposed regulations or will be interim final which means they can be enforced immediately but EPA will still entertain comments on them and modify them if necessary. There are four possible situations in which the Underground Control Regulations would not apply. They are: If the aquifer in question can be left unprotected despite the fact that its solids level is less than 10,000 mg/1; if the aquifer is oil or mineral producing; if the aquifer is located at a depth that would made recovery of drinking water uneconomical; and if the aquifer is already contaminated. However, the individual states have to demonstrate this to the satisfaction of the EPA administrator. If none of the conditions holds, construction, monitoring operating and reporting requirements will be necessary to receive a permit. The economic impact of these requirements is uncertain but could involve significant economic and time expenditures. Permits do not have to be renewed and one permit can serve for a whole field of wells. However, the permit application requires a significant amount of information and will take a considerable amount of time and expense to fill out. Solution mining operations also will incur extra expenses establishing initial water quality profiles and maintaining monitoring wells

[en] Cancer induction in rat skin and human skin are compared following exposure to X-rays. The human data were obtained by follow-up of 2213 children irradiated between 1940 and 1959 for tinea capitis (ringworm) of the scalp. The scalp was irradiated at one session using five fields of 100 kVp X-rays. The scalp dose ranged from 500-800 rads. The rats were irradiated on their dorsal skin with a 1100-rad dose of 30 kVp X-rays. The tumours were predominantly basal cell carcinomas in both species. The proportion of people with tumours as a function of elapsed time since exposure was consistent with a power function with an exponent of 5.4, and had reached 3% or 0.08 tumours per person in most recent survey (35 years after exposure). Of the 64 tumours observed in human skin, a substantial proportion was on the directly irradiated skin just outside the hair-covered regions of the scalp. So far there are no tumours among the 530 irradiated nonwhites in the study when about eight cases would be expected in a comparable group of irradiated whites. Only four skin tumours have been observed in 1396 control patients. The temporal curve of radiation-induced tumours for human skin could be approximately superimposed on that for rats by contracting the time scale by a factor of 37.1. The temporal response of the two species is approximately proportional to their median life spans. (author)

[en] Acute postpartum mastitis (APM) is an inflammatory/infectious condition of the breast, occurring commonly at childbirth or during lactation. A series of 600 women who received x-ray therapy for APM during the 1940s or 1950s have been followed up by mail questionnaire, with medical verification of pertinent conditions, to ascertain their incidence of breast cancer. The groups have been followed for up to 45 years, with an average of 29 years. The relative risk of breast cancer, adjusted for age and interval since irradiation (or an equivalent entry definition for controls) was 3.2 for the irradiated breasts. The dose-response curve appeared to be essentially linear, except for a diminution of risk at high doses (≥ 700 rad). The fact that there were no breasts with doses between zero and 50 rad, however, means it was not possible to evaluate the curvature with the maximum contrast between low and high doses. The dose fractionation analyses showed that the number of dose fractions or the number of days between fractions had no apparent effect upon breast cancer risk, but there was a suggestion that lower doses per fraction led to a higher risk, which runs counter to what one would expect based on radiobiological theory. However, a Cox regression analysis, controlling for total breast dose, did not yield a significant effect for any of the fractionation variables

[en] Monte Carlo calculations have been made to determine the energies delivered by photons and neutrons to the human body irradiated by collimated photon beams. The beams were monoenergetic and ranged from 100 keV to 40 MeV. The energy deposition in the body was sorted into two regions: inside and outside the irradiated volume. Most of the results obtained were for a beam size of 100 cm² although some calculations were also made for 600 cm² beams. The effect of beam size on energy deposition in the two regions was investigated for ⁶⁰Co gamma rays. Graphs are presented which give the integral doses delivered by neutrons and photons to the two regions for therapy beams of various energies. These graphs can be used to calculate the integral doses which are delivered inside and outside the treatment volume for photon spectra from most medical accelerators. Calculations of energy deposition were also made for the spectra from two particular accelerators. These were done using Monte Carlo as well as by simply ''folding'' the spectra into the results for monoenergetic photons. The results obtained by both methods were in good agreement and indicated that the integral doses deposited outside the treatment volume by neutrons are more than two orders of magnitude smaller than those deposited by scattered photons

[en] Basal cell carcinomas (BCCs) were obtained from subjects who had been treated with x-ray for tinea capitis at mean age 8 yr (average dose 3.0 Gy) and who have developed multiple (>5) skin cancers 35-40 years later. By allelic loss analysis, 9/10 tumors from 3 patients exhibited loss of heterozygosity (LOH) in one or more microsatellite markers in chromosome location 9q22.3. The xeroderma pigmentosum A (XPA) and PTCH (nevoid BCC syndrome (NBCCS)) genes are located in region 9q22.3, and often LOH in the region means that alleles of both genes are lost. Mutations were found in the undeleted PTCH allele in 2/9 BCCs, which is consistent with the two-allele inactivation model. A similar analysis for the XPA gene showed 5/9 BCCs with probable inactivating mutations. In 1 patient 5/5 cancers and normal blood showed the same 14 base deletion in codon 256-260 indicating this person was an XPA heterozygote. The same 5 cancers exhibited LOH in region 9q22.3 making it likely that 1 allele of both PTCH and XPA were lost. These results suggest how 2 genes could combine to produce an increase in susceptibility to X-ray-induced carcinogenesis in connection with UV as a second exogenous carcinogen (Supported by NIEHS and NCI). (author)

