National Emission Standards for Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants, 13852-13878 [2011-5530]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 76, Number 49 (Monday, March 14, 2011)]
[Proposed Rules]
[Pages 13852-13878]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-5530]



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Vol. 76

Monday,

No. 49

March 14, 2011

Part V





Environmental Protection Agency





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40 CFR Part 63



National Emission Standards for Hazardous Air Pollutants: Mercury 
Emissions From Mercury Cell Chlor-Alkali Plants; Proposed Rule

Federal Register / Vol. 76 , No. 49 / Monday, March 14, 2011 / 
Proposed Rules

[[Page 13852]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2002-0017; FRL-9278-5]
RIN 2060-AN99


National Emission Standards for Hazardous Air Pollutants: Mercury 
Emissions From Mercury Cell Chlor-Alkali Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental proposed rule.

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SUMMARY: This action proposes amendments to the national emission 
standards for hazardous air pollutants (NESHAP) for mercury emissions 
from mercury cell chlor-alkali plants (Mercury Cell NESHAP). On June 
11, 2008, EPA proposed amendments to this NESHAP in response to a 
petition for reconsideration filed by the Natural Resources Defense 
Council (NRDC). This action is a supplement to the June 11, 2008, 
proposal. Specifically, this action proposes two options for amending 
the NESHAP for mercury emissions from mercury cell chlor-alkali plants. 
The first option would require the elimination of mercury emissions and 
thus encourage the conversion to non-mercury technology. The second 
option would require the measures proposed in 2008. These measures, 
which included significant improvements in the work practices to reduce 
fugitive emissions from the cell room, would result in near-zero levels 
of mercury emissions while still allowing the mercury cell facilities 
to continue to operate. We are specifically requesting comment on which 
of these options is more appropriate, and may finalize either option or 
a combination of elements from them. In addition, this action proposes 
several amendments that would apply regardless of which option we 
select. These proposed amendments are provisions of the existing NESHAP 
that would apply to periods of startup, shutdown, and malfunction 
(SSM), and corrections to compliance errors in the currently effective 
rule.

DATES: Comments must be received on or before May 13, 2011. Under the 
Paperwork Reduction Act, comments on the information collection 
provisions must be received by the Office of Management and Budget 
(OMB) on or before April 13, 2011.
    Public Hearing. If anyone contacts EPA by March 29, 2011 requesting 
to speak at a public hearing, EPA will hold a public hearing on April 
13, 2011. If a public hearing is held, it will be held at EPA's Campus 
located at 109 T.W. Alexander Drive in Research Triangle Park, NC, or 
an alternate site nearby. Contact Virginia Hunt at (919) 541-0832 to 
request a hearing, to determine if a hearing will be held, or to 
determine the hearing location. If no one contacts EPA requesting to 
speak at a public hearing concerning this proposed rule by March 29, 
2011, the hearing will be cancelled without further notice.

ADDRESSES: You may submit comments, identified by Docket ID No. EPA-HQ-
OAR-2002-0017, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov: 
Follow the instructions for submitting comments.
     Agency Web Site: https://www.epa.gov/oar/docket.html. 
Follow the instructions for submitting comments on the EPA Air and 
Radiation Docket Web site.
     E-mail: a-and-r-docket@epa.gov. Include Docket ID No. EPA-
HQ-OAR-2002-0017 in the subject line of the message.
     Fax: (202) 566-9744.
     Mail: National Emission Standards for Hazardous Air 
Pollutants for Mercury Cell Chlor-alkali Plants Docket, Environmental 
Protection Agency, EPA Docket Center (EPA/DC), Air and Radiation 
Docket, Mail Code 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 
20460. Please include a total of two copies. In addition, please mail a 
copy of your comments on the information collection provisions to the 
Office of Information and Regulatory Affairs, Office of Management and 
Budget (OMB), Attn: Desk Officer for EPA, 725 17th St., NW., 
Washington, DC 20503.
     Hand Delivery: EPA Docket Center, Public Reading Room, EPA 
West, Room 3334, 1301 Constitution Ave., NW., Washington, DC 20460. 
Such deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2002-0017. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
https://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
confidential business information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through https://www.regulations.gov or e-mail. The https://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through https://www.regulations.gov, your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically through https://www.regulations.gov or in hard copy at the National Emission Standards 
for Hazardous Air Pollutants for Mercury Cell Chlor-alkali Plants 
Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW., 
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 
p.m., Monday through Friday, excluding legal holidays. The telephone 
number for the Public Reading Room is (202) 566-1744, and the telephone 
number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Sharon Nizich, Sector Policies and 
Programs Division, Office of Air Quality Planning and Standards (D243-
02), Environmental Protection Agency, Research Triangle Park, North 
Carolina 27711, telephone number: (919) 541-2825; fax number: (919) 
541-5450; e-mail address: nizich.sharon@epa.gov.

