An individual may not practice as an environmental sanitarian in the State unless the individual: Is licensed by the Board; or Is employed under a valid sanitarian-in-training certificate or a certificate of eligibility for supervised training issued by the Board. An individual may not practice as an environmental sanitarian under a sanitarian-in-training certificate for more than a total of 3 years, unless approved by the Board in accordance with COMAR 26.07.02.05D(3).