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The J-value is an objective method for determining when life extending measures are sen- sible, applicable to both manufacturing and service industries, including public health and healthcare. A model of human decision making based on the J-value is able to explain the shape of the Preston curve that relates life expectancy at birth and gross domestic product (GDP) per head for all the nations in the world. Making a number of reasonable assumptions, a J-value model produces a population-average life expectancy, which may be translated easily into a corresponding life expectancy at birth when life expectancy is not modified by discounting (net discount rate equals zero). The resultant values may be tested against pan-national data, showing a very good match. Thus the shape of the Preston curve has been explained and, at the same time, validation has been provided for the J-value model. A perturbation analysis shows th a t the J-value explanation for the Preston curve starts to break down as the net discount rate is increased above zero. Thus the Preston curve may be seen to validate the J-value model at a net discount rate of zero, but not at higher net discount rates. The result allows a closed-form expression to be derived for the first time for the pure time discount rate, namely the product of the rate of economic growth and the complement of risk-aversion. A further conclusion from the work is that no discernable limit is apparent before the age of 100 to the process by which people live longer as they get richer; such an intrinsic limit might be overcome by future improved medical technology. [ABSTRACT FROM AUTHOR]

Following the accident at the Chernobyl Nuclear Power Plant in 1986, the United Kingdom Government imposed restrictions on the consumption of sheep meat that became contaminated by nuclear fallout to ensure it was extremely unlikely that any consumers would receive an unacceptable dose. The international context for the restrictions is summarized and a brief review of the strategies employed by the UK is presented. An analysis using the J-value framework, including the de minimis quantum of life expectancy, is made of the cost effectiveness of the sheep meat restrictions in force until 2012, in terms of 4 categories of consumer ranging from the average to the extreme. The paper shows that the risk to the general population was very low indeed at the time the restrictions were removed in 2012. Retaining the restrictions for an extra year, would have averted the dose to the average consumer by a fraction of a microSievert, corresponding to a gain in life expectancy of 8 s. Meanwhile for the ICRP Representative Person, the gain in life expectancy from retaining the restrictions for an extra year ranged between 17 and 25 s. These gains are nugatory, as they are a factor of between 8 and 23 below the de minimis quantum of life expectancy. This new measure provides a meaningful quantitative criterion for judging when the radiation exposure of a large population is trivial in the sense used by the ICRP. The gains in life expectancy for the Field Representative Person and the Extreme Consumer were above the trivial level, but the associated J-values were 10 and 40, an order of magnitude or more above the value of unity where a case could be made for retaining the restrictions for another year. The high J-values and/or de minimis life expectancy ratios suggest that the food restrictions could almost certainly have been ended earlier. Also discussed are: the choice of the Representative Person, the role of intervention levels, the extent to which conservatisms in analysis are warranted and how socio-political factors in decision making can be taken into account in a transparent way. [ABSTRACT FROM AUTHOR]