JUSTICE O'CONNOR delivered the opinion of the Court.
We granted certiorari in this case to determine whether the Court of Appeals for the District of Columbia Circuit correctly concluded that the Food and Drug Administration's longstanding interpretation of 21 U. S. C. § 346 was in conflict with the plain language of that provision. 474 U.S. 1018 (1985). We hold that, in light of the inherent ambiguity of the statutory provision and the reasonableness of the Food
I
A
The Food and Drug Administration (FDA) enforces the Federal Food, Drug, and Cosmetic Act (Act) as the designee of the Secretary of Health and Human Services. 21 U. S. C. § 371(a). See also 21 CFR § 5.10 (1986). The Act seeks to ensure the purity of the Nation's food supply, and accordingly bans "adulterated" food from interstate commerce. 21 U. S. C. § 331(a). Title 21 U. S. C. § 342(a) deems food to be "adulterated"
As this provision makes clear, food containing a poisonous or deleterious substance in a quantity that ordinarily renders the food injurious to health is adulterated. If the harmful substance in the food is an added substance, then the food is deemed adulterated, even without direct proof that the food may be injurious to health, if the added substance is "unsafe" under 21 U. S. C. § 346.
Section 346 states:
Any quantity of added poisonous or added deleterious substances is therefore "unsafe," unless the substance is required in food production or cannot be avoided by good manufacturing practice. For these latter substances, "the Secretary shall promulgate regulations limiting the quantity therein or thereon to such extent as he finds necessary for the protection of public health." It is this provision that is the heart of the dispute in this case.
The parties do not dispute that, since the enactment of the Act in 1938, the FDA has interpreted this provision to give it the discretion to decide whether to promulgate a § 346 regulation, which is known in the administrative vernacular as a "tolerance level." Tolerance levels are set through a fairly elaborate process, similar to formal rulemaking, with evidentiary hearings. See 21 U. S. C. § 371(e). On some occasions, the FDA has instead set "action levels" through a less formal process. In setting an action level, the FDA essentially assures food producers that it ordinarily will not enforce the general adulteration provisions of the Act against them if the quantity of the harmful added substance in their food is less than the quantity specified by the action level.
B
The substance at issue in this case is aflatoxin, which is produced by a fungal mold that grows in some foods. Aflatoxin, a potent carcinogen, is indisputedly "poisonous" or
The FDA has not, however, set a § 346 tolerance level for aflatoxin. It has instead established an action level for aflatoxin of 20 parts per billion (ppb). In 1980, however, the FDA stated in a notice published in the Federal Register:
The notice further specified that such corn was to be used only as feed for mature, nonlactating livestock and mature poultry. Id., at 7447.
In connection with this notice, two public-interest groups and a consumer (respondents here) brought suit against the Commissioner of the FDA (petitioner here) in the United States District Court for the District of Columbia. Respondents alleged that the Act requires the FDA to set a tolerance level for aflatoxin before allowing the shipment in interstate commerce of food containing aflatoxin; that the FDA had employed insufficiently elaborate procedures to set its aflatoxin action level even if a tolerance level was not required; and that the FDA's decision to grant the 1980 exemption from the action level independently violated the Act and the FDA's own regulations.
On a motion for summary judgment, the District Court deferred to the FDA's interpretation of § 346, and therefore ruled that the FDA need not establish a tolerance level for
The Court of Appeals reversed the District Court's conclusion as to the proper interpretation of § 346. 244 U. S. App. D. C. 279, 757 F.2d 354 (1985). The Court of Appeals determined that Congress had spoken directly and unambiguously to the precise question at issue:
After examining the entirety of § 346, the Court of Appeals also concluded that, since tolerance levels make food with added harmful substances unadulterated, tolerance levels were necessary before food could be judged unadulterated. Id., at 283, 757 F. 2d, at 358.
The Court of Appeals considered none of the other issues before the District Court, and therefore only the § 346 issue is before this Court.
