STARR, Circuit Judge:

These consolidated cases arise out of EPA's regulation of hazardous wastes under the Resources Conservation and Recovery Act of 1976 ("RCRA"), as amended, 42 U.S.C. §§ 6901- 6933 (1982 Supp. III 1985). Petitioners, trade associations representing mining and oil refining interests, challenge regulations promulgated by EPA that amend the definition of "solid waste" to establish and define the agency's authority to regulate secondary materials reused within an industry's ongoing production process. In plain English, petitioners maintain that EPA has exceeded its regulatory authority in seeking to bring materials that are not discarded or otherwise disposed of within the compass of "waste."

I

RCRA is a comprehensive environmental statute under which EPA is granted authority to regulate solid and hazardous wastes. RCRA was enacted in 1976, and amended in 1978, 1980, and 1984. See The Quiet Communities Act of 1978, Pub.L. No. 95-609, 92 Stat. 3081; The Solid Waste Disposal Act Amendment of 1980, Pub.L. No. 96-482, 94 Stat. 2334; Hazardous and Solid Waste Amendments of 1984, Pub.L. No. 98-616, 98 Stat. 3221.

Congress' "overriding concern" in enacting RCRA was to establish the framework for a national system to insure the safe management of hazardous waste. H.R. Rep. No. 1491, 94th Cong., 2d Sess. 3 (1976), U.S. Code Cong. Admin.News 1976, pp. 6238, 6240, 6241. In passing RCRA, Congress expressed concern over the "rising tide" in scrap, discarded, and waste materials. 42 U.S.C. § 6910 (a)(2). As the statute itself puts it, Congress was concerned with the need "to reduce the amount of waste and unsalvageable materials and to provide for proper and economical solid waste disposal practices." Id. § 6910(a)(4). Congress thus crafted RCRA "to promote the protection of health and the environment and to conserve valuable material and energy resources." Id. § 6902.

RCRA includes two major parts: one deals with non-hazardous solid waste management and the other with hazardous waste management. Under the latter, EPA is directed to promulgate regulations establishing a comprehensive management system. Id. § 6921. EPA's authority, however, extends only to the regulation of "hazardous waste." Because "hazardous waste" is defined as a subset of "solid waste," id § 6903(5), the scope of EPA's jurisdiction is limited to those materials that constitute "solid waste." That pivotal term is defined by RCRA as

any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility and other discarded material, including solid, liquid, semisolid or contained gaseous material, resulting from industrial, commercial, mining, and agricultural operations, and from community activities....

42 U.S.C. § 6903(27) (emphasis added). As will become evident, this case turns on the meaning of the phrase, "and other discarded material," contained in the statute's definitional provisions.

EPA's interpretation of "solid waste" has evolved over time. On May 19, 1980, EPA issued interim regulations defining "solid waste" to include a material that is "a manufacturing or mining by-product and sometimes is discarded." 45 Fed.Reg. 33,119 (1980). This definition contained two terms needing elucidation: "by-product" and "sometimes discarded." In its definition of "a manufacturing or mining by-product," EPA expressly excluded "an intermediate manufacturing or mining product which results from one of the steps in a manufacturing or mining process and is typically processed through the next step of the process within a short time." Id.

In 1983, the agency proposed narrowing amendments to the 1980 interim rule. 48 Fed.Reg. 14,472 (1983). The agency showed especial concern over recycling activities. In the preamble to the amendments, the agency observed that, in light of the interlocking statutory provisions and RCRA's legislative history, it was clear that "Congress indeed intended that materials being recycled or held for recycling can be wastes, and if hazardous, hazardous wastes." Id. at 14,473. The agency also asserted that "not only can materials destined for recycling or being recycled be solid and hazardous wastes, but the Agency clearly has the authority to regulate recycling activities as hazardous management." Id.

While asserting its interest in recycling activities (and materials being held for recycling), EPA's discussion left unclear whether the agency in fact believed its jurisdiction extended in materials recycled in an industry's on-going production processes, or only to materials disposed of and recycled as part of a waste management program. In its preamble, EPA stated that "the revised definition of solid waste sets out the Agency's view of its jurisdiction over the recycling of hazardous waste ... Proposed section 261.6 then contains exemptions from regulations for those hazardous waste recycling activities that we do not think require regulation." Id. at 14,476. The amended regulatory description of "solid waste" itself, then, did not include materials "used or reused as effective substitutes for raw materials in processes using raw materials as principal feedstocks." Id. at 14,508. EPA explained the exclusion as follows:

[These] materials are being used essentially as raw materials and so ordinarily are not appropriate candidates for regulatory control. Moreover, when these materials are used to manufacture new products, the processes generally are normal manufacturing operations.... The Agency is reluctant to read the statute as regulating actual manufacturing processes.

