This is an appeal from a judgment, entered by a Superior Court judge, upholding the validity of a regulation issued by the commissioner of health and hospitals of Cambridge (commissioner). The regulation prohibits “[t]he testing, storage, transportation and disposal,” within the city of Cambridge, of five highly toxic chemical warfare agents. Arthur D. Little, Inc. (ADL), has challenged the regulation, and the order enforcing it, on a variety of procedural and substantive grounds, contending that: (1) the regulation is invalid because it was issued without a hearing, and without specific findings of any threat to public health; (2) the judge below wrongly deprived ADL of its right to challenge the regulation and order through a trial by jury; (3) the regulation is preempted by the constitutional grant of war and defense powers to the Federal government; (4) the regulation is unreasonable, arbitrary, or capricious; and (5) the regulation violates the contract clause of the United States Constitution, art. I, § 10, cl. 1. We conclude, after examining each of these contentions in turn, that the regulation and order were validly promulgated, and constitute a permissible attempt by the city of Cambridge to protect the health and welfare of its inhabitants.
The facts as established by the materials submitted for the purposes of the summary judgment motions are as follows. In June, 1982, and September, 1983, ADL entered into contracts with the United States Department of Defense (DOD), which called for the testing of small quantities of chemical warfare agents. This testing was commenced in the fall of 1983 at ADL’s Cambridge facility, known as Levins Laboratory. The laboratory was constructed and operated in full accord with all applicable Federal and State standards, including standards issued by the DOD. It is located adjacent to Route 2, and within several hundred feet of a busy commercial area and a residential neighborhood.
On March 13, 1984, the commissioner, pursuant to his authority under G. L. c. Ill, §§ 31 and 143 (1984 ed.),1 adopted *538the regulation at issue here, which prohibits the “testing, storage, transportation and disposal,” within city limits, of five chemical warfare agents being studied at the Levins Laboratory.2 The regulation was to remain in effect until a Scientific Advisory Committee (SAC) study, and an “independent hazard assessment,” of those chemicals were completed and reviewed. Also on March 13, the commissioner issued an order under G. L. c. Ill, §§ 143 and 146 (1984 ed.), requiring ADL to “cease the storage and testing” of the chemicals listed in the regulation.
ADL promply filed a complaint in Superior Court in Middlesex County seeking a review of the commissioner’s order under G. L. c. Ill, § 147 (1984 ed.), and a declaration under G. L. c. 231 A, § 1 (1984 ed.), that the regulation issued by the commissioner was invalid. Shortly thereafter, a judge enjoined the commissioner from enforcing the regulation. This injunction has been extended pending the resolution of the merits of ADL’s complaint.
In June, 1984, a consulting firm hired by the city issued its “independent hazard assessment.” This report contained a detailed scientific analysis “of the potential public hazards involved in experiments with chemical warfare agents” at ADL. The report refrained, however, “from characterizing ... the *539hazard as ‘acceptable’ or ‘unacceptable’ ”3 The SAC issued its report in September. Certain of its findings are set forth in detail in the margin.4 In short, the SAC concluded that ADL’s use of the chemicals listed in the regulation, “within the densely populated City of Cambridge,” was “inappropriate,” and that the risks involved in such research were “unacceptable.” On September 18, 1984, following the submission of these two reports, the commissioner issued a second regulation and order reaffirming the ban on the use of the chemical agents under study at ADL.
The parties filed cross-motions for summary judgment in the Superior Court suit filed by ADL to test the validity of the regulation. On Febuary 27, 1985, by order of a Superior Court judge, judgment was entered on behalf of the commissioner, declaring the regulation valid and enforceable. ADL promptly filed a notice of appeal, as well as a motion for a stay pending appeal. The requested stay, first denied by the Superior Court, was granted on March 15, 1985, by a single justice of the Appeals Court. The commissioner then filed a petition for relief from the stay with a single justice of this court, under G. L. c. 211, § 3 (1984 ed.). The single justice reserved and *540reported this petition to the full bench. The appeal on the merits, pending in the Appeals Court, was also transferred here. Thus both cases are now before us.
I. Procedural challenges.
ADL contends that its statutory and constitutional due process rights were violated, because the regulation was issued without a prior hearing, and without findings of fact based on substantial evidence. We disagree. The State Administrative Procedure Act (APA), G. L. c. 30A, §§ 1 et seq. (1984 ed.), is inapplicable to actions taken by the commissioner pursuant to G. L. c. Ill, §§ 31 and 143. Nor does any other statute, or the Constitution, require a hearing or findings to support this exercise of the commissioner’s rule making authority. Consequently, the regulation was issued in a procedurally adequate fashion.
