Opinion for the Court filed by Senior Circuit Judge BAZELON.
BAZELON, Senior Circuit Judge:
These consolidated petitions1 for review challenge a new permanent health standard limiting occupational exposure to cotton dust,2 which was promulgated by regulation on June 19,1978 by the Occupational Safety and Health Administration of the Depart[62]*62ment of Labor (OSHA), under section 6(b)(5) of the Occupational Safety and Health Act of 1970 (the Act).3 OSHA’s action, which rests on its determination that occupational exposure to cotton dust presents a material health hazard to workers, is attacked by three groups of petitioners: (1) representatives of the cotton textile industry4 and (2) nontextile industries5 who claim that the standard is unwarranted and infeasible; and (3) their employee unions, who attack two provisions of the standard as too lax, but support the rest.6 These very divergent claims reflect the wide variety of conflicting interests that make OSHA’s task a difficult one. On direct review,7 we uphold the standard except for its application to the cottonseed oil industry which we remand for clarification or reconsideration.
To assist a proper understanding of the issues, we discuss (I) the history and context of the agency’s action; (II) the nature of our review under the Act; (III) the claims of the textile industry; (IV) the claims of the non-textile industries; and (V) challenges to a few technical provisions of the standard.
I. BACKGROUND
A. Health Risks
Health impairments associated with exposure to cotton dust range from acute but reversible reactions to irreversible, chronic obstructive pulmonary disease.8 Cotton dust exposure can produce or aggravate respiratory symptoms characteristic of chronic bronchitis, asthma, and emphysema.9 Further, a specific, debilitating disease has been conclusively attributed to the effect of cotton dust on the respiratory passages. This disease, named byssinosis, is more commonly known in its chronic stage as “brown lung disease.” 10 This is the most serious health hazard for cotton workers.
Although the prevalence of the disease among cotton workers has been known for centuries,11 its exact etiology is still not [63]*63completely understood.12 The subjective nature of many early symptoms13 and variations in the composition of cotton dust14 have compounded the uncertainties about the actual way in which cotton dust exposure causes serious health impairments.15 Nonetheless, its progressively ' disabling symptoms are well documented.16
Typically, a person suffering from byssinosis is initially affected by irritated air passages, coughing, breathlessness, and chest tightness. These symptoms are often accompanied by decreased pulmonary functioning, evidenced by objective indicators. At first the symptoms tend to last briefly, and usually remit a few days after exposure. The symptoms recur, however, whenever an affected individual returns to a dusty environment.
As the disease progresses, its symptoms become more pronounced and painful, resembling the effects of bronchitis and asthma. They persist throughout the work week, or period of exposure. During this stage, an affected worker may become temporarily incapacitated and may need to take short but frequent leaves from work.
When byssinosis reaches its advanced stage, the worker exhibits the symptoms of emphysema and chronic bronchitis. Ultimately, irreversible lung damage results. A worker afflicted with chronic byssinosis is [64]*64forced into premature retirement, often after painful efforts to remain on the job. Such individuals must give up all activities that require any physical exertion. The permanent lung damage caused by byssinosis makes every breath painful and difficult. The excess strain these breathing difficulties place on the heart often leads to the worker’s early death from heart failure.
The actual number of persons afflicted with byssinosis is not certain, but it is large. One study estimated that 35,000 people have “disabling loss of lung function related to their work in the cotton textile industry” alone.17 The Senate Report on the Occupational Safety and Health Act stated that as many as 100,000 active or retired workers suffered from the disease in 1970.18
Studies in the record estimate that 250,-000 to 800,000 workers are exposed daily to cotton dust and its attendant risks.19 As the reported incidence of the disease usually ranges as high as 20-30% of the work force in cotton industries,20 each worker faces a substantial risk of health impairment.21
B. History of Cotton Dust Regulation
Prior to the creation of OSHA a private association of governmental industrial hygienists placed cotton dust on its tentative list of substances for which specific exposure limits should be established.22 In 1966 this organization adopted a “threshold limit value” of 1000 micrograms per cubic meter (1000 M-g/m 3) of total dust.23
The federal government first regulated cotton dust in 1968. At that time, the Secretary of Labor, acting pursuant to the Walsh-Healey Act,24 promulgated a 1000 Pg/m 3 maximum total dust exposure as an occupational health requirement for public contractors.25
This was an interim standard adopted upon passage of the Act in 1970 in which section 6(a) required the Secretary immediately to promulgate as occupational safety or health standards all existing “established Federal Standards,” including the 1000 ug/m3 standard for cotton exposure.26 These interim standards were intended to afford workers minimal protection until the [65]*65adoption of permanent standards through OSHA’s rulemaking proceedings.
On September 26, 1974, the Director of the National Institute of Occupational Safety and Health (NIOSH)27 submitted to the Secretary of Labor a set of recommendations for regulating cotton dust. NIOSH recommended28 that cotton dust exposure be “controlled to the lowest feasible limit which shall be less than 0.2 mg lint-free cotton dust/cu.m.,” 29 or 200 ug/m 3.