Id. at 14,488. This, then, seemed clear: EPA was drawing a line between discarding and ultimate recycling, on the one hand, and a continuous or ongoing manufacturing process with one-site "recycling," on the other. If the activity fell within the latter category, then the materials were not deemed to be "discarded."

After receiving extensive comments, EPA issued its final rule on January 4,] 1985. 50 Fed.Reg. 614 (1985) Under the final rule, materials are considered "solid waste" if they are abandoned by being disposed of, burned, or incinerate; or stored, thread, or accumulated before or in lieu of these activities. In addition, certain recycling activities fall within EPA's definition. EPA determines whether a material is a RCRA solid waste when it is recycled by examining both the material or substance itself and the recycling activity involved. The final rule identifies five categories of "secondary materials" (spent materials, sludges, by-products, commercial chemical products, and scrap metal). These "secondary materials" constitute "solid waste" when they are disposed of; burned for energy recovery or used to produce a fuel; reclaimed; or accumulated speculatively. Id. at 618-19, 664. Under the final rule, if a material constitutes "solid waste," it is subject to RCRA regulation unless it is directly reused as an ingredient or as an effective substitute for a commercial product, or is returned as a raw material substitute to its original manufacturing process. Id. In the jargon of the trade, the latter category is known as the "closed-loop" exception. In either case, the material must not first be "reclaimed" (processed to recover a usable product or regenerated). Id. EPA exempts these activities "because they are like ordinary usage of commercial products." Id. at 619.

II

Petitioners, American Mining Congress ("AMC") and American Petroleum Institute ("API"), challenge the scope of EPA's final rule. Relying upon the statutory definition of "solid waste," petitioners contend that EPA's authority under RCRA is limited to controlling materials that are discarded or intended for discard. They argued that EPA's reuse and recycle rules, as applied to inprocess secondary materials, regulated materials that have not been discarded, and therefore exceed EPA's jurisdiction.

To understand petitioners' claims, a passing familiarity with the nature of their industrial processes is required.

Petroleum. Petroleum refineries vary greatly both in respect of their products and their processes. Most of their products, however, are complex mixtures of hydrocarbons produced through a number of interdependent and sometimes repetitious processing steps. In general, the refining process starts by "distilling" crude oil into various hydrocarbon streams or "fractions." The "fractions" are then subjected to a number of processing steps. Various. hydrocarbon materials derived from virtually all stages of processing are combined or blended in order to produce products such as gasoline, fuel oil, and lubricating oils. Any hydrocarbons that are not usable in a particular form or state are returned to an appropriate stage in the refining process so they can eventually be used. Likewise, the hydrocarbons and materials which escape from a refinery's production vessels are gathered and, by a complex retrieval system, returned to appropriate parts of the refining process. Under EPA's final rule, this reuse and recycling of materials is subject to regulation under RCRA.

Mining. In the mining industry, primary metals production involves the extraction of fractions of a percent of a metal from a complex mineralogical matrix (i.e., the natural material in which minerals are embedded). Extractive metallurgy proceeds incrementally. Rome was not built in a day, and all metal cannot be extracted in one fell swoop. In consequence, materials are reprocessed in order to remove as much of the pure metal as possible from the natural ore. Under EPA's final rule, this reprocessed ore and the metal derived from its constitute "solid waste." What is more, valuable metal-bearing and mineral-bearing dusts are often released in processing a particular metal. The mining facility typically recaptures, recycles, and reuses these dusts, frequently in production processes different from the one from which the dusts were originally emitted. The challenged regulations encompass this reprocessing, to the mining industry's dismay.

Against this factual backdrop, we not examine the legal issues presented by petitioners' challenge.

III

We observe at the outset of our inquiry that EPA's interpretation of the scope of its authority under RCRA has been unclear and unsteady. As previously recounted, EPA has shifted from its vague "sometimes discarded" approach of 1980 to a proposed exclusion from regulation of all materials used or reused as effective substitutes for raw materials in 1983, and finally, to a very narrow exclusion of essentially only materials processed within the meaning of the "closed-loop" exception under the final rule. We emphasize, therefore, that we are confronted with neither a consistent nor a longstanding agency interpretation. Under settled doctrine, "[a]n agency interpretation of a relevant provision which conflicts with the agency's earlier interpretation is `entitled to considerably less deference' than a consistently held agency view." I.N.S. v. Cardoza-Forseca, ___ U.S. ___, 107 S.Ct. 1207, 1221 n. 30, 94 L.Ed.2d 434 (1987) (quoting Watt v. Alaska, 451 U.S. 259, 273, 101 S.Ct. 1673, 1681, 68 L.Ed.2d 80 (1981)). See also FEC v. Democratic Senatorial Campaign Committee, 454 U.S. 27, 37, 102 S.Ct. 38, 44, 70 L.Ed.2d 23 (1981); Adamo Wrecking Co. v. United States, 434 U.S. 275, 287 n. 5, 98 S.Ct. 566, 574 n. 5, 54 L.Ed.2d 538 (1978); Skidmore v. Swift Co., 323 U.S. 134, 140, 65 S.Ct. 161, 164, 89 L.Ed. 124 (1944); National Fuel Gas Supply Corp. v. FERC, 811 F.2d 1563 (D.C. Cir. 1987).

