Here's a paper from a party with an interest in selling industrial uv technologies, but not the steri-pen, so far as I've been able to determine. Notice, however, the citations at the end of the article for further reading on the subject. Also notice the basic physical principles and mathematics involved in uv disinfection. Remarkably, the standard unit dose seems to be 20 milliwatt seconds per square centimeter, with safe drinking water doses ranging from 16 to 40 milliwatt seconds per square centimeter. The proposed steri-pen uses a 5 watt light source and proposes that you swish it around in a cup of water for 30 seconds, which advice given these technical specs would appear to suggest over-kill to me, based on the well established dosage requirements. The operating current for the pen is supposed to be 16 mAmp; the proposed battery should last 900 mAmp hours. The tables giving the doses required for 99.9% disinfection appear to me well established in the literature available on the net that I've reviewed. (I'll be happy to clog your system if you want to see them all). Industrial UV technologies to disinfect water appear to flourish in Europe and Asia, but for some reason appear to have some trouble making more than a toe-hold in the US economy. It appears that the labor-intensive maintenance requirements for large, industrial size technologies appears put off US decision makers, rather than any real scientific objection the efficacy of the uv procedure. As a result, American companies appear to be addressing the labor expense issue in industrial sized units with higher intensity, and fewer (therefore less labor) light sources. None of the objections applicable at the industrial level appear applicable at the hiker level, at least to me. So far, I've not seen any real theoretical reason why UV doesn't present an excellent alternative to filters, chemicals, boiling -- other than, of course, price. Any deviation from theory in practice with the steri-pen would appear to me at least easily remediable with appropriate changes to the intensity of the light source. The notion that you need doses lethal to human beings in order to get pure water appears a bit ridiculous to me after my short research. I'd expect the steri-pen to provide, in addition to safe drinking water, some entertainment on the trail when various substances fluoresce under the uv light. Who knows, with several of them you could turn a shelter into a 70s disco and charge day hikers for tanning time. FYI, I checked MedLine+ at the National Medical Library, and used Dog-Pile to simultaneously search about a dozen search engines, including Alta Vista and Lycos. I used the following queries: uv OR "ultra violet" OR ultraviolet AND disinfect* AND "drinking water". Unfortunately, you'll need to wade through tons of commercial sites to find scientific and technical literature on the subject. However, you may find the following URLs of use in your own research: http://www.wqa.org/ http://ourworld.compuserve.com/homepages/ottaway/disinf.htm And, if you're afraid of getting literally burned by your new toy, you could get this: http://home.wxs.nl/~sunburn/uv-meter.htm David
UV TECHNOLOGY FOR WATER SUPPLY TREATMENT (Internet Shortcut)