The 5700 MOS in the Marine Corps is for Chemical, Biological, Radiological, and Nuclear (CBRN) Defense. Marines with this MOS are trained to react to and defend against hazardous attacks. They train for a variety of situations, including gas attacks, chemical spills, bomb disposal, and plagues.
CBRN Defense Specialists are responsible for:
Collecting and analyzing information about CBR exposure status, contaminated areas, and CBRN readiness
Operator level maintenance
Serviceability of CBRN equipment and supplies
The mission of CBRN is to protect personnel from the effects of weapons of mass destruction.