First of all, we reject ADL’s argument that the commissioner is subject to the procedural requirements of the APA. See G. L. c. 30A, §§ 2-7. General Laws c. 30A, § 1 (2), renders the APA applicable to administrative action by “any department, board, commission, division or authority of the state government or subdivision of any of the foregoing, or official of the state government.” Because the responsibilities of the commissioner are “confined to the municipality,” United Food Corp. v. Alcoholic Beverages Control Comm’n, 375 Mass. 238, 242 (1978), the requirements of the APA are inapplicable.5 See also Commonwealth v. Blackgammon’s, Inc., 382 Mass. 610, 626 (1981); Buteau v. Norfolk County Retirement Bd., 8 Mass. App. Ct. 391, 392 (1979).6
*541Nor do we believe that G. L. c. 111, §§ 31 and 143, require either a hearing, Board of Health of Franklin v. Hass, 342 Mass. 421, 423 (1961); Revere v. Blaustein, 315 Mass. 93, 95 (1943), or specific factual findings. See Moysenko v. Board of Health of N. Andover, 347 Mass. 305, 307 (1964). Nothing in the language of either section supports a different interpretation. Section 31 provides that “[b]cards of health may make reasonable health regulations.” The section further requires notice by publication, but does not require a hearing or findings. Section 143 prohibits the establishment in a city or town of trades which may be harmful to the public, “except in such a location as may be assigned by the board of health . . . after a public hearing has been held thereon.” Nonetheless, the same section provides that the board of health may prohibit the exercise of harmful activity “in places not so assigned, in any event.” The absence of any provision for adjudicatory procedures in this latter situation is dispositive. “[WJhere the Legislature has employed specific language in one [portion of a statute], but not in another, the language should not be implied where it is not present.” School Comm. of Brockton v. Teachers’ Retirement Bd., 393 Mass. 256, 263 (1984), quoting Beeler v. Downey, 387 Mass. 609, 616 (1982).* ****7
Finally, ADL claims that due process principles require that it be given a hearing, and that the regulation be supported by *542findings of fact based on substantial evidence. The argument is based on the ground that the regulation is targeted solely at ADL, and thus that the regulation is essentially adjudicatory in nature.
Although the requirements of the APA are inapplicable to the actions taken by the commissioner, the distinction set forth in that statute between “regulation” and “adjudicatory proceeding” is helpful in situations such as that before us now. See Mullin v. Planning Bd. of Brewster, 17 Mass. App. Ct. 139, 141-142 (1983). An “adjudicatory proceeding” involves a determination of the “legal rights, duties or privileges of specifically named persons.” G. L. c. 30A, § 1 (1). On the other hand, a “regulation” includes “every rule, regulation, standard or other requirement of general application and future effect.” G. L. c. 30A, § 1 (5). See, e.g., Borden, Inc. v. Commissioner of Pub. Health, 388 Mass. 707, 716, cert. denied sub nom. Formaldehyde Inst., Inc. v. Frechette, 464 U.S. 936 (1983); Cambridge Elec. Light Co. v. Department of Pub. Utils., 363 Mass. 474, 486-487 (1973); Cast Iron Soil Pipe Inst. v. State Examiners of Plumbers & Gas Fitters, 8 Mass. App. Ct. 575, 586-587 (1979); United States v. Florida E. Coast Ry., 410 U.S. 224, 244-246 (1973). The regulation at issue here, as the judge below concluded, “applies to the operations of other laboratories and defense contractors in the city and is not an adjudication of the rights of a particular party.” We find no reason to disagree. The regulation here is one of “general application and future effect.” G. L. c. 30A, § 1 (5). It “could not be fittingly described as intended simply to determine, the particular legal interests of specifically identified persons.” Cambridge Elec. Light Co. v. Department of Pub. Utils., supra at 486. Cf. Borden, Inc. v. Commissioner of Pub. Health, supra at 717; Milligan v. Board of Registration in Pharmacy, 348 Mass. 491, 499 (1965). We note that this characterization of the commissioner’s action is consistent with other cases decided under § 143, or its predecessor, which hold that such a rule “is not in the nature of an adjudication of a particular case, but of a general regulation of the trade or employment mentioned therein.” Moysenko v. Board of Health *543of N. Andover, supra at 307, quoting Taunton v. Taylor, 116 Mass. 254, 261 (1874). Cochis v. Board of Health of Canton, 332 Mass. 721, 725 (1955).
We recognize that ADL’s use of the banned chemicals precipitated the action by the commissioner. Moreover, it is not disputed that ADL alone was conducting activity proscribed by the regulation. But the fact that ADL’s research alone motivated the ban, and served to “illustrate the general problems, . . . could not have the effect of transforming the regulatory endeavor into an adjudicatory one.” Cambridge Elec. Light Co. v. Department of Pub. Utils., supra at 487. In a similar situation this court has upheld a § 143 regulation prohibiting the painting of trucks within the city limits. Revere v. Blaustein, 320 Mass. 81, 83 (1946). We noted that “no constitutional right of the defendant was impaired even if he were the only one affected by the regulatory action of the board.” Id. Similarly, in Milton v. Donnelly, 306 Mass. 451, 460 (1940), we recognized that even “if the only billboard that could be affected by the enforcement of the by-law is that of the respondent, that circumstance alone would not render the by-law invalid.” See Boston Gas Co. v. Department of Pub. Utils., 387 Mass. 531, 536-537 (1982). Massachusetts Gen. Hosp. v. Belmont, 233 Mass. 190, 203-204 (1919).
