[Federal Register Volume 62, Number 129 (Monday, July 7, 1997)]
[Notices]
[Pages 36436-36446]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-17597]



[[Page 36435]]

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Part VI





Environmental Protection Agency





_______________________________________________________________________



Draft Determination of Adequacy of Section 112 Authorities and Draft 
Determination of Need for Additional Standards; Notice

  Federal Register / Vol. 62, No. 129 / Monday, July 7, 1997 / 
Notices  

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-58536-3; Docket No. A-97-21]
RIN 2060-AH49


Draft Determination of Adequacy of Section 112 Authorities And 
Draft Determination of Need for Additional Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of draft determinations.

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SUMMARY: Today's notice provides, for public comment, the EPA's draft 
determinations that the legal authorities and mandates provided by 
section 112 of the Clean Air Act (CAA) are adequate to prevent serious, 
adverse, public health effects and serious or widespread environmental 
effects associated with atmospheric deposition of hazardous air 
pollutants to the Great Waters. Today's notice also provides EPA's 
draft determination that, at this time, further emission standards or 
control measures under section 112, beyond those otherwise authorized 
by section 112, are not necessary and appropriate to prevent such 
effects. These actions are being taken pursuant to section 112(m)(6) of 
the CAA, as amended in 1990, and a consent decree entered in Sierra 
Club v. Browner, Civ. No. 96-1680. Final determinations are required 
under the consent decree to be made by March 15, 1998.

DATES: Written comments must be submitted by August 6, 1997.

ADDRESSES: Commenters must send an original and two copies of their 
comments, referencing docket number A-97-21, to the Air Docket, U.S. 
Environmental Protection Agency, 401 M Street, SW, Washington, DC 
20460.
    Comments and data may also be submitted electronically by following 
the instructions under SUPPLEMENTARY INFORMATION of this document. No 
Confidential Business Information (CBI) should be submitted through e-
mail.

FOR FURTHER INFORMATION CONTACT: Dianne Byrne, Office of Air Quality 
Planning and Standards (MD-15), U.S. Environmental Protection Agency, 
Research Triangle Park, North Carolina 27711, telephone number (919) 
541-5342.

SUPPLEMENTARY INFORMATION:

Electronic Availability

    The official record for this notice, as well as the public version, 
has been established for this notice under docket number A-97-21 
(including comments and data submitted electronically as described 
below). A public version of this record, including printed, paper 
versions of electronic comments, which do not include any information 
claimed as CBI, is available for inspection from 8 a.m. to 4 p.m., 
Monday through Friday, excluding legal holidays. The official record is 
located at the address in ADDRESSES at the beginning of this document. 
Electronic comments can be sent directly to EPA at A-and-R-
D[email protected]. Electronic comments must be submitted as an 
ASCII file avoiding the use of special characters and any form of 
encryption. Comments and data will also be accepted on disks in Word 
Perfect in 5.1 file format or ASCII file format. All comments and data 
in electronic form must be identified by the docket number (A-97-21). 
Electronic comments on this draft notice may be filed online at many 
Federal Depository Libraries.
    The information in this notice is organized as follows:

I. Background
II. Introduction
    A. Statutory Requirements for Great Waters Program
    B. Scope of Analysis
III. Statutory Analysis--Other Provisions Relative to section 112(m) 
Mandate
    A. Definition of Major Source
    B. Definition of Adverse Environmental Effect
    C. Listing of Pollutants
    D. Listing of Sources
    E. Regulations to Control Emissions of Pollutants
    1. MACT and GACT Standards
    2. Residual Risk Standards
    F. Urban Area Source Program
    G. Studies and Reports to Congress
    1. Mercury
    2. Electric Utilities
    H. Solid Waste Incineration Units
IV. Determination of Adequacy and No Need for Further Regulations

I. Background

    Pursuant to section 112(m)(6) of the CAA, EPA is submitting for 
public comment a draft determination that the legal authorities and 
mandates provided by section 112 of the CAA are adequate to prevent 
serious, adverse, public health effects and serious or widespread 
environmental effects associated with atmospheric deposition of 
hazardous air pollutants (HAP) to the Great Waters. The EPA is also 
submitting for public comment its draft determination that further 
emissions standards or control measures under section 112(m)(6), beyond 
those otherwise authorized or required by section 112, are not at this 
time necessary or appropriate to prevent such effects. The bases for 
these draft determinations are discussed in today's notice and are 
briefly summarized below.
    Section 112(m)(6) of the CAA requires that EPA determine whether 
adequate authority exists within the provisions of section 112, other 
than subsection (m)(6) to prevent serious, adverse, effects to public 
health and serious or widespread environmental effects associated with 
atmospheric deposition of HAP to the Great Waters. In conducting this 
assessment, EPA reviewed the authorities granted by section 112, as 
they may function to reduce adverse effects caused by deposition of HAP 
to the Great Waters. It should be emphasized that this determination 
pertains to the authority within the CAA to take actions as appropriate 
to address the enumerated effects; it does not pertain to the efficacy 
of prior or future actions. In addition, the scope of this 
determination is focused on the authority within section 112 to address 
those pollutants and sources that can be regulated under that section's 
authority. As such, pollutants that are not listed as HAP, pursuant to 
section 112(b), and source categories that could not be listed pursuant 
to section 112(b) are not included within the scope of this 
determination. While not part of this determination, it may be useful 
to note that some unlisted pollutants that are pollutants of concern to 
the Great Waters are regulated by other sections of the CAA (such as 
nitrogen oxides which are regulated pursuant to sections 108, 109, 202, 
and section 407). Similarly, source categories that are outside the 
scope of section 112 can be regulated under other provisions of the CAA 
(such as mobile sources regulated pursuant to section 202). Emissions 
of the Great Waters' pollutants of concern that are addressed by other 
statutes (e.g., wastewater discharges addressed by the Clean Water Act) 
are also not within the scope of this adequacy determination.
    Section 112 establishes a statutory scheme by which EPA is to 
identify HAP which may cause or contribute to adverse effects to public 
health or the environment, develop performance standards for the 
control of emissions from stationary sources of such HAP (in addition 
to the HAP listed by Congress in the CAA), and adjust these control 
requirements as needed to address any remaining unacceptable risk that 
may be present after sources have complied with the emission standards. 
The types of adverse environmental effects to be prevented are defined 
in the CAA and are broad in scope. An adverse environmental effect is 
defined by section 112(a)(7) as ``any significant and widespread 
adverse effect, which may reasonably be anticipated, to wildlife,

[[Page 36437]]

aquatic life, or other natural resources, including adverse impacts on 
populations of endangered or threatened species or significant 
degradation of environmental quality over broad areas.''
    Authorities provided by other provisions of section 112 that may be 
particularly relevant to the Great Waters' pollutants and sources are 
briefly summarized below. Section 112 authorizes EPA to:

--Identify and list any air pollutant that may cause adverse effects 
due to atmospheric deposition (section 112(b)).
--Identify and list any stationary source category that emits 
pollutants with the potential to cause adverse effects (section 
112(c)).
--Establish a lesser quantity (e.g., below 10 tons per year for a 
single pollutant) emission rate based on several factors, including 
persistence and potential to bioaccumulate. Such emission rate, once 
established, would replace the 10 ton per year rate, per pollutant, 
that is otherwise used to define a major source (section 112(a)(1)).
--Establish test methods and analytic procedures for monitoring and 
measuring emissions, ambient concentrations, deposition, and 
bioaccumulation of HAP (section 112(b)(5)).
--List sources of 7 specific HAP to assure at least 90 percent of 
emissions of each pollutant are subject to national emission standards 
(section 112(c)(6)). These pollutants are of particular concern for the 
Great Waters.
--Promulgate performance standards (section 112(d)) for major sources 
and listed area sources. These standards are to reflect the maximum 
degree of emission reduction that is achievable, taking into 
consideration the cost of achieving such reduction, non-air quality 
health and environmental impacts, and energy requirements. In addition, 
these standards are to apply pollution prevention measures, processes, 
methods, systems or techniques which reduce the volume of or eliminate 
emissions through process changes, substitution of materials, enclosure 
of systems or processes, and other measures.
--Require additional controls, as necessary to provide an ample margin 
of safety to protect public health or to prevent an adverse 
environmental effect. Authority to take action, as needed, to help 
prevent the effects identified under section 112(m)(6) is provided by 
the ``residual risk'' provision (section 112(f)).
--Complete and transmit to Congress two studies that are especially 
relevant to the Great Waters program. The first is a study of mercury 
emissions from electric utilities, municipal waste combustors, and 
other sources, including smaller (i.e., area) sources. When the study 
becomes final, the results will be helpful in prioritizing mercury 
reduction strategies. The second study addresses the hazards to public 
health expected to occur as a result of HAP emissions from electric 
utilities. Section 112(n)(1)(A) further requires that EPA determine, 
based on the results its study, whether regulations to reduce utility 
emissions are warranted. This regulatory determination has not yet been 
made (section 112(n)(1)).

