concurring in part ' and dissenting in part.
The Supreme Court very recently reiterated its well-established view that a reviewing court must accord substantial deference to an agency’s interpretation of its own regulations where the interpretation is neither irrational nor an impermissible construction of the enabling statute. See Allentown Mack Sales and Serv., Inc. v. NLRB, — U.S.-, 118 S.Ct. 818, 828, 139 L.Ed.2d 797 (1998) (National Labor Relations Board/National Labor Relations Act). In the instant appeal before this court, the Director, Office of Workers’ Compensation Programs, United States Department of Labor,1 (the “Director” or the “Agency”) advanced two alternative legal standards for evaluating the extent of an employer’s liability for medical expenses incurred by an employee who has already been found to be entitled to medical benefits under the Black Lung Benefits Act.2 Besides argu*518ing that a Doris Coai-like presumption, see Doris Coal Co. v. Director, OWCP, U.S. Dep’t of Labor, 938 F.2d 492, 496 (4th Cir.1991), would be entirely consistent with the policies underlying the Act, the Director has stressed its view that such a presumption is, in any event, unnecessary since under 20 C.F.R. § 725.701(b), an employer/operator who has already been found at the first stage to be liable for a miner’s total disability due to pneumoconiosis will be responsible at the second stage for the medical treatment of all pulmonary conditions contributing secondarily to the total respiratory disability of the claimant, whether or not such pulmonary conditions are otherwise related to or aggravated by the pneumoconiosis. Because I believe this court should defer to the Agency’s reasonable interpretation of its own regulations, I must respectfully dissent.
I. DEFERENCE
Pursuant to the Supreme Court’s decision in Chevron, U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), it is well-settled that “[w]hen Congress, through express delegation or the introduction of an interpretive gap in the statutory structure, has delegated policy-making authority to an administrative agency, the extent of judicial review of the agency’s policy determinations is limited.” Pauley v. BethEnergy Mines, Inc., 501 U.S. 680, 696, 111 S.Ct. 2524, 115 L.Ed.2d 604 (1991) (Secretary of Labor/Black Lung Benefits Act). Here, the statutory language does not expressly define the exact scope of employer/operator liability for medical expenses but rather delegates broad discretion to the Secretary of Labor to promulgate “additional provisions, not inconsistent with those specifically excluded by this subsection, as he deems necessary to provide for the payment of benefits by such operator to persons entitled thereto as provided in this part.” 30 U.S.C. § 932(a); see also 30 U.S.C. § 936 (providing the Secretary of Labor and the Secretary of Health and Human Services with authorization to issue such regulations as each deems appropriate to carry out the provisions of the subchapter comprising the Act); see generally 30 U.S.C. §§ 931— 945 (Part C of the Act). The regulations promulgated by the Agency require that a “responsible operator [or] other employer ... furnish a miner entitled to benefits under this part with such medical, surgical, and other attendance and treatment, nursing and hospital services, medicine ,and apparatus, and any other medical service or supply, for such periods as the nature of the miner’s pneumoconiosis and ancillary pulmonary conditions and disability require.” 20 C.F.R. § 725.701(b) (emphasis added). The Agency interprets this provision as requiring a responsible operator or other employer to pay for the cost of treating not only pneumo-coniosis, but also any ancillary pulmonary conditions and the resulting pulmonary disability. The Agency further explains that an “ancillary” pulmonary condition is a pulmonary condition that is unrelated to pneumo-coniosis except to the extent that it contributes, along with the pneumoconiosis, to the total pulmonary disability. Petitioners Glen Coal Company and Old Republic Insurance Company (together the “Company”), on the other hand, contend that an “ancillary” pulmonary condition must be one that is aggravated by or related to the pneumoconiosis in some other meaningful way besides merely contributing, along with the pneumoconiosis, to the total pulmonary disability.3
This court must give deference to an agency’s interpretation of its own regulations unless the interpretation is unreasonable or irrational. See Pauley, 501 U.S. at 696, 111 S.Ct. 2524; Sharondale Corp. v. Ross, 42 F.3d 993, 998 (6th Cir.1994). The term “ancillary” is not defined in either the regulations or the statute, and its exact meaning as *519used in 20 C.F.R. § 725.701(b) is uncertain from the plain language of this regulatory provision. Medical dictionaries define “ancillary” to mean “auxiliary, accessory, or secondary.” See Stedman’s Concise Medical Dictionary 49 (2d ed.1994); International Dictionary of Medicine and Biology 115 (1986) (“subordinate; auxiliary; supporting”); see also Random House Unabridged Dictionary 76 (2d ed.1993) (defining “ancillary” to mean: “1. subordinate;' subsidiary. 2. auxiliary; assisting”). It is thus uncertain whether the pulmonary conditions “ancillary” to the pneumoconiosis referred to in- 20 C.F.R. § 725.701(b) must not only have contributed, along with the pneumoconiosis, to the total pulmonary disability in' an auxiliary, accessory, subordinate and/or secondary capacity but also have been aggravated by or otherwise related to the pneumoconiosis itself. Therefore, while the Company’s interpretation is a plausible one; the plain language of the regulation is ambiguous and certainly allows for the Agency’s interpretation.