Shortly thereafter, OSHA published an Advanced Notice of Proposed Rulemaking on cotton dust. OSHA requested interested parties to submit their views on the NIOSH recommendations and related issues concerning a proposed standard.30 OSHA received comments from scientists, labor unions, industries, cotton growers, and governmental representatives. A proposed revision, published on December 28, 1976, called for an exposure limit of 200 pg/m3 of cotton dust.31 OSHA provided 90 days for interested parties to submit written comments.32
At the close of the comment period, OSHA conducted hearings in three cities for a total of 14 days.33 The comments and exhibits received before the hearings, the written and oral testimony of the hearing participants, and post-hearing comments and briefs comprise the informal rulemaking record for the final cotton dust standard promulgated by the agency. This record exceeds 105,000 pages in length; it includes comments from 263 parties and testimony from 109 participants at the hearing. The Final Standard and its accompanying statement of reasons fill 68 pages of the Federal Register.34
C. The OSHA Standard
On the basis of the massive rulemaking record, OSHA promulgated the cotton standard in an effort to reduce the health risks to cotton workers.35 Part of the standard sets “permissible exposure limits” (PELs) for each manufacturing operation and industry that exposes workers to cotton [66]*66dust.36 Thus, OSHA set (1) 200 micrograms per cubic meter (200 pg/m3) as the PEL for lint-free respirable cotton dust in yarn manufacturing; (2) 750 pg/m3 for slashing and weaving operations in the cotton industry; and (3) 500 pg/m 3 for all other processes in the cotton industry and for all non-textile industries that expose workers to cotton dust.37
Implementation of the standard depends primarily on the adoption of engineering and work practice controls by employers. OSHA established a four-year implementation period during which employers are expected to achieve compliance. If an employer establishes that the required controls are infeasible, he can obtain an administrative variance from the standard,38 but he must make respirators available to protect his employees until he achieves compliance.39 The standard also requires employers to monitor employees’ exposure to cotton dust, to provide medical surveillance and employee education, and to post warning signs about the health risks.
Before examining petitioners’ objections, we consider the limits of our review.
II. SCOPE OF REVIEW
The Occupational Safety and Health Act of 1970 is one of a number of recent Congressional statutes that designates the stringent “substantial evidence” test for judicial review of notice-and-comment rulemaking.40 The explicit language of the Act,41 its legislative history,42 and its application by the courts43 confirm that regulations promulgated under the Act are
[67]*67to be upheld on review if supported by “substantial evidence on the record considered as a whole.”44
The substantial evidence test provides for more rigorous scrutiny than the usual “arbitrary and capricious”45 test applicable to informal rulemaking.46 Although Congress required this more rigorous judicial review, it nevertheless delegated unusually broad discretionary authority to regulate against possible harms.47 We have already resolved this seeming anomaly in Industrial Union Dep’t v. Hodgson, 162 U.S.App.D.C. 331, 499 F.2d 467 (D.C.Cir. 1974). There we concluded that the reviewing court’s task under the Act is to provide a careful check on the agency’s determinations without substituting its judgment for that of the agency48 Congress apparently created an “uneasy partnership” between the agency and the reviewing court49 to check extravagant exercises of the agency’s [68]*68authority to regulate risk.50 Our role in this partnership is to ensure that the regulations resulted from a process of reasoned decisionmaking consistent with the agency’s mandate from Congress.51 By statute, this process must include notice to interested parties of issues presented in the proposed rule.52 The agency must also provide opportunities for these parties to offer contrary evidence and arguments.53
OSHA adopted additional procedures to improve its decision-making process.54 A qualified hearing examiner must preside at oral hearings on proposed standards. A verbatim transcript of the hearing is required, and cross-examination is permitted. These procedures, which were followed in this case, transform OSHA’s action into “hybrid” rulemaking,55 and produce a record more susceptible to rigorous judicial review than the more usual informal rule-making record.56
The tasks of this reviewing court are thus to ensure that the agency has (1) acted within the scope of its authority;57 (2) followed the procedures required by statute and by its own regulations;58 (3) explicated the bases for its decision; (4) adduced substantial evidence in the record to support its determinations.59
The meaning of “substantial evidence” in this context is problematic. Factual proof about particular health risks may not be substantial in the traditional sense simply because the medical and scientific [69]*69communities do not yet completely understand the nature of threatening diseases. To protect workers from material health impairments, OSHA must rely on predictions of possible future events and extrapolations from limited data. It may have to fill gaps in knowledge with policy considerations. Congress recognized this problem by authorizing the agency to promulgate rules on the basis of the “best available evidence.”60 OSHA’s mandate necessarily requires it to act — even if information is incomplete — when the best available evidence indicates a serious threat to the health of workers.61 Thus, a court entrusted with the rigorous “substantial evidence” review must examine not only OSHA’s fac- ' tual support, but also the “judgment calls” and reasoning that contribute to its final decision.62 Otherwise, an agency’s claim of ignorance would clothe it with unreviewable discretion.
Therefore, the reviewing court must examine both factual evidence and the agency’s policy considerations set forth in the record. To facilitate this review of the record, the agency must pinpoint the factual evidence and the policy considerations upon which it relied.63 This requires explication of the assumptions underlying predictions or extrapolations,64 and of the basis for its resolution of conflicts and ambiguities.65 In enforcing these requirements, the court does not reach out to resolve controversies over technical data.66 Instead, it seeks to ensure public accountability. Ex[70]*70plicit explanation for the basis of the agency’s decision not only facilitates proper judicial review but also provides the opportunity for effective peer review, legislative oversight, and public education. This requirement is in the best interest of everyone, including the decision-makers themselves. If the decision-making process is open and candid, it will inspire more confidence in those who are affected. Further, by opening the process to public scrutiny and criticism, we reduce the risk that important information will be overlooked or ignored. Instructed by these ends, this court on review will “combine supervision with restraint.”67
III. CHALLENGES BY THE TEXTILE INDUSTRY
The textile industry petitioners acknowledge that textile workers who are exposed to cotton dust may risk contracting byssinosis.68 Their challenge focuses on the regulatory approach OSHA has chosen to reduce that risk. Specifically, they ask us to find that OSHA’s regulatory approach is not “reasonably necessary” to protect textile workers from the admitted danger posed by cotton dust.69 Further, they ask us to find that approach technologically and economically infeasible.70
A. Challenge to the Regulatory Approach
OSHA chose a “dust control strategy” that requires engineering and work practice controls to limit worker exposure to the “lowest feasible [cotton] dust levels” within four years.71
The textile industry rejects OSHA’s approach as unnecessarily expensive. The industry contends that workers can be fully protected from “ ‘material impairment of [their] health or functional capacity’ ” by a higher permissible exposure level coupled with a medical surveillance program.72 The industry’s alternative would permit an exposure level of 500 ng/m3 in all cotton manufacturing operations except weaving, for which a PEL of 1000 pg/m3 is proposed. This alternative would also require workers to wear respirators or accept transfers to lower exposure work areas if medical surveillance shows that they are suffering from byssinosis symptoms “which, with years of continued exposure, could lead to [material health] impairment.”73
The textile industry petitioners claim that OSHA failed to seriously consider their alternative or to provide adequate reasons for rejecting it. The industry also claims that the regulatory approach adopted by OSHA is not permitted by the Act.74 We disagree with both claims.
