While it's all well and good to read the MSDS for the stuff we use (or want to try) I think a little care is needed when assessing the actual dangers.

Two examples.
http://www.jtbaker.com/msds/englishhtml/p4830.htm
Now this is for drinking quality water. Under Hazards Identification it has a danger warning! But if you look closer it relates ONLY to a tiny impurity of nitric acid.

The next example comes from a thread in SSW where it seems that Thunderbolt glow plugs have a warning on the packet that they contain a chemical known to cause cancer. Now this may be just to warn Californians not to breathe or eat glow plugs but for interest's sake I looked up the MSDS for platinum wire at http://hazard.com/msds/f/cbn/cbnwh.html
One of the things it warns against is that inhalation may be harmful! Well duhhhhh....when was the last time you heard of someone snorting a roll of wire??

OK, so I'm being a bit fascetious here...but the point is that with moderate care even something as dangerous as nitro (look it up) can be used quite safely. There are other ingredients that used to be used that are avoided like the plague nowadays.