The director shall examine any interested person qualified under Section 33113 for certification as a registered dairy inspector. Such an examination shall be both written and oral. A certificate as a registered dairy inspector shall be issued to any person who passes the examination.

No person shall be eligible for the examination given under Section 33111 or any employment as a dairy inspector by an approved milk inspection service, unless he is certificated pursuant to the provisions of this section. Such certification shall be valid for four years after a person discontinues his employment as a registered dairy inspector or a registered sanitarian.

The director may adopt such regulations as are necessary to carry out the provisions of this article.