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That is a very good question and not easy to answer. This will depend on the individual, the risk they are taking and the benefit that they will receive from it. As pointed out in the Radiation and Us page, we receive approximately 360 mrem of radiation every year. The legal limit imposed by the federal government in this country for an occupationally exposed worker is 5,000 mrem per year. If we look first at doses received in a short amount of time, (acute doses), the first biological effect begins to be able to be detected by laboratory analysis at 10,000 to 25,000 mrem. Actual immediate life threatening doses are limited to levels of 100,000 mrem and above. The life shortening doses may be lower than that, and are approximated by taking the data at higher doses where the effects are apparent and extrapolating the risk down to lower doses. Being conservative, the regulators use a model of a straight line from high doses down through the zero dose/zero risk point, so that any dose presents some small risk. Also you need to know that doses received over a longer period of time allows for repair of cells by the body, and presents less of a risk. See the Radiation and Risk page for more information. So to answer the question, the doses receive by the workers in nuclear power, an extra 100 to 5,000 mrem per year (average about 500 mrem), are seen by most scientific organizations as presenting a low risk compared to normal occupational hazards encountered during a working lifetime. Children, fetuses and embryos are more sensitive and have a longer expression time than adults, and so have smaller allowable doses. It is really a personal choice how much is too much. In some situations, such as to save someone's life, I personally would accept around 100 rem, but in the normal course of my work, I would rather keep my dose to less than 5 rem per year.

Question 2: Do you have any information about Dr. Luckey's work and where can you get more info on "Hormesis"

Answer question 2:

By hormesis, you mean radiation hormesis. The idea of hormesis goes back to ancient Greece, where it was thought those frequent small doses of a poison would fine-tune the body and cause positive health effects. The same idea has been thought to apply to radiation, such that small amounts of radiation are actually good for humans and that without it, our health actually suffers.

Dr. Luckey is the probably the most famous of the public believers in hormesis, but not the only one. He edited/authored a book for the CRC Press company on Hormesis that is pretty good. The CRC can be reached at:

CRC Press, Inc. 2000 Corporate Blvd. N.W. Boca Raton, Florida 33431 USA Phone: (407)-994-0555 or 1-800-272-7737 (US only)

Other references for Hormesis:

Health Physics, Vol. 52, No. 5, May 1987, is entitled "Special Issue on Radiation Hormesis," and was edited by Leonard Sagan. The table of contents is a bit lengthy, but here are the section headings:

• Editorial Comment (by Genevieve Roessler)
• Preface (by Jerry J. Cohen)
• Guest Editorial (by Leonard Sagan)
• Hormesis Overview
• Cellular and Tissue Level Effects
• Plant and Animal Effects
• Alpha-Particle Exposures
• Human Effects Mechanisms
• Correspondence (a brief exchange between John Gofman and Leonard Sagan)

Macklis Beresford published an article "Radiation Hormesis" in the Journal of Nuclear Medicine Vol32, 2, P350, '91 that includes 77 references, that you may find useful.

You can subscribe to the BELLE (Biological Effects of Low Level Exposures) by contacting:

Northeast Regional Environmental Public Health Center Univ. of Massachusetts Amherst, MA phone 413-545-1239 or FAX 413-545-4692

This is an informative publication, covering low level exposure to many toxic agents, including radiation. The December 93 issue has a good article by Leonard Sagan of EPRI on "The Low Dose Effects Paradigm", which considers the pluses and minuses of this approach. It is published quarterly and is quite well done.

There is also a new web site: Hormesis and Radioadaptive Response Page that has information on Hormesis.

Question 3: What is the danger of dental x rays?

Answer questions 3:

The danger would be a slight increase in the risk of cancer. But, from a health standpoint, dental x rays have a much bigger benefit than risk. You will notice though, that your dentist and dental hygienist will not stay in the same room as you, for there is no reason for them to receive doses several times a day, 5 days a week. Their leaving and the lead apron that you may be asked to wear are measures to reduce all of the doses so that they are as low as reasonably achievable.

Mobile phones radiate and receive electromagnetic radiation in the band of 800 - 900 MHz. This is non-ionizing radiation, but thought by some to have adverse health effects. There is an EMF news letter which has current information on EMF, plus at least two articles on cellular phones including a summary of a new German study that found no correlation with use and cancer. It can be found at the home page for EMF-Link. It would seem that the newest information does not show a link to cancer from the use of mobile phones.

Question 6: What are the different types of radioactive decay?

Answer question 6:

The forms of radioactive decay and other associated processes are as follows:

Decays -

• Beta - positive and negatively charged particles that are mass equivalent to electrons that are given off from the nucleus
• Alpha - the emission of a particle made up of two neutrons and two protons, but no electrons, so it has a mass of four amu and a charge of -2
• Isomeric transition - a metastable isotope gives off some energy in the form a photon. Can only happen following the formation of a metastable isotope by one of the other modes of decay
• Internal Conversion - the nucleus gives up some of its energy to a orbital electron
• Electron capture - the nucleus "captures" an orbital electron
• Fission - division of an atom into two smaller atoms

Other processes related to decay -

Natural radiation takes the same forms as "human-caused" radiation. All the same decays discussed above happen naturally. Radiation we are exposed to from our environment include Cosmic (high energy particles and EM from outside of our galaxy), Cosmic induced (C-14, Tritium made in the atmosphere by interactions with cosmic radiation), Solar (UV from the sun mostly, but in space can be particles), and terrestrial (Uranium, Thorium, Radon contained in the Earth itself). Life forms have incorporated all of these into their biomass, so all life on Earth has some amount of radioactivity in it. That includes the food and water we ingest, and humans in general.