Because we conclude that the commissioner’s action was rule making, and not adjudication, ADL’s contention that it is entitled to findings of fact, and a hearing, before adoption of the regulation is meritless. It is well established that “an agency is not. . . obliged to provide a statement of the reasons which support its adoption of a regulation.” Borden, Inc. v. Commissioner of Pub. Health, supra at 723 n.9. Cambridge Elec. Light Co. v. Department of Pub. Utils., supra at 490-491. Moreover, “[a]ny constitutional claim to a trial type hearing fails if the proceeding was . . . regulatory or legislative or political. ... A regulation, like legislation, often increases costs or diminshes business expectations or even proprietary rights, but neither demands a prior confrontation resembling a lawsuit. ” Id. at 488. See also American Grain Prods. Processing Inst. v. Department of Pub. Health, 392 Mass. 309, 323 *544n.20 (1984). Bi-Metallic Inv. Co. v. State Bd. of Equalization of Colo., 239 U.S. 441, 445-446 (1915).8
ADL further contends that it was entitled to a hearing and findings before issuance of the order prohibiting further use of the specified chemicals. We disagree. General Laws c. Ill, § 147, provides ADL with an adequate means of challenging an order issued pursuant to a regulation validly enacted under §§ 31 and 143. See, e.g., Revere v. Blaustein, 315 Mass, at 95; Swansea v. Pivo, 265 Mass. 520, 523 (1929). In addition, we have interpreted § 148 to provide for a “discretionary stay” of the order pending judicial review. Board of Health of Franklin v. Hass, supra at 426. Finally, § 150 provides for damages to the plaintiff in the event that the order is overturned. These “safeguards ... at least satisfy, and may exceed, what is constitutionally required.” Id.
ADL’s final procedural challenge to the judgment below is premised on the ground that the trial judge wrongly, deprived it of the right to a jury trial under G. L. c. Ill, § 147 (1984 ed.). This contention is meritless. Section 147 provides, in pertinent part, that “[wjhoever is aggrieved by an order made under section one hundred and forty-three . . . may . . . file a petition for a jury in the superior court . . . and . . . may have a trial in the same manner as other civil cases are tried by jury.” As the judge below noted, ADL failed to make a demand for a jury trial, either in its complaint or in any other timely fashion. See Mass. R. Civ. P. 38(b), 365 Mass. 800 *545(1974). According to rule 38 (d), “[t]he failure of a party to serve a demand . . . constitutes a waiver by him of trial by jury.” See Greenberg v. Greenberg, 10 Mass. App. Ct. 827 (1980). We note that other courts have strictly enforced cognate demand requirements, even when the relevant statute, like § 147, expressly provides for trial by jury. See Scharnhorst v. Independent School Dist. # 710, 686 F.2d 637, 641 (8th Cir. 1982), and cases cited, cert. denied, 462 U.S. 1109(1983). Consequently, ADL has waived its right to a trial by jury.9
n. Substantive challenges.
A. Preemption. ADL contends that the regulation is inconsistent with the Federal Constitution and Federal statutes, and thus that it is invalid under the supremacy clause of the United States Constitution. Art. VI, cl. 2. We consider this argument in light of two principles which have traditionally informed our preemption analysis. First of all, “[preemption ... is not favored, and State laws should be upheld unless a conflict with Federal law is clear.” Attorney Gen. v. Travelers Ins. Co., 385 Mass. 598, 602 (1982) (Travelers I), vacated, 463 U.S. 1221 (1983), reaffirmed, 391 Mass. 730 (1984), aff’d sub nom. Metropolitan Life Ins. Co. v. Massachusetts, 471 U.S. 724 (1985). See Commonwealth v. McHugh, 326 Mass. 249, 265-266 (1950); Exxon Corp. v. Governor of Md., 437 U.S. 117, 132 (1978). State law is not preempted merely by reference to some vaguely defined Federal policy, or on the ground that Congress has enacted a statute which is tangentially relevant to the subject at issue. Instead, the plaintiff here is obligated to show preemption “with hard evidence of conflict ... on the basis of the record evidence in this case.” Grocery Mfrs. of Am., Inc. v. Department of Pub. Health, 379 Mass. 70, 81-82 (1979), quoting Kargman v. Sullivan, 552 *546F.2d 2, 6 (1st Cir. 1977). Generally speaking, “a finding of no preemption is regarded as preferable because Congress can overrule it by appropriate legislation, while a finding of preemption cannot be changed by the states.” Agency Rent-A-Car, Inc. v. Connolly, 686 F.2d 1029, 1038 (1st Cir. 1982). See Pacific Gas & Elec. Co. v. State Energy Resources Conservation & Dev. Comm’n, 461 U.S. 190, 216 (1983).
Secondly, this court, and the United States Supreme Court, have been particularly reluctant to overturn State laws which are “deeply rooted in local feeling and responsibility.” Travelers I, supra at 611, quoting San Diego Bldg. Trades Council v. Garmon, 359 U.S. 236, 243-244 (1959). Massachusetts Elec. Co. v. Massachusetts Comm’n Against Discrimination, 375 Mass. 160, 174 (1978). This principle applies with special force to laws designed to protect the public health and welfare, a subject of “particular, immediate, and perpetual concern” to any municipality. 6 E. McQuillin, Municipal Corporations § 24.01 (3d ed. rev. 1980). In fact, according to an early decision of this court, Vandine, petitioner, 6 Pick. 187, 191 (1828), “[t]he great object of the city is to preserve the health of the inhabitants.” Accordingly, municipal health and safety regulations, such as that at issue here, carry a heavy presumption of validity, and are only rarely preempted by Federal law. Travelers I, supra at 612. See Malone v. White Motor Corp., 435 U.S. 497, 513 n.13 (1978). “The States traditionally have had great latitude under their police powers to legislate as ‘to the protection of the lives, limbs, health, comfort, and quiet of all persons. ’ ” Metropolitan Life Ins. Co. v. Massachusetts, 471 U.S. 724, 756 (1985), quoting Slaughter-House Cases, 16 Wall. (83 U.S.) 36, 62 (1873). Huron Portland Cement Co. v. Detroit, 362 U.S. 440, 442-443 (1960).