SUPPLEMENTARY INFORMATION:
    The supplementary information in this preamble is organized as 
follows:

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments to EPA?

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    C. Where can I get a copy of this document?
    D. When would a public hearing occur?
II. Background Information
    A. What is the history of the Mercury Cell NESHAP?
    B. What petitions were filed after promulgation of the Mercury 
Cell NESHAP in 2003?
    C. What were the reconsideration decisions proposed in 2008?
    D. What current legislation is related to this effort?
III. Summary of Proposed Amendments
    A. What is the non-mercury technology option (Option 1)?
    B. What is the enhanced work practices option (Option 2)?
    C. What amendments are being proposed that are independent of 
which option is selected?
IV. Request for Comment
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations

I. General Information

A. Does this action apply to me?

    The regulated categories and entities potentially affected by this 
proposed action include:

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                                                  Examples of regulated
            Category              NAICS code\1\          entities
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Industry.......................          325181  Alkalis and Chlorine
                                                  Manufacturing.
Federal government.............  ..............  Not affected.
State/local/Tribal government..  ..............  Not affected.
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\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
action. To determine whether your facility would be regulated by this 
action, you should examine the applicability criteria in 40 CFR 63.7682 
of subpart IIIII, National Emission Standards for Hazardous Air 
Pollutants (NESHAP): Mercury Emissions from Mercury Cell Chlor-Alkali 
(hereafter called the ``2003 Mercury Cell NESHAP''). If you have any 
questions regarding the applicability of this action to a particular 
entity, consult either the air permitting authority for the entity or 
your EPA regional representative as listed in 40 CFR 63.13 of subpart A 
(General Provisions).

B. What should I consider as I prepare my comments to EPA?

    Do not submit information containing CBI to EPA through https://www.regulations.gov or e-mail. Send or deliver information identified 
as CBI only to the following address: Roberto Morales, OAQPS Document 
Control Officer (C404-02), Environmental Protection Agency, Office of 
Air Quality Planning and Standards, Research Triangle Park, North 
Carolina 27711, Attention Docket ID EPA-HQ-OAR-2002-0017. Clearly mark 
the part or all of the information that you claim to be CBI. For CBI 
information in a disk or CD ROM that you mail to EPA, mark the outside 
of the disk or CD ROM as CBI and then identify electronically within 
the disk or CD ROM the specific information that is claimed as CBI. In 
addition to one complete version of the comment that includes 
information claimed as CBI, a copy of the comment that does not contain 
the information claimed as CBI must be submitted for inclusion in the 
public docket. Information so marked will not be disclosed except in 
accordance with procedures set forth in 40 CFR part 2.

C. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of 
this proposed action will also be available on the World Wide Web (WWW) 
through the Technology Transfer Network (TTN). Following signature, a 
copy of this proposed action will be posted on the TTN's policy and 
guidance page for newly proposed or promulgated rules at the following 
address: https://www.epa.gov/ttn/oarpg/. The TTN provides information 
and technology exchange in various areas of air pollution control.

D. When would a public hearing occur?

    If anyone contacts EPA requesting to speak at a public hearing 
concerning the proposed amendments by March 24, 2011, we will hold a 
public hearing on April 13, 2011. If you are interested in attending 
the public hearing, contact Ms. Virginia Hunt at (919) 541-0832 to 
verify that a hearing will be held. If a public hearing is held, it 
will be held at 10 a.m. at the EPA's Environmental Research Center 
Auditorium, Research Triangle Park, NC, or an alternate site nearby.