The Agency’s interpretation also seems reasonable as a matter of regulatory construction. “Pneumoconiosis” is defined by the Act to be “a chronic dust disease of the lung and its sequelae,4 including respiratory and pulmonary impairments, arising out of coal mine employment.” 30 U.S.C. § 902(b) (emphasis added). The regulations clarify that “a disease ‘arising out of coal mine employment’ includes any chronic pulmonary disease resulting in respiratory or pulmonary impairment significantly related to, or aggravated by, dust exposure in coal mine employment.” 20 C.F.R. § 727.202 (emphasis added). Under this legal definition established by the statute and the regulations, a pulmonary condition resulting from, aggravated by, or otherwise significantly related to pneumoconiosis would itself also be considered pneumoconiosis. Therefore, as the Agency has explained, it is most likely that the term “ancillary pulmonary condition” is referring to a pulmonary condition unrelated to pneumoconiosis or to dust exposure in coal mine employment except that it contributes, along with the pneumoconiosis, to the claimant’s total pulmonary disability. Otherwise the term “ancillary pulmonary conditions” would become surplusage. As a basic principle of regulatory construction, a court should strive to avoid interpretations that would lead to terms being mere surplusage, a result which presumably would not have been intended by the drafting party. See Wisconsin Public Intervenor v. Mortier, 501 U.S. 597, 613, 111 S.Ct. 2476, 115 L.Ed.2d 532 (1991).
To summarize, under the Agency’s interpretation, a company found liable at the first stage for a miner’s pneumoconiosis will be responsible at the second stage for medical treatment of the pneumoconiosis (which by definition includes all pulmonary conditions aggravated by, resulting from, or significantly related to the pneumoconiosis) as well as those pulmonary conditions which contribute, along with the pneumoconiosis, to the miner’s total pulmonary disability (i.e., any ancillary pulmonary conditions).
This is not a case where “the statute simply will not bear the meaning the [agency] has adopted.” Pittston Coal Group v. Sebben, 488 U.S. 105, 113, 109 S.Ct. 414, 102 L.Ed.2d 408 (1988) (reaching this conclusion with respect to the Secretary’s interpretation of the term “criteria” as used in the Act which mandated that the criteria applied by the Secretary of Labor not be more restrictive than the criteria applicable under the interim HEW regulation). As this court previously noted in Sharondale, “the Act is remedial legislation that should be liberally construed so as to include the largest number of miners within its entitlement provisions.” Id., 42 F.3d at 996 (quotation omitted).
Moreover, those miners whose medical expenses are at issue in this case have already been determined to be totally disabled due at least partially to pneumoconiosis and thus entitled to benefits under the Act. The Agency asserted at oral argument that only a very small percentage of those claimants who apply for black lung benefits under- the Act ever pass the first stage. Whether an em*520ployer who has already been found liable at the first stage for an employee’s pneumoconi-osis should be responsible for the cost of treating pulmonary conditions that may not be directly related to the pneumoconiosis but are related to the total pulmonary disability is a determination that would logically depend heavily on scientific/medical expertise and policy judgments. According to the Director, “[t]he policy reason underlying broad coverage is simple: each person has only one set of lungs, and it is difficult, if not impossible, to separate the effects of various assaults on the lungs, or conversely, to determine the synergy or interrelationship between these assaults.” Respondents’ Br. at 23. The Act creates a “complex and highly technical regulatory program,” see Pauley, 501 U.S. at 697, 111 S.Ct. 2524, and the agency charged with administering the Act is certainly in a better position than the courts to know how far medical science has advanced-in understanding black lung disease and whether physicians have the capability of determining how one pulmonary condition may impact on and affect the treatment of another condition involving the same system of the body and of parsing out the various effects of different pulmonary conditions.
