gnu, there is no evidence that there is any risk of "losing an arm or a foot" after breaking or even stepping on one of these bulbs: see this snopes article:

Internet-falsehood

In April 2012 these photographs were circulated as part of a Salisbury [Maryland] Fire Department training newsletter. The Salisbury Fire Department denies authorship of the piece and admits to having been hoaxed, saying:
Although attempts were made to verify the validity of the information, initial Internet searches provided no compelling evidence to dispute the information. We now believe that the information we used as the basis for our April 2012 Newsletter was an Internet-falsehood which started circulating numerous years ago and had an ulterior motive and purpose.

Read more at http://www.snopes.com/photos/medical/cfl.asp#7iIRsfCqeBq3lt7f.99

These scary pictures ring alarm bells in me- they are typical of internet hoaxes aimed at getting attention for people with ulterior motives.
(The pictures are probably of a case of necrotizing fasciitis,a bacterial infection, not something caused by exposure to mercury.)


Please check stuff you find on the internet before believing it!