Aucbvax.1914 fa.energy utzoo!duke!decvax!ucbvax!OAF@MIT-MC Wed Jun 24 15:34:22 1981 short message no digest Date: 23 Jun 1981 10:23:37-EDT From: cjh at CCA-UNIX (Chip Hitchcock) Subject: lung pollution I did some work on this while studying inhalable sprays and particulate sprays that weren't supposed to be inhaled. This is a fair summary although I won't promise the precise accuracy of the details. Basically, the lungs themselves are far too fragile to support any cleaning mechanism; if you take a look at a lung tissue slide you'll see it's mostly empty spaces separated by very thin walls. (If you look at a slide from someone who had silicosis, the walls are no thicker but the spaces are much larger.) The lungs are protected by a layer of mucus in the pharynx and trachea; this material is extremely sticky (so it catches much of what comes by) and is continually born upward to the top of the esophagus where it can be swallowed or coughed out. Coughing is the only mechanism that can clean the lungs themselves, and it's not very effective for anything that has actually gotten down into the individual air sacs. Given that a gram of plutonium would be a cube between a third and a half of a centimeter on a side, a microgram all together would be (if cubical) 33-50 microns on a side. This is within the range for dust particles to be trapped by the mucus and carried away from the lungs (my recollection is that above 150 microns particles get stoppped near the top of the pharynx and only below 10-20 microns do many of them get into the lungs), but dust particles should be much easier to seize and carry upwards than something as dense as plutonium. Also, particles this large are unlikely to be windborne; smaller particles in quantities greater than one are more likely to be an inhalation danger. Physical erosion can be halted and perhaps even healed over time; this is why smokers are encouraged to quit even if they've been at it a while (At the least, each additional puff adds to the load of particles tearing up the lungs.) But lightweight ash would be much easier to encyst and possibly expel than plutonium. Also, encystment alone doesn't help, since lung tissue is thin enough that I would expect even alpha particles to smash through several layers. To make matters worse, the plutonium can also be chewing up random blood cells in the vicinity, although a fine dusting like this is less apt to damage enough blood cells to cause serious effects in the cells' natural lifetime of 3 weeks. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.