A simple model for discounting radiation health effects risks with time

In estimating human health effects resulting from ionizing radiation exposures, it is often assumed that the age of the person at the time of exposure and the latency period for the appearance of any associated health effects are values that maximize the consequences of the exposure. Such assumptions are obviously conservative, but they can result in distortions and errors when nondiscounted radiation-related health effects arising from nonradiation-related risks. Human life expectancy obviously decreases with age, and the latency period for radiation-related health effects can range from a few years to several decades. For example, if a man is 45 yr old at the time of exposure and this exposure results in a lethal health effect 20 yr after exposure, then the expected number of years of life loss is ∼5 yr and not 70 yr, as is commonly assumed in radiation risk assessment studies. If one full-health effect is equivalent to 70 person-yr, then this example exposure results in only 0.07 full-health effects