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I How long can you be exposed to gamma radiation for

  1. Apr 28, 2016 #1
    So my question is, how long can you be exposed to a gamma radiation for?

    Specifically, I've been working with a sealed cobalt-60 source for a final presentation. Now my professor noted to me that these sources we're using aren't radioactive enough to cause us any harm. However, I've been working with this source for approximately 3-4 hours at a time for approximately 4 different days now.

    Its a cobalt-60 source labelled at 0.1microcuries. Can someone provide inside into what the difference between all the units of radiation are including rad,rem,curie,roentgen, becquerel, etc. I've found so many units its hard to differentiate and make sense of them all. I also want to make sure I'm not overstepping my bounds when it comes to the amount of time I'm being exposed to this source for. Also whether or not the headaches i get aren't just a placebo effect and worrying too much about it.

  2. jcsd
  3. Apr 29, 2016 #2

    Simon Bridge

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    Depends on who "you" are and how strong the source is.

    The sources you use in lab are usually very weak - unless you swallow them, you won't get more than normal background radiation off them at any reasonable distance. Even if swallowed, there is a bigger choking hazard because of the size of the slug - and some sources are poisonous.

    1 Curie is the radiation from 1g of radium ... forms a useful standard since early knowledge of the harm due to exposure came from people working with radium (i.e. in paint used for watch dials).

    See also:
    Radiation measures: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radrisk.html
    EPA guidelines: https://www.epa.gov/radiation
    ... the safe levels are usually worked out so that you cannot get a dose high enough to make you sick even after 70 or so years of continuous exposure.
    There was a scare awhile ago about radium in the drinking water in parts of Texas... which is the last time I looked at it.
    If you are not in the USA, your government will have similar regulations.
  4. Apr 29, 2016 #3


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    I had this big long response, but I closed the tab by accident. :mad:

    Without going through all the working for you, as I did before, if you just sat 1m from the source, and didn't do anything silly like eat it, you will have received about 16 μSv of dose in total over 16 hours. The average person, just living their lives, receives about 10 μSv of dose a day. If you've ever been in a airplane, you've received a higher dose. If you've ever been on a black sand beach, you can have exposure rates up to 100 μSv/hr. If you've ever had an x-ray at a dentist, you'd have a dose there of about 150 μSv. A slight headache from radiation poisoning is only possible at a whole body dose several orders of magnitude higher than your absorbed dose (1 Gy of whole body absorbed dose).
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