| One of the scientists working on the Manhattan | | | | coal-and oil-burning power plants are responsible |
| Project of the U.S. was Italian physicist Enrico | | | | for far more radioactive pollution in the United |
| Fermi (1901-1954), who used radium and beryllium | | | | States. |
| powder to construct a neutron source for making | | | | This is not to say that nuclear energy poses no |
| new radioactive materials. Fermi and his associates | | | | dangers, as the disaster at Chernobyl in the |
| succeeded in producing radioisotopes of sodium, | | | | former Soviet Union has shown. In April 1986, an |
| iron, copper, gold, and numerous other elements. | | | | accident at a nuclear reactor in what is now the |
| As a result of Fermi's work, for which he won | | | | Ukraine killed 31 workers immediately and |
| the 1938 Nobel Prize in Physics, scientists have | | | | ultimately led to the deaths of some 10,000 |
| been able to develop radioactive versions of | | | | people subsequently and consequently. The fact |
| virtually all elements. Interestingly, the ideas of | | | | that the radiation was allowed to spread had |
| radioactivity, fission reactions, and fusion reactions | | | | much to do with the secretive tactics of the |
| collectively represent the realization of a goal | | | | Communist government, which attempted to |
| sought by the medieval alchemists: the | | | | cover up the problem rather than evacuate the |
| transformation of one element into another, | | | | area. Another danger associated with nuclear |
| particularly the baser metals into noble ones. | | | | power plants is radioactive waste. Spent fuel rods |
| The alchemists, forerunners of chemists, believed | | | | and other waste products from these plants have |
| they could transform ordinary metals into gold by | | | | to be dumped somewhere, but it cannot simply |
| using various potions, though an impossible dream. | | | | be buried in the ground because it will create a |
| Yet among the radioisotopes generated by | | | | continuing health hazard through the water supply. |
| Fermi's neutron source was gold. The "catch," of | | | | No fully fail-safe storage system has been |
| course, is that this gold was unstable; | | | | developed, and the problem of radioactive waste |
| furthermore, the amount of energy and human | | | | poses a continuing threat due to the extremely |
| mental effort required to generate it far | | | | long half-lives of some of the isotopes involved. |
| outweighed the monetary value of the gold itself. | | | | In addition to their uses in applications related to |
| Radioactivity is, in the modern imagination, typically | | | | nuclear energy, isotopes play a significant role in |
| associated with fallout from nuclear war, or with | | | | dating techniques. The latter may sound like a |
| hazards resulting from nuclear power hazards | | | | subject that has something to do with romance, |
| that, as it turns out, have been greatly | | | | but it does not: dating techniques involve the use |
| exaggerated as radioactivity is not always harmful | | | | of materials, including isotopes, to estimate the |
| to humans. For instance, with its applications in | | | | age of both organic and inorganic materials. |
| medicine, as a means of diagnosing and treating | | | | Uranium-238, for instance, has a half-life of 4.47 |
| thyroid problems, or as a treatment for cancer | | | | · 109 years, which is nearly the age of Earth; in |
| patients, it can actually save lives. | | | | fact, uranium-dating techniques have been used to |
| It is a good thing that not only radiation but also | | | | determine the planet's age, which is estimated at |
| even the harmful variety of radiation, known as | | | | about 4.7 billion years. Potassium-argon dating, |
| ionizing radiation, is not fatal in small doses that is | | | | which involves the isotopes potassium-40 and |
| evident from the fact that every person on Earth | | | | argon-40, has been used to date volcanic layers in |
| is exposed to small quantities of radiation every | | | | east Africa. Because the half-life of potassium-40 |
| now and then. About 82% of this comes from | | | | is 1.3 billion years, this method is useful for dating |
| natural sources and only 18% from manmade | | | | activities that are distant in the human scale of |
| sources. Of course, some people are at much | | | | time, but fairly recent in geological terms. |
| greater risk of radiation exposure than others, for | | | | Another dating technique is radiocarbon dating, |
| example, coal miners are exposed to higher levels | | | | used for estimating the age of things that were |
| of the radon-222 isotope present underground, | | | | once alive. All living things contain carbon, both in |
| while cigarette smokers ingest much higher levels | | | | the form of the stable isotope carbon-12 and the |
| of radiation than ordinary people, due to the | | | | radioisotope carbon-14. While a plant or animal is |
| polonium-210, lead-210, and radon-222 isotopes | | | | living, there is a certain proportion between the |
| present in the nitrogen fertilizers used to grow | | | | amounts of these two isotopes in the organism's |
| tobacco. | | | | body, with carbon-12 being far more abundant. |
| Nuclear weapons, as most people know, produce | | | | When the organism dies, however, it ceases to |
| a great deal of radioactive pollution but | | | | acquire new carbon, and the carbon-14 present in |
| atmospheric testing of nuclear armaments has | | | | the body begins to decay into nitrogen-14. The |
| long been banned, and though the isotopes | | | | amount of nitrogen-14 that has been formed is |
| released in such tests are expected to remain in | | | | thus an indication of the amount of time that has |
| the atmosphere for about a century, they do not | | | | passed since the organism was alive. Because it |
| constitute a significant health hazard to most | | | | has a half-life of 5,730 years, carbon-14 is useful |
| Americans. (It should be noted that nations not | | | | for dating activities within the span of human |
| inclined to abide by international protocols might | | | | history, though it is not without controversy. |
| still conduct atmospheric tests in defiance of the | | | | Some scientists contend, for instance, that |
| test bans.) Nuclear power plants, despite the great | | | | samples may be contaminated by carbon from |
| deal of attention they have received from the | | | | the surrounding soils, thus affecting ratios and |
| media and environmentalist groups, do not pose | | | | leading to inaccurate dates. |
| the hazard that has often been claimed: in fact, | | | | |