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This paper starts by describing the historical evolution of assessment of biologic effects of ionizing radiation leading to the linear non-threshold (LNT) system currently used to regulate exposure to ionizing radiation. The paper describes briefly the concept of Best Available Science (BAS) and Metrics for Evaluation of Scientific Claims (MESC) derived for BAS. It identifies three phases of regulatory science consisting of the initial phase, when the regulators had to develop regulations without having the needed scientific information; the exploratory phase, when relevant tools were developed; and the standard operating phase, when the tools were applied to regulations. Subsequently, an attempt is made to apply the BAS/MESC system to various stages of LNT. This paper then compares the exposure limits imposed by regulatory agencies and also compares them with naturally occurring radiation at several cities. Controversies about LNT are addressed, including judgments of the U.S. National Academies and their French counterpart. The paper concludes that, based on the BAS/MESC system, there is no disagreement between the two academies on the scientific foundation of LNT; instead, the disagreement is based on their judgment or speculation.

Scientific research, discovery, and application have had, and continue to have, a significant impact on society. The description of how various scientific disciplines have impacted society would be a daunting task. The evolution of scientific organizations and their roles in development of occupational and environmental standards are described. Following the enactment of various laws in the U.S., the authors suggest that the role of scientific organizations is to ensure that the best available scientific information is provided to regulatory agencies, who in turn use that information in the development of standards. The authors also describe the role of stakeholders in the development of standards.

In a three-year study, the possible biological concentration of 3H in rabbits was investigated. Tritiated water was used to grow alfalfa that was used exclusively as feed for the rabbits. Feed and water were kept at a constant 3H-to-1H ratio. The foundation group consisted of 18 female rabbits maintained on a 3H diet for 2 wk before mating. The subsequent generations were maintained with tritiated water and feed. At appropriate intervals, animals were sacrificed and selected tissues were analyzed for 3H. The specific activity of 3H in aqueous and organic fractions of tissues of all the animals remained essentially equal to that in the original water and feed. Results of this experiment indicate that under the steady-state equilibrium conditions of the experiment, no preferential concentration of 3H in animals occurred.

An evaluation of available personnel monitoring data and radium body burden records of dial painters handling an annual average of 1.5 Ci of radium indicates that they received an average of about 2 rem/person whole body exposure, 3 rem to the lungs from radon inhalation and 0.2 rad to the bone from radium body burdens. Among groups of similar workers handling tritium in Texas plants, the highest occupational exposures were about 160 mrem annually per person received by refinishers of tritium dial timepieces and back-lit watch assemblers. Based upon scenarios of exposures to 147Pm, repairers of timepieces containing 147Pm receive about 4.4 X 10(-4) mrem/person/yr whole body dose equivalent. The amounts that they process are in the microcurie range. Although the trend is away from the use of radium as a luminizing activator, there are indications that it is still used in timepieces even as tritium and 147Pm are increasingly being used for this purpose.