I saw through the history search that a number of people here have had barium exams. Could there be a risk of exposure that we don't know about?
This is one hypothesis that links MS to barium. It seems that so called MS clusters have occurred in areas with high barium. I know my hometown was a paper town--we had about five or six paper mills. Barium is used to make paper. It's also used in the military and could help explain some of the military MS cases. http://www.ncbi.nlm.nih.gov/pubmed/15082100