A

Because the issue is one of statutory interpretation, the principles enunciated in Chevron U.S.A., Inc. v. NRDC, 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), and its progeny guide our inquiry. In Chevron, a unanimous Supreme Court laid out a now familiar, general framework for analyzing agency interpretations of statutes. First, the reviewing court is to consider whether Congress "has directly spoken to the precise question at issue." Id. at 842. This inquiry focuses first on the language and structure of the statute itself. If the answer is not yielded by the statute, then the court is to look to secondary indicia of intent, such as the measure's legislative history. As the Chevron Court emphatically declared: "[I]f the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress." Id. at 842-43.

In case, where Congress' intent is not clear, the Supreme Court set forth a second analytical step: "[I]f the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency's answer is based on a permissible construction of the statute.... In such a case, a court may not substitute its own construction of a statutory provision for a reasonable interpretation made by the administrator of an agency." Id. at 843-44.

We thus begin our inquiry with the first step of Chevron's analysis: did Congress clearly intend to limit EPA's regulatory jurisdiction to materials disposed of or abandoned, as opposed to materials reused within an ongoing production process? Before directly addressing this question, we should not fail to observe that in its very recent decision in Cardoza-Fonseca the Supreme Court reaffirmed that Chevron's first step is by no means an empty formality, but is to the contrary a vital part of the judicial inquiry. Because of its importance in statutory-analysis cases, we pause briefly to examine that latest descendent in the Chevron lineage.

In that case, the Court addressed the question whether the standard of proof under section 208(a) of the Refugee Act, 8 U.S.C. § 1158(a), which authorizes the Attorney General, in his discretion, to grant asylum to an alien who is unable or unwilling to return to his or her home country "because of persecution or a well-founded fear of persecution" is coextensive with the standard employed under section 243(h) of the Immigration and Nationality Act, 8 U.S.C. § 1253(h), which requires the Attorney General to withhold deportation of an alien who demonstrates that his or her "life or freedom would be threatened" if he or she was deported. Using "traditional tools of statutory construction," the Court concluded that "Congress did not intend the two standards to be identical." 107 S.Ct. at 1221. In its analysis of the deference due the agency's interpretation, the Court, citing Chevron, drew a distinction between "pure" questions of statutory construction and questions of interpretation that arise in the application of a statute to a particular set of facts. Id. The "narrower" task of interpreting a statute in the abstract, according to the Cardoza-Fonseca Court, is "well within the province of the judiciary." Id. at 1222.

As we are confronted in this case with a "pure" question of statutory construction, we remain mindful of the fact that "[t]he judiciary is the final authority on issues of statutory construction.... If a court, employing traditional tools of statutory construction, ascertains that Congress had an intention on the precise question at issue, that intention is the law and must be given effect." Id. at 1221 (quoting Chevron, 467 U.S. at 843 n. 9, 104 S.Ct. at 2781 n. 9).

B

Guided by these principles, we turn to the statutory provision at issue here. Congress, it will be recalled, granted EPA power to regulate "solid waste." Congress specifically defined "solid waste" as "discarded material." EPA then defined "discarded material" to include materials destined for reuse in an industry's ongoing production processes. The challenge to EPA's jurisdictional reach is founded, again, on the proposition that in-process secondary materials are outside the bounds of EPA's lawful authority. Nothing has been discarded, the argument goes, and thus RCRA jurisdiction remains untriggered.

1

The first step in statutory interpretation is, of course, an analysis of the language itself. As the Supreme Court has often observed, "the starting point in every case involving statutory construction is `the language employed by Congress.'" CBS v. FCC, 453 U.S. 367, 377, 101 S.Ct. 2813, 2820, 69 L.Ed.2d 706 (1981), (quoting Reiter v. Sonotone Corp., 442 U.S. 330, 337, 99 S.Ct. 2326, 2330, 60 L.Ed.2d 931 (1979)). In pursuit of Congress' intent, we "start with the assumption that the legislative purpose is expressed by the ordinary meaning of the words used." Securities Industry Ass'n v. Board of Governors, 468 U.S. 137, 149, 104 S.Ct. 2979, 2986, 82 L.Ed.2d 107 (1984) (quoting Richards v. United States, 369 U.S. 1, 9, 82 S.Ct. 585, 591, 7 L.Ed.2d 492 (1962)). These sound principles governing the reading of statutes seem especially forceful in the context of the present case. Here, Congress defined "solid waste" as "discarded material." The ordinary, plain-English meaning of the word "discarded" is "disposed of," "thrown away" or "abandoned." Encompassing materials retained for immediate reuse within the scope of "discarded material" strains, to say the least; the everyday usage of that term.