[en] To determine late health effects of radiation in atomic bomb survivors, the Radiation Effects Research Foundation has been conducting studies on the Life Span Study (LSS) population, which consists of 93 000 atomic bomb survivors and 27.000 controls. A recent report on the incidence of solid cancers estimates that at the age of 70 y, after exposure at the age of 30 y, solid-cancer rates increase by about 35 % per Gy for men and 58 % per Gy for women. The age-at-exposure is an important risk modifier. Furthermore, it seems that radiation-associated increases in cancer rates persist throughout life. In addition, radiation has similar effects upon first-primary and second-primary cancer risks. A recent report on leukemia mortality suggested that the effect of radiation on leukemia mortality persisted for more than five decades. In addition, a significant dose-response for myelodysplastic syndrome is found in Nagasaki LSS members 40-60 y after radiation exposure. In view of the nature of the continuing increase in solid cancers, the LSS should continue to provide important new information on cancer risks, as most survivors still alive today were exposed to the atomic bomb radiation under the age of 20 y and are now entering their cancer-prone years. (authors)

[en] Radiation epidemiology is the study of human disease following radiation exposure to populations. Epidemiologic studies of radiation-exposed populations have been conducted for nearly 100 years, starting with the radium dial painters in the 1920s and most recently with large-scale studies of radiation workers. As radiation epidemiology has become increasingly sophisticated it is used for setting radiation protection standards as well as to guide the compensation programmes in place for nuclear weapons workers, nuclear weapons test participants, and other occupationally exposed workers in the United States and elsewhere. It is known with high assurance that radiation effects at levels above 100–150 mGy can be detected as evidenced in multiple population studies conducted around the world. The challenge for radiation epidemiology is evaluating the effects at low doses, below about 100 mGy of low-linear energy transfer radiation, and assessing the risks following low dose-rate exposures over years. The weakness of radiation epidemiology in directly studying low dose and low dose-rate exposures is that the signal, i.e. the excess numbers of cancers associated with low-level radiation exposure, is so very small that it cannot be seen against the very high background occurrence of cancer in the population, i.e. a lifetime risk of incidence reaching up to about 38% (i.e. 1 in 3 persons will develop a cancer in their lifetime). Thus, extrapolation models are used for the management of risk at low doses and low dose rates, but having adequate information from low dose and low dose-rate studies would be highly desirable. An overview of recently conducted radiation epidemiologic studies which evaluate risk following low-level radiation exposures is presented. Future improvements in risk assessment for radiation protection may come from increasingly informative epidemiologic studies, combined with mechanistic radiobiologic understanding of adverse outcome pathways, with both incorporated into biologically based models. (paper)

[en] There are controversies surrounding radiation effects in human population in the range of radiation doses encountered by patients resulting from one to several CT scans. While it is understandable why the effects from low levels of diagnostic radiation are controversial, the situation is complicated by the media which may distort the known facts. There is need to understand the state of science regarding low-level radiation effects and also to understand how to communicate the potential risk with patients, the public and media. This session will seek to come to a consensus in order to speak with one voice to the media and the public. This session will review radiation effects known so far from a variety of exposed groups since the nuclear holocaust, provide clarification where effects are certain and where they are not, at what level extrapolation is the only way and at what level there is weak but agreeable acceptance. We will depict where and why there is agreement among organizations responsible for studying radiation effects, and how to deal with situations where effects are uncertain. Specific focus on radiation effects in children will be provided.Finally, the session will attempt to bridge the communication gap from the science to how to be an effective communicator with patients, parents, and media about ionizing radiation. Learning Objectives: To have a clear understanding about certainties and uncertainties of radiation effects at the level of a few CT scans To understand the results and limitations from 3 major pediatric CT scientific studies on childhood exposures published recently. To understand successful strategies used in risk communication

[en] The recently published NCRP Commentary No. 27 evaluated the new information from epidemiologic studies as to their degree of support for applying the linear nonthreshold (LNT) model of carcinogenic effects for radiation protection purposes (NCRP 2018 Implications of Recent Epidemiologic Studies for the Linear Nonthreshold Model and Radiation Protection, Commentary No. 27 (Bethesda, MD: National Council on Radiation Protection and Measurements)). The aim was to determine whether recent epidemiologic studies of low-LET radiation, particularly those at low doses and/or low dose rates (LD/LDR), broadly support the LNT model of carcinogenic risk or, on the contrary, demonstrate sufficient evidence that the LNT model is inappropriate for the purposes of radiation protection. An updated review was needed because a considerable number of reports of radiation epidemiologic studies based on new or updated data have been published since other major reviews were conducted by national and international scientific committees. The Commentary provides a critical review of the LD/LDR studies that are most directly applicable to current occupational, environmental and medical radiation exposure circumstances. This Memorandum summarises several of the more important LD/LDR studies that incorporate radiation dose responses for solid cancer and leukemia that were reviewed in Commentary No. 27. In addition, an overview is provided of radiation studies of breast and thyroid cancers, and cancer after childhood exposures. Non-cancers are briefly touched upon such as ischemic heart disease, cataracts, and heritable genetic effects. To assess the applicability and utility of the LNT model for radiation protection, the Commentary evaluated 29 epidemiologic studies or groups of studies, primarily of total solid cancer, in terms of strengths and weaknesses in their epidemiologic methods, dosimetry approaches, and statistical modelling, and the degree to which they supported a LNT model for continued use in radiation protection. Recommendations for how to make epidemiologic radiation studies more informative are outlined. The NCRP Committee recognises that the risks from LD/LDR exposures are small and uncertain. The Committee judged that the available epidemiologic data were broadly supportive of the LNT model and that at this time no alternative dose-response relationship appears more pragmatic or prudent for radiation protection purposes. (memorandum)