    Based on its analysis of these section 112 provisions, and on 
current knowledge of emission sources, atmospheric transport and 
deposition, and bioaccumulation, EPA believes that section 112 
authority is adequate to prevent serious adverse effects to public 
health and serious or widespread environmental effects associated with 
the deposition of HAP to Great Waters. If the other authorities of 
section 112 are found inadequate, section 112(m)(6) of the CAA provides 
additional authority to EPA to adopt further emission standards or 
other control measures not otherwise mandated or authorized by section 
112, if necessary and appropriate, to fully comply with the protective 
mandate of the Great Waters provisions. Since EPA believes that the 
authorities in section 112 are adequate to prevent the enumerated 
effects, EPA believes that it would not be appropriate, at this time, 
to promulgate further emission standards or other control measures 
under section 112(m)(6) to prevent such effects beyond those already 
authorized or required by section 112. In making these draft 
determinations, EPA is not determining that air deposition of HAP does 
not currently cause or contribute to adverse effects to the public 
health or the environment.

II. Introduction

    There are three important prerequisites to EPA's ability to 
identify the need for, and to develop, appropriate actions to address 
adverse health and environmental effects associated with atmospheric 
deposition of HAP. First, EPA must have adequate data and methods 
(e.g., air emissions inventories, ambient and deposition sampling and 
analysis techniques, and atmospheric fate and transport models) with 
which to collect and analyze relevant information. Additionally, there 
must be scientific support for the establishment of appropriate health 
thresholds, dose-response relationships and effects mechanisms.
    This information must be sufficient to support scientific and 
policy judgments about those effects that should be considered 
``serious adverse,'' in the case of human health, and ``serious or 
widespread,'' in the case of environmental effects. Finally, the Agency 
must have adequate legal authority to adopt regulations which can 
effectively reduce the emissions of the pollutants of concern in order 
to prevent such effects.
    Much of the effort to evaluate the extent to which the first two 
prerequisites (technical and science) have been met is summarized in 
the first and second Reports to Congress, and EPA expects to continue 
significant efforts to develop and improve our understanding of the 
scientific and technical issues. Today's notice discusses the third 
prerequisite to effective actions, that is, the adequacy of legal 
authorities provided by section 112 to prevent the effects specified in 
section 112(m)(6), and announces EPA's draft adequacy determination 
under that subsection. In addition, today's notice announces EPA's 
draft determination regarding whether additional emissions standards or 
control measures under section 112, beyond those otherwise authorized 
or required by section 112, are at this time necessary and appropriate 
to prevent such effects.

A. Statutory Requirements for Great Waters Program

    Section 112(m) of the CAA, as amended in 1990, 42 U.S.C. 7401 et 
seq. establishes the Great Waters program under which EPA has ongoing 
responsibilities to identify and assess the extent of atmospheric 
deposition of HAP to the Great Lakes, Chesapeake Bay, Lake Champlain, 
and coastal waters (Great Waters, (42 U.S.C. 7412(m)). As part of this 
program, EPA is to monitor for atmospheric deposition of HAP in the 
Great Waters, investigate the sources of HAP deposition, research the 
relative contribution of atmospheric pollutants to total loadings in 
the Great Waters, evaluate adverse effects to public health or the 
environment caused by HAP deposition, assess the contribution of HAP 
deposition to violations of water quality or drinking water standards, 
and sample for HAP in

[[Page 36438]]

biota, fish, and wildlife of the Great Waters, (42 U.S.C. 7412(m)(1) 
(A)-(E)).1
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    \1\ 42 U.S.C. 7412(m)(1) provides:
    The Administrator, in cooperation with the Under Secretary of 
Commerce for Oceans and Atmosphere, shall conduct a program to 
identify and assess the extent of atmospheric deposition of 
hazardous air pollutants (and in the discretion of the 
Administrator, other air pollutants) to the Great Lakes, the 
Chesapeake Bay, Lake Champlain and coastal waters. As part of such 
program, the Administrator shall--
    (A) monitor the Great Lakes, the Chesapeake Bay, Lake Champlain 
and coastal waters, including monitoring of the Great Lakes through 
the monitoring network established pursuant to paragraph (2) of this 
subsection and designing and deploying an atmospheric monitoring 
network for coastal waters pursuant to paragraph (4);
    (B) investigate the sources and deposition rates of atmospheric 
deposition of air pollutants (and their atmospheric transformation 
precursors);
    (C) conduct research to develop and improve monitoring methods 
and to determine the relative contribution of atmospheric pollutants 
to total pollution loadings to the Great Lakes, the Chesapeake Bay, 
Lake Champlain, and coastal waters;
    (D) evaluate any adverse effects to public health or the 
environment caused by such deposition (including effects resulting 
from indirect exposure pathways) and assess the contribution of such 
deposition to violations of water quality standards established 
pursuant to the Federal Water Pollution Control Act [33 U.S.C.A. 
1251 et seq.] and drinking water standards established pursuant to 
the Safe Drinking Water Act [42 U.S.C.A. 300f et seq.]; and
    (E) sample for such pollutants in biota, fish, and wildlife of 
the Great Lakes, the Chesapeake Bay, Lake Champlain and coastal 
waters and characterize the sources of such pollutants.
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    In addition, EPA is to provide periodic Reports to Congress 
describing the results of any monitoring, studies, and investigations 
conducted under the Great Waters program, addressing the same issues as 
mentioned above, and describing any revisions to the requirements, 
standards and limitations under the CAA or other Federal laws that are 
necessary to protect the public health and environment from atmospheric 
deposition (42 U.S.C. 7412(m)(5)).2 The Agency's 
implementation of the Great Waters program to date is discussed in the 
first two Reports to Congress issued under section 112(m)(5): 
``Deposition of Air Pollutants to the Great Waters: First Report to 
Congress'', EPA-453/R-93-055 (May 1994); and ``Deposition of Air 
Pollutants to the Great Waters: Second Report to Congress'', EPA-453/R-
97-011 (June 1997). Copies of these reports can be obtained, as 
supplies permit, from the Library Services Offices (MD-35), U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711, or, for a nominal fee, from the National Technical Information 
Service, 5285 Port Royal Road, Springfield, Virginia 22161, phone: 1-
800-553-NTIS or 703-487-4650.
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    \2\ 42 U.S.C. 7412(m)(5) provides:
    Within 3 years of November 15, 1990, and biennially thereafter, 
the Administrator, in cooperation with the Under Secretary of 
Commerce for Oceans and Atmosphere, shall submit to the Congress a 
report on the results of any monitoring, studies, and investigations 
conducted pursuant to this subsection. Such report shall include, at 
a minimum, an assessment of--
    (A) the contribution of atmospheric deposition to pollution 
loadings in the Great Lakes, the Chesapeake Bay, Lake Champlain and 
coastal waters;
    (B) the environmental and public health effects of any pollution 
which is attributable to atmospheric deposition to the Great Lakes, 
the Chesapeake Bay, Lake Champlain and coastal waters;
    (C) the source or sources of any pollution to the Great lakes, 
the Chesapeake Bay, Lake Champlain and costal waters which is 
attributable to atmospheric deposition;
    (D) whether pollution loadings in the Great lakes, the 
Chesapeake Bay, Lake Champlain or coastal waters cause or contribute 
to exceedances of drinking water standards pursuant to the Safe 
Drinking Water Act [42 U.S.C.A. 300f et seq.] or water quality 
standards pursuant to the Federal Water Pollution Control Act [33 
U.S.C. 1251 et seq.] or, with respect to the Great lakes, 
exceedances of the specific objectives of the Great Lakes Water 
Quality Agreement; and
    (E) a description of any revisions of the requirements, 
standards, and limitations pursuant to this chapter and other 
applicable Federal laws as necessary to assure protection of human 
health and the environment.
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    Finally, section 112(m)(6) requires that the Administrator 
determine whether the other provisions of section 112 are adequate to 
prevent serious, adverse effects to public health and serious or 
widespread environmental effects, including such effects resulting from 
indirect exposure pathways, associated with atmospheric deposition to 
the Great Waters of HAP (and their atmospheric transformation products, 
(42 U.S.C. 7412(m)(6)).3 In making this determination, EPA 
is to take into consideration the tendency of HAP to bioaccumulate. If 
EPA determines that the other provisions of section 112 are not 
adequate, section 112(m)(6) provides that EPA must then promulgate, in 
accordance with section 112, such further emission standards or control 
measures as may be necessary and appropriate to prevent such effects, 
including effects due to bioaccumulation and indirect exposure 
pathways. Id. As an initial matter, EPA interprets this latter mandate 
to be a requirement to determine, in the first instance, whether 
additional controls are necessary and appropriate, rather than as an 
absolute requirement to promulgate some additional controls. (See, 
e.g., Environmental Defense Fund v. Thomas, 870 F.2d 892, 898-900 (2nd 
Cir. 1989) (While district court did not have jurisdiction to compel 
the Administrator to revise the national ambient air quality standards 
(NAAQS), it did have jurisdiction to compel EPA to take some formal 
action either revising the NAAQS or declining to revise them)).
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    \3\ 42 U.S.C. 7412(m)(6) provides:
    As part of the report to Congress, the Administrator shall 
determine whether the other provisions of this section are adequate 
to prevent serious adverse effects to public health and serious or 
widespread environmental effects, including such effects resulting 
from indirect exposure pathways, associated with atmospheric 
deposition to the Great Lakes, the Chesapeake Bay, Lake Champlain 
and coastal waters of hazardous air pollutants (and their 
transformation products). The Administrator shall take into 
consideration the tendency of such pollutants to bioaccumulate. 
Within 5 years after November 15, 1990, the Administrator shall, 
based on such report and determination, promulgate, in accordance 
with this section, such further emission standards or control 
measures as may be necessary and appropriate to prevent such 
effects, including effects due to bioaccumulation and indirect 
exposure pathways. Any requirements promulgated pursuant to this 
paragraph with respect to coastal waters shall only apply to the 
coastal waters of the States which are subject to section 7627(a) of 
this title.
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B. Scope of Analysis