First, OSHA gave serious attention to the medical studies conducted by the textile industry and proffered to support the industry’s alternative.75 These studies purport to show that medical surveillance pro[71]*71grams at various textile plants have already afforded workers a level of protection comparable to that offered by OSHA’s approach. The record shows that OSHA specifically addressed and scrutinized these studies, and concluded that their validity had largely been discredited.76 OSHA’s judgment on this issue is sufficiently supported on this basis.77
Besides this careful treatment of the medical surveillance proposal, OSHA rejected the industry’s proposed reliance on job transfers and respirators to protect workers suffering from acute symptoms of byssinosis on the basis of testimony in the record and express policy considerations.78 The industry was unable to show that job transfers would be available in sufficient number to respond to the likely prevalence of byssinosis in plants with dust levels at the 500 pg/m3 proposed by the industry.79 Further, the agency found uncontradicted testimony in the record that respirators can cause severe physical discomfort and create safety problems of their own.80 OSHA concluded that the industry’s proposal inappropriately placed the burden of compliance on the employees.81 On this express policy [72]*72ground, and on the basis of the evidence in the record, OSHA reasonably rejected these elements in the industry alternative.
Finally, the textile industry argues that the agency’s effort to reduce workers’ cotton dust exposure to the lowest feasible level is not “reasonably necessary or appropriate.” 82 This argument rests on the claim that the agency need not guard against the acute but reversible symptoms of byssinosis because they do not themselves constitute a “material impairment of health.”83 We find that this claim and its attendant argument must fall in the face of the agency’s evidence and reasons.
The agency adopted a “dust control strategy” after finding conclusive evidence of a causal relation between exposure to cotton dust and the contraction of respiratory diseases, such as byssinosis. The agency acknowledged gaps in medical understanding of the specific causal relationship between cotton dust and disease.84 Nonetheless, the agency’s mandate requires it to protect workers’ health even before the resolution of all medical and scientific uncertainties about the particular health risk.85 Further, OSHA heard several witnesses conclude that at present, “there is no basis for any programs of prevention and control of byssinosis other than those based on prevention of exposure to respirable cotton dust.”86 Virtually without exception, key textile industry witnesses along with public health experts rejected medical surveillance as an alternative to dust reduction.87 Accordingly, the agency adduced considerable evidence to support its dust control strategy-
The agency’s approach, which is similar to its strategy in regulating asbestos,88 is authorized by the primary purpose and by the special mandate of the Act. Section 2(b) sets out the Act’s broad protective purpose: “to assure so far as possible every working man and woman in the Nation safe and healthful working conditions.” Toward this end, section 6(b)(5) authorizes [73]*73OSHA to set permanent standards for occupational exposure to “toxic materials or harmful physical agents” at the level
which most adequately assures, to the extent feasible, on the basis of the best available evidence, that no employee will suffer material impairment of health or functional capacity even if such employee has regular exposure to the hazard dealt with by such standard for the period of his working life.89
Contrary to the industry’s view, this mandate does not restrain the agency from acting to prevent irreversible health damage until workers actually suffer the early symptoms of byssinosis. Instead it is a mandate to reduce the risk of that irreversible damage — especially for those workers who have regular exposure to the causal agent, cotton dust. In the present case, OSHA adequately documented the risk of such damage attributable to continued exposure to cotton dust. Medical experts testified on the record that the early, acute symptoms of byssinosis weaken the worker’s pulmonary system and increase his susceptibility to the adverse effects of subsequent cotton dust exposure.90 We therefore uphold OSHA’s decision to reduce the prevalence of chronic byssinosis through regulations stringent enough to reduce even the occurrence of the reversible acute stage of the disease.
B. Feasibility of the Standard
All parties acknowledge that OSHA must evaluate technological and eeonomic feasibility in setting permanent standards under section 6(b)(5) of the Act. These considerations set constraints on the agency’s mandate to assure employees “the highest degree of health and safety.” 91 In light of petitioners’ claims, we must examine the record to ensure that OSHA has not exceeded its mandate by neglecting these constraints.
We are assisted here by this court’s interpretation of the feasibility requirement in Industrial Union Dep’t, AFL-CIO v. Hodgson. In that case, we concluded that the feasibility requirement reflects Congress’ recognition that employees would not be protected if their employers were put out of business.92 This possibility is all too real if the agency inflexibility requires protective devices unavailable under existing technology or otherwise makes financial viability impossible.93 At the same time, we concluded, standards do not become infeasible simply because they may impose substantial costs on an industry, force the development of new technology, or even force some employers out of business.94 Otherwise the Act’s commitment to protect workers might be forever frustrated.