II. Background Information

A. What is the history of the Mercury Cell NESHAP?

    On December 19, 2003, EPA promulgated the 2003 Mercury Cell NESHAP 
(40 CFR part 63, subpart IIIII, 68 FR 70904). This rule for mercury 
cell chlor-alkali plants implements section 112(d) of the Clean Air Act 
(CAA), which requires all categories and subcategories of major sources 
listed under section 112(c) to meet hazardous air pollutant emission 
standards reflecting the application of the maximum achievable control 
technology (MACT). Mercury cell chlor-alkali plants are a subcategory 
of the chlorine production source category listed under the authority 
of section 112(c)(1) of the CAA. In addition, mercury cell chlor-alkali 
plants are listed as an area source category under section 112(c)(3) 
and (k)(3)(B) of the CAA. The 2003 Mercury Cell NESHAP satisfied our 
requirement to issue 112(d) regulations under each of these listings 
(for mercury). The 2003 Mercury Cell NESHAP required both existing 
major and area sources to meet mercury emission limits on stack 
emission sources from both chlorine production and from the recovery of 
mercury from wastes and other scrap in mercury thermal recovery units. 
The 2003 Mercury Cell NESHAP also required the facilities to monitor 
and minimize fugitive mercury emissions from the cell room by 
conducting either daily work practices or work practices performed in 
response to high levels of mercury emissions determined from continuous 
mercury monitoring. The 2003 rule required facilities to comply with

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applicable emission limitations and work practice requirements at all 
times, except during periods of SSM. Finally, the 2003 Mercury Cell 
NESHAP prohibited mercury emissions from new and reconstructed 
facilities.

B. What petitions were filed after promulgation of the Mercury Cell 
NESHAP in 2003?

    On February 17, 2004, the NRDC submitted an administrative petition 
to EPA asking us to reconsider several aspects of the 2003 Mercury Cell 
NESHAP under CAA section 307(d)(7)(B). On the same day as the 
administrative petition, NRDC and the Sierra Club also filed a petition 
for judicial review of the 2003 Mercury Cell NESHAP in the U.S. Court 
of Appeals for the DC Circuit (Civ. No. 04-1048).
    By a letter dated April 8, 2004, Jeffrey Holmstead, then-EPA 
Assistant Administrator for the Office of Air and Radiation, notified 
the NRDC that EPA had granted NRDC's petition for reconsideration of 
the 2003 Mercury Cell NESHAP. On July 20, 2004, the Court granted EPA's 
motion to hold the case for judicial review in abeyance pending EPA's 
action on the reconsideration of the 2003 Mercury Cell NESHAP.

