[Beowulf] Re: Earthquakes and raised floors...

[Jim Lux]

At 08:43 AM 1/9/2006, David Mathog wrote:
>Robert G. Brown wrote:
>
> > The whiskers are too small to filter without filters that would
> > seriously impede airflow.  Zinc whisker dust in the quantities
> > likely to be breathed in while working on or under raised
> > floors is not thought to be dangerous to humans, as humans
> > actually use tiny amounts of zinc as a nutrient.
>
>We do need a little zinc but the normal way to get it is through
>the digestive system.  Even then it is single zinc atoms that
>are absorbed, not big chunks of metal (biologically a whisker
>is a big chunk of metal).
>
>I'm a bit dubious about the claim that zinc whiskers aren't
>dangerous when inhaled.   Not because it's zinc so much (although
>other forms are definitely bad if inhaled) but because of
>the long needle shape (like asbestos).  Whiskers seem like exactly
>the sort of material that could get stuck in the lung and cause
>local inflamation and/or cell proliferation. Enough of the former
>effect could eventually lead to emphysema.  The latter effect probably
>has no lower dose limit, since cancers can grow up from a single cell.
>I'd be a lot more convinced if the safety claims actually
>cited experimental data (for instance with rats or mice) where the
>health effects of these whiskers was actually measured.  If there
>has been such a study I was not able to find it with a few keyword
>searches through the journal indices at our library.


Zinc might be fairly benign, but zinc oxide certainly is not.  It's a real 
problem if you're welding galvanized metal, for instance.