In this case, the textile industry petitioners contend that the record does not support OSHA’s findings of technological and economic feasibility. First, they argue that the standard is technologically infeasible for the spinning through weaving stages of textile manufacturing.95 Further, they ar[74]*74gue that the record does not support the agency’s finding that the standard is economically feasible. In addition, they argue that “OSHA failed to satisfy its obligation seriously to weigh even its grossly understated costs against the benefits sought to be secured by the Standard.”96
Our review of these challenges is not designed to resolve the technical and economic debates. Our duty is simply to determine from close scrutiny of the entire record whether the feasibility of the standard is adequately supported by data and policy considerations. In addition, the agency must have considered and responded to serious challenges to the claim of feasibility. On both counts, we find that OSHA has performed its task adequately.
1. Technological feasibility
The textile industry does not argue that the exposure level set for the initial stages of textile manufacturing is technologically infeasible.97 Its attack is limited to the feasibility of the level set for the later stages of spinning through weaving,98 and to the four-year deadline for compliance.99
Judging the technological feasibility of a particular agency goal is beyond the expertise of the judiciary especially where the assessment involves predictions of technological changes.
Instead, our task on review is to find whether the agency sufficiently supported its feasibility determination with material in the record. Here, the agency’s position is supported with evidence that existing dust control techniques can bring about compliance in the textile industry.100
First, OSHA points to evidence in the record that many employers already are in compliance with the 200 pg/m 3 PEL set for spinning through warping operations. This finding at least in part refutes the industry’s charge that on technological grounds it cannot meet the required exposed level for these operations. Notably, three-fourths of the spinning operations described in the industry’s own study had dust levels below the 200 pg/m 3 level and others were very close to voluntary compliance.101
The textile industry does not contend that the looms or frames not yet in compliance in any way differ from those already complying with the new PEL. Rather, the industry asserts that the noncomplying mills run dustier cotton. This contention, as OSHA answers, is belied by the record, for the requisite PEL has been met in spin[75]*75ning operations running 100% coarse cotton, which is the dustiest variety.102
There is also evidence that some mills have achieved low dust levels in the twisting, winding, spooling, and warping operations.103 OSHA admits that these operations have been studied less than spinning, apparently because these operations generate very little cotton dust.104 The agency nevertheless obtained evidence that existing dust control principles can be adapted to these operations as the need arises.105
Similarly, the PEL set for slashing and weaving operations appears reasonable in light of the record. The industry’s own chief witness estimated that 72% of the weaving operations met the requirement of 750 pg/m3 when studied.106 OSHA also cited a study in the record that identified three basic approaches to permit compliance by the remaining mills in these operations: (1) isolating the weaving rooms; (2) separating room ventilation systems; and (3) installing local exhaust ventilation equipment.107
Thus, for each operation of textile manufacturing, the agency established evidence of present compliance and existing control measures capable of increasing compliance. The agency therefore concluded that a
combination of specific control measures the adoption and modification of general dust controls, and further utilization of technological developments already underway, should achieve compliance for the textile industry.108
The industry objects that OSHA drew unwarranted generalizations from dust measurements at small numbers of plants109 and from expert testimony on general principles of dust control.110 We agree that OSHA might have improved the quality of the record with more extensive studies at different mills and over different periods of time.111 Further study, however, [76]*76would have added substantial additional cost and delay to an already costly and prolonged rulemaking proceeding.112 Rather than directing the agency to wait for the best evidence, the OSH Act requires the agency to develop standards based upon “the best available evidence.” 113 This court will not require further survey research from the agency especially where it has made an informed decision to rely on other credible sources of information, such as the extensive expert testimony, written comment and briefs, and research studies used here.114
Indeed, other circuits have upheld permanent health standards supported by less extensive and persuasive evidence than that present here. Those courts have upheld similar OSHA standards that require cornpliance with PELs that had never before been attained,115 or that had been reached only at the “newest, cleanest” plants.116 Here, OSHA has shown that much of the textile industry already has demonstrated its ability to comply with the cotton dust standard. It also points to evidence in the record that little, if any, technological innovation will be necessary for compliance to be reached in the entire industry.117 Thus, thé agency’s finding of technological feasibility here is even more persuasive than findings affirmed in other cases that require the creation of new technology.
In sum, the agency fairly considered and took account of objections to its assessment of technological feasibility for the textile industry.118 The agency linked its determi[77]*77nation to evidence and policy considerations in the record. We support its judgment.
2. Economic Feasibility
The petitioners concede that OSHA’s estimate of $550 million in capital costs would be economically feasible for the textile industry, but they claim that OSHA’s estimate grossly understates the actual costs the industry will incur if the standard goes into effect. To evaluate this claim, we must first consider the accuracy of OSHA’s cost estimate and then review its feasibility determination.