ADL argues that any regulation which interferes with the conduct of a DOD research program is preempted by the Constitution’s grant of war and defense powers to the Federal government. For example, the Constitution provides Congress with the power to “provide for the common Defence,” art. I, § 8, cl. 1, “[t]o raise and support Annies,” art. I, § 8, cl. 12, and “[t]o make Rules for the Government and Regulation of the *547land and naval Forces,” art. I, § 8, cl. 14. The Constitution further directs that the President “shall be Commander in Chief of the Army and Navy.” Art. II, § 2, cl. 1. We agree with ADL that these provisions constitute an explicit constitutional commitment of the national defense to the Federal government. Nevertheless, we further recognize that not every regulation which has some incidental effect on a defense program is invalid under the supremacy clause. Cf. DeCanas v. Bica, 424 U.S. 351, 355 (1976) (State laws involving aliens are not “per se pre-empted” by exclusive Federal power over immigration); see also Plyler v. Doe, 457 U.S. 202, 228 n.23 (1982). Nothing in the record before us suggests that the commissioner’s action would have anything more than a “speculative and indirect impact,” DeCanas v. Bica, supra, on the national defense. Accordingly, we conclude that the regulation is not preempted by the Constitution’s allocation of war and defense powers to the Federal government.
First of all, we reject ADL’s contention that the regulation at issue impermissibly interferes with an integral part of an important national defense program. Nothing in the record suggests that the densely populated city of Cambridge is somehow uniquely suited to research on chemical warfare agents. Banning research on these chemicals within that city hardly requires the abandonment of the DOD’s chemical warfare program. The DOD remains free to conduct its research elsewhere. Accordingly, the city of Cambridge has not attempted to dictate the scope of permissible strategic research, or otherwise to interfere with congressional power to “provide for the common Defence.” Instead, it has merely taken the position that research on certain chemical warfare agents must be conducted, if at all, outside the city limits.
Nor are we persuaded by what the commissioner has termed “ADL’s domestic domino theory.” Even if the Cambridge regulation alone does not substantially interfere with national defense, ADL asserts that other municipalities may enact similar prohibitions, and thus seriously hinder the DOD’s ability to study chemical warfare agents. We believe that the scenario posited by ADL is far too “hypothetical,” Rice v. Norman Wil*548liams Co., 458 U.S. 654, 659 (1982), to warrant preemption. According to the record only one other city has even considered the problem, and there is no indication that it will respond as the city of Cambridge has. Moreover, as the judge below recognized, even if a significant number of municipalities did enact such regulations, the DOD would always be free to conduct such research on its military bases. See McQueary v. Laird, 449 F.2d 608, 612 (10th Cir. 1971) (“Federal Government has traditionally exercised unfettered control with respect to internal management and operation of federal military establishments”).10
ADL next contends that the regulation at issue is preempted by Federal legislation authorizing and regulating chemical warfare research.11 State law, including municipal regulations, can be preempted by an act of Congress if the State law “‘conflicts with federal law or would frustrate the federal scheme, or [if] the courts discern from the totality of the circumstances that Congress sought to occupy the field to the exclusion of the States. ’ ” Metropolitan Life Ins. Co. v. Massachusetts, 471 U.S. 724, *549747-748 (1985), quoting Allis-Chalmers Corp. v. Lueck, 471 U.S. 202, 209 (1985). Silkwood v. Kerr-McGee Corp., 464 U.S 238, 248 (1984). Pacific Gas & Elec. Co. v. State Energy Resources Conservation & Dev. Comm’n, 461 U.S. 190, 216 (1983). In applying this analysis, “we start with the assumption that the historic police powers of the States were not to be superseded by the Federal Act unless that was the clear and manifest purpose of Congress.” Id. at 206, quoting Rice v. Santa Fe Elevator Corp., 331 U.S. 218, 230 (1947).
ADL bases its preemption argument on several Federal statutes which we briefly summarize. In 10U.S.C. § 2358 (1982), Congress authorized “the Secretary of Defense . . . [to] engage in basic and applied research projects that are necessary to the responsibilities of the Department of Defense in the field of basic and applied research and development and that relate to weapons systems and other military needs.” See also 10 U.S.C.A. §§ 2302 et seq. (Supp. 1985) (controlling the authority of Secretary of Defense to contract for defense purposes). In 50 U.S.C. §§ 1511-1520 (1982), Congress set forth certain restrictions on the DOD’s chemical and biological warfare programs. For example, § 1511 requires that the Secretary of Defense submit an annual report to Congress detailing the research conducted during the preceding year on “lethal and nonlethal chemical and biological agents.” Section 1512 prohibits the expenditure of funds for the transportation, open air testing, or disposal of chemical warfare agents unless certain specified procedures are followed, while § 1516 prohibits the expenditure of funds “for the procurement of delivery systems specifically designed to disseminate” such materials, unless the President certifies that such procurement is essential to the national defense. Sections 1517 and 1518 prohibit, except in emergency situations, the disposal of chemical or biological warfare agents unless they have first been detoxified, and § 1520 regulates the use of human subjects for the testing of these weapons. Finally, we note that the Clean Water Act, 33 U.S.C. § 1311 (f) (1982), prohibits the discharge of any “chemical, or biological warfare agent. . . into the navigable waters.”
