The National Board of Public Health Examiners now offers members of the . (COA) free access to the (CPH) Study Guide. The study guide will prepare one to sit for the CPH credential, which is the only voluntary core credential for public health professionals. The CPH designation demonstrates that an individual graduate from a CEPH-accredited school or program of public health has mastered foundational competencies in public health. CPH professionals raise the bar and enhance the public health profession through their exemplary academic and leadership skills.