    In reviewing the language of section 112(m)(6), it is significant 
to note the CAA's specific reference to the ``other provisions'' of 
section 112 in describing EPA's duty to assess its ability to prevent 
the specified effects. This reference to the statutory authorities is 
in contrast to a consideration of particular regulatory actions that 
might be taken or have already been taken under those provisions, or of 
their individual effectiveness. The EPA views this language as calling 
for an analysis of the adequacy of the regulatory authorities and 
mandates provided by section 112, rather than of specific actions which 
might be taken pursuant to this section. In other words, EPA must 
determine whether the authorities provided by these provisions can 
adequately prevent the enumerated health and environmental effects. In 
the event that EPA determines that they cannot, the CAA further 
provides limited authority to adopt additional rules not specifically 
mandated or authorized by the other provisions of section 112 as needed 
to fully comply with section 112(m)(6)'s protective mandate. This 
authority is limited by its terms to developing rules ``in accordance 
with'' section 112; EPA may not act, pursuant to section 112(m)(6), 
inconsistently with the requirements of, or outside the scope of, 
section 112. This means that any additional regulations promulgated 
pursuant to section 112(m)(6) could apply only to stationary sources of 
HAP.
    As noted above, EPA does not interpret this language as calling for 
an analysis of the adequacy of specific rules or actions which have 
been, or will be, taken pursuant to the provisions of section 112. That 
is, based on the statutory language itself, for the

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purposes of conducting the required analysis, EPA must presume that the 
provisions will be implemented in ways which fully comply with the 
substantive requirements of the appropriate subsections of section 112 
and not speculate about what actual degree of emissions control results 
from a specific rule adopted in accordance with section 112. The EPA's 
interpretation of the scope of this analysis is supported by the dates 
by which Congress anticipated that this determination and any further 
regulations would be adopted, compared to the deadlines imposed under 
the Act for full implementation of section 112. Section 112(m)(6) 
provides that EPA was to make the determination in the Report to 
Congress required by section 112(m)(5). The first Report to Congress 
was due on November 15, 1993. The EPA was then required to promulgate 
additional regulations, if any, based on the report and determination 
by November 15, 1995. However, many of the deadlines for other actions 
under section 112 do not fall until much later. By requiring that EPA 
complete the process of making this determination and adopting further 
standards or control measures within 5 years after November 15, 1990, 
EPA presumes Congress knew that a large number of mandated emission 
standards, programs, and regulations under section 112 would either not 
yet be commenced, or would still be in the early stages of development. 
Moreover, even those section 112 controls that had already been 
promulgated would not yet have demonstrated either success or failure 
at preventing adverse effects to the public health and environment. 
Consequently, Congress could not have expected that EPA, at the time 
this determination was due, would have sufficient information with 
which to judge the actual scientific or technical adequacy of those 
recently adopted or future actions or regulations to achieve specific 
degrees of protection. Indeed, section 112(c)(6), which requires that 
EPA identify the sources of seven specific pollutants which are of 
primary concern for the Great Waters, requires only an identification 
and listing of sources of those pollutants as of November 15, 1995, the 
same date by which EPA must determine whether additional regulations 
are necessary and appropriate. Standards to subject these sources to 
regulations are not required under section 112(c)(6) to be established 
until 5 years thereafter.
    While on the surface there might appear to be some conflict between 
the section 112(c)(6) and 112(m)(6) deadlines for regulatory action, 
EPA believes this tension is reconciled by the Agency's interpretation 
of its section 112(m)(6) duty to be to determine adequacy based solely 
on an a priori statutory analysis; if after review of the section 112 
authorities, EPA concludes that they are inadequate to prevent the 
enumerated public health or environmental effects, EPA is required to 
establish further regulations based partly on the conclusion that those 
other authorities, when eventually implemented, cannot possibly prevent 
those effects. In other words, EPA is required under section 112(m)(6) 
to plug any gaps it identifies early. But, if the Agency concludes that 
section 112 is adequate, the section 112(m)(6) ``duty'' to establish 
further regulations is not triggered, and the ``conflict'' with other 
provisions' deadlines for regulatory actions becomes moot.
    One question that EPA must resolve in making its determination 
under section 112(m)(6) concerns the sources of pollutants which are 
transported through the atmosphere and the extent to which EPA's 
determination must encompass all such sources. This issue is 
potentially significant because available information indicates that, 
in addition to domestic stationary sources of HAP emissions which may 
be subjected to regulation under section 112, atmospheric deposition of 
some HAP partially results from mobile source emissions, as well as 
transport of emissions from foreign sources. Also, some HAP, which were 
historically introduced to the environment by human activities, are 
continually being recycled in the environment. That is, pollutants such 
as PCBs, certain pesticides, and, to some extent, mercury, can 
revolatilize from soils and waterbodies into the air, where they can be 
transported downwind to new locations and redeposited, revolatilizing 
again back into the air from these new locations and transporting 
further downwind.
    Nothing in the language of section 112(m)(6) suggests that the 
Agency must consider these other sources in determining whether the 
provisions of section 112 are adequate to prevent the adverse health or 
environmental effects. That is, the statutory language does not extend 
the scope of EPA's analysis to encompass impacts from HAP emissions 
from sources that could not conceivably be subjected to section 112 
regulation. Section 112(m)(6) goes on to provide that if EPA has 
determined the other provisions of section 112 are inadequate, EPA must 
promulgate additional necessary and appropriate emission standards or 
other control measures ``in accordance with this section,'' i.e., in 
accordance with section 112 (42 U.S.C. 7412(m)(6)). Section 112 does 
not confer authority on the Agency to regulate mobile sources, 
nondomestic sources of HAP emission, or contaminated sediments. 
Instead, section 112, and the potential remedy to address an 
``inadequacy'' determination under section 112(m)(6), is restricted in 
application to stationary sources of HAP within the possible regulatory 
reach of section 112. Moreover, EPA believes that Congress, in enacting 
the section 112(m)(6) duty to evaluate the adequacy of section 112, 
clearly understood that section 112, and the section 112 remedy 
contained in section 112(m)(6), could only extend to stationary sources 
already within the scope of the section. This is because it would have 
been unnecessary to ask whether section 112 is adequate to control 
sources that are clearly beyond its scope, such as mobile sources. For 
these reasons, it is EPA's view that the scope of the section 112(m)(6) 
determination should be limited to consideration of the adequacy of 
section 112 provisions to prevent the enumerated adverse effects 
associated with HAP emissions from sources which are within the scope 
of EPA's authority to regulate under section 112. It is important to 
note that it does not follow from this interpretation that in order to 
determine that there are, or to address, adverse effects to public 
health or serious or widespread effects to the environment under 
section 112, EPA must consider only the contributions from domestic 
stationary sources subject to regulation under section 112.

III. Statutory Analysis--Other Provisions Relative to Section 112(m) 
Mandate

    Among other things, section 112 establishes a statutory scheme 
through which EPA is to identify HAP which present or may present a 
threat of adverse human health effects or adverse environmental 
effects, develop standards for the control of emissions from major 
stationary and area sources of such HAP (and the HAP listed by Congress 
in the CAA), and adjust these emission control requirements to address 
any remaining unacceptable risk which may be present once sources have 
complied with the emission standards. The following sections discuss 
these provisions in further detail, describing the extent to which they 
authorize or enable actions to prevent serious adverse public health 
effects and serious or widespread environmental effects associated with 
atmospheric HAP deposition to the Great Waters, as described in section 
112(m)(6).