Although the "ordinary and obvious meaning of the [statutory] phrase is not to be lightly discounted," Cardoza-Fonseca, 107 S.Ct. at 1213, we are hesitant to attribute decisive significance to the ordinary meaning of statutory language. To be sure, our inquiry might well and wisely stop with the plain language of the statute, since it is the statute itself that Congress enacts and the President signs into law. But as the Supreme Court recently observed, the "more natural interpretation" (or plain meaning) is not necessarily determinative. Young v. Community Nutrition Institute, 477 U.S. 974, 106 S.Ct. 2360, 2364, 90 L.Ed.2d 959 (1986). And it is not infrequently said, odd as it may seem in a society governed by codified and thus knowable rules, that a matter may be within the letter of a statute but not within its spirit. See, e.g., California Federal Savings Loan Association v. Guerra, ___ U.S. ___, 107 S.Ct. 683, 93 L.Ed.2d 613 (1987); Steelworkers v. Weber, 443 U.S. 193, 99 S.Ct. 2721, 61 L.Ed.2d 480 (1979); Holy Trinity Church v. United States, 143 U.S. 457, 12 S.Ct. 511, 36 L.Ed. 226 (1892).

We hasten to add that this is by no means to say that language employed by a legislative body in that which we call law is doomed to remain inherently unclear and ambiguous. The Supreme Court has held, in a variety of contexts, that the statutory terms themselves can and do clearly express Congress' intent. See, e.g., Cardoza-Fonseca, 107 S.Ct. at 1212-13 ("well-founded fear" standard obviously focuses on subjective belief); Board of Governors v. Dimension Financial Corp., 474 U.S. 361, 106 S.Ct. 681, 686, 88 L.Ed.2d 691 (statutory language "legal right" means "just that"); Sorenson v. Secretary of Treasury, 475 U.S. 851, 106 S.Ct. 1600, 89 L.Ed.2d 855 (1986) (phrasing of statute revealed clear Congressional directive); Securities Industry, 104 S.Ct. at 2988 (literal meaning of "notes" sufficiently clear, rendering "functional analysis" impermissible); Library of Congress v. Shaw, ___ U.S. ___, ___ 106 S.Ct. 2957, 2983, 92 L.Ed.2d 250 (U.S. 1986) (recognizing that statutory language can clearly express Congress' intent to waive immunity); International Union, 816 F.2d 761, 765 (ordinary meaning of "employment" is "powerful evidence" of Congressional intent); see also Westmoreland v. CBS, 770 F.2d 1168, 1173-75 (D.C. Cir. 1985) (language of Rule 11, Fed.R.Civ.P., requires court to impose sanctions if violation is found). But see Chemical Manufacturers Association v. NRDC, 470 U.S. 116, 105 S.Ct. 1102, 1108, 84 L.Ed.2d 90 (1985) (where literalistic reading of statutory language would lead to absurd results, language has no plain meaning). In view of this considerable body of learning with respect to the reading of statutes, pointing in quite different directions, we are frank to admit that in our analysis we dare accord the ordinary meaning of "discarded" — i.e., disposed of — considerable, but by no means conclusive, weight in our interpretive task.

In short, a complete analysis of the statutory term "discarded" calls for more than resort to the ordinary, everyday meaning of the specific language at hand. For, "the sense in which [a term] is used in a statute must be determined by reference to the purpose of the particular legislation." Burnet v. Chicago Portrait Co., 285 U.S. 1, 6, 52 S.Ct. 275, 277, 76 L.Ed. 587 (1932). The statutory provision cannot properly be torn from the law of which it is a part; context and structure are, as in examining any legal instrument, of substantial import in the interpretive exercise. See, e.g., Stafford v. Briggs, 444 U.S. 527, 535, 100 S.Ct. 774, 780, 63 L.Ed.2d 1 (1980); Offshore Logistics, Inc. v. Tallentire, 477 U.S. 207, 106 S.Ct. 2485, 2494, 91 L.Ed.2d 174 (1986); Pennhurst State School v. Halderman, 451 U.S. 1, 18-19, 101 S.Ct. 1531, 1540, 67 L.Ed.2d 694 (1981).

As we previously recounted, the broad objectives of RCRA are "to promote the protection of health and the environment and to conserve valuable material and energy resources...." 42 U.S.C. § 6902. But that goal is of majestic breadth, and it is difficult, as Dimension Financial taught us, to pour meaning into a highly specific term by resort to grand purposes. Somewhat more specifically, we have seen that RCRA was enacted in response to Congressional findings that the "rising tide of scrap, discarded, and waste materials" generated by consumers and increased industrial production had presented heavily populated urban communities with "serious financial, management, intergovernmental, and technical problems in the disposal of soiled wastes." Id. § 6901(a). In light of this problem, Congress determined that "[f]ederal action through financial and technical assistance and leadership in the development, demonstration, and application of new and improved methods and processes to reduce the amount of waste and unsalvageable materials and to provide for proper and economical solid waste disposal practices was necessary." Id. Also animating Congress were its findings that "disposal of solid and hazardouse waste" without careful planning and management presents a danger to human health and the environment; that methods to "separate usable materials from solid waste" should be employed; and that usable energy can be produced from solid waste. Id. § 6901(b), (c), (d).

