way of being exposed to radiation is through internal exposure, contamination, This can happen through two ways: or internal direct contamination or indirect contamination. It should be recalled that a nuclear explosion results in the creation of approximately 200 radioactive elements, or isotopes, Many of these are short-lived, such as polonium (Po? 7? or Po84) which has a half-life of 3.0 minutes, ox astatine (At218 or at85) with a half-life of 2.0 seconds (PRP, p. 55) and actually become ineffective or return to their stable forms hefore they can reach the ground. However, longer-lived isotopes like strontium and cesium (cst37) have half-lives of about 30 years, (xt31) has a half-life of ahout eight days. (sr?) Radioactive iodine It is these three elements which are among the most dangerous to man in terms of fallout, or the material which returns to earth after being lifted into high altitudes by the explosion, This fallout material may result in exposure of human beings (and animals and fish) should they fall into their source of drinking water, onto food, ox if they are inhaled. Or, as happened in a few cases where the fallout material landed on or near the people, curiosity compelled them to pick up a flake of material and taste it to determine what it was, result in the radioactive material, All of these which emits both gamma and beta radiation, being deposited internally into the human body. A second way inan may be exposed to radioactivity internally is what might be called "indirect" exposure. It is through a more complicated mechanism: the processes of his own environment. The emphasis on ecology and environmental protection during the past few years helps clarify how a person can become radioactively contaminated internally from a nuclear explosion which occurred thousands of miles away and years ago, The present emphasis on protection of our environment from pollution has made the general public aware of the interrelationships between 5010280