Archived posting to the Leica Users Group, 2009/01/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]There wouldn't be a measurable health effect at any distance, risk is another can of worms. Currently any dose has risk associated. The current model predicts 800 additional cancer in population of 100,000 people of all ages who have been exposed to between 10 and 100 rems at any time in their lives. On average 42 of 100 people will get cancer in their lifetime anyway so on average one additional cancer could be caused by a radiation dose in that range. Assume the risk is linear, @ 10 rem risk is 0.01, @ 1 rem risk is 0.001 (Stockholm after Chernobal), @ 100 mrem risk is 0.0001, etc. Luckily the Thorium series produces mostly alphas and low energy electrons and photons, but, down the chain there is a Thallium-208 which has quite energetic photon and electron. The maximum range in the air for the electron will be about 20 feet. The photon requires a good amount of shielding if it were high activity which I doubt (I have no reference for how much activity they put into these things), so even for the photons the dose should be negligible at twenty feet. If you slept with the lens under your pillow I would guess your dose wouldn't exceed 100 mrem/year which is a risk of 10 additional cancers attributable to radiation in an exposed population of 100,000. At 20 feet your dose would drop to below background. Children are the most sensitive in the population having about a 4x difference in incidence between exposure at 5 and 65 years old, BYW. Chris At 10:24 PM 1/7/2009, you wrote: >Hi Chris ,never occured to me before but you are the person to inquire about >the health hazards of the kodak aero ektar 175 /2.8 lens?I have read many >articles about it but didn't find anywhere howfar one has to be away from >thorium glass lets's say in a bedroom to have negkigable health risk. >Best simon jessurun > >On Wed, Jan 7, 2009 at 9:23 PM, Chris Saganich ><chs2018@med.cornell.edu>wrote: > > > Phill, > > > > Scary really, the one I disassembled had a haze of extremely fine > > particles > > coating the mirror, much like the haze in an old lens. I'll have to > > reevaluate some of my film developing conclusions since I use the > scanner to > > determine things like relative acutance and edge effects from > developer/film > > combinations. Hmmm. > > Chris > > > > At 01:13 PM 1/7/2009, you wrote: > > > >> Chris Saganich wrote: > >> The clue was there in the previous discussion when someone wondered > >> why the bleeding was reversed from conventional film developing. It > >> makes > >> sense now. Now we know, thanks again. > >> ================================= > >> > >> That was me, Chris. At the time I thought about the possibility of a > >> scanner problem but didn't follow up in my comments. > >> Impressive to see the difference a clean mirror can make. > >> > >> -- > >> Phil Swango > >> 307 Aliso Dr SE > >> Albuquerque, NM 87108 > >> 505-262-4085 > >> > >> _______________________________________________ > >> Leica Users Group. > >> See http://leica-users.org/mailman/listinfo/lug for more information > >> > > > > Chris Saganich MS, CPH > > Senior Physicist, Office of Health Physics > > Weill Medical College of Cornell University > > New York Presbyterian Hospital > > chs2018@med.cornell.edu > > http://intranet.med.cornell.edu/research/health_phys/ > > Ph. 212.746.6964 > > Fax. 212.746.4800 > > Office A-0049 > > > > > > > > > > > > > > > > > > "I am the radiation" > > _______________________________________________ > > Leica Users Group. > > See http://leica-users.org/mailman/listinfo/lug for more information > > > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information Chris Saganich MS, CPH Senior Physicist, Office of Health Physics Weill Medical College of Cornell University New York Presbyterian Hospital chs2018@med.cornell.edu http://intranet.med.cornell.edu/research/health_phys/ Ph. 212.746.6964 Fax. 212.746.4800 Office A-0049 "I am the radiation"