*550The purportedly preemptive effect of these statutes does not require extended discussion. First of all, we fail to see how the challenged regulation “conflicts with federal law or would frustrate the federal scheme.” Metropolitan Life Ins. Co. v. Massachusetts, supra at 2393. Certainly, there is no “conflict” in the sense that “compliance with both federal and state regulations is a physical impossibility.” Pacific Gas & Elec. Co. v. State Energy Resources Conservation & Dev. Comm’n, supra at 204, quoting Florida Lime & Avocado Growers, Inc. v.Paul, 373 U.S. 132, 142-143 (1963). Nowhere in the Federal scheme is there any requirement that ADL conduct research on the banned chemicals within the Cambridge city limits. Nor do we observe any “conflict” here in the sense that enforcement of the regulation “would frustrate the federal scheme.” Metropolitan Life Ins. Co. v. Massachusetts, supra at 2393. In fact, there is no Federal scheme whatsoever which either promotes or encourages the research at issue here. Cf. 42 U.S.C. § 2013 (d) (1982) (purpose of Atomic Energy Act to “encourage widespread participation in the development and utilization of atomic energy”). In the absence of some “clear and manifest purpose” on the part of Congress to foster private research on chemical warfare agents, Pacific Gas & Elec. Co. v. State Energy Resources Conservation & Dev. Comm’n, supra at 206, we are unable to infer any conflict with the Federal statutory framework.
Finally, we do not see any indication in these statutes that Congress “sought to occupy the field” of chemical warfare regulation “to the exclusion of the States.” Metropolitan Life Ins. Co. v. Massachusetts, supra at 2393. Only a few of the Federal statutory provisions cited by ADL even apply to parties other than the Secretary of Defense. See 33 U.S.C. § 1311 (f); 50 U.S.C. §§ 1517, 1518, 1520.12 Of these, only one places restrictions on ADL’s testing of chemical warfare agents. That statute, 50 U.S.C. § 1520, prohibits the use of *551human subjects except under specified conditions. This isolated provision hardly constitutes congressional occupation of the field sufficient to warrant preemption. Cf. Illinois v. General Elec. Co., 683 F.2d 206, 214 (7th Cir. 1982) (preemption warranted in light of “comprehensive scheme of federal regulation of atomic energy”), cert. denied sub nom. Hartigan v. General Elec. Co., 461 U.S. 913 (1983); Washington State Bldg. & Constr. Trades Council v. Spellman, 518 F. Supp. 928, 931 (E.D. Wash. 1981) (same), aff’d, 684 F.2d 627,(9th Cir. 1982), cert. denied sub nom. Don’t Waste Washington Legal Defense Found. v. Washington, 461 U.S. 913 (1983).
We recognize that Congress has plenary authority in exercising its war and defense powers. See Ullmann v. United States, 350 U.S. 422, 436 (1956); United States v. Onslow County Bd. of Educ., 728 F.2d 628, 640-641 (4th Cir. 1984); St. John’s River Shipbuilding Co. v. Adams, 164 F.2d 1012, 1015 (5th Cir. 1947). Nonetheless, it is also well established that a State court, before invalidating State laws, should be “thoroughly convinced” of the arguments in favor of preemption, “lest it discover later that it has retreated where the Federal government will not advance and has therefore been derelict in its duty.” Commonwealth v. McHugh, 326 Mass. 249, 265-266 (1950). In the absence of any congressional action which clearly conflicts with the regulation at issue, and in the absence of congressional intent to occupy the field, we conclude that the regulation is not preempted by Federal legislation.
Finally, ADL suggests that a contract between the DOD and a private defense contractor, authorized by Federal statutes, preempts inconsistent local regulations. We agree that ADL’s obligations under its contracts with the DOD, and under the regulation, are flatly inconsistent.13 Compliance with both is *552a “physical impossibility.” Pacific Gas & Elec. Co. v. State Energy Resources Conservation & Dev. Comm’n, supra at 204. Nonetheless, this court has been unable to locate authority in this or any other jurisdiction which supports the proposition that a contract to which the Federal government is a party somehow constitutes Federal law for the purposes of the supremacy clause. In fact, relevant authority strongly suggests that Federal power does not extend that far. The United States Supreme Court recently held that the constitutional immunity of Federal instrumentalities from State taxation cannot depend on a “government functionary . . . changing a few words in a contract.” United States v. New Mexico, 455 U.S. 720, 737 (1982), quoting Kern-Limerick, Inc. v. Scurlock, 347 U.S. 110, 126 (1954) (Douglas, J., dissenting). See Baltimore & A. R.R. v. Lichtenberg, 176 Md. 383, 393, appeal dismissed, 308 U.S. 525 (1939); Tribe, Intergovernmental Immunities in Litigation, Taxation & Regulation: Separation of Powers Issues in Controversies about Federalism, 89 Harv. L. Rev. 682, 710 (1976). Allowing the DOD to contract itself, as well as private defense firms, out of local health and safety requirements would seriously compromise the city’s ability to protect its inhabitants. Moreover, it would constitute a grant of power to the executive branch which, in the absence of congressional authorization, is wholly inconsistent with our federalist system. See Washingtonv. United States, 460 U.S. 536,546 (1983); United States v. New Mexico, supra at 737-738; Tribe, supra at 711. Accordingly, we agree with the judge below that the regulation is not preempted by the contracts between ADL and the Federal government.14
*553B. Arbitrariness. General Laws c. 111, § 143, authorizes the commissioner to prohibit activities that “may result” in a nuisance or be harmful to the inhabitants” (emphasis added). See Waltham v. Mignosa, 327 Mass. 250, 252 (1951) (activity “need not in fact be a nuisance . . . before the power of prohibition arises”). Construing this broad delegation of authority, we have held that regulations promulgated under § 143 may be struck down only if they are shown to be “unreasonable, arbitrary, whimsical, or capricious.” Moysenko v. Board of Health of N. Andover, 347 Mass. 305, 308 (1964), quoting Butler v. East Bridgewater, 330 Mass. 33, 38 (1953). In mounting a challenge on these grounds, ADL “has the burden of proving on the record ‘the absence of any conceivable ground upon which [the rule] may be upheld. ’ ” American Grain Prods. Processing Inst. v. Department of Pub. Health, 392 Mass. 309, 329 (1984), quoting Purity Supreme, Inc. v. Attorney Gen., 380 Mass. 762, 776 (1980). See Borden, Inc. v. Commissioner of Pub. Health, supra at 722. “If the question is fairly debatable,” we cannot substitute our own judgment for that of the commissioner. Id. at 722, quoting Druzik v. Board of Health of Haverhill, 324 Mass. 129, 136 (1949). See Minnesota v. Clover Leaf Creamery Co., 449 U.S. 456, 469 (1981). This deferential attitude “is necessary to maintain the separation between the powers of the Legislature and administrative agencies and the powers of the judiciary.” Borden, Inc. v. Commissioner of Pub. Health, supra at 723. Plenary review of administrative regulations “would have an unhealthy tendency to substitute the court for the agency as policymaker.” Id. at 724, quoting Cambridge Elec. Light Co. v. Department of Pub. Utils., 363 Mass. 474, 491 (1973).
