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Asked by hydohannah to Ben, Jony, Katharine, Mark, Peter on 21 Nov 2011.
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Ben Still answered on 21 Nov 2011:
Beta radiation can penetrate some skin and soft tissue because they are just energetic electrons, alpha radiation on the other hand is much larger (a nucleus of Helium) and so is stopped by much less – a sheet of paper would do it. Electromagnetic radiation (gamma and x-ray) can also penetrate skin and soft tissue.
Radioactivity is all around us naturally and for the most part is harmless, and something our bodies have learnt to deal with. The danger is really in the size of a dose you receive – how many beta or other radiation particles you are exposed to. A really good chart showing radiation dose from various sources, bananas to nuclear power plants, was drawn up by the brilliant online comic XKCD http://xkcd.com/radiation/
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Peter Williams answered on 21 Nov 2011:
it is ionising radiation, so the danger to life is that it can ionise atoms in cells causing radiation burns and long term effects such as cancer.
beta radiation is comprised of high energy electrons (or positrons). unlike alpha radiation it can penetrate paper, or your skin. but is stopped by a thin sheet of aluminium. it is not as penetrative as gamma or neutron radiation, that is only stopped by lead or concrete.it’s worth bearing in mind that you are exposed to radiation all the time – the natural background. this is ~3 millisieverts per year in the UK (but can be three times that if you live in certain parts of cornwall, due to the geology). other than radiation from the ground (including radon), the other major components are from your own body, particularly calcium in your bones, also cosmic radiation from space. next down in importance is radioactivity in food – particularly potassium in bananas. then intentional exposure from medical procedures – like having X-rays done.
the occupation that will get you exposed to most radiation is being flight crew for an airline. in fact if you fly to new york and back once you will get an extra 0.1 millisievert.
in the uk the maximum allowed occupational dose is 20 millisieverts per year additional to background. in my organisation, STFC, the limit has been chosen to be 1 millisievert per year. it is similar in the nuclear industry. Cetainly at Daresbury, i do not know of anyone who has got remotely close to that.
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Katharine Schofield answered on 21 Nov 2011:
Beta radiation is dangerous because it’s energetic enough to be ionising. All ionising radiation is dangerous (ionising means that the radiation is energetic enough to knock an electron out of one of the shells of an atom), but it depends on how much you’re exposed to. Ionising radiation can damage cells and DNA which can result in cells growing abnormally and becoming cancerous. However, we can also take advantage of this property of radation to help cure cancer, by killing the cancerous cells in a very targeted, controlled way. You have to be very careful in doing this to not damage too much healthy tissue.
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Mark Basham answered on 21 Nov 2011:
Pretty much covered here, I think the key thing with radiation in general is that we didn’t respect it in the past, and there were some nasty consequences. So we now have a pretty hefty respect for radiation now, and we generally subscribe to the “as low as practicably possible” policy rather than risking it. I am technically a Radiation worker as diamond generates x-rays, but I will receive basically no more dosage than any one else.
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