I have heard it is bad to inhale pastel dust. Why? Is the dust like carcinogenic like asbestos and (possibly) talc? What does it do to a person who inhales it?
Pastel dust comprises particles of pigment and binder, some of which are small enough to pass deep into the lung, possibly into the alveoli. Many pigments are based on toxic heavy metals, and others are organic chemicals that, while not known to be hazardous, have not been rigorously assessed for toxicity, and are closely related to some that are known carcinogens.
Now I know. This site is great! 
Not all pastels or all colors are toxic. It varies by manufacturer. For example, I use PanPastels and the red I use is made of iron oxide, not cadmium.
Check this out.
http://www.sun-eden.com/tips/tip_pastel.html