<<Disclaimer: Verify this information before applying it to your situation.>>
 
Note:   I am not a physician.
 
From what I know, it would seem likely that inhaling flour dust would be
virtually the same as ingesting it.  Particles inhaled into the lungs are
cleaned out by the cilia, which pass them up into the throat where they go
"down the hatch" thru the digestive system.    Perhaps wearing a dust mask
might be sufficient to protect against this (depends on how fine the flour
particles can be and how good the filter is.
 
As for the skin absorption route - it  would seem unlikey that gluten and
other antigenic proteins could be absorbe thru the skin BUT there are
various "carrier" chemicals around that can readily transport molecules
across the skin barrier and across lipid bilayers that are not normally
absorbed through this route (Dimethylsufloxide  (DMSO) is a good example of
this).     I do not know of any such carriers that would be likely to be
present in a kitchen environment, but what do they use to get the dye into
playdough?     Gloves* might be a reasonable precaution for making bread,
but try telling a kid to wear gloves while playng with playdough.   I would
suggest you contact the manufacuturer to find out what may be present in
playdough.
 
Not an "expert" opinion - just common sense.
 
Jim Barron
Chapel Hill, NC
 
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* Frequent use of latex gloves may cause latex allergies in some people.
There have been concerns about this in the health professions where latex
gloves are often worn routinely.