15 kg of plutonium was used in the Fat Boy bomb that was dropped on Nagasaki with devastating, horrific results. We remember on this day the colossal tragedy of a weapon of mass destruction used against Japanese people with terrible consequences, and all the grief ensuing. May we never forget. The politics, legal and human rights aspects of the Hiroshima and Nagaski events will remain everlasting issues. It is unthinkable that this day will be forgotten if the human species survives for another thousand years. Plutonium of course will survive very much longer. Future visitors from space would be able to infer that a technological society lived on earth - perhaps after more visible human artifacts are gone - since plutonium and its decay products do not occur in Nature. It is a man made element. Something less well known is that only 1.5 kgm of the Nagasaki plutonium was fissioned in the explosion - and the remaining 13.5 kg were vaporized. Within two years, due to the mixing effect of winds and dispersal, this plutonium was estimated to be uniformly distributed throughout the Northern Hemisphere. It was detected in ice layers in the Canadian North - as examples of clean, remote deposition. The implication is therefore that it was equally located in water, soil, plants, other creatures and people. There are billions of atoms of plutonium in 13.5 kgm and every person of the northern hemisphere is likely to have some of these plutonium atoms within them. In a very real sense - we are all children of the bomb. What is the effect of this plutonium in living systems - it is well known now that there is no safe lower limit. Radiation inside living systems causes ionization and molecular damage. It can cause genome damage and other harmful consequences. Some will say that the quantity is too small to be concerned about - but the Nagasaki plutonium was only the first installment - and this has been added to by the nuclear testing and accidents. There is still great difficulty in bringing all the necessary facts together in a truly responsible way. Plutonium 238 is 170 times more dangerous to living systems than Pu239. Pu238 is being used in some satellites as a stable source for long-life electrical power. The Cassini probe has 32 kgm on board. It is greatly to be hoped that this payload does not contaminate the earth's atmosphere - since a burn-up accident on its Fly-By could cause a major plutonium increment. There has been the Stone Age, the Copper Age, the Iron Age - and now there is the Plutonium Age - it has become the defining element of our time. The Mayor of Hiroshima said recently that nuclear weapons and humankind cannot co-exist - that "the Hope of Hiroshima is for a world without nuclear weapons." There is much to think about - but is just thinking enough? These thoughts are based information in a published 1994 scientific symposium "Plutonium in the Environment" in Ottawa, by Elsevier - reference http://www.elsevier.nl/estoc/publications/store/3/09698043/SZ955324.shtml Related concerns and details are available via the Nuclear Legacy section of the website below. Notification of additional relevant information and scientific studies on this problem is welcome. I believe the matter of radiation contamination of the environment and biosphere (including the oceans) has a potential significance comparable to "The Greenhouse Effect." At what point will people begin to recognize "The Plutonium Effect?" Ross Wilcock http://www.pgs.ca/