essentially /the whole body at a rate of approximately one milliroentgen (0.001 roentgens) per year (the natural background rate). The Data - Since nuclear weapons testing started there have been 511 million tons total yield released. Considering the conditions of firing (surface versus air bursts) about the same amount of carbon-14 was from all past tests produced/as is normally present in that part of the earth's biosphere that determines radiation exposure to man. Assuming that most of the carbon-14 produced by the detonation will "disappear" into the deep ocean with a half-time of 33 years, the estimated whole body exposure for 70 years is 37 milliroentgens (0.037 roentgens)?-. After this 70 year period the dose rate from bomb produced carbon-14 will be about one-quarter of that at the start, i.e., about one-quarter of one milliroentgen (0.00025 roentgens) per year. There- after, the activity will slowly decrease but some will persist for thousands of years. (As a purely mathematical exercise - the total dose from carbon-14 produced from all past tests could accumulate to 420 milliroentgens (9.42 roentgens Le but one would have to live to an age of absut 10,000 years to receive all of this exposure.) Of course, Whatever radiation level persists, even if quite low, will irradiate future generations. Evaluation The radiation exposure from carbon-14 may account for roughly one-third of the total radiation dose from fallout over the next 70