The fumes are definitely nasty and a carbon filter respirator is a really good idea. I found this information on a MSDS regarding the dust:
HEALTH HAZARD INFORMATION:
Ingestion is unlikely due to physical state. Physical injury only.
Solid or dust may cause irritation or corneal injury due to mechanical action.
Considered to be physiologically inert. No adverse effects anticipated by this route of exposure incidental to proper industrial handling.
Dust may cause irritation to upper respiratory tract. No significant levels of exposure to blowing agent or fire retardant during normal industrial procedures post manufacture. For further information contact Dow or Aero. Dev. (Mfg.) for unabridged MSDS.
OTHER HEALTH HAZARD INFORMATION:
Repeated exposures to this product are not anticipated to cause any significant adverse effects.