The Florentine artist was just 25, and justly proud enough to append his signature (the only surviving example), visible on the Madonna's sash . Since a religious fanatic attacked it with a hammer in 1972, the statue is protected by bullet-proof glass.
Someone tried to attack the statue in the 1970s.
For example, EPA's web site provided detailed information on its 1999 proposed rules on lead and lead compounds and other persistent bioaccumulative toxins.