My first reaction to this question was "well, it depends". The effect of X-rays depends on (among other things) the energy (wavelength) and the intensity (and of course the dose). But I decided not to write about this until...
In response to Michael's note below, I want to point out that instruments constantly improve: I just re-wrote our safety plan because we have to renew our radiation license for our new in-house instrument. On this plan, they ask you to write a worst-case scenario. For an in-house sealed tube instrument, producing CuKa radiation, we calculated (with the help of the friendly manufacturer, thank you) that if you had a direct exposure to the beam, for example because your hand would be in the wrong place at the wrong time, you would burn a 7mm deep hole in your hand. Interestingly and surprisingly, when compared to our old rotating anode generator, the estimated worst case scenario for the old setup was an order of magnitude less severe (less than 1 mm deep burn). The constant improvement of instruments also makes them just a little more dangerous. The old days of 'tingle' are long gone and you *really* need to watch yourself, even on in-house instruments. Indeed, if you do not tinker with the safety system and have shielding in place at all time, as you say, the exposure is never above background. So: obey all the rules and worry very little. At the synchrotron, if I recall my safety training correctly, the worst case scenario (which is very nearly impossible to accomplish, even if you tried, which of course you should not), is instant death. So yes, that gets you kicked out, but not the way you imagined. There are many less severe variations, but probably all are much more severe than the in-house case. There is a reason for all the safety systems. The original question (what happens and how bad is it), is not that easy to answer. Apart from burns, there are of course the known effects of DNA damage etc. Since we share a building with people who call their profession "radiation health physics", I was reminded with an interesting discussion that there are people who study how you can use radiation for your benefit - use enough to kill bad things, but not so much to badly harm the good things - and these people make a living that way, quite successfully. In the end, it is hard to know what anything does to your body and it is best to stay on the safe side. Remember ALARA and observe it. It is possibly the most sensible safety rule I have seen in my life. Hopefully now nobody will be tempted to see if it tingles when you stick your finger in the beam. Mark -----Original Message----- From: R. M. Garavito <rmgarav...@gmail.com> To: CCP4BB <CCP4BB@JISCMAIL.AC.UK> Sent: Fri, Jul 12, 2013 10:14 am Subject: Re: [ccp4bb] Harmful effect of X-ray Most modern textbooks have sections on the proper protections and measures to take, although the information may be dated. See chapter 6 in Volume III of the International Tables for X-ray Crystallography. With the modern equipment and regulatory measures in most countries, you really have to work hard to be exposed at dangerous levels (which can lead to skin lesions and burns). However, you can get yourself exposed if you intentionally circumvent the safety measures and interlocks. In my experience, X-ray exposure in crystallography labs is very low and not dangerous. Our radiation safety people find our labs to be very "clean" with respect to scattered radiation around the sample compared to medical X-ray labs. Talk to your institute's safety people for advice. For in-house equipment, you are most at risk of exposure during aligning the equipment. If you talk to the old crystallographers (or their students who are now +50 year old), you might hear stories of aligning collimators and cameras by the "tingle" on your eye as you look into the beam. By the time protein crystallography came around (50s-60s), phosphors and film were used for alignment so the "danger" comes mostly from scattered radiation and poor shielding. In all the years I have worked with X-rays without protection (I only wore a lab coat to prevent film developer from staining my clothes), neither I nor my colleagues have ever had X-ray exposures above background as determined by film badges and ring badges. In fact, we once exposed a film badge intentionally to see if anyone cared. We caught hell for doing that. For synchrotron sources, chances of being exposed as a general user are now nil unless you really work hard to subvert the safety measures (which will get you kicked out). Hope this helps, Michael **************************************************************** R. Michael Garavito, Ph.D. Professor of Biochemistry & Molecular Biology 603 Wilson Rd., Rm. 513 Michigan State University East Lansing, MI 48824-1319 Office: (517) 355-9724 Lab: (517) 353-9125 FAX: (517) 353-9334 Email: rmgarav...@gmail.com **************************************************************** On Jul 12, 2013, at 11:14 AM, diptimayee mishra wrote: Dear All, Can anyone please tell me regarding the harmful effects of X-ray , we are using for protein crystallography, on human being and what are the precautions we should take. Thanks