a. Accuracy of cost estimates
OSHA derived its cost estimates from two principal sources: the Research Triangle Institute (RTI) estimates for the entire textile process119 and industry estimates for part of the textile process.120 OSHA tried to account for the divergence between the estimates from these two sources by exploring the assumptions each employed.121 After examination, the agency decided that both sets of estimates are overstatements, and chose to rely on what it regarded the best portions of each estimate.122
All parties agreed that the largest cost imposed by the standard is the capital cost of engineering controls. OSHA found the RTI capital cost figures to be overstated on several bases.123 OSHA concluded that RTI inappropriately included estimates for plants processing blends between cotton and synthetics.124 Further, OSHA found that RTI neglected the cost advantages available when compliance is achieved through modernizing rather than retrofitting the machinery.125 RTI also assumed industry-wide compliance with the old standard of 1000 Mg/m3.126 Thus, RTI estimated only the incremental cost necessary to achieve compliance with the new PEL. This estimate necessarily was inaccurate, as some of the industry had not yet complied with the old standard, while other plants [78]*78already had met the stricter new standard.127 Further, industry witnesses testified that “substantial amounts of [recommended] controls are, in fact, in operation.” 128
OSHA found the industry’s capital cost estimates to be overstated as well. Like RTI, the industry estimated only the costs of retrofitting old machines; it did not consider replacing them with new machines that are more productive and generate less dust.129 Similarly, the industry “may have included some equipment which is used exclusively for synthetics” and thus inappropriately included in cotton dust control cost estimates.130 The agency also noted that the industry estimates failed to account for improvements in technology that can reasonably be expected during the four-year compliance period.131
Finding both sets of capital cost estimates in the record to be exaggerated, the agency chose to rely on the substantially lower industry estimate. Unlike the RTI study, the industry’s assessment reflected concrete data on actual industry dust levels and use of controls.132
Ironically, it is now the industry that challenges the accuracy of its own data.133 The textile industry petitioners argue that OSHA’s reliance on the industry’s capital cost estimate is invalid because it is “wholly unrelated to the exposure limits set by the Standard.”134 The industry notes that its $550 million figure was advanced as the projected capital cost of compliance with a PEL of 200 ixg/m3 in opening through roving, 500 (xg/m 3 in spinning through warping, and 1000 ug/m 3 in slashing and weaving.135 Thus, for spinning through weaving, the industry’s estimate assumed a PEL requirement higher than the ones ultimately adopted — the 200 ug/m3 level for spinning through warping and 750 |xg/m3 in slashing and weaving. The textile industry contends that by ignoring this fact, OSHA’s final standard is based on a grossly understated cost estimate.
OSHA, however, marshals sufficient support and analysis for its decision to use the industry’s capital cost estimate. Contrary to the industry’s claim that this estimate, is “wholly unrelated” to the PELs in the final standard, OSHA’s technological assessment concluded that little more than the dust control measures assumed by the industry would be necessary to achieve the final PEL.136 OSHA also explained that even the industry capital estimates were exaggerated because they included some unnecessary costs.137 Thus, OSHA reasonably viewed the industry’s figure as an overstated estimate for exposure levels set slightly higher than those in the agency’s final standard.
[79]*79Since the only other available figure was the far less accurate RTI estimate138 the agency’s ultimate reliance on the industry’s capital cost estimate is reasonable. The RTI estimate lacked a basis in the industry’s actual dust reduction. It also presumed a PEL for weaving and slashing far lower than the final PEL, which more nearly approximated the exposure level and control technology assumed by the industry.139
The very nature of economic analysis frequently imposes practical limits on the precision which reasonably can be required of the agency. This is especially the case where, as .here, the industry chooses to withhold from the agency part of the data underlying the industry’s cost estimates.140 OSHA’s mandate authorizes it to promulgate standards on the basis of the “best available evidence.”141 We find that OSHA reasonably evaluated the cost estimates before it, considered criticisms of each, and selected suitable estimates of compliance costs.142
b. Feasibility of compliance costs
The actual test for economic feasibility has yet to be fully developed by the courts.143 This court has suggested that the costs cannot be “prohibitively expensive” for Congress would not have intended OSHA to make “financial viability generally impossible” for a regulated industry.144
Here, the agency had evidence in its record that the industry would be able to pass compliance costs on to consumers.145 Although the record also contained testimony suggesting that older and smaller firms might bear a disproportionate financial burden,146 it does not support the industry’s claim of infeasibility. Even if a few firms are forced to shut down, the standard is not necessarily economically infeasible. As this court observed in Industrial Union,
It would appear to be consistent with the purposes of the Act to envisage the economic demise of an employer who has lagged behind the rest of the industry in protecting the health and safety of employees and is consequently financially [80]*80unable to comply with new standards as quickly as other employers.147
Here the agency expressed concluded “that although some marginal employers may shut down rather than comply, the industry as a whole will not be threatened by the capital requirements of the regulation.”148
Of course, the agency’s underlying cost estimates are not free from imprecision. Nonetheless, on reviewing the record we believe that OSHA fairly considered all the economic data submitted before constructing its estimates. The agency responded to significant criticisms of the cost estimates it used, and explained the economic impact it projected for the textile industry. As a result, this court is satisfied that OSHA has substantial support in the record for its cost estimates and findings of economic feasibility for the textile industry. The position of the union petitioners on this issue149 buttresses OSHA’s conclusion that the standard will not put the industry out of business.150
3. Cost-Benefit and Cost-Effectiveness Analysis
Industry petitioners would have this court impose an additional constraint on OSHA’s authority to determine standards. They claim that under the feasibility requirement, OSHA must demonstrate that “the benefits of the standard are in proportion with the costs which it imposes.” 151 This amounts to a claim that no standard may be promulgated under section 6(b)(5) of the Act absent a formal cost-benefit analysis.152 The industry similarly ar[81]*81gues that OSHA must justify the expense imposed by its standard by comparing it with the industry’s proposed alternative.153
OSHA agrees that a systematic evaluation of costs and benefits is to be encouraged within the limits of available estimation techniques,154 yet it contends that such analysis is not required. OSHA argues that the OSH Act constrains its regulation of dangerous substances “only by the limits of feasibility.”155 We agree. We also find that no additional constraint is imposed by the Act’s definition of a health or safety standard as “reasonably necessary or appropriate to provide safe or healthful employment.” 156 The language of the Act and the clear intention of Congress permit no other conclusion.
