delivered the opinion of the Court.
A regulation of the Equal Employment Opportunity Commission authorizes refusal to hire an individual because his performance on the job would endanger his own health, owing to a disability. The question in this case is whether the Americans with Disabilities Act of 1990, 104 Stat. 328, 42 U. S. C. § 12101 et seq. (1994 ed. and Supp. V), permits the regulation. 1 We hold that it does.
I
Beginning in 1972, respondent Mario Echazabal worked for independent contractors at an oil refinery owned by petitioner Chevron U. S. A. Inc. Twice he applied for a job directly with Chevron, which offered to hire him if he could рass the company’s physical examination. See 42 U. S. C. § 12112(d)(3) (1994 ed.). Each time, the exam showed liver abnormality or damage, the cause eventually being identified as Hepatitis C, which Chevron’s doctors said would be aggravated by continued exposure to toxins at Chevron’s refinery. In each instance, the company withdrew the offer, and the second time it asked the contractor employing Echazabal either to reassign him to a job without exposure to hаrmful chemicals or to remove him from the refinery altogether. The contractor laid him off in early 1996.
Echazabal filed suit, ultimately removed to federal court, claiming, among other things, that Chevron violated the Americans with Disabilities Act (ADA or Act) in refusing to
On appeal, the Ninth Circuit asked for briefs on a threshold question not raised before, whether the EEOC’s regulation recognizing a threat-to-self defense,
ibid.,
exceeded the scope of permissible rulemaking under the ADA.
The decision conflicted with one from the Eleventh Circuit,
Moses
v.
American Nonwovens, Inc.,
II
Section 102 of the ADA, 104 Stat. 328, 42 U. S. C. § 12101
et seq.,
prohibits “discrimination] against a qualified individual with a disability because of the disability ... in regard to” a number of actions by an employer, including “hiring.” 42 U. S. C. § 12112(a). The statutory definition of “discrimination]” covers a number of things an employer might do to block a disabled pеrson from advancing in the workplace, such as “using qualification standards . . . that screen out or tend to screen out an individual with a disability.” § 12112(b)(6). By that same definition,
ibid.,
as well as by separate provision, § 12113(a), the Act creates an affirmative defense for action under a qualification standard “shown to be job-related for the position in question and ... consistent with business necessity.” Such a standard may include “a requirement that an individual shall not pose a direct threat to the health or safety of other individuals in the workplace,” § 12113(b), if the individual cannot perform the job safely with reasonable accommodation, § 12113(a). By regulation, the EEOC carries the defense one step further, in allowing an employer to screen out a potential worker with a disability not only for risks that he would pose to others in the workplace but for risks on the job to his own health or safety as well: “The term ‘qualification standard’ may include a requiremеnt that an individual shall not pose
Chevron relies on the regulation here, since it says a job in the refinery would pose a “direct threat” to Echazabal’s health. In seeking deference to the agency, it argues that nothing in the statute unambiguously precludes such a defense, while the regulation was adopted under authority explicitly delegated by Congress, 42 U. S. C. § 12116, and after notice-and-comment rulemaking. See
United States
v.
Mead Corp.,
A
As for the textual bar to any agency action as a matter of law, Echazabal says that Chevron loses on the threshold question whether the statute leaves a gap for the EEOC to fill. See
id.,
at 843-844. Echazabal recognizes the generality of the language providing for a defense when a plaintiff is screened out by “qualification standards” that are “job-related and consistent with business necessity” (and reasonable accommodation would not cure the difficulty posed by employment). 42 U. S. C. § 12113(a). Without more, those provisions would allow an employer to turn away someone whose work would pose a serious risk to himself. That possibility is said to be еliminated, however, by the further specification that “‘qualification standards’ may include a requirement that an individual shall not pose a direct threat to the health or safety of other individuals in the workplace.” § 12113(b); see also §12111(3) (defining “direct threat” in terms of risk to others). Echazabal contrasts this provision with an EEOC regulation under the Rehabilitation Act of 1973, 87 Stat. 357, as amended, 29 U. S. C. § 701
et seq.,
ante
The argument follows the reliance of the Ninth Circuit majority on the interpretive canon,
expressio unius est exclusio alterius,
“expressing one item of [an] associated group or series excludes another left unmentioned.”
United States
v.
Vonn,
The first strike against the expression-exclusion rule here is right in the text that Echazabal quotes. Congress included the harm-to-others provision as an example of legitimate qualifications that are “job-related and consistent with business necessity.” These are spacious defensive categories, which seem to give an agency (or in the absence of agency action, a court) a gоod deal of discretion in setting the limits of permissible qualification standards. That discretion is confirmed, if not magnified, by the provision that “qualification standards” falling within the limits of job relation and business necessity “may include” a veto on those who would directly threaten others in the workplace. Far from supporting Echazabal’s position, the expansive phrasing of “may include” points directly away from the sort of exclusive specification he claims.
United States
v.