[[Page 36440]]

A. Definition of Major Source

    Section 112(a) sets forth several definitions that partly define 
the scope of EPA's regulatory authority under section 112. The 
definition of ``major source'' at section 112(a)(1), for example, 
functions in part to establish which types of stationary sources must 
be subjected to the most stringent controls. In addition, however, it 
provides authority to include more sources within the definition, and 
thus allows EPA to subject additional sources to more stringent 
controls than is otherwise required under section 112 (42 U.S.C. 
7412(a)(1)).\4\ While a major source is initially defined to mean any 
stationary source or group of stationary sources located within a 
contiguous area and under common control that emits or has the 
potential to emit, considering controls, in the aggregate, 10 tons per 
year of any HAP or 25 tons per year of any combination of HAP, EPA may 
establish a lesser quantity for a major source based on the potency of 
the air pollutant, persistence, potential for bioaccumulation, other 
characteristics of the air pollutant, or other relevant factors.
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    \4\ 42 U.S.C. 7412(a)(1) provides:
    The term ``major source'' means any stationary source or group 
stationary sources located within a contiguous area and under common 
control that emits or has the potential to emit considering 
controls, in the aggregate, 10 tons per year or more of any 
hazardous air pollutant or 25 tons per year or more of any 
combination of hazardous air pollutants. The Administrator may 
establish a lesser quantity, or in the case of radionuclides 
different criteria, for a major source than that specified in the 
previous sentence, on the basis of the potency of the air pollutant, 
persistence, potential for bioaccumulation, other characteristics of 
the air pollutant, or other relevant factors.
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    Section 112(m)(6) requires EPA to consider the tendency of HAP to 
bioaccumulate when making its determination as to the adequacy of 
section 112 (42 U.S.C. 7412(m)(6)). Since section 112(a)(1) allows EPA 
to base lesser quantity emission rates for defining major sources on 
bioaccumulation and other relevant factors, the authority in section 
112(a)(1) can be used, in concert with other provisions of section 112 
as discussed below, to impose controls that could help prevent the 
enumerated effects associated with atmospheric deposition of HAP to the 
Great Waters.

B. Definition of Adverse Environmental Effect

    Section 112(a)(7) defines ``adverse environmental effect'' to mean 
``any significant and widespread adverse effect, which may be 
reasonably anticipated, to wildlife, aquatic life, or other natural 
resources, including adverse impacts on populations of endangered or 
threatened species or significant degradation of environmental quality 
over broad areas'' (42 U.S.C. 7412(a)(7)). The EPA interprets the scope 
of this term to apply as broadly as the language included in section 
112(m)(6) requiring EPA to prevent serious or widespread environmental 
effects associated with atmospheric deposition to the Great Waters of 
HAP and their transformation products. The EPA notes that the language 
of section 112(a)(7) and 112(m)(6) is different: where the former 
refers to ``significant and widespread adverse effect,'' the latter 
refers to ``serious or widespread environmental effects.''
    The legislative history does not provide further clarification of 
the reasons for the differences in the terminology used in these two 
provisions or otherwise suggest that Congress intended for the two 
phrases to have different meanings. Rather, references to the House 
Amendments that became section 112(m)(6) indicate that the sponsors 
understood the language in the Amendments to have the same meaning as 
that used elsewhere in section 112 to describe ``adverse'' 
environmental effects. (See, e.g., remarks of Mr. Levine, House Debate 
5-21-90, reprinted in A Legislative History of the Clean Air Act 
Amendments of 1990, at 2633; Remarks of Mr. Bilirakis, House Debate 5-
23-90, id., at 2941; Remarks of Mr. Lagomarsino, House Debate 5-23-90, 
id., at 2946; Remarks of Mr. Levine, House Debate 5-23-90, id., at 
2938.) The EPA believes that these differences do not impose materially 
different standards, and that for purposes of the section 112(m)(6) 
determination, the standard imposed under section 112(a)(7) is 
substantially the same as that in section 112(m)(6). This is because 
EPA interprets section 112(m)(6) as directing EPA to assure that only 
``adverse'' environmental effects from HAP deposition are prevented, 
rather than effects that are not ``adverse,'' if any exist. In this 
context, EPA believes that the differing language in the two 
subsections functions interchangeably. (See, e.g., De Sylva v. 
Ballentine, 351 U.S. 570 (1956) (``the word `or' is often used as a 
careless substitute for the word `and,' that is, it is often used in 
phrases where `and' would express greater clarity''); See also, U.S. v. 
Moore, 613 F.2d 1029 (D.C. Cir. 1979); U.S. v. 1973 One Rol ls Royce, 
43 F.3d 794 (3rd Cir. 1994); Kelly v. Wauconda Park Dist., 801 F.2d 269 
(7th Cir. 1986); U.S. v. Smeathers, 884 F.2d 363 (8th Cir. 1989). While 
the use of different terminology in ections 112(a)(7) and 112(m)(6) 
does raise some ambiguity regarding Congress' intent, EPA believes that 
the most reasonable way to resolve this ambiguity is to read the 
slightly different language in section 112(m)(6) consistently with how 
Congress defined environmental effects of concern for 11 other purposes 
under section 112. (See Chevron U.S.A., Inc. v. NRDC, 467 U.S. 837 
(1984).) Otherwise, under a literal reading, Congress might be viewed 
as having charged EPA with the duty to prevent environmental effects 
which by definition under section 112 are not ``adverse.'' The EPA does 
not believe such a reading would make sense, either as a matter of 
statutory interpretation or as a matter of environmental policy.
    Moreover, other language in section 112(m) suggests that Congress 
intended for the different terminology in section 112(a)(7) and 
112(m)(6) to have the same meaning. In section 112(m)(1), the initial 
subsection directing EPA to establish the Great Waters program, 
Congress required EPA to evaluate ``any adverse effects to public 
health or the environment caused by [HAP] deposition (including effects 
resulting from indirect exposure pathways'' (42 U.S.C. 7412(m)(1)(D)). 
This provision's use of the section 112(a)(7) defined the term 
``adverse environmental effect,'' as inclusive of the same ``effects 
resulting from indirect exposure pathways'' as defined in section 
112(m)(6), indicates that Congress assumed the scope of environmental 
impacts to be covered by section 112(a)(7) and 112(m)(6) would be the 
same. Indeed, if Congress had thought otherwise, it would have been 
unnecessary for it to have asked EPA to assess whether the other 
substantive provisions of section 112 are adequate to prevent the 
effects identified in section 112(m)(6). If the environmental effects 
in section 112(m)(6) are by definition broader in scope than those 
included in the definition of ``adverse environmental effects'' in 
section 112(a)(7), the other provisions of section 112 would 
necessarily be inadequate to prevent them, and no administrative 
expertise on EPA's part would be needed in order to assess this.
    While section 112(a)(7) provides as one example of an ``adverse 
environmental effect,'' ``significant degradation of environmental 
quality over broad areas,'' the use of the term ``widespread'' should 
not be viewed as requiring in all cases an environmental effect to 
occur in multiple geographic areas. For example, in other contexts, EPA 
has interpreted ``widespread'' economic impacts as being those that

[[Page 36441]]

apply to a single affected community. (See EPA final rule, Water 
Quality Standards Regulation, 48 FR 51400, 51401 (November 8, 1983); 40 
CFR 131.10(g)(6).) In addition, section 112(a)(7) provides as another 
example of ``adverse environmental effects'' impacts on populations of 
endangered or threatened species; such populations are especially 
likely to occur in limited geographic areas. EPA believes Congress did 
not intend the ``widespread'' criterion to exclude impacts that might 
occur within a limited geographic range that might include, for 
example, one of the Great Lakes, the Chesapeake Bay, another Great 
Waters waterbody, or a significant portion of such a waterbody. Thus, 
to the extent that specific provisions in section 112, such as the 
residual risk provisions in section 112(f), allow or require EPA to 
prevent ``adverse environmental effects,'' this authority is adequate 
to prevent the effects enumerated in section 112(m)(6).

C. Listing of Pollutants

    Before EPA may adopt standards or other measures to prevent or 
control emissions of a given pollutant under section 112, the pollutant 
must first be formally listed as a HAP pursuant to section 112(b). 
Section 112(b)(1) provides an initial list of 189 chemicals which 
Congress concluded are HAP.\5\ Section 112(b)(2) also provides in part 
that the Administrator shall periodically review the list and publish 
the results thereof and, where appropriate, revise the list by rule, 
adding pollutants which present, or may present, through inhalation or 
other routes of exposure, a threat of adverse human health effects or 
adverse environmental effects whether through ambient concentrations, 
bioaccumulation, deposition, or otherwise (42 U.S.C. 7412(b)(2)).\6\ 
Section 112(b)(3)(B) further provides that EPA shall add substances to 
the list, upon a showing by outside petitioners or on the Agency's own 
determination, that ``the substance is an air pollutant and that 
emissions, ambient concentrations, bioaccumulation or deposition of the 
substance are known to cause or may reasonably be anticipated to cause 
adverse effects to human health or adverse environmental effects'' (42 
U.S.C. 7412(b)(3)). To assist the Agency in its efforts, section 
112(b)(4) provides that, where information on the health or 
environmental effects of a substance is not sufficient to make a 
determination required by section 112(b), ``the Administrator may use 
any authority available to the Administrator to acquire such 
information'' (42 U.S.C. 7412(b)(4)). Moreover, section 112(b)(5) 
allows EPA to establish, by rulemaking test measures and other analytic 
procedures for monitoring and measuring emissions, ambient 
concentrations, deposition, and bioaccumulation of hazardous air 
pollutants (42 U.S.C. 7312(b)(5)).
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    \5\ This list now contains 188 HAP, as a result of EPA's final 
decision to remove the compound caprolactam from the section 
112(b)(1) list. See 61 FR 30816 (June 18, 1996), codified at 40 CFR 
63.60.
    \6\ 42 U.S.C. 7412(b)(2) provides:
    The Administrator shall periodically review the list established 
by this subsection and publish the results thereof and, where 
appropriate, revise such list by rule, adding pollutants which 
present, or may present, through inhalation or other routes of 
exposure, a threat of adverse human health effects (including, but 
not limited to, substances which are known to be, or may reasonably 
be anticipated to be, carcinogenic, mutagenic, teratogenic, 
neurotoxic, which cause reproductive dysfunction, or which are 
acutely or chronically toxic) or adverse environmental effects 
whether through ambient concentrations, bioaccumulation, deposition, 
or otherwise, but not including releases subject to regulation under 
subsection (r) of this section as a result of emissions to the air. 
No air pollutant which is listed under section 7408(a) of this title 
may be added to the list under this section, except that the 
prohibition of this sentence shall not apply to any pollutant which 
independently meets the listing criteria of this paragraph and is a 
precursor to a pollutant which is listed under section 7408(a) of 
this title or to any pollutant which is in a class of pollutants 
listed under such section. No substance, practice, process or 
activity regulated under subchapter VI of this chapter shall be 
subject to regulation under this section solely due to its adverse 
effects on the environment.
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    The EPA believes that, taken together, the provisions of section 
112(b) discussed above provide adequate authority to identify and 
formally list any HAP which has the potential for causing adverse 
public health or environmental effects due to atmospheric deposition. 
Of the 15 chemicals or chemical classes that have been identified as 
pollutants of concern in the Great Waters program, 13 are already 
listed as HAP. The two unlisted pollutants (or pollutant classes) are 
nitrogen compounds and the pesticide, Dieldrin. The EPA has authority 
to regulate emissions of nitrogen oxides under other sections of the 
CAA (e.g., sections 108, 109, 129, 202, and 407). There are currently 
no known air emission sources of Dieldrin in the United States. This 
substance is a pollutant of concern because it continues to be measured 
in the Great Waters at levels considered to be potentially harmful. 
However, these levels are the result of prior use of the pesticide and 
its recycling in the environment. Thus, there is currently no basis for 
adding Dieldrin to the HAP list in section 112.