The question we face, then, is whether, in light of the National Legislature's expressly stated objectives and the underlying problems that motivated it to enact RCRA in the first instance, Congress was using the term "discarded" in its ordinary sense — "disposed of" or "abandoned" — or whether Congress was using it in a much more open-ended way, so as to encompass materials no longer useful in their original capacity though destined for immediate reuse in another phase of the industry's ongoing production process.

For the following reasons, we believe the former to be the case. RCRA was enacted, as the Congressional objectives and findings make clear, in an effort to help States deal with the ever-increasing problem of solid waste disposal by encouraging the search for and use of alternatives to existing methods of disposal (including recycling) and protecting health and the environment by regulating hazardous wastes. To fulfill these purposes, it seems clear that EPA need not regulate "spent" materials that are recycled and reused in an ongoing manufacturing or industrial process. These materials have not yet become part of the waste disposal problem; rather, they are destined for beneficial reuse or recycling in a continuous process by the generating industry itself.

The situation in this case thus stands in sharp contrast to that in Riverside Bayview, another post- Chevron case. There, the Corps of Engineers had defined "the waters of the United States" within the meaning of the Clean Water Act, 33 U.S.C. §§ 1311, 1362 (1972), to include "wetlands." Recognizing that it strained common sense to conclude that "Congress intended to abandon traditional notions of `waters' and include in that term `wetlands' as well," the Court performed a close and searching analysis of Congress' intent to determine if this counterintuitive results was nonetheless what Congress had in mind. Id. at 461-65. The Court based its holding (that the agency's expansive definition of "waters of the United States" was reasonable) on several factors: Congress' acquiescence in the agency's interpretation; provisions of the statute expressly including "wetlands" in the definition of "waters", and, importantly, the danger that forbidding the Corps to regulate "wetlands" would defeat Congress' purpose since pollutants in "wetlands" water might well flow into "waters" that were indisputably jurisdictional. Id. at 465. Thus, due to the nature of the water system, the very evil that Congress sought to interdict — the befouling of the "waters of the United States" — would likely occur were the Corps of Engineers' jurisdiction to stop short of wetlands. Riverside Bayview, 106 S.Ct. at 463.

The present case, on the other hand, seems to us more analogous to Dimension Financial, in which a unanimous Court rebuffed the attempt of the Federal Reserve Board to extend its jurisdiction to so-called "non-bank" banks, financial services institutions that were, in the Fed's view, functional equivalents of banks. The Court looked to the language and purpose of the governing statute and concluded that Congress' intent was clear: its definition of "bank" did not confer regulatory power over "non-bank banks." 106 S.Ct. at 686-89. In Dimension Financial, no serious contention was advanced to the effect that the banking industry had a "seamless-web" nature. That is to say, the Federal Reserve Board's inability to regulate the functional equivalent of a bank, while obviously likely to leave unregulated activities similar to those animating Congress in enacting the banking laws, would not frustrate or defeat federal regulation of the banking industry. Here too, EPA's regulation of in-process materials, like the Fed's attempted regulation of "non-bank banks," seems to us an effect to get at the same evil (albeit, very broadly defined) that Congress had identified by extending the agency's regulatory compass, rather than, as with the regulation of wetlands, an attempt to reach activities that if left unregulated would sabotage the agency's regulatory mission. We are thus not presented with a situation in which Congress likely intended that the pivotal jurisdictional term be read in its broadest sense, detached from everyday parlance; instead, we have a situation in which Congress, perhaps through the process of legislative compromise which courts must be loathe to tear asunder, employed a term with a widely accepted meaning to define the materials that EPA could regulate under RCRA. See Dimension Financial, 106 S.Ct. at 689. And it was that term which the Congress of the United States passed and the President ultimately signed into law.

2

Our task in analyzing the statute also requires us to determine whether other provisions of RCRA shed light on the breadth with which Congress intended to define "discarded." As the Supreme Court reiterated a few years ago, in interpreting a statute, "[w]e do not ... construe statutory phrases in isolation; we read statutes as a whole." United States v. Morton, 467 U.S. 822, 828, 104 S.Ct. 2769, 2773, 81 L.Ed.2d 680 (1984). The structure of a statute, in short, is important in the sensitive task of divining Congress' meaning.