Other statutory schemes explicitly require such particular kinds of analysis. In the Clean Air Act, for example, Congress required the Environmental Protection Agency to perform a “cost benefit analysis” before prohibiting the manufacture or sale of a fuel or fuel additive which endangers public health or welfare.157 Some Congressional Acts require a showing of “unreasonable risk” prior to regulation.158 The legislative histories of these acts have led the courts to construe this provision to require regulatory agencies to balance costs and benefits of proposed action.159
In the OSH Act, in contrast, Congress itself struck the balance between costs and benefits in the mandate to the agency. Section 6(b)(5) unequivocally mandates OSHA to
set the standard which most adequately assures, to the extent feasible, on the basis of the best available evidence, that [82]*82no employee will suffer material impairment of health or functional capacity.160
Thus Congress concluded that the benefits of health protection warranted the expense of an effective standard.161 In the legislative debates on the Act, Senator Yarborough who sponsored the bill responded in no uncertain terms to the claim that the proposed legislation would be too expensive:162 We are talking about people’s lives, not the indifference of some cost accountants.
. We are talking about assuring our American workers who work with deadly chemicals that when they have accumulated a few years seniority they will not have accumulated lung congestion and poison in their bodies, or something that will strike them down before they reach retirément age.163
In contrast to the Acts for which Congress contemplated a cost-benefit requirement, the legislative history of the OSH Act contains no reference to this kind of economic analysis.164
Instead, Congress determined in the OSH Act that any severe risk to employee health must be eliminated or reduced if feasible means to do so exist.165 This calls for a two-step analysis by the agency: (1) determining whether health impairment is threatened by the suspect substance, and (2) determining whether the selected strategy to protect workers from this risk is both technologically and economically feasible. Nothing in the statute or its legislative history requires a further determination that the costs of the standard bear a “reasonable” relationship to its benefits.166 Nor [83]*83may this court impose additional procedural requirements.167 Indeed, the only authorities cited by petitioners are not binding on this circuit,168 and in any event, they are not persuasive in this context.169
Further, cost-benefit analysis would not necessarily improve agency health and safety determinations.170 These techniques require the expression of costs, benefits and performance in often arbitrary, measureable terms.171 They may hide assumptions and qualifications in the seeming objectivity of numerical estimates. Especially where a policy aims to protect the health and lives of thousands of people, the difficulties in comparing widely dispersed benefits with more concentrated and calculable costs may overwhelm the advantages of such analysis.172
[84]*84OSHA considered the alternative proposed by the industry and found it inadequate to protect against the health risk at issue. We recognize that the agency’s control strategy is costly. But it is the result of long and comprehensive investigation by the agency assisted by extensive public participation.173 We find that the health risk posed by cotton dust warranted agency action, and that the final standard chosen by the agency is technologically and economically feasible for the textile industry within the meaning of the Act.174
IV. NON-TEXTILE INDUSTRIES
In the final standard, OSHA set a permissible exposure level of 500 ng/m3 for all non-textile industries covered by the standard.175 Three such industries here challenge the standard:176 (1) the cottonseed oil mills, which process cottonseed and its byproducts; (2) the cotton warehouses, which store raw, baled cotton; and (3) the classing offices, which classify samples of cotton fiber.177
The non-textile petitioners claim that OSHA failed to establish that their workers risk material health impairment and that the PEL set for these industries is arbitrary. Further, they claim that the standard is infeasible on both technological and economic grounds.
A. Health Risks and Permissible Dust Exposure
Petitioners do not dispute that their employees are exposed to cotton dust,178 often at higher levels than in textile mills. They assert, however, that the work processes, dust composition, and worker exposure to dust in nontextile industries differ significantly from the textile industry.179 In this way, petitioners seek to challenge OSHA’s general position that exposure to cotton dust poses a serious hazard to workers regardless of where the dust is encountered.180
The exact nature of the health hazard posed by cotton dust remains subject to medical debate.181 The agency had before it conclusive evidence that dust found in textile mills causes debilitating disease;182 [85]*85it also had some evidence of related, though less severe, health impairments among workers in nontextile industries.183 Although petitioners point to differences among the industries, OSHA’s mandate requires it to protect workers in all industries.184 We find that OSHA fulfilled this mandate by reasonably relying on medical evidence from the textile industry185 and evidence of health impairments among non-textile workers.186 The differences in the industries that were cited by petitioners do not undermine the agency’s determination.
The agency did acknowledge that health effects in the nontextile industries appear to be less prevalent and less severe than in the textile mills,187 but concluded that the individual nontextile workers still run the risk of material health impairment. The agency reasoned that high worker turnover and movement in the workplace, rather than a lesser risk from exposure to dust, may explain the less severe aggregate pattern of disease.188 We find no reason to disturb this judgment in favor of the more dubious conclusion that the nontextile workers are not endangered.
Moreover, the agency took account of the pattern of health effects when it raised the final PEL for the nontextile industries to 500 ng/m3 from the proposed 200 pg/m3 level.189 The agency fairly concluded that the industries’ data lent guidance to the permissible dust exposure level, but did not cast doubt on the agency’s evidence of health risks to nontextile workers.190
[86]*86OSHA thus explained the evidence it used, the reasons for its conclusions, and its responses to the industries’ evidence and objections. When agencies are entrusted with regulating risks on the frontiers of scientific and medical knowledge, we cannot ask for more.191
Petitioners nevertheless argue that we should find it arbitrary and unreasonable for OSHA to set the standard before NIOSH completes its study of the non-textile industries.192 Certainly, OSHA should take advantage of the ongoing research of NIOSH and other major inquiries into occupational health and safety. But by law, OSHA need not wait for NIOSH recommendations before protecting against occupational health risks.193 Nor are such recommendations conclusive.194 A legitimate challenge to a health and safety standard can be raised as new data emerges,195 but OSHA did not exceed its authority by regulating as soon as it knew of the risks of material health impairment from dust exposure.196
B. Feasibility
Judgments about the technological capabilities and financial positions of the industries affected by the standard depend on the evidence for each one, so we examine [87]*87evidence on the warehouse, classing office, and cottonseed oil mill industries.