D. Listing of Sources

    Once a pollutant has been listed as a HAP pursuant to section 
112(b), EPA is required by section 112(c)(1) to publish and to 
periodically review and revise a list of all categories and 
subcategories of major sources and area sources of these pollutants (42 
U.S.C. 7412(c)(1)).7 Section 112(c)(2) then requires EPA to 
establish emissions standards under section 112(d) for the listed 
categories and subcategories (42 U.S.C. 7412(c)(2)). Additionally, 
section 112(c) imposes requirements to list categories or subcategories 
of sources, including area sources, meeting certain specified criteria. 
Significant to section 112(m) are the requirements of section 
112(c)(6)--EPA is required to identify and to list categories and 
subcategories of sources to assure that at least 90 percent of the 
aggregate emissions of each of seven specific pollutants are subject to 
emission standards under section 112 (d)(2) or (d)(4) and 42 U.S.C. 
7412(c)(6)).8 These seven pollutants, alkylated lead 
compounds, polycyclic organic matter, hexachlorobenzene, mercury, 
polychlorinated biphenyls, 2,3,7,8-tetrachlorodibenzofurans and 
2,3,7,8-tetrachlorobenzo-p-dioxin--are identified as pollutants of 
concern to the Great Waters, and standards for them must be promulgated 
by November 15, 2000.
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    \7\ 42 U.S.C. 7412(c)(1) provides:
    Not later than 12 months after November 15, 1990, the 
Administrator shall publish, and shall from time to time, but no 
less often than every 8 years, revise, if appropriate, in response 
to public comment or new information, a list of all categories and 
subcategories of major sources and area sources (listed under 
paragraph (3)) of the air pollutants listed pursuant to subsection 
(b) of this section. To the extent practicable, the categories and 
subcategories listed under this subsection shall be consistent with 
the list of source categories established pursuant to section 7411 
of this title and part C of this subchapter. Nothing in the 
preceding sentence limits the Administrator's authority to establish 
subcategories under this section, as appropriate.
    \8\ 42 U.S.C. 7412(c)(6) provides:
    With respect to alkylated lead compounds, polycyclic organic 
matter, hexachlorobenzene, mercury, polychlorinated biphenyls, 
2,3,7,8-tetrachlorodibenzofurans and 2,3,7,8-tetrachlorodibenzo-p-
dioxin, the Administrator shall, not later than 5 years after 
November 15, 1990, list categories and subcategories of sources 
assuring that sources accounting for not less than 90 per centum of 
the aggregate emissions of each such pollutant are subject to 
standards under subsection (d)(2) or (d)(4) of this section. Such 
standards shall be promulgated not later than 10 years after 
November 15, 1990. This paragraph shall not be construed to require 
the Administrator to promulgate standards for such pollutants 
emitted by electric utility steam generating units.
---------------------------------------------------------------------------

    Moreover, section 112(c)(5) provides EPA with broad discretion to 
list additional categories and subcategories of area sources of HAP any 
time the Agency finds they present a threat of

[[Page 36442]]

adverse effects to human health or the environment, either in the 
aggregate or individually (42 U.S.C. 7412(c)(5)).9 Finally, 
section 112(c)(3) imposes two additional requirements on EPA. First, 
EPA must list each category or subcategory of area sources (i.e., 
nonmajor stationary sources of HAP) which EPA finds presents a threat 
of adverse effects to human health or the environment (by such sources 
individually or in the aggregate) warranting regulation under section 
112; and second, EPA must list, based on actual or estimated aggregate 
emissions of a listed pollutant or pollutants, sufficient categories or 
subcategories of area sources to ensure that area sources representing 
90 percent of the area source emissions of the 30 HAP that present the 
greatest threat to public health in the largest number of urban areas 
are subject to regulation under section 112 (42 U.S.C. 
7412(c)(3).10 These regulations must be promulgated by 
November 15, 2000.
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    \9\ 42 U.S.C. 7412(c)(5) provides:
    In addition to those categories and subcategories of sources 
listed pursuant to paragraphs (1) and (3), the Administrator may at 
any time list additional categories and subcategories of sources of 
hazardous air pollutants according to the same criteria for listing 
applicable under such paragraphs. In the case of source categories 
and subcategories listed after publication of the initial list 
required under paragraph (1) or (3), emission standards under 
subsection (d) of this section for the category or subcategory shall 
be promulgated within 10 years after November 15, 1990, or within 2 
years after the date on which such category or subcategory is 
listed, whichever is later.
    \10\ 42 U.S.C. 7412(c)(3) provides:
    The Administrator shall list under this subsection each category 
or subcategory of area sources which the Administrator finds 
presents a threat of adverse effects to human health or the 
environment (by such sources individually or in the aggregate) 
warranting regulation under this section. The Administrator shall, 
not later than 5 years after November 15, 1990, and pursuant to 
subsection (k)(3)(B) of this section, list, based on actual or 
estimated aggregate emissions of a listed pollutant or pollutants, 
sufficient categories or subcategories of area sources to ensure 
that area sources representing 90 percent of the area source 
emissions of the 30 hazardous air pollutants that present the 
greatest threat to public health in the largest number of urban 
areas are subject to regulation under this section. Such standards 
shall be promulgated not later than 10 years after November 15, 
1990.
---------------------------------------------------------------------------

    In its use of the terms ``category'' and ``subcategory'' of 
sources, the CAA does not provide definitive guidance and, thus, EPA's 
discretion in how to apply those terms is broad. The CAA does provide 
definitions of ``major,'' ``stationary'' and ``area'' sources, the 
latter meaning any stationary source of HAP that is not a major source 
and excluding motor vehicles or nonroad vehicles subject to title II of 
the CAA (42 U.S.C. 7412(a)(2).) 11 Thus, section 112(c) 
provides for the listing of stationary sources only and does not reach 
such sources as motor vehicles, aircraft, nonroad engines or vehicles 
such as locomotives.
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    \11\ 42 U.S.C. 7412(a)(2) provides:
    The term ``area source'' means any stationary source of 
hazardous air pollutants that is not a major source. For purposes of 
this section, the term ``area source'' shall not include motor 
vehicles or nonroad vehicles subject to regulation under subchapter 
II of this chapter.
---------------------------------------------------------------------------

    While this might appear to be a deficiency in the scope of section 
112, to the extent that emissions from such sources can cause or 
contribute to significant and harmful atmospheric deposition of HAP, 
they can be regulated under other provisions of the CAA such that 
section 112 is not necessarily rendered ``inadequate'' due to its focus 
on stationary sources. For example, in the case of emissions from motor 
vehicles, section 202(a)(1) requires EPA to promulgate emissions 
standards for any air pollutants from new motor vehicles or their 
engines which in the Administrator's judgment cause or contribute to 
air pollution which may reasonably be anticipated to endanger public 
health or welfare (42 U.S.C. 7521(a)(1)). In addition, section 
211(k)(1) requires EPA to promulgate requirements for the reformulation 
of gasoline to control toxic air pollutants from motor vehicles which 
reflect the greatest degree of emission reduction achievable through 
the reformulation of gasoline, taking into consideration cost and 
various factors. ``Toxic air pollutants'' are defined to include 
polcyclic organic matter (POM), a pollutant of concern for the Great 
Waters (42 U.S.C. 7545(k)(1), (10)(C)). Finally, section 213(a)(4) 
allows EPA to promulgate regulations applicable to emissions from 
nonroad engines or vehicles, in addition to those covering ozone and 
carbon monoxide, whenever the Administrator determines that those 
emissions may reasonably be anticipated to endanger public health or 
welfare (42 U.S.C. 7547(a)(4)).
    Based on this analysis, EPA believes that its authority to list 
stationary sources of the listed HAP is sufficiently comprehensive for 
domestic stationary sources, including small stationary sources. The 
EPA is not aware of any basis by which a category or subcategory of 
stationary sources of a listed HAP that is of concern under the Great 
Waters program could evade listing for regulation under section 112. 
While this authority is limited to stationary sources and thus does not 
authorize regulation of mobile sources under section 112, EPA's other 
CAA authority provides sufficient authority to address HAP emissions 
from nonstationary sources subject to the CAA such that the listing 
provisions of section 112(c) are adequate for purposes of section 
112(m)(6).