In its brief, EPA directed us to a number of statutory provisions, arguing that they support its expansive definition of "discarded." This turned out, however, to be a wild goose chase through the labyrinthine maze of 42 U.S.C., for as counsel for EPA commendably recognized at oral argument, those statutory provisions speak in terms of "hazardous" (or "solid") waste." In consequence, EPA's various arguments based on the statute itself are, upon analysis, circular, relying upon the term "solid waste" or "hazardous waste" to extend the reach of those very terms. This, all would surely agree, will not do.

EPA has, however, advanced two arguments of potential merit based on specific RCRA provisions, and those therefore deserve our careful attention. First, EPA argues that § 6924(r)(2) of RCRA implicitly authorizes the agency to regulate recycled secondary materials. That subsection, we note at the outset, is highly specific; it exempts from a general labelling requirement fuels produced from petroleum refining waste containing oil if such materials (1) are "generated and reinserted on-site into the refining process" and (2) meet two other requirements, not relevant, for our purposes. It cannot go unnoticed that this subsection can be interpreted to come into play only where the material has become "hazardous waste" by being disposed of, and then is generated and reinserted on-site into the refining process. This interpretation, needless to say, would be singularly unhelpful to the agency's case, involving once more the now familiar problem of circularity of argument. EPA asserts, however, that the more natural reading of this provision is that materials generated and reinserted on-site into the refining process can be "hazardous waste," and are exempted from the otherwise applicable labelling requirement. The House Report explained in this regard:

This provision provides a limited and conditional exemption from the labelling requirement for certain petroleum fuel refiners. Refineries often take only refining wastes and reintroduce these wastes into the refining process where the oil component is incorporated into product [sic] and contaminants are removed. The committee does not believe that the refinery should automatically have to place a warning label on these fuels should EPA fail to exempt refineries from the labelling requirements within twelve months.

H.R. No. 198, 98th Cong., 2d Sess. at 43 (1984), U.S. Code Cong. Admin.News 1984, pp. 5676, 6602. Although we frankly agree that EPA's reading of this specific provision provides some support for its construction of RCRA's reach, it is, dispassionately viewed, of marginal force. For one thing, the provision has "no application to conventional fuels made by normal refining processes from recaptured hydrocarbon materials never intended to be discarded and never discarded." API's Reply Brief at 18-19. And, even more significantly, § 6924 itself is a provision defining "standards applicable to owners and operators of hazardous waste treatment, storage, and disposal facilities." This strongly suggests that the labelling subsection is directed at material which has indeed become hazardous waste, has reached a hazardous waste treatment facility, and is being recycled at that point. Such a construction would, of course, render EPA's argument in this respect as circular as its other contentions.

Second, EPA argues that § 6924(q)(1) evinces Congressional intent to include recycled in-process materials within the definition of "solid waste." We note at the outset that this provision is likewise a subsection of § 6924 and is therefore directed towards hazardous waste treatment facilities. The ever-present circularity problem thus looms here as well. But that is not all. EPA's argument is deficient in other respects too. Section 6924(q)(1) commands the agency to promulgate standards applicable to persons who produce, market, distribute, or burn fuels produced from or otherwise containing hazardous waste. The final sentence of that subparagraph states:

[F]or purposes of this subsection, the term "hazardous waste listed under section 6921 of this title" includes any commercial chemical products which is listed under section 6921 of this title and which, in lieu of its original intended use, is (i) produced for use as (or as a component of) a fuel, (ii) distributed for use as a fuel, or (iii) burned as a fuel.

Congress apparently added this language to override a then-existing EPA regulation which provided that unused commercial chemical products were solid wastes only when "discarded." 40 C.F.R. § 261.33 (1983). "Discarded" was at that time defined as abandoned (and not recycled) by being disposed, burned, or incinerated (but not burned for energy recovery). 40 C.F.R. § 261.2(c) (1983). As the House Report described the provision's scope:

Hazardous waste, as used in this provision [6294(q)], includes not only wastes identified or listed as hazardous under EPA's regulations, but also includes any commercial chemical product (and related materials) listed pursuant to 40 C.F.R. § 261.33, which is not used for its original intended purpose but instead is burned or processed as fuel. (Under current EPA regulations, burning is not deemed to be a form of discard; hence listed commercial chemical products, unlike spent materials, by-products or sludges, are not deemed to be `waste' when burned as fuel. They are only `waste' when actually discarded or intended for discard.)

H.R. Rep. No. 198, 98th Cong., 1st Sess. 40, U.S. Code Cong. Admin.News 1984, p. 5599.

We think it likely that in this provision Congress meant only to speak to the specific problem it identified — the burning of commercial chemicals as fuels, contrary to their original intended use. Congress addressed this problem by deeming the offending materials to be "discarded" and therefore within the statutory definition of "solid waste." This specific measure did not, however, revamp the basic definitional section of the statute.