Seals’s claim is governed by the Longshore and Harbor Workers’ Compensation Act (“LHWCA”), 33 U.S.C. § 901-950, which is incorporated by reference into Part C of the Black Lung Act pursuant to 30 U.S.C. § 932(a), and the Company argues that requiring employers to pay for the treatment of pulmonary conditions unrelated to pneu-moconiosis .even though they contribute, along with the pneumoconiosis, to the claimant’s total pulmonary disability would be contrary to the LHWCA which intends to render employers liable only for employment-related injuries. Petitioners’ Reply Br. at 7-8. I disagree that under the LHWCA employers can only be held responsible for medical treatment of conditions/injuries that are themselves employment-related. The Sixth Circuit’s recent adoption of the aggravation rule with respect to pre-existing conditions serves as a good example of a situation where an employer is held responsible for treatment of conditions that are employment-related only to the extent that the condition combines with an employment-related injury and contributes to producing disability.
The Company is correct that under the LHWCA an employer is obligated to “furnish such medical, surgical, and other attendance or treatment ... for such period as the nature of the injury or the process of recovery may require” and that the term “injury” is defined by the statute to mean an “accidental injury or death arising out of and in the course of employment.” 33 U.S.C. §§ 907(a), 902(2) (emphasis added). However, in determining what medical expenses are compensable under the LHWCA, several circuits, including the Sixth Circuit, follow the aggravation rule — a general workers’ compensation doctrine providing that “when an ‘employment injury aggravates, accelerates, or combines with a preexisting impairment to produce a disability greater than that which would have resulted from the employment injury alone, the entire resulting disability is compensable.’ ” Morehead Marine Servs., Inc. v. Washnock, 135 F.3d 366, 371 (6th Cir.1998) (quoting Port of Portland v. Director, OWCP, 932 F.2d 836, 839 (9th Cir.1991)) (emphasis added); see also Director, OWCP v. Bath Iron Works Corp., 129 F.3d 45, 50 (1st Cir.1997); Director, OWCP v. Ingalls Shipbuilding, Inc., 125 F.3d 303, 306 (5th Cir.1997); Director, OWCP v. Luccitelli, 964 F.2d 1303, 1304 (2d Cir.1992); SAIF Corp./Oregon Ship v. Johnson, 908 F.2d 1434, 1441 (9th Cir.1990) (explaining that under the aggravation doctrine, an employer must fully compensate an employee whose employment-related injury aggravates a preexisting injury in the sense that it combines with the preexisting injury to produce disability). The logic behind the aggravation rule is akin to the common law doctrine that a tortfeasor takes his victim as he finds him. See Ingalls Shipbuilding, 125 F.3d at 306. Thus, an LHWCA claimant whose respiratory disability results partially from employment-related asbestos exposure and partially from unrelated obstructive pulmonary conditions caused by obesity and smoking would nevertheless be compensated for the treatment of all of these conditions. See, e.g., Bath Iron Works, 129 F.3d at 53; SAIF Corp., 908 F.2d at 1441. In light of *521this background, the Agency’s interpretation of 20 C.F.R. § 725.701(b) is neither extraordinary nor novel as a matter of policy judgment. In fact, the Agency’s interpretation seems perfectly consistent with other established principles under the LHWCA like the aggravation rule and long-held doctrines of workers’ compensation law. In sum, the Agency’s interpretation of 20 C.F.R. § 725.701(b) is neither irrational nor unreasonable. Moreover, since “[tjhere is simply no reason to suspect that the interpretation does not reflect the [Ajgency’s fair and considered judgment on the matter in question,” the fact that the interpretation may be a litigating position does not reduce the amount of deference that we must give it. Auer v. Robbins, 519 U.S. 452, 117 S.Ct. 905, 912, 137 L.Ed.2d 79 (1997); see also Martin v. OSH Review Comm’n, 499 U.S. 144, 157, 111 S.Ct. 1171, 113 L.Ed.2d 117 (1991); Lovilia Coal Co. v. Harvey, 109 F.3d 445, 452 (8th Cir.1997). Accordingly, I would defer to the Agency’s interpretation of its own regulation.5
II. REBUTTABLE PRESUMPTION