1. Warehouses and Classing Offices
The warehousing industry does not dispute the feasibility of the standard. Indeed, OSHA determined that most warehouses are already in compliance with the standard now that the final PEL for that industry has been raised to 500 pg/m3.197 For those portions of the industry not in compliance, the record indicates that improved ventilation and housekeeping will adequately, assure compliance.198
OSHA also reasonably concluded that most classing offices199 are “substantially in compliance” with the 500 pg/m3 PEL.200 Where dust control is necessary, the record supports OSHA’s finding that minor ventilation modifications can effectively reduce dust exposure in classing offices to the requisite level.201
Thus we uphold the agency’s finding that dust control is both technologically and economically feasible for warehousing and classing offices. These two industries claim, however, that non-engineering controls required by OSHA — medical surveillance and provision of respirators — will impose burdensome and unjustified costs.202 Congress itself rejected this claim. It authorized the agency to regulate even if industries become financially burdened,203 so long as the burden is not “prohibitively expensive.” 204 OSHA need not “justify” its health and safety standards through a cost-benefit analysis 205 as the petitioners imply. Rather, OSHA must simply establish the risk of material health impairment and demonstrate the economic and technological feasibility of its standard for the regulated industries.206 We hold that it has satisfied these requirements for the warehousing and classing office industries.
2. Cottonseed Oil Mills
Perhaps the most hotly contested aspect of the standard is its feasibility for the cottonseed oil industry. OSHA admits that considerable effort will be required for this industry to comply with the standard. We find that OSHA has adequately demonstrated the technological feasibility of the standard for this industry, but the record does not sufficiently establish its economic feasibility.
[88]*88First, the record does sufficiently support the agency’s conclusion that existing methods of dust control will permit compliance with the dust exposure level set for this industry. OSHA relied in part on evidence of dust control techniques already effective in related industries.207 It also found support in the industry’s own theoretical study that was designed as if the authors “were consulting engineers given the task of lowering dust levels in a typical cottonseed oil mill to the lowest feasible level.” 208 As that study was commissioned by the industry in response to the proposed 200 ug/m3 PEL,209 we find no reason to disturb the agency’s judgment that the techniques proposed by the study would allow compliance with the final 500 ug/m3 PEL.210 Agencies are permitted to rely on estimates and policy judgments of this kind so long as they are fully explained and authorized by statute.211 We therefore affirm the agency’s finding of technological feasibility for this industry.
The agency’s position on economic feasibility, in contrast, is neither clear nor adequately supported by the record. OSHA acknowledged that “[m]uch of the testimony on cottonseed processing . . . predicted dire economic effects including a substantial number of plant closings.”212 The industry estimated that 62 of the existing 83 mills, or approximately 52 percent of the industry’s production capacity, will be forced to shut down if the standard is put into effect.213
In response, OSHA merely criticized the industry’s estimate without constructing an alternative or fully explaining the basis for its criticism.214 For example, OSHA suggested that the industry calculated “retro[89]*89fit” costs twice.215 Yet the agency never located these calculations in the record nor identified the amount by which the cost estimate should be reduced to eliminate double-counting. Similarly, OSHA asserted without further explanation that the industry overstated production losses because the dust control strategy was designed to minimize such losses.216 Also, OSHA claimed that the industry’s cost estimate fails to acknowledge existing compliance with the standard, but the only evidence OSHA provides is the existence of a medical surveillance program in one company.217 Absent more evidence on the extent of existing compliance, or the other asserted grounds of overestimation, we are unable to determine whether the industry’s total cost estimate is unreasonable, as the agency contends. Even if the industry’s estimate is exaggerated, OSHA offered no evidence that the cost of compliance will not cause “serious disruption,” as petitioners claim.218
Instead, the agency concedes that the standard may “accelerate” an existing trend of financial and economic decline in the cottonseed oil industry.219 The agency apparently assumed that the standard’s economic feasibility is not challenged because other factors will contribute to the anticipated shutdowns. In so assuming, the agency fails to indicate the number of shutdowns it anticipates or the role that the standard, as [90]*90opposed to other economic pressures, will play in plant closings.220 As a result, this court has no basis for reviewing the agency’s conclusion that the standard is economically feasible for the cottonseed oil industry.221
Finally, the agency suggests that the industry will be able to pass the costs of the standard back to cotton growers.222 OSHA argues that cotton growers will inevitably have a constant supply of cottonseed and will be willing to accept a lower price for the seed, shifting the loss forward to purchasers of raw cotton.223 But the agency adduces no evidence or testimony to support this theory. In fact, the record shows only the contrary conclusion, drawn by the industry’s, economic impact study, that cotton producers will switch to other produce if the industry seeks to lower the price of cotton byproducts.224 OSHA itself acknowledges that many past shutdowns of cottonseed oil mills have been due to contractions in the supply of cottonseed.225 Absent more information, this court cannot determine whether the agency’s cost pass-back theory adequately responds to the industry’s estimate of massive shutdowns.
If the constraint of economic feasibility is to have any effect on the agency’s rulemaking, it demands more serious consideration than it was given here.226 The agency is allowed to rely on the best available evidence,227 but here it simply gives general criticisms of the cottonseed industry’s cost estimate. It failed to offer an alternative estimate of the standard’s impact on this industry. As a result, the agency’s position [91]*91is too unclear to permit us to complete our reviewing function. We therefore remand this issue for clarification or reconsideration by the agency.228
V. OTHER CHALLENGES
We conclude that the standard withstands the remaining challenges to the standard’s implementation period, employee-transfer provision, and use of pulmonary function tables.