C. What were the reconsideration decisions proposed in 2008?

    On June 11, 2008 (73 FR 33257), EPA responded to NRDC's petition 
for reconsideration. In their petition, NRDC asked EPA to reconsider 
five issues: (1) The decision to develop a set of work practice 
requirements under CAA section 112(h) in lieu of a numeric emission 
limitation for cell rooms; (2) the decision to make the promulgated 
work practices optional for sources that choose to undertake continuous 
monitoring; (3) the decision to not require existing facilities to 
convert to a non-mercury chlorine manufacturing process; (4) the 
elimination of the previously applicable part 61 rule's 2,300 grams/day 
plant-wide emission limitation; and (5) the decision to create a 
subcategory of mercury cell chlor-alkali plants within the chlorine 
production category. In the 2008 proposal, EPA addressed each of these 
issues and proposed amendments where we determined them to be 
appropriate. Following are brief summaries of our reconsideration 
decisions. For a full explanation of these decisions and the rationale 
supporting them, please see the preamble for the June 11, 2008 proposal 
(73 FR 33258). The 2008 proposed amendments, which are being co-
proposed in this action as Option 2, are discussed in section III.B of 
this document.
    In addition, while not specifically listed as a major issue in 
their petition, the uncertainty related to the magnitude of fugitive 
mercury emissions was clearly a basis for much of NRDC's concern. This 
was also addressed in the 2008 proposal and is summarized below after 
the five specific issues cited by NRDC in the petition.
1. Emission Limitation for Cell Room
    In its petition for reconsideration, NRDC stated that EPA failed to 
adequately justify that a numeric emission limitation was not feasible 
per the criteria prescribed in section 112(h) of the CAA. In our 2008 
reconsideration, we concluded that it is not feasible to prescribe or 
enforce an emission limitation for fugitive emissions from the cell 
room. We maintained that fugitive emissions from mercury cells and 
associated equipment are a clear example of the type of situation to be 
addressed by the provisions of section 112(h). The various points which 
led to our opinion on the feasibility of establishing an emission 
standard were discussed in detail in the 2008 proposal (73 FR 33267-
33271). In summary, consistent with CAA section 112(h), we believe that 
it is not feasible to prescribe or enforce an emission standard in this 
case. There are two independent bases for this conclusion. First, 
consistent with CAA section 112(h)(2)(A), we concluded that fugitive 
mercury emissions from a mercury cell chlor-alkali plant cannot be 
emitted through a conveyance designed and constructed to emit or 
capture such pollutant. Second, consistent with CAA section 
112(h)(2)(B), we established that the application of measurement 
technology to mercury cell rooms is not practicable due to 
technological and economic limitations.
2. Optional Work Practices
    The 2003 Mercury Cell NESHAP requires facilities to follow a set of 
detailed work practices. The NESHAP also allows facilities to institute 
a cell room monitoring program to continuously monitor the mercury 
vapor concentration in the upper portion of each cell room as an 
alternative to these work practice standards. One of the objections 
raised by NRDC was that this provision backtracked from the Agency's 
proposed work practice standards. NRDC pointed out that in the 
development of the Mercury Cell NESHAP, EPA concluded that the 
housekeeping activities that facilities in the industry follow to 
comply with the part 61 mercury NESHAP (40 CFR 61, subpart E) 
represented the MACT floor and that requiring practices based upon the 
most detailed activities in the industry (i.e., ``beyond-the-floor'' 
practices) was justified. But NRDC was concerned because the work 
practices in the 2003 Mercury Cell NESHAP were optional if facilities 
chose to do continuous monitoring and, therefore, this option would 
allow sources to avoid conducting activities that represent the MACT 
floor. NRDC argued that this was a violation of section 112(d)(3) of 
the CAA, which requires all facilities to meet the MACT floor.
    As a result of our consideration of NRDC's point, we included 
proposed amendments in 2008 that would require that all plants 
institute a cell room monitoring program and comply with work practice 
standards (73 FR 33271-33272). As part of today's action, we are re-
proposing the combination of work practices and cell room monitoring 
program as option 2. The specific proposed amendments are discussed in 
section III.B of this document.
3. Requiring Conversion to a Non-Mercury Chlorine Manufacturing Process
    In its petition, NRDC argued that the 2003 Mercury Cell NESHAP does 
nothing to limit the use of mercury cell technology by existing chlor-
alkali plants, and that the Agency ignored a known technique for 
reducing mercury emissions from this industry, namely, conversion to 
non-mercury processes. According to NRDC, requiring the industry to 
convert to a non-mercury process is cost-justified and would provide 
significant non-air quality benefits. In response to NRDC's concerns 
that we did not evaluate the conversion of mercury cell chlor-alkali 
production plants to non-mercury technology, we performed an analysis 
to estimate the capital and annual costs of this action. In performing 
the analysis, we used information from all readily available sources of 
information. Based on the results of this analysis, we proposed to 
reject the option of requiring conversion to non-mercury technology 
because of the high cost impact this forced conversion would impose on 
the facilities in the industry (73 FR 33274-33275).
    Following the 2008 proposal, one commenter provided detailed 
comments on our proposed decision to not require existing facilities to 
convert to a non-mercury chlorine manufacturing process. In addition to 
comments on the EPA cost analysis described in our 2008 proposal, the 
commenter provided a report to support its comments. We