3

After this mind-numbing journey through RCRA, we return to the provision that is, after all, the one before us for examination. And that definitional section, we believe, indicates clear Congressional intent to limit EPA's authority. First, the definition of "solid waste" is situated in a section containing thirty-nine separate, defined terms. This is definitional specificity of the first order. The very care evidenced by Congress in defining RCRA's scope certainly suggests that Congress was concerned about delineating and thus cabining EPA's jurisdictional reach.

Second, the statutory definition of "solid waste" is quite specific. Although Congress well knows how to use broad terms and broad definitions, as for example, "waters of the United States" in Riverside Bayview, or in an altogether different setting, the term "intelligence source" in CIA v. Sims, 471 U.S. 159, 105 U.S. 1881, 85 L.Ed.2d 173 (1985), the definition here is carefully crafted with specificity. It contains three specific terms and then sets forth the broader term, "other discarded material." That definitional structure brings to mind a long-standing canon of statutory construction, ejusdem generis. Under that familiar canon, where general words follow the enumeration of particular classes of things, the general words are most naturally construed as applying only to things of the same general class as those enumerated. Lest the reader jump to unwarranted conclusions about an unwelcome renaissance of mechanical jurisprudence, we hasten to express our wariness of formalism and woodenness in the sensitive exercise of statutory construction. But, the precept of ejusdem generis contains more than a modicum of common sense and reason in the ascertainment of meaning. See Department of State v. Washington Post Co., 456 U.S. 595, 600, 102 S.Ct. 1957, 1961, 72 L.Ed.2d 358 (1982) (specific terms are "benchmarks for measuring" the general term). Here, the three particular classes — garbage, refuse, and sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility — contain materials that clearly fit within the ordinary, everyday sense of "discarded." It is most sensible to conclude that Congress, in adding the concluding phrase "other discarded material," meant to grant EPA authority over similar types of waste, but not to open up the federal regulatory reach of an entirely new category of materials, i.e., materials neither disposed of nor abandoned, but passing in a continuous stream or flow from one production process to another.

In sum, our analysis of the statute reveals clear Congressional intent to extend EPA's authority only to materials that are truly discarded, disposed of, thrown away, or abandoned. EPA nevertheless submits that the legislative history evinces a contrary intent. In that respect, a unanimous Supreme Court has recently provided guidance on the proper role of legislative history in statutory interpretation. In Burlington Northern Railroad Co. v. Oklahoma Tax Commission, ___ U.S. ___, 107 S.Ct. 1855, 95 L.Ed.2d 404 (1987), the Court stated:

The parties have canvassed at length the 15-year legislative history of the [Railroad Revitalization and Regulatory Reform] Act [49 U.S.C. § 11503], and of the protection against discriminatory state taxation which became § 11503. We find the results of that investigation inconclusive and irrelevant. Legislative history can be a legitimate guide to a statutory purpose obscured by ambiguity, but "[i]n the absence of a `clearly expressed legislative intention to the contrary,' the language of the statute itself `must ordinarily be regarded as conclusive.'" United States v. James, 478 U.S. ___, ___ [ 106 S.Ct. 3116, 3122, 92 L.Ed.2d 483] (1986), (quoting Consumer Product Safety Comm'n v. GTE Sylvania, Inc., 447 U.S. 102, 108 [ 100 S.Ct. 2051, 2056, 64 L.Ed.2d 766] (1980). Unless exceptional circumstances dictate otherwise, "[w]hen we find the terms of a statute unambiguous, judicial inquiry is complete." Rubin v. United States, 449 U.S. 424, 430 [ 101 S.Ct. 698, 701, 66 L.Ed.2d 633] (1981).

Id. at 1859-60; see also Cardoza-Fonseca, 107 S.Ct. at 1213 n. 12. Although we find RCRA's statutory language unambiguous, and can discern no exceptional circumstances warranting resort to its legislative history, we will nonetheless in an abundance of caution afford EPA the benefit of consideration of those secondary materials.

4

EPA points first to damage incidents cited by Congress in 1976 as justification for establishing a hazardous waste management system. See H.R. Rep. No. 1491, 94th Cong., 2d Sess. at 18, 22 (1976). Neither of the incidents noted by EPA, however, involved commercial, in-process reuse or recycling activities. Instead, both incidents provide clear examples of waste disposal, which, of course, indisputably falls within EPA's jurisdiction conferred by RCRA.

