I was very confused about all the different thoughts/concerns about luster, pearl, shimmer dusts and colors...So I finally spoke with the FDA. All the concerns seem to come from the Mica-based pearlescent pigments.  You can read the page about it here.

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=73.350

Basicly ALL luster/pearl or shimmer items have a percentage of Mica-based pearlescent in them.

All of them CK, Wilton, americolor sheen colors etc.  Pearlized sugar pearl etc etc.

The FDA says that it will only approve if the amount is less than 1%.

Of course I'm sure the amount in the jars of luster dusts is probably greater than 1%.

Once you have used it as a decoration on parts of the cake and then the cake is cut into slices can the amount of Mica-based pearlescent be all that significant?  

When I spoke with CK products they said basicly the same as the FDA and that it is not to be consumed That you really shouldn't sit and just eat right out of the jars. I doubt anyone would do that but who knows...    Wilton just told me they do not sell anything that would hurt you. But when I bought their shimmer dusts they do have a warning on the back of the package about the Mica-based pearlescent.

Americolor shows that their airbrush sheen colors are FDA approved so the pearlescent in those must be less than 1% in the bottle.

I have not found solid information on all the different color pigments or the ingredient Carmine so I don't know about those....

I don't see a problem in using the dusts in decorating and if anyone is concerned then they should just take it off.....

Please add any information you have or let me know if the information I received is incorrect...

Thanks so much for your research!  So much of the info about this stuff second hand.
 

So it's the Mica that's restricted?  And what about in Europe, does anyone know if it's restricted there?

Thank you for sharing this info.