Here's a link for the MSDS on it.

http://www2.itap.purdue.edu/msds/docs/7079.pdf

That's just one of the versions of "Great Stuff" here's the link for the listing page of MSDS Letter "G", scroll down to get the MSDS for the product you are using:

MSDS - Search Results

It doesn't seem to pose too much of a hazard, being polyurethane. But everyone has their own comfort level, so check out the sheet, and see if it's something you'd be okay with using.