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reviewed these comments, examined the commenter's report, and concluded 
that our cost analysis could be improved. Therefore, we incorporated 
some aspects of the commenter's cost analysis, and gathered additional 
cost information. The results of our revised analyses, and our 
consideration of the policy and legal comments made by the commenter 
regarding the benefits of non-mercury technology to produce chlorine, 
provided the impetus for the non-mercury mercury option being proposed 
today as Option 1. Details of this proposed option are provided in 
section III.A of this document.
4. Elimination of Part 61 NESHAP Numeric Limit
    NRDC stated that EPA illegally eliminated the 2,300 g/day limit on 
plant-wide mercury emissions that existed under the part 61 Mercury 
NESHAP. Upon reconsideration, we disagreed with NRDC's argument. We 
determined that the plant-wide emission limit from the part 61 Mercury 
NESHAP was a standard to which no mercury cell facility had ever 
demonstrated compliance by way of emissions testing, that it is not an 
enforceable standard today, and, more importantly, and that it did not 
reflect the MACT level of emissions control required under CAA section 
112(d)(3)(B). Therefore, we concluded that we did not unlawfully remove 
any actual requirement of the part 61 Mercury NESHAP. Instead, the 2003 
Mercury Cell NESHAP adopted a set of MACT-level work practice 
requirements under section 112(h) that are more stringent in terms of 
controlling fugitive mercury emissions than was allowed in the part 61 
NESHAP. Details on this conclusion were provided on pages 73 FR 33270 
and 33271 of the June 11, 2008 proposal.
5. Mercury Cell Chlor-Alkali Subcategory
    As stated in the preamble to the final 2003 Mercury Cell NESHAP (68 
FR 70905), we divided the chlorine production source category into two 
subcategories: (1) Mercury cell chlor-alkali plants and (2) chlorine 
production plants that do not rely upon mercury cells for chlorine 
production. In December 2003 (68 FR 70949), we issued our final 
decision to delete the subcategory of the chlorine production source 
category for chlorine production plants that do not utilize mercury 
cells to produce chlorine and caustic. This action was made under our 
authority in CAA section 112(c)(9)(B)(ii), and was not challenged in a 
petition for judicial review. Nor did anyone ask us to reconsider that 
action pursuant to CAA section 307(d)(7)(B). The objection raised by 
NRDC in its petition for reconsideration of the 2003 Mercury Cell 
NESHAP was that it was not appropriate to create a mercury cell chlor-
alkali plants subcategory. According to NRDC, if the MACT floor for 
mercury emissions was determined for the chlorine production source 
category as a whole, the best-performing 12 percent of sources in the 
category would be mercury-free. In our 2008 proposal (73 FR 33273-
33274), we explained that EPA has a long history of using 
subcategorization to appropriately differentiate between types of 
emissions and/or types of operations when analyzing whether air 
pollution control technology is feasible for groups of sources. Upon 
reconsideration of this situation for mercury cell chlor-alkali plants, 
we concluded that our earlier decision to create the mercury cell 
chlor-alkali plant subcategory was sound.
6. Magnitude of Fugitive Mercury Emissions
    Prior to 2008, the uncertainty associated with fugitive mercury 
emissions from mercury cell chlor-alkali plants had long been an issue. 
Few studies had been conducted to measure these fugitive mercury 
emissions, and the studies that had been conducted were short-term and 
did not account for a range of operating and maintenance conditions. 
For around 30 years, mercury cell chlor-alkali plants had reported 
fugitive mercury emissions of 1,300 grams per day (g/day), which 
equates to around 0.5 tons per year per plant. These estimates were 
based on two limited studies conducted by EPA in the early 1970's.
    The sensitivity and concern over the actual levels of fugitive 
mercury emissions from the cell rooms was exacerbated by the inability 
of the industry to fully account for all the mercury that was added to 
the cells. In 2000, there were approximately 65 tons of mercury 
unaccounted for at the 12 mercury cell plants in operation at that 
time. This discrepancy was based on the difference between the amount 
of mercury used, as reported in the Chlorine Institute's 2001 annual 
report to EPA's Binational Toxics Strategy Mercury Workgroup,\a\ and 
the amount of mercury released to all media, as reported in the 2000 
Toxics Release Inventory, or TRI (the EPA requires industrial 
facilities to annually report on releases and transfers of certain 
toxic chemicals to a public database known as the TRI.) While industry 
representatives provided explanations for this discrepancy, they could 
not fully substantiate their theories. NRDC maintained that this 
``missing'' mercury was being emitted as fugitive emissions.
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    \a\ Binational Toxics Strategy Mercury Workgroup--Reducing 
Mercury in the Great Lakes Region. U.S. Environmental Protection 
Agency. https://www.epa.gov/reg5oair/mercury/reducing.html#regulation.
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    We recognized that the body of fugitive mercury emissions data 
could be improved. Therefore, as part of our reconsideration of the 
2003 Mercury Cell NESHAP, we collected additional information on 
fugitive mercury emissions from mercury cell chlor-alkali plants. The 
primary purpose of this effort was to address whether the fugitive 
emissions from a mercury cell chlor-alkali plant are on the order of 
magnitude of the historical assumption of 1,300 g/day, corresponding to 
0.5 tons per year (tpy) per plant, or an order of magnitude higher as 
estimated by NRDC.
    Consequently, as part of our reconsideration efforts leading the 
2008 proposal, we sponsored a test program to address the issue of the 
magnitude of the fugitive mercury emissions at mercury cell chlor-
alkali plants. In addition to this EPA test program, we also collected 
mercury emissions data from the continuous mercury monitoring systems 
installed at three mercury cell plants.
    The daily fugitive mercury emission rates extrapolated from these 
data sets ranged from around 20 to 1,300 g/day per facility. The 
average daily emission rates ranged from around 420 g/day to just under 
500 g/day per facility, with the mean of these average values being 
slightly less than 450 g/day per facility. Therefore, the information 
we obtained in the almost one million dollar study of fugitive 
emissions from mercury cell chlor-alkali plants shows that fugitive 
emissions are on the order of magnitude of the historical assumption of 
1,300 g/day or less. There was no evidence obtained during any of the 
studies that indicated that fugitive mercury emissions were at levels 
higher than 1,300 g/day. All of the studies that produced these data 
were of sufficient duration to encompass all types of maintenance 
activities. Further, the length of these studies was also sufficient to 
include emissions from a variety of process upsets, such as: Liquid 
mercury spills, leaking cells and other process equipment, and other 
process upsets.
    We also note that since 2008, the mercury cell plants with 
continuous monitoring systems and methods to estimate the flow rates 
have reported even lower mercury emissions than

