Mass. Gen. Laws ch. 111 § 27A
Two or more municipalities may, by vote of their respective boards of health and, in a city having a Plan E charter by the affirmative vote of a majority of all members of the city council, in other cities by a vote of the city council and approval of the mayor, and in a town by a vote of the board of selectmen, form a district for the purpose of employing therein a health officer and necessary assistants and clerks, all of whom shall be appointed and may be removed by a joint committee composed of either the boards of health of the municipalities or 1 or more representatives from the board of health of each municipality. Persons so employed shall perform such duties and receive such compensation as the joint committee shall determine and, in so far as their duties in a given municipality are concerned, shall be the employees of and responsible to the regularly constituted board of health of such municipality. The department, in consultation with the department of environmental protection, may adopt regulations to set minimum qualifications for health officer pursuant to this section. The joint committee shall annually elect a chairman and a secretary and shall determine the relative amount of service to be performed in each municipality of the district by employees of the district. The treasurer of 1 of the municipalities of the district, designated by the joint committee, or such other treasurer designated by the joint committee, shall be treasurer of the district and shall give to the district a bond with a surety company authorized to transact business in the commonwealth as surety, for the faithful performance of his duties as treasurer of the district, in such sum and upon such conditions as the joint committee may require. The joint committee, annually in the month of December, shall estimate the amount of money required to pay the costs and expenses of the district for the following year, shall fix and determine the proportion of such costs and expenses to be paid by the respective municipalities thereof during the year and shall certify the amount so determined for each such municipality to its assessors who shall include such amount in the tax levy of such year. Upon order of the board of health of each municipality, the municipal treasurer thereof shall, from time to time and subject to section 52 of chapter 41, pay to the district treasurer such sums not exceeding the amount certified by the joint committee as the municipality's share of the costs and expenses of the district. The district treasurer shall disburse the money so received, upon warrants approved by the health officer. A member municipality of a regional health district formed pursuant to this section may withdraw by majority vote of its legislative body and the vote to withdraw shall become effective on the last day of the next fiscal year. This section shall not apply in the county of Barnstable.
Nothing in this section shall be construed to prohibit a board of health that is not part of a regional health district from appointing as its health agent, a health agent employed by another municipality pursuant to section 30, and setting the salary and terms of employment thereof if such health agent has received written approval from the original appointing authority and the health agent is either: (a) a physician, having graduated from an accredited approved school of medicine and registered, or eligible for registration, to practice medicine in the commonwealth, with 1 year of full-time graduate public health academic training or 2 years of full-time experience in public health; or (b) a lay person with professional academic training equivalent to a bachelor's degree and with 5 years of administrative experience and supervision of generalized public health programs or a registered sanitarian, certified pursuant to section 87 OO of chapter 112. If a lay health officer is employed, a registered physician shall also be employed to perform such medical functions as are required.
For purposes of this section, the term "board of health" shall include any body politic or political subdivision of the commonwealth that acts as a board of health, public health commission or a health department for a municipality.
Mass. Gen. Laws ch. 111, § 27A