II
The FDA's longstanding interpretation of the statute that it administers is that the phrase "to such extent as he finds necessary for the protection of public health" in § 346 modifies the word "shall." The FDA therefore interprets the statute to state that the FDA shall promulgate regulations to the extent that it believes the regulations necessary to protect the public health. Whether regulations are necessary to protect the public health is, under this interpretation, a determination to be made by the FDA.
Our analysis must begin with Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837 (1984). We there stated:
While we agree with the Court of Appeals that Congress in § 346 was speaking directly to the precise question at issue in this case, we cannot agree with the Court of Appeals that Congress unambiguously expressed its intent through its choice of statutory language. The Court of Appeals' reading of the statute may seem to some to be the more natural interpretation, but the phrasing of § 346 admits of either respondents' or petitioner's reading of the statute. As enemies of
The FDA has therefore advanced an interpretation of an ambiguous statutory provision.
We find the FDA's interpretation of § 346 to be sufficiently rational to preclude a court from substituting its judgment for that of the FDA.
To read § 346 as does the FDA is hardly to endorse an absurd result. Like any other administrative agency, the FDA has been delegated broad discretion by Congress in any number of areas. To interpret Congress' statutory language to give the FDA discretion to decide whether tolerance
Nor does any other portion of § 346 prohibit the FDA from allowing the shipment of aflatoxin-tainted food without a tolerance level, despite the Court of Appeals' conclusion to the contrary. The Court of Appeals stated:
The premise of the Court of Appeals is of course correct: the Act does provide that when a tolerance level has been set and a food contains an added harmful substance in a quantity below the tolerance level, the food is legally not adulterated. But one cannot logically draw from this premise, or from the Act, the Court of Appeals' conclusion that food containing substances not subject to a tolerance level must be deemed adulterated. The presence of a certain premise (i. e., tolerance levels) may imply the absence of a particular conclusion (i. e., adulteration) without the absence of the premise implying the presence of the conclusion. For example, the presence of independent and adequate state-law grounds in the decision of a state supreme court means this Court has no jurisdiction over the case, but the absence of independent and adequate state grounds does not mean that this Court necessarily has jurisdiction. The Act is silent on what specifically to do about food containing an unavoidable, harmful, added substance for which there is no tolerance level; we must therefore assume that Congress intended the general provisions of § 342(a) to apply in such a case. Section 342(a) thus remains available to the FDA to prevent the shipment of any food "[i]f it bears or contains any poisonous or deleterious substance which may render it injurious to health." See generally United States v. Lexington Mill & Elevator Co.,
The legislative history of the Act provides no single view about whether Congress intended § 346 to be mandatory or permissive with respect to tolerance levels. Compare, e. g., Confidential House Committee Print 2, on Interstate and Foreign Commerce, 75th Cong., 1st Sess., S. 5, § 406(a), reprinted in 5 Legislative History of the Federal Food, Drug, and Cosmetic Act and its Amendments 767, 792 (Dept. of Health, Education, and Welfare 1979) (changing, without explanation, words "is authorized to" to "shall" in relevant provision), with H. R. Rep. No. 2139, 75th Cong., 3d Sess. 6 (1938) (stating that, under the Act, "the establishment of tolerances is authorized") (emphasis added). A clearer indication of Congress' intentions with regard to tolerance levels occurred in 1954, when Congress condemned the cumbersomeness of the tolerance-level procedure as applied to pesticides. Congress fashioned a more streamlined procedure for those and other deliberately added substances. See 21 U. S. C. § 346a. But in revisiting § 346, Congress did not change the procedures governing unintentionally added substances like aflatoxin. This failure to change the scheme under which the FDA operated is significant, for a "congressional failure to revise or repeal the agency's interpretation is persuasive evidence that the interpretation is the one intended by Congress." NLRB v. Bell Aerospace, Co., 416 U.S. 267, 275 (1974). See FDIC v. Philadelphia Gear Corp., ante, at 437; Zenith Radio Corp. v. United States, 437 U.S. 443, 457 (1978). In sum, although the legislative history is not unambiguous, it certainly is no support for assertions that the FDA's interpretation of § 346 is insufficiently rational to warrant our deference.
