I would imagine unless the beef was raised organically, you will not know.
Is the meat that you are eating tested? I doubt it. Meat has to be butchered properly...animals cannot be sick or down, or dead before being butchered. I highly doubt that they test for any chemicals,lead,etc. Cows don't seem to get cancer all that often either.
I don't think steroids are allowed in meat animals anymore? (at least in Canada).
Honestly I would worry more about the chemicals you give in the flea and heartworm products, and repeated vaccinations, more then the occasional marrow bone given.
Gina