Rudi H. Nussbaum

The linear no-threshold dose-effect relation: is it relevant to radiation protection regulation?

Official radiogenic cancer risk estimates for low-dose, protracted exposure conditions have been based on linear, no-threshold downward extrapolation from medium and high-dose effects among a population of A-bomb survivors, with the application of a downward correction for an assumed reduced biological effectiveness at low doses and low dose rates (DDREF correction). Neither in the follow-up of populations exposed to the high-dose A-bomb flash, nor from epidemiological data after low-dose occupational or medical irradiation is there any convincing evidence for this DDREF hypothesis--even less for a zero-effect threshold dose. To the contrary, for external low-dose exposures of nuclear workers or general populations, cancer risks per unit dose have been found to be about 1 order of magnitude larger than those derived from the Japanese survivors, with larger discrepancies for persons above 50 years of age, and for x-rayed fetuses. This may be due to a dose and dose-rate effect exactly opposite from that postulated by the DDREF assumption, and a dose-dependent bias due to selection for exceptionally high immune competence among the > 5 years A-bomb survivor cohort. Excess cancer mortality following occupational exposures to ingested fission products and radiation-associated teratogenic, genetic, and cancer detriment among diverse populations who had ingested small amounts of radioactivity after the precipitation of fallout at great distances from the Chernobyl nuclear explosion, suggest discrepancies of as much as 2 orders of magnitude with official risk estimates. Contrary to widely publicized statements, claiming that current regulations of population exposures are far too restrictive, thus unnecessarily costly for the radiation industries, the aggregate of radiation epidemiological evidence suggests that current standards are inadequate to protect public health.

Hypothyroidism and Spontaneous Abortions among Hanford, Washington, Downwinders

Spontaneous abortions occurred more than twice as frequently in hypothyroid women, compared with nonhypothyroid women. Both groups of women had lived in the same environment during the same period of time. The high incidence of hypothyroidism in a cohort of several hundred women who lived downwind of the Hanford, Washington, nuclear installation was likely associated with environmental contamination from deliberate releases of radioactive iodine from the facility.

Cancers among Residents Downwind of the Hanford, Washington, Plutonium Production Site

A community-based health survey for the time period between 1944 and 1995 was collected from 801 individuals who had lived downwind of the U.S. plutonium production facility located in Hanford, Washington. The results of the survey revealed high incidences of all cancers, including thyroid cancer. There were greater than expected numbers of central nervous system tumors and cancers that invaded the female reproductive system (e.g., cancers of the uterus, ovary, cervix, and breast). The authors argue that the greater-than-expected numbers found cannot be accounted for by selection bias alone. Comparisons of crude incidence rates, as well as of occurrence ratios between pairs of cancer types among Downwinders and reasonably similar populations, suggested that the excess neoplasms may be associated with radioactive contamination of food, water, soil, and/or air. In addition, a synergistic effect may exist with agricultural toxins. Previously neglected biophysical and physiological properties of internally lodged, long-lived 129I may be a significant etiological factor in the development of thyroid diseases, including cancer, and other malignancies in exposed populations.

Reassessment of Radiogenic Cancer Risk and Mutagenesis at Low Doses of Ionizing Radiation

Since the discovery of the physical properties of ionizing radiation, about a century ago, its application has grown at an unprecedented rate. More and more people in all parts of the world are being exposed to man-made ionizing radiation from medical, scientific, and technological applications, as well as from deliberate and accidental releases of radioactive materials into the biosphere. Exposure to cosmic and terrestrial sources (background radiation) has been part of man’s evolutionary environment for eons. The mutagenic and cancerogenic effects of high doses of ionizing radiation have long been known, in particular through the pioneering work of H. J. Muller in the mid- 1920s. Yet, the view that human progress did take place in the presence of ionizing radiation is the basis for the popular belief that radiation in the dose range of geographical variations of background — and relatively small additions due to human activities — would not cause any deleterious effects on human health. Some radiation experts went even further and claim beneficial health effects of low-dose exposures (hormesis).

Community-Based Participatory Health Survey of Hanford, WA, Downwinders: A Model for Citizen Empowerment

Residents around the Hanford, WA, plutonium production facility have long suspected damage to their health due to radioactive releases from the plant. From 1944 to 1986 the government denied environmental contamination, let alone any health impact. An alliance of residents (Downwinders), physicians, scientists, and social justice activists designed, distributed, collected, and analyzed a health survey concerning persons who had been at risk for exposure to internally lodged radioisotopes. This community-participatory health study suggests an excess of illnesses among Hanford Downwinders. These findings cast doubts on conclusions drawn from a widely publicized government study: that radioactive emissions from Hanford did not lead to increases in thyroid disease. The described collaborative grass-roots project may serve as a model for identifying health effects among other populations exposed to radioactive fallout or other environmental contaminants. Concomitantly, a community-participatory survey can provide a sense of validation and empowerment by affording affected populations valuable data in support of their demands for large-scale epidemiological studies of environmental links to their health problems, followed by remedial actions.

Evidence for stable interstitial and substitutional sites of cobalt in gold from Mössbauer studies

Abstract Two interstitial models are suggested, and the predicted equilibrium concentrations are compared with experimental measurements of the zero-phonon fraction of samples quenched from various temperatures. Transition rates between the substitutional and the interstitial sites appear to be diffusion limited. The existence of a 〈100〉 impurity dumbbell is favored by all available information.

Reproductive outcomes after radiation exposure.

Reproductive Outcomes after Radiation Exposure Charles Grossman;William Morton;Rudi Nussbaum; Epidemiology

Zunahme des Strahlenrisikos bei niedrigen Dosen: Übereinstimmung zwischen bisher als unvereinbar bezeichneten Studien

Wenn wir aus gebuhrendem Abstand die vorherrschenden Denkweisen uber die Wirkung niedriger Strahlendosen auf den Menschen betrachten, dann erkennen wir in erster Linie, das diese Denkweisen von den als unbezweifelbare Tatsachen hingestellten Gutachten einer Anzahl internationaler und nationaler Kommissionen bestimmt werden. Zu den sich teilweise selbst ernennenden Ausschussen gehoren vor allem die ICRP (International Commission on Radiological Protection), UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) und BEIR (US National Academy’s Committee on the Biological Effects of Ionizing Radiation). Diese Kommissionen erklarten mehrmals wahrend der vergangenen 30 Jahre, das Strahlenbelastungen unterhalb von circa 5 cSv (rem) als harmlos zu werten seien.

Consistencies and Discrepancies: Current Perspectives on Low Dose Health Effects of Ionizing Radiation

Abstract Analyses of cancer mortalities among Japanese atomic bomb survivors, limited to the lowest DS86 (1950–1985) dose groups, suggest that excess radiogenic risks per unit dose for single exposures below 20 cGy may be two to three times higher than that in the 20- to 200-cGy range. Low dose exposures of survivors down to a few centigrays have resulted in excess leukemias, and prenatal exposures have resulted in brain damage. In normal populations, in utero exposures and exposures of children to X rays at doses below and just above 1 cGy have resulted in excess cancers. Some, though not all, studies of nuclear workers exposed to much lower fractionated doses found excess radiogenic risk values per unit dose more than three times those for the 0- to 20-cGy dose range among the Japanese survivors. These positive findings of cancers are in conflict with assumptions that low dose, low rate exposures have a reduced biological effectiveness compared with linear extrapolations from higher doses [dose rate eff...

Survivor studies and radiation standards

Findings from studies of atomic-bomb survivors were used to establish tolerable exposures to low-level radiation. But three other studies suggest that those risks may have been greatly underestimated.