(1) A registered sanitarian shall not engage in or have an interest in any work, project, or operation prejudicial to his or her professional interest and shall not engage in the practice of professional engineering as defined in section 2001 of the occupational code, 1980 PA 299, MCL 339.2001, unless the activity is consistent with that as defined in section 18401(c).

  (2) The standards of the national environmental health association as they exist on the effective date of the amendatory act that added this subsection relative to qualifications, education, and examinations are adopted by reference. The department shall accept the certification by the national environmental health association of the successful completion of any education or examination for purposes of registration under this part.

  (3) Notwithstanding section 16148, the department may by rule adopt any other or additional appropriate standards and may adopt any updates or amendments to the national environmental health association standards adopted under subsection (2).