I also do not believe we should reject outright the Doris Coaipresumption, specifically that “when a miner receives treatment for a pulmonary disorder, a presumption [should arise] that the disorder was caused or at least aggravated by the miner’s pneu-moconiosis____” Doris Coal, 938 F.2d at 496. The record before this court does not contain sufficient evidence on which either to accept or reject the adoption or creation of a Doris Coal-like presumption. Since the administrative law judge (“ALJ”) tried this ease believing he was bound by the Fourth Circuit’s ruling in Doris Coal, it is not surprising that he saw no need to develop or pursue this issue at trial. In the absence of an alternative basis for ruling, I would remand this case to the ALJ for a determination of whether a scientific or evidentiary basis exists to support such a presumption. The ALJ may find, for example, that scientific proof exists that “most pulmonary disorders are going to be related [to] or at least aggravated by the presence of pneumoconio-sis,” as the Fourth Circuit in Doris Coal believed to be true. Id., 938 F.2d at 496. A finding that such interrelationships can rarely be confirmed or rebutted with any certainty by present medical technology might also serve as an evidentiary basis for our relying on such a presumption.
On remand the ALJ will have the opportunity to develop a record as to whether an evidentiary basis exists to support a Doris Coal-like presumption and to decide whether or not to utilize such a presumption. The Benefits Review Board would then determine whether or not to affirm the ALJ’s decision. Certainly as with other such decisions, this decision would be appealable to this court, which would then review under the appropriate standards to. determine whether to approve or create such a presumption.
On appeal to this court, I see no reason why despite such findings, the Act itself would stand as an obstacle to our judicially creating such a presumption. While uniformity may indeed have been one goal of the Act, I agree with Judge Boggs that reading Director, OWCP v. Greenwich Collieries, 512 U.S. 267, 114 S.Ct. 2251, 129 L.Ed.2d 221 (1994), as mandating a prohibition of all non-statutory presumptions is overly broad and unwarranted. As explained in 1 Stephen A. Saltzburg et al., Federal Rules of Evidence Manual 163-64 . (7th ed.1998), “[cjourts can and have created and applied presumptions as a matter of federal common law when necessary to further congressional *522policy (i.e., when Congress would have wanted a presumption created).”
A Doris Coai-like presumption would be wholly consistent with the remedial purposes of the Act and the principles on which it was enacted and amended. The Senate Report that accompanied the passage of the Act in 1972, which broadened the definition of “pneumoconiosis,” recognized the uncertain state of medical knowledge and the need to compensate for this uncertainty. See S.Rep. No. 92-743, at 9-11 (1972), reprinted in 1972 U.S.C.C.A.N. 2305, 2313-15; see also Adams v. Director, OWCP, 886 F.2d 818, 825 (6th Cir.1989) (noting the Act’s concern with inflexible proof of causation requirements, as illustrated by the Act’s reliance on rebuttable presumptions, as support for requiring only that a miner’s pneumoconiosis be a partial cause of his total respiratory disability) (citing Southard v. Director, OWCP, 732 F.2d 66, 70-71 (6th Cir.1984)). In particular, the report noted the testimony of an acknowledged expert in the field of pulmonary impairments of coal workers:
Other conditions of the lung, in addition to [clinical] pneumoconiosis, are commonly encountered among coal miners. While the exact causes of these conditions are not completely understood and while other nonoecupational factors may be in part responsible, no medical authority can prove these conditions to be unassociated with the mining exposure---- [W]e do not know all of the specific disease entities which can arise as a consequence of the mining industry, we do not even know for that matter all of the specific causes of these impairments,----
S.Rep. No. 92-743, at 10-11 (1972), reprinted in 1972 U.S.C.C.A.N. 2305, 2314-15. The report concluded that “[i]n the absence of definitive medical conclusions there is a clear need to resolve doubts in favor of the disabled miner or his survivors.” S.Rep. No. 92-743, at 11 (1972), reprinted in 1972 U.S.C.C.A.N. 2305, 2315.