New York Telephone Co.,
Strike two in this case is the failure to identify any such established series, including both threats to others and threats to self, from which Congress appears to have made a deliberate choice to omit the lattеr item as a signal of the affirmative defense’s scope. The closest Echazabal comes is the EEOC’s rule interpreting the Rehabilitation Act of 1973, 87 Stat. 357, as amended, 29 U. S. C. § 701
et seq.,
a precursor of the ADA. That statute excepts from the definition of a protected “qualified individual with a handicap” anyone who would pose a “direct threat to the health or safety of other individuals,” but, like the later ADA, the Rehabilitation
But two reasons stand in the way of treating the omission as an unequivocal implication of congressionаl intent. The first is that the EEOC was not the only agency interpreting the Rehabilitation Act, with the consequence that its regulation did not establish a clear, standard pairing of threats to self and others. While the EEOC did amplify upon the text of the Rehabilitation Act exclusion by recognizing threats to self along with threats to others, three other agencies adopting regulations under the Rehabilitation Act did not. See 28 CFR §42.540(0(1) (1990) (Department of Justice), 29 CFR § 32.3 (1990) (Department of Labor), and 45 CFR § 84.3(k)(l) (1990) (Depаrtment of Health and Human Services). 4 It would be a stretch, then, to say that there was a standard usage, with its source in agency practice or elsewhere, that connected threats to others so closely to threats to self that leaving out one was like ignoring a twin.
Even if we put aside this variety of administrative expérience, however, and look no further than the EEOC’s Rehabil
There is even a third strike against applying the expression-exclusion rule here. It is simply that there is no apparent stopping point to the argument that by specifying a threat-to-others defense Congress intended a negative implication about those whose safety could be considered. When Congress specified threats to others in the workplace, for example, could it possibly have meant that an employer could not defend a refiisal to hire when a worker’s disability
B
Since Congress has not spoken exhaustively on threats to a worker’s own health, the agency regulation can claim adherence under thе rule in
Chevron,
Eehazabal points out that there is no known instance of OSHA enforcement, or even threatened enforcement, against an employer who relied on the ADA to hire a worker willing to accept a risk to himself from his disability on the job. In Echazabal’s mind, this shows that invoking OSHA policy and possible OSHA liability is just a red herring to excuse covert discrimination. But there is another side to this. The text of OSHA itself says its point is “to assure so far as possible every working man and woman in the Nation safe and healthful working conditions,” § 651(b), and Congress specifically obligated an employer to “furnish to each of his employees employment and a place of employment which are free from recognized hazards, that are causing or are likely to cause death or seriоus physical harm to his employees,” § 654(a)(1). Although there may be an open question
Nor can the EEOC’s resolutiоn be fairly called unreasonable as allowing the kind of workplace paternalism the ADA was meant to outlaw. It is true that Congress had paternalism in its sights when it passed the ADA, see § 12101(a)(5) (recognizing “overproteetive rules and policies” as a form of discrimination). But the EEOC has taken this to mean that Congress was not aiming at an employer’s refusal to place disabled workers at a specifically demonstrated risk, but was trying to get at refusals to give an even break to classes of disabled people, while claiming to act for their own good in reliance on untested and pretextual stereotypes.
5
Its regu
Accordingly, we reverse the judgment of the Court of Appeals and remand the case for proceedings consistent with this opinion.
It is so ordered.
Notes
We do not consider the farther issue passed upon by the Ninth Circuit, which held that the respondent is a “ ‘qualified individual’ ” who “can perform the essential functions of the employment position,” 42 U. S. C. §12111(8) (1994 ed.).
Chevron did not dispute for purposes of its summary-judgment motion that Echazabal is “disabled” under the ADA, and Echazabal did not argue that Chevron could have mаde a ‘“reasonable accommodation.’” App. 184, n. 6.
In saying that the expansive textual phrases point in the direction of agency leeway we do not mean that the defense provisions place no limit on agency rulemaking. Without deciding whether all safety-related qualification standards must satisfy the ADA's direct-threat standard, see
Al-
In fact, we have said that the regulations issued by the Department of Health and Human Services, which had previously been the regulations of the Department of Health, Education, and Welfare, are of “particular significance” in interpreting the Rehabilitation Act because “HEW was the agency responsible for coordinating the implementation and enforcement of § 504 of the Rehabilitation Act, 29 U. S. C. § 794,” prohibiting discrimination against individuals with disabilities by recipients of federal funds.
Toyota Motor Mfg., Ky., Inc.
v.
Williams,
Echazabal’s contention that the Act’s legislative history is to the contrary is unpersuasive. Although some of the comments within the legislative history decry paternalism in general terms, see,
e. g.,
H. R. Rep. No. 101-485, pt. 2, p. 72 (1990) (“It is critical that paternalistic concerns for the disabled person’s own safety not be used to disqualify an otherwise qualified applicant”); ADA Conf. Rep., 136 Cong. Rec. 17377 (1990) (statement of Sen. Kennedy) (“[A]n employer could not use as an excuse for not hiring a person with HIV disease the claim that the employer was simply ‘protecting the individual’ from opportunistic diseases to which the individual might be exposed”), those comments that elaborate actually express the more pointed concern that such justifications are usually pretextual,
Similarly, Echazabal points to several of our decisions expressing concern under Title VII, which like the ADA allows employers to defend otherwise discriminatory practices that are “consistent with business necessity,” 42 U. S. C. § 2000e-2(k), with employers adopting rules that exclude women from jobs that are seen as too risky. See,
e. g., Dothard
v.
Rawlinson,
Respect for this distinction does not entail the requirement, as Echaza-bal claims, that qualification standards be “neutral,” stating what the job requires, as distinct from a worker’s disqualifying characteristics. Brief for Respondеnt 26. It is just as much business necessity for skyscraper