E. Regulations to Control Emissions of Pollutants

1. Maximum Achievable Control Technology and Generally Available 
Control Technology Standards
    Once a pollutant is formally listed under section 112(b), and EPA 
has also listed the stationary source categories or subcategories of 
that pollutant, the Agency is required by section 112(d)(2) to 
promulgate regulations to establish emission standards requiring the 
maximum degree of reduction in emissions of the HAP, including a 
prohibition on such emissions where achievable, that the Administrator, 
taking into consideration the cost of achieving these emission 
reductions and any non-air quality health and environmental impacts and 
energy requirements, determines is achievable for new or existing 
sources in the category or subcategory to which the emission standard 
applies (42 U.S.C. 7412(d)(2)).12 These standards are 
referred to as MACT standards, and they must require application of 
measures, processes, methods, systems or techniques which reduce the 
volume of, or eliminate, emissions of HAP. Such reduction or 
elimination of HAP may occur through process changes,

[[Page 36443]]

substitution of materials or other modifications, enclosing systems or 
processes to eliminate emissions, and taking other specified measures. 
Id.
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    \12\ 42 U.S.C. Sec. 7412(d)(2) provides:
    Emissions standards promulgated under this subsection and 
applicable to new or existing sources of hazardous air pollutants 
shall require the maximum degree of reduction in emissions of the 
hazardous air pollutants subject to this section (including a 
prohibition on such emissions, where achievable) that the 
Administrator, taking into consideration the cost of achieving such 
emission reduction, and any non-air quality health and environmental 
impacts and energy requirements, determines is achievable for new or 
existing sources in the category or subcategory to which such 
emission standard applies, through application of measures, 
processes, methods, systems or techniques including, but not limited 
to, measures which--
    (A) reduce the volume of, or eliminate emissions of, such 
pollutants through process changes, substitution of materials or 
other modifications,
    (B) enclose systems or processes to eliminate emissions,
    (C) collect, capture or treat such pollutants when released from 
a process, stack, storage or fugitive emissions point,
    (D) are design, equipment, work practice, or operational 
standards (including requirements for operator training or 
certification) as provided in subsection (h) of this section, or
    (E) are a combination of the above.
    None of the measures described in subparagraphs (A) through (D) 
shall, consistent with the provisions of section 7414 of 
this title, in any way compromise any United States patent or United 
States trademark right, or any confidential business information, or 
any trade secret or any other intellectual property right.
---------------------------------------------------------------------------

    Subsection 112(d)(3) goes on to establish that these emission 
standards may not be less stringent than the emission control that is 
achieved in practice by the best controlled similar source, in the case 
of new sources; by the average emission limitation achieved by the best 
performing 12 percent of the existing sources; or by the average 
emission limitation achieved by the best performing five existing 
sources, where there are fewer than 30 sources in the category or 
subcategory, whichever is applicable (42 U.S.C. 7412(d)(3)). 
13 Moreover, for source categories or subcategories of area 
sources listed under section 112(c), section 112(d)(5) allows EPA, in 
lieu of requiring MACT for such sources, to promulgate standards which 
provide for the use of GACT) or management practices to reduce 
emissions of HAP (42 U.S.C. 7412(d)(5)). Additional provisions are made 
for emission standards for coke ovens, and an exclusion from regulation 
is provided for radionuclides and their sources licensed by the Nuclear 
Regulatory Commission if certain findings are made. Finally, section 
112(d)(7) provides that any more stringent requirements or emissions 
limitations established under provisions of the Act other than section 
112 or under State authority are preserved (42 U.S.C. 7412(d)(7)).
---------------------------------------------------------------------------

    \13\ 42 U.S.C. Sec. 7412(d)(3) provides:
    The maximum degree of reduction in emissions that is deemed 
achievable for new sources in a category or subcategory shall not be 
less stringent than the emission control that is achieved in 
practice by the best controlled similar source, as determined by the 
Administrator. Emissions standards promulgated under this subsection 
for existing sources in a category or subcategory may be less 
stringent than standards for new sources in the same category or 
subcategory but shall not be less stringent, and may be more 
stringent than--
    (A) the average emission limitation achieved by the best 
performing 12 percent of the existing sources (for which the 
Administrator has emissions information), excluding those sources 
that have, within 18 months before the emission standard is proposed 
or within 30 months before such standard is promulgated, whichever 
is later, first achieved a level of emission rate or emission 
reduction which complies, or would comply if the source is not 
subject to such standard, with the lowest achievable emission rate 
(as defined by section 7501 of this title) applicable to the source 
category and prevailing at the time, in the category or subcategory 
for categories and subcategories with 30 or more sources, or
    (B) the average emission limitation achieved by the best 
performing 5 sources (for which the Administrator has or could 
reasonably obtain emissions information) in the category or 
subcategory for categories or subcategories with fewer than 30 
sources.
---------------------------------------------------------------------------

    While section 112(d)(5) of the CAA allows EPA to restrict 
application of MACT standards to major sources and to promulgate less 
stringent GACT standards for area sources, the Agency is not required 
to do so. As discussed earlier in this notice, although major sources 
are defined as those which emit 10 tons per year or more of any HAP or 
25 tons per year of any combination of HAP, EPA is granted discretion 
under section 112(a)(1) to establish a lesser quantity emissions rate 
(LQER) for a major source on the basis of the potency of the air 
pollutant, persistence, potential for bioaccumulation, other 
characteristics of the air pollutant, or other relevant factors (42 
U.S.C. 7412(a)(1)). In addition, EPA interprets section 112(d)(5) as 
authorizing the Administrator to establish GACT standards for area 
sources when the imposition of MACT is determined to be unreasonable 
(See 60 FR 4948, 4953, January 25, 1995). Thus, while EPA is permitted 
by section 112(d)(5) to establish standards or requirements which 
provide for the use of GACT or management practices to reduce emissions 
of HAP, EPA retains discretion to subject area source categories or 
subcategories to MACT where appropriate.
    While the provisions of section 112(d) require EPA to focus the 
potentially more stringent performance standards and control efforts on 
major sources, they also allow EPA the discretion to apply these 
requirements to smaller sources.
    Section 112(e) establishes an aggressive schedule for establishing 
section 112(d) standards. In addition to requiring all emission 
standards for all categories and subcategories to be promulgated no 
later than November 15, 2000, section 112(e)(2) requires EPA to 
consider the known or anticipated adverse effects of HAP on public 
health and the environment and other factors when determining 
priorities for promulgating section 112(d) standards (42 U.S.C. 
7412(e)(2)).
2. Residual Risk Standards
    The Agency expects to achieve the vast majority of HAP emissions 
reductions under section 112 through application of the section 112(d) 
MACT and GACT programs. It must be stressed, however, that MACT and 
GACT standards are not required to achieve a specified health-based 
result or prevent specified environmental effects. Consequently, 
section 112 provides another mechanism to address situations where 
additional reductions are necessary to protect the public health or 
prevent an adverse environmental effect, even after imposition of 
controls such as MACT or GACT. The EPA is required by section 
112(f)(2)(A) to promulgate more stringent standards within 8 years 
after the adoption of the initial MACT standards, if such action is 
necessary to provide an ample margin of safety to protect public health 
or to prevent, taking into consideration costs, energy, safety, and 
other relevant factors, an adverse environmental effect (42 U.S.C. 
7412(f)(2)(A)).14 Whenever MACT standards under section 
112(d) applicable to a source category or subcategory emitting a 
pollutant classified as a known, probable or possible human carcinogen 
do not reduce lifetime excess cancer risks to the individual most 
exposed to emissions from a source in the category or subcategory to 
less than one in one million, standards are required under section 
112(f). If providing an ample margin of safety to protect public health 
is not adequate to prevent an adverse environmental effect, a more 
stringent standard must be promulgated. In addition, while section 112 
does not require EPA to conduct residual risk analyses for GACT 
standards, the Agency retains the discretion to establish residual risk 
standards in appropriate cases after application of GACT. The EPA views 
this provision as providing the Agency the authority to prevent any 
remaining adverse environmental effect, as defined in section 
112(a)(7), presented by HAP emissions from stationary sources after