Finally, we note that our interpretation of § 346 does not render that provision superfluous, even in light of Congress' decision to authorize the FDA to "promulgate regulations for the efficient enforcement of [the] Act." 21 U. S. C. § 371(a).
For the reasons set forth, the judgment is reversed, and the case is remanded to the Court of Appeals for the District of Columbia Circuit for further proceedings consistent with this opinion.
Reversed.
JUSTICE STEVENS, dissenting.
The parties agree that aflatoxins are added, unavoidable contaminants of food and as such are governed by the following provision of the Federal Food, Drug, and Cosmetic Act:
To one versed in the English language, the meaning of this provision is readily apparent. The plain language of the section tells us when the Secretary's duty to promulgate regulations arises — "when such substance . . . cannot be so avoided"; it tells us the purpose of the regulations — to establish
The Court's contrary conclusion reflects an absence of judgment and of judging. Before exploring either infirmity, it is worthwhile to summarize the Court's reason for reading the section to authorize, but not require, the promulgation of regulations. First, the Court declares that the qualifying language — "to such extent as he finds necessary for protection of the public health" — is a "dangling participle" that might or might not modify the words "shall promulgate regulations." Ante, at 981. Second, as between the two readings of this "ambiguous statutory provision," ibid., deference dictates that the Commissioner of the Food and Drug Administration (FDA) (to whom enforcement of the Act has been delegated) may take his pick.
The Court's finding of ambiguity is simply untenable. The antecedent of the qualifying language is quite clearly the phrase "limiting the quantity therein or thereon," which immediately precedes it, rather than the word "shall," which appears eight words before it. Thus, the Commissioner is to "limi[t] the quantity [of an added, unavoidable poisonous or deleterious substance] therein or thereon to such extent as he finds necessary for the protection of public health."
I respectfully dissent.
FootNotes
"The Commission next argues that its interpretation of the statute — that the statute authorizes successive suspension orders — has been both consistent and longstanding, dating from 1944. It is thus entitled to great deference. See United States v. National Assn. of Securities Dealers, 422 U.S. 694, 710 (1975); Saxbe v. Bustos, 419 U.S. 65, 74 (1974).
"While this undoubtedly is true as a general principle of law, it is not an argument of sufficient force in this case to overcome the clear contrary indications of the statute itself. In the first place it is not apparent from the record that on any of the occasions when a series of consecutive summary suspension orders was issued the Commission actually addressed in any detail the statutory authorization under which it took that action.
.....
"[S]ince this Court can only speculate as to the Commission's reasons for reaching the conclusion that it did, the mere issuance of consecutive summary suspension orders, without a concomitant exegesis of the statutory authority for doing so, obviously lacks `power to persuade' as to the existence of such authority. [Adamo Wrecking Co. v. United States, 434 U.S. 275, 287-288, n. 5 (1978)]."
As we emphasized in FMC v. Seatrain Lines, Inc., 411 U.S. 726, 745 (1973), "an agency may not bootstrap itself into an area in which it has no jurisdiction by repeatedly violating its statutory mandate." Instead, "our clear duty in such a situation is to reject the administrative interpretation of the statute." SEC v. Sloan, 436 U. S., at 119.
The Sloan case also provides an adequate answer to the argument that Congress has revisited the statute from time to time without condemning the FDA's "action level" practice:
"We are extremely hesitant to presume general congressional awareness of the Commission's construction based only upon a few isolated statements in the thousands of pages of legislative documents. That language in a Committee Report, without additional indication of more widespread congressional awareness, is simply not sufficient to invoke the presumption in a case such as this. For here its invocation would result in a construction of the statute which not only is at odds with the language of the section in question and the pattern of the statute taken as a whole, but also is extremely far reaching in terms of the virtually untrammeled and unreviewable power it would vest in a regulatory agency." Id., at 121.
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