Radiation protection information: can you trust the government's risks or risk the government's trust?: 1997 G. William Morgan lecture.

Public acceptance of information concerning radiation risks has been impacted by the erosion of trust in government agencies and by societal images that personify radiation or its effects in terms of monsters and ogres. The loss of trust in government agencies, particularly the Atomic Energy Commission and later the Department of Energy, has been influenced by a number of key events and individuals. Examples of these are given, including the anti-Viet Nam war movement, the Watergate incident, the activities of the Union of Concerned Scientists, Ralph Nader and the Critical Mass movement, the claims of Ernest Sternglass, and the widely publicized views of John Gofman and Arthur Tamplin. The use of negative images, pictures, and symbols in the mass media has reinforced the public perception of radiation as a thing to be feared. There is growing evidence that the public perception of radiation risks is related more to mistrust and negative images than it is to the technical information health physicists provide or to the issue of whether or not the linear no-threshold theory of radiation risks is correct. Attempts by federal agencies to regain public trust in radiation risk information generated by health physicists or other radiation scientists appear to be largely unsuccessful. If health physicists hope to be successful in changing such public perceptions, they may have to focus efforts on the next generation and concentrate on assuring that elementary and secondary school children receive sound instruction on radiation risks. Additional research at the molecular biology level is needed to elucidate the risks, if any, at low doses so that the practice of extrapolating low dose responses from high dose data can be eliminated.

Future role of the health physicist.

What is the future role of the health physicist? Ten external societal forces and five internal forces that may have significant impact on the health physics profession are presented. What changes are taking place in our profession that will shape the way we conduct our business? What changes are likely in technology, education and training? Methods of strengthening the educational area of our profession are proposed. Comments to the author are welcomed.

Current status of bioassay procedures to detect and quantify previous exposures to radioactive materials. Bioassay Procedures Working Group.

This report was prepared by a working group established by the Oak Ridge Associated Universities (ORAU) for the purpose of assessing the current capabilities of bioassay methods that can be used to determine the occurrence and magnitude of a previous internal deposition of one or more radionuclides. The first five sections discuss general features of the use of in-vitro bioassay samples to achieve this purpose. The remainder of the report is focused on the possible use of urine bioassay procedures to detect and quantify internal depositions of radionuclides that may have occurred in United States occupation troops in Hiroshima or Nagasaki, Japan, prior to 1 July 1946, or to personnel who participated in atmospheric nuclear weapons tests conducted between 1945 and 1962. Theoretical calculations were made to estimate the quantities of various radionuclides produced in a 20-kiloton (kt) nuclear detonation that might still be present in measurable quantities in people today if they were exposed 25 to 40 y ago. Two radionuclides that emerged as good choices for this type of bioassay analysis were 90Sr, which emits beta particles, and 239,240Pu, which emits alpha particles. The current status and future prospects of chemical procedures for analyzing in-vitro urine bioassay samples for these two radionuclides were examined to determine the minimum amounts that could be detected with current methods and how much one might expect the sensitivity of detection to improve in the near future. Most routine 239,240Pu bioassay analyses involve detection by alpha spectrometry. The current minimum detectable amount (MDA) is about 0.74 mBq L-1 (20 fCi L-1), but this could be lowered to 74 muBq L-1 (2 fCi L-1). An MDA of 0.74 mBq L-1 (20 fCi L-1) is adequate for routine bioassay analyses but is too high to detect most uptakes of 239,240Pu that may have occurred 25 to 40 y ago. Methods under development that are or can be much more sensitive and have lower MDAs than alpha spectrometry for 239Pu are fission track analysis and mass spectrometry. Currently, the fission track analysis method has an MDA of about 19 muBq L-1), and this may eventually be lowered to 1.9 muBq L-1 (0.005 fCi L-1). The current MDA for 239Pu by mass spectrometry is about 7.4 mBq L-1 (200 fCi L-1), but the potential exists that it could be lowered to a value of about 0.37 muBq L-1 (0.01 fCi L-1).(ABSTRACT TRUNCATED AT 400 WORDS)

Radionuclide content of and 222Rn emanation from building materials made from phosphate industry waste products.

The radionuclide content and 222Rn emanation coefficients of selected construction materials were determined. The materials were analyzed for 226Ra, 228Ra and 40K by gamma-ray spectrometry. Mineral wool insulation, which is made from Tennessee phosphate slag, and commonly used insulation, which is made from blast furnace slag, had similar concentrations of these radionuclides. Concrete blocks made with phosphate slag had enhanced 226Ra and 228Ra contents when compared to ordinary concrete block. The mineral wool insulation materials which were examined had emanation coefficients that were a few (2-6) times 10(-3). All other materials had emanation coefficients that ranged from 6 X 10(-4) to 4 X 10(-2).

The effects of particle size and moisture content on the emanation of Rn from coal ash.

Measurements of the emanation coefficients of 222Rn from coal ash were performed. Samples of coal ash from a stoker-fired furnace were mechanically sized into four categories. The mean 226Ra concentration of these categories ranged from 11.82-16.77 dpm g-1 and increased as a function of decreasing particle size. The mean bulk density and mean specific gravity of these categories ranged from 0.488-0.944 g cm-3 and 2.017-2.390 g cm-3, respectively, and both increased as a function of decreasing particle size. Samples of coal ash from four pulverized coal-fired furnaces were obtained, and demonstrated mean 226Ra concentrations ranging from 6.44-7.59 dpm g-1. The mean bulk density and mean specific gravity of these samples ranged from 1.254-1.520 g cm-3 and 2.357-2.588 g cm-3, respectively. Construction of chambers and methods for measuring 222Rn emanation coefficients are described. The measured emanation coefficient is shown to be insensitive to ingrowth time at times greater than three days. Measurements of emanation coefficients from ash samples were conducted at moisture contents of 0, 1.0, 10, 20 and 40% moisture by weight, and showed an increase in the emanation coefficient as a function of moisture content up to about 20% moisture by weight. Above 20% moisture content, most samples showed a trend toward decreasing emanation coefficients. The fractionated ash samples showed an increase in the emanation coefficient as a function of decreasing particle size. An experiment was also conducted which confirmed that sample depth was insignificant in explaining the observed emanation coefficient over the range of depths used in the other experiments.

Distribution and clearance of 63Ni administered as 63NiCl2 in the rat: intratracheal study.

Microgram amounts of nickel as 63NiCl2 were administered intratracheally to male rats. Regardless of time after instillation, the lungs and kidneys retained the greatest concentration of 63Ni, and 21 days after dose administration they were the only organs where 63Ni was still measurable. Urinary excretion was the main excretion route with 72% of the initial body burden eliminated by the urine at one day. By day 21, almost all 63Ni was excreted in the urine (96.5% of the initial body burden). The lungs retained 29% of their initial (35 min) burden at day 1, decreasing to 0.1% on day 21.

Uptake and distribution of cadmium in mice following repeated administrations.

The research was undertaken to analyze the uptake and distribution of cadmium-109 in mice following repeated injections and to observe how the simultaneous administrations of zinc affected the cadmium retention. Mice were given one, two, or three intravenous administrations at 48-hr intervals. Animals were sacrificed 2 min to 48 hr after each injection. Zinc had little effect on the retention of cadmium in the samples analyzed, and injections behaved independently of each other.