[[Page 36444]]

imposition of controls under section 112(d).
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    \14\ 42 U.S.C. Sec. 7412(f)(2)(A) provides:
    If Congress does not act on any recommendation submitted under 
paragraph (1), the Administrator shall, within 8 years after 
promulgation of standards for each category or subcategory of 
sources pursuant to subsection (d) of this section, promulgate 
standards for such category or subcategory if promulgation of such 
standards is required in order to provide an ample margin of safety 
to protect public health in accordance with this section (as in 
effect before November 15, 1990) or to prevent, taking into 
consideration costs, energy, safety, and other relevant factors, an 
adverse environmental effect. Emission standards promulgated under 
this subsection shall provide an ample margin of safety to protect 
public health in accordance with this section (as in effect before 
November 15, 1990), unless the Administrator determines that a more 
stringent standard is necessary to prevent, taking into 
consideration costs, energy, safety, and other relevant factors, an 
adverse environmental effect. If standards promulgated pursuant to 
subsection (d) of this section and applicable to a category or 
subcategory of sources emitting a pollutant (or pollutants) 
classified as a known, probable or possible human carcinogen do not 
reduce lifetime excess cancer risks to the individual most exposed 
to emissions from a source in the category or subcategory to less 
than one in one million, the Administrator shall promulgate 
standards under this subsection for such source category.
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    As discussed earlier in today's notice, for purposes of section 112 
in general, the term ``adverse environmental effect'' is defined by 
section 112(a)(7) to include ``any significant and widespread adverse 
effect, which may reasonably be anticipated, to wildlife, aquatic life, 
or other natural resources, including adverse impacts on populations of 
endangered or threatened species or significant degradation of 
environmental quality over broad areas'' (42 U.S.C. 7412(a)(7)). Again, 
EPA interprets the scope of this defined term to apply as broadly as 
the effects discussed in section 112(m)(6). Moreover, section 
112(f)(2)(A) allows the Agency to promulgate appropriate further 
emissions standards for a source category or subcategory as necessary 
to provide an ample margin of safety to protect public health or to 
prevent any adverse environmental effect. Where the risk of harm to 
public health or the risk of an adverse environmental effect is 
presented by only certain sources within a source category or 
subcategory, EPA believes it may appropriately tailor the section 
112(f)(2) regulations applicable to the source category or subcategory 
such that the requirement to achieve additional emissions reductions or 
undertake other control efforts is imposed only on those sources within 
the category or subcategory that present the risk. This approach would 
avoid possible unnecessary imposition of these risk-based requirements 
on any sources in the category or subcategory whose emissions do not 
present such risk, and allow EPA to most effectively craft the section 
112(f)(2)(A) requirements applicable to the category or subcategory to 
specifically address the risks at issue. This interpretation is 
supported by section 112(f)(2)(A)'s provision that EPA is authorized to 
promulgate additional standards to prevent ``an'' adverse environmental 
effect. The reference to ``adverse environmental effect'' in the 
singular contemplates a situation where, for example, an adverse 
environmental effect is presented by a limited number of sources within 
a source category or subcategory, over a limited geographic or 
situational range. Moreover, while EPA recognizes that section 
112(f)(2)(A) requires the Agency to consider cost, energy, safety and 
other relevant factors when establishing a more stringent limit than is 
necessary to protect the public health with an ample margin of safety, 
EPA has substantial discretion in determining how to evaluate those 
factors and what weight to give them. (See, New York v. Reilly, 969 
F.2d 1147, 1150 (D.C. Cir. 1992) (citing Center for Auto Safety v. 
Peck, 751 F.2d 1336, 1342 (D.C, Cir. 1985), Weyerhaeuser Co. v. Costle, 
590 F.2d 1011, 1045 (D.C. Cir. 1978)(Congress ``left EPA with 
discretion to decide how to account for the consideration of factors, 
and how much weight to give each factor'').) The presence of these 
factors further supports EPA's view that it has substantial discretion 
in developing the most appropriate approaches to addressing residual 
risks presented by source categories or subcategories. For example, EPA 
could use its section 112(f) residual risk authority to address adverse 
environmental effects to Great Waters waterbodies that are associated 
with the atmospheric deposition of HAP emitted by particular sources 
within source categories.
    In developing additional standards to address residual risk 
following adoption of MACT standards, section 112(f) states that the 
Administrator shall not be required to conduct any residual risk review 
or promulgate additional emission limitations for any category or 
subcategory of area sources that is listed under section 112(c)(3) for 
which a GACT emission standard is promulgated pursuant to section 
112(d)(5) (42 U.S.C. 7412(f)(5)).15 In effect, this 
provision grants discretionary authority to EPA to provide an exemption 
for area sources from the more stringent residual risk standards. It is 
important to emphasize, however, that this exemption is wholly within 
EPA's discretion so that, should the Agency determine that emissions of 
one or more HAP from area sources within a source category or 
subcategory pose unacceptable remaining risks to human health or the 
environment, even after application of section 112(d) emission 
controls, it has authority under section 112(f) to adopt more stringent 
standards governing these sources as well. This is in addition to EPA's 
discretionary authority to apply more stringent MACT standards to area 
sources in the first instance. Thus, the CAA provides authority in 
section 112(f)(2)(A) to take action with respect to stationary source 
categories or subcategories as needed to prevent the same sorts of 
effects identified under section 112(m)(6), and to focus such action so 
that the duty to undertake measures in compliance with the residual 
risk standard is triggered by sources within the subject category or 
subcategory that present the risk of causing these effects.
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    \15\ 42 U.S.C. 7412(f)(5) provides:
    The Administrator shall not be required to conduct any review 
under this subsection or promulgate emission limitations under this 
subsection for any category or subcategory of area sources that is 
listed pursuant to subsection (c)(3) of this section and for which 
an emission standard is promulgated pursuant to section (d)(5) of 
this section.
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F. Urban Area Source Program

    Section 112(k) requires EPA to implement the urban area source 
program. After conducting research to monitor, analyze and consider HAP 
emissions from area sources in urban areas and their public health 
risks, EPA is required under section 112(k)(3)(B)(I) to identify the 30 
HAP emitted from area sources that present the greatest threat to 
public health in the largest number of urban areas (42 U.S.C. 
7412(k)(3)(B)(I)). The EPA must then identify the source categories for 
listing under section 112(c), assuring that sources accounting for at 
least 90 percent of the aggregate emissions of each of the 30 
identified HAP will be subject to standards pursuant to section 112(d) 
(42 U.S.C. 7412(k)(3)(B)(ii)).
    Section 112(k)(3)(C) then requires EPA to prepare a strategy 
including a schedule of specific actions to reduce public health risks 
posed by emissions of HAP by area sources, which would be implemented 
by EPA or the States under several Federal and State environmental 
statutes. This strategy must achieve at least a 75 percent reduction in 
the incidence of cancer attributable to exposure to HAP emitted by 
stationary sources (42 U.S.C. 7412(k)(3)(C)). In addition to this 
national urban area source strategy, EPA shall also encourage and 
support areawide strategies developed by State and local agencies 
intended to reduce risks from emissions by area sources in particular 
urban areas, and prepare guidelines for control technologies or 
management practices which may be applicable to various source 
categories (42 U.S.C. 7412(k)(4)).
    To the extent that the urban area source program identifies and 
achieves reductions in HAP that are also pollutants of concern in the 
Great Waters, section 112(k) provides an additional tool for reducing 
HAP emissions that present serious adverse effects to the public health 
or environment through atmospheric deposition. For example, this 
program could result in significant reductions in emissions of POM, 
with incidental benefits for the specific environmental values required 
to be protected under the Great Waters provisions, if POM is identified 
as one of the 30 most hazardous air pollutants emitted by area sources.

[[Page 36445]]

G. Studies and Reports to Congress

1. Mercury
    Section 112(n)(1)(B) requires EPA to study and report to Congress 
on mercury emissions from electric utility steam generating units, 
municipal waste combustion units, and other sources, including area 
sources (42 U.S.C. 7412(n)(1)(B)). 16 This study must 
consider the rate and mass of such mercury emissions, the health and 
environmental effects of the emissions, available technologies to 
control these emissions, and the costs of applying such technology.
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    \16\ 42 U.S.C. 7412(n)(1)(B) provides:
    The Administrator shall conduct, and transmit to the Congress 
not later than 4 years after November 15, 1990, a study of mercury 
emissions from electric utility steam generating units, municipal 
waste combustion units, and other sources, including area sources. 
Such study shall consider the rate and mass of such emissions, the 
health and environmental effects of such emissions, technologies 
which are available to control such emissions, and the costs of such 
technologies.
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    When the report becomes final, the results of the study will be 
helpful in prioritizing mercury reduction strategies.
2. Electric Utilities
    Under section 112(n)(1)(A), EPA must also study and report to 
Congress on the hazards to public health reasonably anticipated to 
occur as a result of emissions of HAP by electric utility steam 
generating units after imposition of the CAA requirements (42 U.S.C. 
7412(n)(1)(A)).17 This report must develop and describe 
alternative control strategies for emissions which may warrant 
regulation under section 112, and EPA is required by section 
112(n)(1)(A) to regulate electric utility steam generating units under 
section 112 if EPA finds such regulation is necessary and appropriate 
after considering the study.
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    \17\ 42 U.S.C. 7412(n)(1)(A) provides:
    The Administrator shall perform a study of the hazards to public 
health reasonably anticipated to occur as a result of emissions by 
electric utility steam generating units of pollutants listed under 
subsection (b) of this section after imposition of the requirements 
of this chapter. The Administrator shall report the results of this 
study to the Congress within 3 years after November 15, 1990. The 
Administrator shall develop and describe in the Administrator's 
report to Congress alternative control strategies for emissions 
which may warrant regulation under this section. The Administrator 
shall regulate electric utility steam generating units under this 
section, if the Administrator finds such regulation is appropriate 
and necessary after considering the results of the study required by 
this subparagraph.
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    These provisions provide EPA the authority to achieve reductions in 
HAP emissions from electric utilities as necessary and appropriate to 
prevent reasonably anticipated hazards to public health and the 
environment, which would have benefits for the Great Waters. For 
example, if EPA determines that regulation of mercury emissions from 
electric utilities is necessary and appropriate, EPA would have the 
full set of regulatory tools available under section 112 to address 
those emissions, including section 112(f), as well as any additional 
alternative control strategies the Agency has identified in its Report 
to Congress.

