QUESTION:
Is there some harmful particles in the dust you are studying?

ANSWER from Scott Sandford on May 13:
Many of the components of interstellar dust clouds can, in fact, be 
considered to be hazardous.  All interstellar clouds contain carbon monoxide 
(CO).  This molecule binds with the hemoglobin in your blood and prevents 
oxygen from getting to the cells of your body.  [CO is produced by cars 
burning gasoline, especially by cars that aren't tuned properly.  That's why 
you should never run your car in a closed garage.  The CO can build up and 
kill you.]  Another molecule that is common in clouds is methanol (CH3OH).  
Methanol is sometimes called 'wood alcohol' and it is poisonous.  One of the 
things it can do is cause blindness.  Interstellar clouds also contain 
compounds called Polycyclic Aromatic Hydrocarbons (this is such a mouthful 
that we usually just call them PAHs).  PAHs are one of the main components 
of soot and are produced by candles, wood fires, barbecues, car engines 
(especially diesels), etc.  Many PAHs are known to be carcinogens or 
mutagens.  Fortunately, none of these compounds present a real danger to 
us because they are far away.  Also, many of the materials in interstellar 
clouds are NOT hazardous in any way.  

For example, much of the dust is in the form of silicates (basically 
just plain ol' dirt) and 'micro-diamonds', and the most abundant molecule 
in the ices is H2O.  None of these are dangerous.