EPA next asserts that the "most significant" aspect of the 1976 legislative history is the sense that Congress enacted broad grants of regulatory authority in order to "`eliminate the last remaining loophole in environmental law.'" EPA Brief at 25-26 (quoting H.R. Rep. No. 1491, 94th Cong., 2d Sess. at 4, U.S. Code Cong. Admin.News 1976, p. 6241). EPA, however, neglects to favor us with the entire sentence, and thereby misses the thrust of this passage. In pertinent part, the Report states as follows: "[The Committee] believes that the approach taken by this legislation eliminates the last remaining loophole in environmental law, that of unregulated land disposal of discarded materials and hazardous wastes." Id. (emphasis added)

Wanting support for its position in the 1976 legislative history, EPA argues that the 1984 legislative history of RCRA amendments ratifies the agency's interpretation. The agency relies heavily on the following passage from the Report of the House Committee on Energy and Commerce, which states:

This proposed section of the bill amends [proposed section 6921] to RCRA to require the Administrator to issue regulations regarding use, reuse, recycling, and reclamation of hazardous wastes. This provision is intended to reaffirm the Agency's existing authority to regulate as [sic] hazardous waste to the extent it may be necessary to protect human health and the environment. The Committee affirms that RCRA already provides regulatory authority over these activities (which authority the Agency has exercised to a limited degree) and in this provision is amending to clarify that materials being used, reused, recycled, or reclaimed can indeed be solid and hazardous wastes and that these various recycling activities may constitute hazardous waste treatment, storage, or disposal.

H.R. Rep. No. 198, 98th Cong., 2d Sess. at 46 (1984) U.S. Code Cong. Admin.News 1984, p. 5605 (emphasis added). This language is ambiguous at best. The Report refers to the agency's existing authority to regulate hazardous waste, which, as we saw before, renders EPA's argument circular. It is only in the context of "these activities" — regulation of "hazardous waste" — that the Report states that materials being used, reused, recycled, or reclaimed can be solid and hazardous wastes. Moreover, the Conference Report accompanying the bill enacted into law states: "The Conference substitute does not include the House provision on the use, reuse, recycling, and reclamation of hazardous waste. EPA has the authority to regulate such activities and an explicit mandate is not necessary." H.R. Conf.Rep. No. 1133, 98th Cong., 2d Sess. at 82, U.S. Code Cong. Admin.News 1984, p. 5652 (1984) (emphasis added). Thus, with the exception of one passing phrase, which seems to us of limited probative value, EPA is unable to point to any portion of the legislative history which supports its expansive and counterintuitive interpretation of the pivotal term, "discarded."

To the contrary, a fair reading of the legislative history reveals intimations of an intent to regulate under RCRA only materials that have truly been discarded. Not only is the language of the legislative history fully consistent with the use of "discarded" in the sense of "disposed of," but it strains the language to read it otherwise. Most significantly, in discussing its choice of the words "discarded materials" to define "solid waste," the House Committee stated:

Not only solid wastes, but also liquid and contained gaseous wastes, semi-solid wastes and sludges are the subjects of this legislation. Waste itself is a misleading word in the context of the committee's activity. Much industrial and agricultural waste is reclaimed or put to new use and is therefore not a part of the discarded materials disposal problem the committee addresses.

H.R. Rep. No. 1491, 94th Cong., 2d Sess. at 2, U.S. Code Cong. Admin.News 1976, p. 6240 (emphasis added). The Committee then went on to explain that "the term discarded materials is used to identify collectively those substances often referred to as industrial, municipal or post-consumer waste; refuse, trash, garbage, and sludge." Id. (emphasis added). Later in the Report, the Committee stated: "The overwhelming concern of the Committee, however, is the effect on the population and environment of the disposal of discarded hazardous wastes.... Unless neutralized or otherwise properly managed in their disposal, hazardous wastes present a clear danger...." Id. at 3, U.S. Code Cong. Admin.News 1976, p. 6241 (emphasis added). Throughout the Report, the Committee refers time and again to the problem motivating the enactment of RCRA as the disposal of waste.

In the Senate, a brief discussion took place as to the scope of the definition of "solid waste." In response to Senator Domenici's expression of concern that RCRA be aimed only at "the disposal of municipal and industrial wastes and not at the regulation of mining." Senator Randolph, the chairman of the Committee, unequivocally stated: "The bill definitely is directed at the disposal of municipal and industrial wastes." 122 Cong. Rec. 21,424 (1976) (emphasis added). To the extent this colloquy has probative value, see supra text at 1190-91 n. 19, it cuts squarely against expansive agency notions of the breadth of its jurisdictional reach.

After all is said and done, we are satisfied that the legislative history, rather than evincing Congress' intent to define "discarded" to include in-process secondary materials employed in an ongoing manufacturing process, confirms that the term was employed by the Article I branch in its ordinary, everyday sense.

IV

We are constrained to conclude that, in light of the language and structure of RCRA, the problems animating Congress to enact it, and the relevant portions of the legislative history, Congress clearly and unambiguously expressed its intent that "solid waste" (and therefore EPA's regulatory authority) be limited to materials that are "discarded" by virtue of being disposed of, abandoned, or thrown away. While we do not lightly overturn an agency's reading of its own statute, we are persuaded that by regulating in-process secondary materials, EPA has acted in contravention of Congress' intent. Accordingly, the petition for review is

Granted.