Archived posting to the Leica Users Group, 2000/09/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]William, Do you happen to know what mercury compound is in fluorescent tubes? I wonder how much is in one industrial size light, vs. one PX-625? Anybody else? John William Gower wrote: > > With regards to the recent postings on Hg, batteries and Minamata: > > > From: "Raimo Korhonen" <raimo.korhonen@pp2.inet.fi> > > > Metallic mercury is not particularly harmful - but some organic compounds > > that contain mercury are lethal and thatīs what caused Minamata, not > > mercury batteries. > > Partly true: Metallic (elemental Hg) is not "harmless" per se, but the rate > of absorption into the bloodstream via the skin slow. Slow enough, that you > would have to be in direct contact for long periods of time for any > significant symptoms to manifest themselves. Not that it wouldn't or > couldn't happen, mind you - it's just that the likelihood is small. > > Remember handling the stuff as a kid when you broke a thermometer or old > thermostat ? How about good old dental fillings (amalgams of Mercury and > Tin). Although I wouldn't recommend it, accidental swallowing some Hg is > generally considered harmless (save for a tummy ache). > > My point - exposure by handling or occasional ingestion of elemental Hg (the > good old silver liquid) is, for all intensive purposes, benign. The skin is > a pretty good barrier to uptake of Hg. > > However, increase the rate of absorption of Hg into the bloodstream, and > trouble begins. > > How to you increase the absorption ? Via the respiratory tract is one. > Exposure to Hg dust (mining of sulphide ores rich in cinnabar) or vapour > (heating Hg in the presence of oxygen, forming HgO) are the two most common > and toxic occupational exposure routes. > > Dimethyl Mercury (CH3)2Hg is the real bugger in the environment. This is an > organic mercury compound that is readily absorbed into the bloodstream. In > nature, certain aquatic organisms will break down elemental Mercury into > this organic form. If the level of Mercury in natural waters is high, the > concentration of of Dimethyl Mercury will be high as well. This translates > into accumulation of Hg in marine life (i.e. fish). > > Minamata is a prime example. It was the high concentrations of Hg in the bay > from industrial processes that caused an elevated level of Dimethyl Hg in > the aquatic life. This, combined with a diet rich in seafood that caused the > high incidence of Hg poisoning in the areas surrounding Minamata Bay, Japan. > > There have been other cases of widespread Hg poisoning due to eating > contaminated grains that had been treated with organic Mercury pesticides. I > believe it was in somewhere in the middle east (Iraq or ?) > > No, I'm no "expert", but I took enough toxicology and biochemistry courses > to know that Hg is bad news. And yes, I have a Rollei 35s that needs to be > recalibrated to the '625 alkaline cells. > > Kind regards > > William Gower