Our reluctance to intrude too deeply into the administrative process is also grounded firmly on the principle that “the respective roles of the agency and the reviewing court should be *554worked out on the basis of full understanding of the comparative qualifications of each.” 5 K.C. Davis, Administrative Law § 29:3, at 343-344 (2d ed. 1984) “[A]gencies may be relatively the experts on many problems of discretion or policy within the areas of their specialization.” Id. This is undoubtedly the case with respect to the relative capabilities of this court and the commissioner in weighing the public health risks involved in ADL’s testing of chemical warfare agents within the Cambridge city limits.
On the record before us, the plaintiff cannot meet its burden of showing the absence of any conceivable ground for the commissioner’s action. Both the SAC and an independent consultant recognized that a release of hazardous chemical warfare agents from Levins Laboratory was either “unlikely” or “very unlikely,” “but not impossible” (emphasis added). See notes 3 and 4, supra. The study conducted by the SAC concluded that the risks associated with the ADL research were “unacceptable.” See noted, supra. The other study refrained from making any such conclusion, asserting that “[perspective on what is acceptable involves comparison with other risks people are exposed to as well as consideration of other factors such as whether the risks are voluntary or involuntary and what benefits accompany the risk.” See note 3, supra. From these reports, the conclusion is inescapable that the necessity for the regulation is, at the very least, “fairly debatable.” Borden, Inc. v. Commissioner of Pub. Health, supra at 722.
ADL notes that it made a “commitment” to use only a limited quantity of the chemicals at a single time, and thus argues that the SAC report is “wildly inaccurate” for failure to adjust its risk assessment accordingly. Even if ADL’s “commitment” diminishes the risk posed by thé research conducted at the Levins Laboratory, it does not affect other research institutions in Cambridge which may have had occasion to use the banned chemicals. As the judge below found, “[t]he regulation is aimed at the chemicals themselves and not merely at the ADL facility.” Once the commissioner determined that the use of these chemicals, under some conceivable circumstances, would pose an unreasonable risk, he was under no duty to consider the *555specific conditions at the Levins Laboratory before issuing his order of prohibition. Moysenko v. Board of Health of N. Andover, 347 Mass. 305, 307 (1964). Sea Borden, Inc. v. Commissioner of Pub. Health, supra at 727 n.19. See also Weinberger v. Salfi, 422 U.S. 749, 777 (1975) (statute need not “precisely filter[ ] out those, and only those, who are in the factual position which generated the congressional concern reflected in the statute”). Under § 143, the commissioner is empowered “to prohibit the exercise of the trade or employment as a whole whenever by any of the methods employed it has become or may become a nuisance or otherwise offensive” (emphasis added). Moysenko v. Board of Health of N. Andover, supra, quoting Board of Health of Wareham v. Marine By-Prods. Co., 329 Mass. 174, 178 (1952).
C. Contract clause. ADL next challenges the regulation on the ground that it violates the contract clause, U.S. Const, art. I, § 10, cl. 1, by impermissibly impairing ADL’s contractual obligations to the DOD.15 The regulation undoubtedly “worked a severe, permanent, and immediate change” in the relationship between the contracting parties. Allied Structural Steel Co. v. Spannaus, 438 U.S. 234, 250 (1978). See note 13, supra. Nonetheless, we conclude, because the regulation is a reasonable and appropriate exercise of the city’s police power, that ADL’s contract clause challenge is meritless. See Exxon Corp. v. Eagerton, 462 U.S. 176, 190-191 & n.12 (1983); Energy Reserves Group, Inc. v. Kansas Power & Light, 459 U.S. 400, 412 (1983).
