The department is designated as the state's mental retardation, related disabilities, head injuries, and spinal cord injuries authority for the purpose of administering federal funds allocated to South Carolina for mental retardation programs, related disability programs, head injury programs, and spinal cord injury programs. This authority does not include the functions and responsibilities granted to the South Carolina Department of Health and Environmental Control or to the South Carolina Department of Vocational Rehabilitation or the administration of the "State Hospital Construction and Franchising Act".