The board shall consist of six members. One member shall be a public member who meets the requirements of section 38-165. Each of the other members shall have been engaged in environmental health for at least ten years, shall have had responsible charge of work for at least five years at the time of his or her appointment, and shall be a registered environmental health specialist. At the expiration of the three-year terms of the members serving on December 1, 2008, successors shall be appointed for five-year terms.