A. The Four-Year Implementation Program
The standard does not require any employer to complete implementation of engineering or work practice controls until four years after its effective date.229 The textile industry challenges this time period as too stringent; 230 the union challenges it as too lax.231 Both groups of petitioners claim that the agency’s decision lacks support in the record, authorization under the OSH Act, and adequate explanation by the agency-
We find no basis to petitioners’ claims. OSHA reasonably set the four-year compliance period to accommodate the competing needs of employers who need time to achieve compliance and the needs of employees who need protection from health risks.232 The agency decided that to meet the standard’s requirements, employers should first monitor employee health, consult with experts, and prepare detailed compliance plans.233 The four-year period it chose we find will permit orderly, industry-wide compliance.234 Employers for whom this period is infeasible can seek an administrative variance.235 The agency still as[92]*92sures protection to workers during the implementation period with the standard’s respirator provisions.236 We cannot disturb the agency’s decision simply because petitioners would have struck a different balance between the needs of employers and employees.237 We find that the four-year period reflects reasoned decisionmaking on the basis of the rulemaking record.
B. The Medical Transfer and Wage Guarantee Provisions238
The standard includes special provisions for employees who, for medical reasons, cannot wear respirators. Section 1910.1023(f)(2)(v) provides for the transfer of such employees to positions outside the dusty areas: which later becomes available having a dust level at or below the PEL.239 This section also guarantees the wages and benefits of transferred employees:
Whenever a physician determines that an employee is unable to wear any form of respirator, . . . the employee shall be given the opportunity to transfer to another position which is available or
The employer shall assure [that] an employee who is transferred due to an inability to wear a respirator suffers no loss of earning or other employment rights or benefits as a result of the transfer.240
The textile petitioners argue that this provision exceeds OSHA’s statutory authority.241 We find to the contrary that this provision falls within the agency’s authority to include in its standards such “practices, means, methods, operations, or processes, [that are] reasonably necessary or appropriate to provide safe or healthful employment.” 242 OSHA determined that a limited number of employees cannot be protected even temporarily by respirators.243 Absent the medical transfer and wage guarantee provisions, during the interim compliance period these employees would be forced to suffer continuing exposure to impermissibly high dust levels or else risk disadvantageous [93]*93transfers, or even risk losing their jobs.244 Given these alternatives, such employees may refrain from disclosing actual health impairments from the dust exposure. OSHA is authorized to guard against such problems. Its mandate is to assure that “no employee will suffer material impairment of health or functional capacity” on the job.245 In light of the Act’s purposes,246 OSHA sought to avoid these problems and properly placed the cost of employee protection on the employer.
Employers will be burdened for only a short time by the medical transfer and wage guarantee provisions. Once employers achieve the requisite exposure levels, no employees, to be protected, will need respirators or job transfers. In the meantime, the provisions provide a reasonable incentive for employers to speed compliance efforts. They also sensibly allocate the transfer decision to doctors surveying the individual workers. We find, therefore, that the medical transfer and wage guarantee provisions fall within OSHA’s authority to adopt methods reasonably necessary to ensure safe working conditions.247
C. Pulmonary Function Tables
OSHA included as Appendix C to the standard a set of tables that establishes predicted pulmonary function values as the norm against which employees’ actual lung functions are to be measured.248 Under the standard’s medical surveillance provisions, if an employee’s actual lung function falls more than twenty percent below the appropriate value specified in these tables, the employee must be retested every six months until the table’s values are met.249
The textile industry asks us to vacate these tables.250 The industry claims that the tables and the studies on which they are based were not made part of the record and were not available for public comment before the promulgation of the final standard. Further, the industry claims that the tables rely on studies of a sample population that does not share important characteristics with the employees who will be measured against the tables.251
We find petitioners’ claims unwarranted. This is not an instance of a final standard that contains a provision substantially different from the proposed version.252 The [94]*94proposed version contained similar tables and the agency explicitly solicited comments on their use.253 There is no doubt that the general concept of pulmonary function tables as benchmarks in medical surveillance was thoroughly discussed during the informal rulemaking proceeding.254
Petitioners still ask us to vacate the tables finally adopted because their exact form and contents were not available for comment during the rulemaking process. Were we to agree, we would essentially preclude the agency from responding to comments during the rulemaking process,255 for the tables finally adopted were a logical outgrowth of testimony received during the rulemaking proceeding.256 The sample population employed improve the scientific reliability of these tables when compared with those used in the proposed standard.257 Thus, we find the adoption of these tables consistent with the requirements of informal rulemaking and with the agency’s duty to base the standard on the “best available evidence.”258
CONCLUSION
Our task on review has not been easy. The record is massive and unwieldy; 259 it reveals numerous medical and technical issues in need of continued study. Congress, however, has made it clear that OSHA must protect every worker from the risks of material health impairment due to occupational exposure to hazardous materials. OSHA is constrained only by the requirement that its standards be technologically and economically feasible for the regulated [95]*95industries. In sum, our review leads us to uphold the standard, except for its application to the cottonseed oil industry. In every aspect except that one, OSHA explained the evidence in the record it found persuasive and the policies that guided its judgment when facts proved insufficient. As for the cottonseed oil industry, however, we are unable to discern the basis for the agency’s feasibility determination. We do not conclude that the standard is infeasible for that industry; rather, we remand that portion for reconsideration or clarification by the agency.
Ordinarily, we would remove the stay of the standard that was granted for the pend-ency of this litigation. In view of the alleged magnitude of the consequences, however, we will defer action regarding the stay to afford petitioners 20 days to show cause why the stay should not be lifted.
It is so ordered.