H. Solid Waste Incineration Units

    Solid waste incineration units such as those that combust municipal 
waste, medical waste, and industrial and commercial waste, are 
regulated under sections 111 and 129 of the CAA. While this is not 
literally a section 112 program, the types of standards to be applied 
under section 129(a)(2) are MACT standards, and shall be based on 
methods and technologies for removal or destruction of pollutants 
before, during or after combustion. For new units, they must 
incorporate siting requirements that minimize, on a site-specific 
basis, to the maximum extent practicable, potential risks to public 
health or the environment (42 U.S.C. 7429(a)(2), (3)).18 
These standards are required for certain HAP (as well as specified 
criteria pollutants) identified in section 129: solid waste 
incineration units must be subjected to numerical emission limitations 
for lead, cadmium, mercury, dioxins and dibenzofurans (42 U.S.C. 
7429(a)(4)).19 Moreover, section 129(h)(3) requires EPA to 
promulgate residual risk standards under section 112(f)(2) for 
emissions of these pollutants from solid waste incineration units, if 
such standards are required in order to provide an ample margin of 
safety to protect the public health or to prevent an adverse 
environmental effect as set forth in section 112(f)(2)(A) (42 U.S.C. 
7429(h)(3)).20 Finally, State and local government agencies 
are authorized under section 129(h)(1) to adopt and enforce 
regulations, requirements, limitations or standards relating to solid 
waste incineration units that are more stringent than those promulgated 
by EPA (42 U.S.C. 7429(h)(1); (b)(2)).
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    \18\ 42 U.S.C. 7429(a)(2) and (3) provide:
    (2) Standards applicable to solid waste incineration units 
promulgated under section 7411 of this title and this section shall 
reflect the maximum degree of reduction in emissions of air 
pollutants listed under section (a)(4) that the Administrator, 
taking into consideration the cost of achieving such emission 
reduction, and any non-air quality health and environmental impacts 
and energy requirements, determines is achievable for new or 
existing units in each category. The Administrator may distinguish 
among classes, types (including mass-burn, refuse-derived fuel, 
modular and other types of units), and sizes of units within a 
category in establishing such standards. The degree of reduction in 
emissions that is deemed achievable for new units in a category 
shall not be less stringent than the emissions control that is 
achieved in practice by the best controlled similar unit, as 
determined by the Administrator. Emissions standards for existing 
units in a category may be less stringent than standards for new 
units in the same category but shall not be less stringent than the 
average emissions limitation achieved by the best performing 12 
percent of units in the category (excluding units which first met 
the lowest achievable emissions rates 18 months before the date such 
standards are proposed or 30 months before the date such standards 
are promulgated, whichever is later).
    (3) Standards under section 7411 of this title and this section 
applicable to solid waste incineration units shall be based on 
methods and technologies for removal or destruction of pollutants 
before, during, or after combustion, and shall incorporate for new 
units siting requirements that minimize, on a site specific basis, 
to the maximum extent practicable, potential risks to public health 
or the environment.
    \19\ 42 U.S.C. 7429(a)(4) provides:
    The performance standards promulgated under section 7411 of this 
title and this section and applicable to solid waste incineration 
units shall specify numerical emission limitations for the following 
substances or mixtures: particulate matter (total and fine), opacity 
(as appropriate), sulfur dioxide, hydrogen chloride, oxides of 
nitrogen, carbon monoxide, lead, cadmium, mercury, and dioxins and 
dibenzofurans. The Administrator may promulgate numerical emissions 
limitations or provide for the monitoring of postcombustion 
concentrations of surrogate substances, parameters or periods of 
residence time in excess of stated temperatures with respect to 
pollutants other than those listed in this paragraph.
    \20\ 42 U.S.C. 7429(h)(3) provides:
    The Administrator shall promulgate standards under section 
7412(f) of this title for a category of solid waste incineration 
units, if promulgation of such standards is required under section 
7412(f) of this title. For purposes of this preceding sentence 
only--
    (A) the performance standards under subsection (a) of this 
section and section 7411 of this title applicable to a category of 
solid waste incineration units shall be deemed standards under 
section 7412(d)(2) of this title, and
    (B) the Administrator shall consider and regulate, if required, 
the pollutants listed under subsection (a)(4) of this section and no 
others.
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    This program will result in significant reductions in emissions of 
pollutants of concern for the Great Waters from solid waste 
incineration units. Especially in light of the authority to subject 
these units to residual risk standards under section 112(f)(2) and 
EPA's substantial discretion afforded under that subsection, EPA 
believes that it has adequate authority to prevent solid waste 
incineration unit emissions of the specified HAP in section 129(a)(4) 
from causing serious adverse public health and environmental effects 
associated with deposition to the Great Waters.

IV. Determinations of Adequacy and No Need for Further Regulations

    Based on available information and on the foregoing analysis, 
guided by EPA's interpretation of the statutory

[[Page 36446]]

requirements of section 112(m), EPA believes that the other provisions 
of section 112 are adequate to prevent serious, adverse effects to 
public health and serious or widespread environmental effects 
associated with the deposition of HAP which are emitted by stationary 
sources for which EPA has authority and jurisdiction under section 112 
to regulate. As a result, the Agency also believes that no further 
emissions standards or control measures under section 112(m)(6), beyond 
those authorized or required by the other provisions of section 112, 
are necessary and appropriate at this time. The EPA further believes 
that even if section 112 were found to be inadequate under section 
112(m)(6), because much scientific information is still lacking 
concerning such things as the relative contribution of air emissions of 
pollutants of concern to adverse effects, it would not be possible at 
this time for the Agency to conclude confidently that further 
regulatory actions beyond those authorized or required to be taken 
under section 112 are necessary and appropriate. The EPA solicits 
comments on the draft determination, and on the analysis contained in 
today's notice. The Agency reserves its right to reconsider these draft 
determinations if the public comments on the draft determinations 
convince EPA that it is incorrect in its analysis, or if future events 
or additional information indicate EPA's determinations are not 
accurate. In addition, when EPA finalizes these determinations, EPA 
reserves its right to promulgate any necessary and appropriate further 
regulations pursuant to section 112(m)(6), in the event that EPA in the 
future, based on new information, revisits and reverses these 
determinations.
    The EPA is committed to continuing its analyses, research and 
assessments of all aspects of atmospheric transport, deposition, fate 
and effects of hazardous air pollutants emitted by section 112 sources. 
The EPA is further committed to faithfully implementing the mandates 
and authorities under section 112 of the CAA, and to pursuing other 
available authorities, as appropriate, to minimize unreasonable threats 
to humans and to the environment as a result of exposure to toxic 
pollutants, whether such exposures result directly from emissions into 
the air, through introduction to watersheds or waterbodies, or through 
other pathways. The EPA will continue to work cooperatively with the 
National Oceanic and Atmospheric Administration and the scientific 
community to refine methods for measuring or estimating atmospheric 
transport and deposition of HAP in order to more reliably characterize 
and quantify the significance of atmospheric deposition to 
environmental quality.
    It is important to distinguish between EPA's draft determinations 
in this notice and the Agency's judgments about the extent to which 
adverse effects may be occurring due to atmospheric deposition of HAP 
from all sources, or about the extent to which additional actions 
within the scope of its other authorities under section 112 may be 
warranted. In today's notice, EPA is announcing only that it believes 
it has adequate authority under section 112 to prevent the section 
112(m)(6) enumerated adverse health or environmental effects associated 
with emissions of HAP from sources which section 112 was intended to 
regulate, and that, at this time, EPA does not believe that further 
emissions standards or control measures under section 112(m)(6) to 
prevent such effects, beyond those that are authorized or required by 
the other provisions of section 112, are necessary or appropriate for 
stationary sources of HAP. These draft determinations in no way 
represent a conclusion on EPA's part that air deposition of HAP does 
not currently cause or contribute to adverse effects to the public 
health or the environment.

    Dated: June 30, 1997.
Carol Browner,
Administrator.
[FR Doc. 97-17597 Filed 7-3-97; 8:45 am]
BILLING CODE 6560-50-P