“Literalism in the construction of the contract clause . . . would make it destructive of the public interest by depriving the State of its prerogative of self-protection. ” Allied Structural Steel Co. v. Spannaus, supra at 240, quoting W.B. Worthen Co. v. Thomas, 292 U.S. 426, 433 (1934). Consequently, a regulation “does not violate the Contract Clause simply because it has the effect of restricting, or even barring altogether, the performance of duties created by contracts entered into prior *556to its enactment” (emphasis added). Exxon Corp. v. Eagerton, supra at 190. Instead, in reviewing regulations which substantially impair contractual obligations, we examine “whether the adjustment of ‘the rights and responsibilities of contracting parties [is based] upon reasonable conditions and [is] of a character appropriate to the public purpose justifying [the (regulation’s)] adoption. ’ ” Energy Reserves Group, Inc. v. Kansas Power & Light, supra at 412, quoting United States Trust Co. v. New Jersey, 431 U.S. 1, 22 (1977). The impairment need not be justified on the basis of “an emergency or temporary situation.” Energy Reserves Group, Inc. v. Kansas Power & Light, supra. Instead, any “significant and legitimate public purpose” will suffice. Id. at 411.
On the basis of this authority, we conclude that the commissioner’s action should be evaluated, under the contract clause, against essentially the same standard of reasonableness which we applied to ADL’s challenge to the regulation as arbitrary or capricious. See Borden, Inc. v. Commissioner of Pub. Health, supra at 737-738. See also Travelers I, supra at 616. The standard is not a stringent one. “[U]nless the State itself is a contracting party,” Energy Reserves Group, Inc. v. Kansas Power & Light, supra 412, we will defer to legislative or administrative judgment as to the wisdom of any particular measure. Any other rule would invite parties to enter into contracts to “estop the legislature from enacting laws intended for the public good.” Manigault v. Springs, 199 U.S. 473, 480 (1905). Exxon Corp. v. Eagerton, supra at 190-191 & nn.ll & 12.
For the reasons set forth in our discussion of ADL’s challenge to the regulation on the ground it is arbitrary or capricious, we conclude that the action taken by the commissioner constitutes a reasonable, and thus permissible, impairment of ADL’s contractual obligations to the DOD. This is not a regulation aimed at “providing a benefit to special interests.” Energy Reserves Group, Inc. v. Kansas Power & Light, supra at 412. Instead, the regulation imposes “a generally applicable rule of conduct,” Exxon Corp. v. Eagerton, supra at 192, designed to protect all Cambridge citizens from what the commissioner *557has concluded is an unacceptable risk. Because “the police power ... is paramount to any rights under contracts between individuals,” the regulation does not run afoul of the contract clause. Allied Structural Steel Co. v. Spannaus, supra at 241, quoting Manigault v. Springs, supra.
HI. Conclusion.
We affirm the judgment of the Superior Court declaring the commissioner’s regulation valid and enforceable. The stay of judgment pending appeal, granted in the Appeals Court, is vacated herewith.
So ordered.
The Legislature has conferred on the commissioner all powers granted to local boards of health under G. L. c. Ill, §§ 31 and 143. St. 1976, c. 201, amending St. 1946, c. 108.
The regulation, in its entirety, provides that “[t]he following materials are hereby determined to be highly toxic, and extremely hazardous in the event of an accident, to the public health and safety of the population of the City of Cambridge. The testing, storage, transportation and disposal of the following chemical materials is hereby prohibited within the City of Cambridge: 1. Soman-GD (nerve agent) 2. Sarin-GB (nerve agent) 3. VX (nerve agent) 4. Mustard-HD (blister agent) 5. Lewisite (blister agent). This regulation shall remain in effect until the Scientific Advisory Committee Study and an independent hazard assessment has been completed, and these recommendations have been reviewed by this office.”
In an affidavit signed shortly after the regulation was issued, the commissioner summarized how some of the banned substances are characterized in Goodman & Gilman, The Pharmacological Basis of Therapeutics (6th ed.). “Sarin and Soman are listed as extremely toxic ‘nerve gases’ . . . [and] are among the most potent synthetic toxic agents known. They are lethal to laboratory animals in submilligram doses .... Mustard refers to sulphur and nitrogen mustard compounds . . . [which are] powerful local vesicants (blister agent[s]).... Lewisite is listed as an arsenical war gas.”
The independent consulting firm explained its reluctance to characterize definitively the hazard as follows: “Perspective on what is acceptable involves comparison with other risks people are exposed to as well as consideration of other factors such as whether the risks are voluntary or involuntary and what benefits accompany the risk.” In an affidavit submitted to the court prior to the publication of this report, a senior consultant concluded, as did the subsequent SAC report, that the accidental or intentional release of nerve gas into the environment “is very unlikely but not impossible.” This assessment of the risk of release is also shared by the director of health and safety at ADL.
The SAC found that “[a]n accident in which chemical warfare agents are released from the ADL facility is unlikely but not impossible. In the event of such a release, members of the general public might be located within range of lethal levels of such agents. . . . The benefits of research with these chemicals, in the opinion of the Committee, do not justify lethal risks to the general public. For this reason, the SAC believes that storage and testing of these chemical warfare agents within the densely populated City of Cambridge in the quantities and concentrations used by ADL is inappropriate. Furthermore, the majority of SAC members judge the risks associated with any such work to be unacceptable.”
Nabhan v. Selectmen of Salisbury, 12 Mass. App. Ct. 264 (1981), is not to the contrary. In that case the Appeals Court assumed, without deciding, that a local board of selectmen was an agency subject to the APA, but held that the hearing requirement of G. L. c. 30A, § 2, was inapplicable on other grounds. Id. at 273.