Some well-established reasons for creating a presumption include: (1) the high probability that the presumed fact follows from the basic facts, (2) access to proof, (3) procedural convenience, and (4) social and economic policy reasons. See Charles Alan Wright and Kenneth W. Graham, Jr., Federal Practice and Procedure: Evidence § 5122, at 569-70 (1977 & Supp.1997). Thus, while I agree with Judge Dowd that the likelihood of fraud is an important consideration to take into account in evaluating the wisdom of reliance on a presumption, the danger of fraud is but one factor that should be weighed and can be properly evaluated only when a complete evi-dentiary record is available to this court.
III. CONCLUSION
To the extent that the majority fails to accord proper deference to the Agency’s reasonable interpretation of 20 C.F.R. § 725.701(b) as rendering the Company liable for the medical treatment of all pulmonary conditions contributing, along with pneumoconiosis, to Seals’s total respiratory disability whether or not such conditions are otherwise related to Seals’s pneumoconiosis, I respectfully dissent. I also note my disagreement with any outright rejection of the Doris Coal presumption without first remanding the case to the ALJ so that a record can be developed as to whether a sufficient evidentiary/medical basis exists for our adopting such a standard. I concur with the majority’s opinion to the extent that it is not inconsistent with the views that I have expressed.
. The Director, as designee of the Secretary of Labor, see 20 C.F.R. § 701.202(f), “is vested with [the] authority to administer the Black Lung Benefits Act.” Director, OWCP, U.S. Dep't of Labor v. Saulsberry, 887 F.2d 667, 670 (6th Cir.1989). Besides the federal respondent, claimant Jess Seals is also a respondent in this appeal.
. Title IV of the Federal Coal Mine Health and Safety Act of 1969, Pub.L. 91-173, 83 Stat. 792 (1969), as amended by the Black Lung Benefits Act of 1972, Pub.L. 92-303, 86 Stat. 150 (1972), and as further amended by the Black Lung Benefits Reform Act of 1977, Pub.L. 95-239, 92 Stat. 95 (1978), the Black Lung Benefits Revenue Act *518of 1977, Pub.L. 95-227, 92 Stat. 11 (1978); the Black Lung Benefits Revenue Act of 1981 and the Black Lung Benefits Amendments of 1981, Pub.L. 97-119, 95 Stat. 1635 (1981) (hereinafter together referred to as the "Act").
. In other words, under the Company’s interpretation pulmonary condition X could not be considered "ancillary” to the pneumoconiosis of a claimant if it merely combined with the pneumo-coniosis to create total pulmonary disability, but could be considered "ancillary” if pulmonary condition X was also itself the result of or aggravated by the pneumoconiosis.
. "Sequelae" are “abnormal condition[s] resulting from a previous disease.” See Random House Unabridged Dictionary 1747 (2d ed.1993); see also Stedman’s Medical Dictionary 1407 (25th ed. 1990) (sequelae are those "condition[s] following as a consequence of a disease").
. While a proposed regulation codifying the Dons Coal presumption is currently under consideration by the Agency, such changes have not yet been formally adopted. See 62 Fed.Reg. 3338, 3369 (Jan. 22, 1997). At the present time, the Agency’s position is that 20 C.F.R. § 725.701(b) renders employers liable for all pulmonary conditions that contribute to the claimant's total respiratory disability whether or not such conditions are otherwise' related to the pneumoconiosis suffered by the claimant, and this present interpretation should be the focus of this court’s analysis. The Agency certainly has the prerogative to change its policies in the future and to adopt the proposed regulation. After all, leaving such discretion to the agency charged with implementing a statute is the whole point of Chevron. See Lovilia Coal, 109 F.3d at 452 (concluding that a change in agency position is not invalidating unless it is arbitrary, capricious, or an abuse of discretion).