1. How harmful is nuclear radiation? It depends on the dose received.

Tsunami-related Fukushina accident will probably renew debates about nuclear electricity. Such debates should be based on what is known about negative effects of nuclear radiation. Numerical data below should be useful in that context.

The effect of penetrating radiation on a person depends on the dose received. The common unit of dose is Sievert (Sv). Smaller doses are expressed in milliseverts (mSv) or microseveret. The old unit of dose, rem, is also used widely (1Sv=100 rem)

A dose of 10 Sv will most likely results in death, within a day or two.
5 Sv would is kill about 50% of exposed people.
2 Sv can also be fatal, especially without prompt treatment.

0.25 Sv = 250 mSv is the limit for emergency workers in life-saving operations.
0.10 Sv = 100 mSv dose is clearly linked to later cancer risks.
0.05 Sv = 50 mSv is the yearly limit for for radiation workers.

0.004 Sv= 4 mSv typical yearly dose due to natural radiation (cosmic rays, etc).
0.003 Sv= 3 mSV typical dose from mammogram

The one day dose, due to Fukushima accident, at a distance of 30 miles from the damaged reactors, was reported (on 3/16 and 3/17) as 0.0036 mSv. I do not have data on doses received by those who worked near or inside reactors. But I have no doubt that each of them was carrying an individual dosimeter. No deaths due to radiation have been reported in Japan, as far as I know. Many lives, however, were lost in Chernobyl, by those who worked to minimize damage. Some of them probably received very high doses.

Ludwik

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4. As a rough guide, based on an article in New Scientist, and with the experience of Hiroshima, it appears that a single dose of 80 mSv will not cause measurable harm. By comparison, the average dose received over 12 months, from background radioactivity is 2.6 mSv.

It is actually very uncommon for someone to be harmed by radioactivity from a man-made source. That is because humans have become good at handling the stuff without harm. At this point, it appears probable that the death toll from radioactivity in Japan will be zero.

5. At high doses, immediate effects are easily noticed, such as burns, tissue damage and blood cell drop. Relatively high doses also have evident effects as high incidence of certain cancers are observed. Lower (and usually long-term) exposure have also harmful effects although they can only be notices after long periods of time. Studies following Chernobyl survivors for 20 years revealed not only high cancer rates but also cataracts and high risk of cardiovascular disease. Source: chernobyl-accident-an-epidemiological-perspective

6. Kelvin

|While what you say is doubtless correct, it means little without numbers. According to iNow's chart, the minimum dose known to have led to cancer is 100 mSv. What are the doses you are talking about? What is the dose the Fukushina people were exposed to? Without this data, the post means nothing.

7. Don't you think that this particular topic should be discussed in the physics forum??

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