Although ADL was not entitled to the public hearing afforded by G. L. c. 30A, § 2, we note that ADL was given substantial opportunity to comment on the adoption of the regulation. The record shows that the SAC welcomed ADL’s participation in preparing its report, and that ADL was kept well informed of the course of the SAC’s deliberations. Moreover, ADL representatives were heard by, or allowed to distribute material to, the SAC *541on a number of occasions. For example, at the third meeting of the SAC, ADL representatives made a presentation on “Levins Laboratory construction, contract work currently being conducted, safety precautions, lethal dosages, and self imposed limitfs]” on the quantity of chemical agents present at the laboratory at any given time.
ADL contends that Moysenko v. Board of Health of N. Andover, supra, and Board of Health of Wareham v. Marine By-Prods. Co., 329 Mass. 174, 178 (1952), require both a public hearing and findings in cases such as this. We disagree. In Moysenko v. Board of Health of N. Andover, supra, we noted that the adoption of the § 143 order was preceded by a public hearing, but never suggested that such a hearing was required. In Board of Health of Wareham v. Marine By-Prods. Co., supra at 177, we explicitly refrained from deciding “to what extent, if at all, a board of health acting under § 143 is bound to make express findings of fact to support its order. ”
ADL cites Penn Cent. Co. v. Department of Pub. Utils., 356 Mass. 478, 485 (1969), to bolster its argument that the regulation must be based on findings supported by substantial evidence. Our holding in that case is limited to circumstances where the regulation at issue may create “unfortunate conflicts between State and Federal interests.” Id. We have since held that Penn Cent. Co. applies “only to extraordinary situations.” Cambridge Elect. Light Co. v. Department of Pub. Utils., supra at 492. See Grocery Mfrs. of Am., Inc. v. Department of Pub. Health, 379 Mass. 70, 82-83 n.7 (1979). Other cases dated by ADL require trial-type administrative procedures, but these are distinguishable because they all involve administrative action which is adjudicatory in nature. See Yerardi’s Moody St. Restaurant & Lounge, Inc. v. Selectmen of Randolph, 19 Mass. App. Ct. 296, 302-304 (1985); General Chem. Corp. v. Department of Envtl. Quality Eng’g, 19 Mass. App. Ct. 287, 290 (1985).
In light of the consequences of ADL’s failure to demand a jury trial, we need not consider the commissioner’s further arguments that ADL waived its right to a jury by acquiescing in a jury-waived trial assignment, or by moving for summary judgment. Nor need we decide what issues, if any, were left for jury determination once ADL admitted that it was storing and testing the prohibited chemical agents.
The cases cited by ADL are primarily addressed to the scope of Federal immunity from private suits challenging military decisions, and are thus inapplicable here. See McQueary v. Laird, 449 F.2d 608 (10th Cir. 1971); Luftig v. McNamara, 373 F.2d 664 (D.C. Cir.), cert. denied, 387 U.S. 945 (1967). See also Pratt v. Hercules, Inc., 570 F. Supp. 773, 802-804 (D. Utah 1982) (scope of derivative sovereign immunity afforded to defense subcontractor); Concerned About Tridents. Schlesinger, 400 F. Supp. 454, 482-483 (D.D.C. 1975) (political question doctrine), aff’d in part and rev’d in part sub nom. Concerned About Trident v. Rumsfeld, 555 F.2d 817 (D.C. Cir. 1976).
The commissioner argues that the Federal Toxic Substances Control Act (TSCA), 15 U.S.C. §§ 2601 et seq. (1982), indicates that Congress intended, with exceptions not applicable here, to permit State and local regulation of hazardous chemicals. Section 2617 (a) (1) of that statute provides that “[n\othing in this chapter shall affect the authority of any State or political subdivision of a State to establish or continue in effect regulation of any chemical substance, mixture, or article containing a chemical substance or mixture” (emphasis added). This section disposes of any preemption argument based on other provisions of TSCA, but does not, we conclude, obviate the possibility of preemption either by the Constitution’s grant of defense powers to the Federal government, or by other Federal legislation regulating the manufacture, use, transportation or disposal of hazardous chemicals.
Most of the other relevant statutes, such as 50 U.S.C. §§ 1511-1513, 1516, 1519, place restrictions on the expenditure of funds by the Secretary of Defense.
The commissioner contends that the regulation does not conflict with ADL’s contracts with the DOD, on the ground that the contracts themselves require that ADL “conform to all Federal, State and local laws and ordinances which apply to operations with toxic materials at the location of [the] facility.” This contention is meritless. “[L]aws enacted after the execution of an agreement are not commonly considered to become part of the agreement unless its provisions clearly establish that the parties intended to incorporate subsequent enactments into their agreement.” Feakes v. Bozy*552czko, 373 Mass. 633, 636 (1977). Mayor of Salem v. Warner-Amex Cable Communications Inc., 392 Mass. 663, 666-667 (1984). Nothing in the record before us reflects any such intention.
ADL alludes in its brief to an argument based on the “implied constitutional immunity of the national government from state taxation and from state regulation.” Penn Dairies, Inc. v. Milk Control Comm’n, 318 U.S. 261, 269 (1943). See generally C. Antieau, Modem Constitutional Law §§ 10.66 et seq. (1969). We note that such immunity does not generally extend to private contractors who agree “to furnish supplies or render services to the government.” Penn Dairies, Inc. v. Milk Control Comm’n, *553supra. See Stewart & Co. v. Sandrakula, 309 U.S. 94, 105 (1940). See also United States v. New Mexico, supra at 735 (immunity from State tax applicable only when “agency or instrumentality so closely connected to the Government that the two cannot realistically be viewed as separate entities”).
Article I, § 10, cl. 1, provides that “[n]o State shall. . . pass any . . . Law impairing the Obligation of Contracts.”