The current code for the United States of America is F 2412-05.
This code has been issued by the American Society for Testing and
Materials. The code has replaced the Z41 1999 code, which
was issued by the American National Standards Institute. If you
do own a safety shoe which is compliant with the old Z41 1999 code,
then you probably have nothing to worry about. The new F 2412-05
code removed the impact and compression requirements of the previous
Z41 1999 code; therefore, your shoes should comply with the new
regulations, and possible may exceed them - though this may not
be the case. The F 2412-05 code is primarily concerned with
providing protection against; metatarsal, toe, and foot sole injuries.