Left tampon in a long time...?

I accidentally left my tampon in for 12 and 1/2 hours last night-- am I going to get Toxic Shock Syndrome? Or something else?
I know they say to not leave it in for any longer than 8 hrs on the box, but I have to wonder, what is the actual amount of time that, if it's left in, is dangerous?
Thanks for your feedback.