[[Page 13856]]

those reported in the 2008 proposal. In 2008, these plants reported 
fugitive mercury emissions averaging around 225 g/day/plant.

D. What current legislation is related to this action?

    There is also U.S. legislation, both recently enacted and proposed, 
that has or will have an impact on these mercury chlor-alkali 
facilities. On October 14, 2008, President Bush signed the Mercury 
Export Ban Act of 2008 into law. This law bans U.S. export of elemental 
mercury (effective in 2013), requires the Department of Energy (DOE) to 
designate and manage a long-term storage facility for elemental 
mercury, and prohibits the transfer of elemental mercury by Federal 
agencies.
    Both houses of Congress are currently considering legislation that, 
if enacted, would affect this industry (S. 1428 and H.R. 2190). These 
bills would amend the Toxic Substances Control Act to prohibit the use 
of mercury at chlor-alkali facilities. The House bill would require the 
facilities to cease using mercury by 2013 if the plant chooses to close 
or by 2015 if the plant chooses to convert to non-mercury. If this 
legislation passes Congress and is signed by the President into law, we 
will evaluate the appropriate action for EPA in light of the scope and 
impact of the law.

III. Summary of Proposed Amendments

    In today's action, we are proposing two options for amending the 
Mercury Cell NESHAP. The first option (non-mercury technology option) 
would encourage the conversion to non-mercury technology by requiring 
the elimination of mercury emissions. The second option (enhanced work 
practices option) would require improvements in the work practice 
standards to reduce fugitive emissions from the cell room including the 
requirement that every facility institute a cell room monitoring 
program and implement detailed work practices. These options, along 
with the estimated impacts of each, are described below in sections 
III.A and III.B. Also included is rationale for the selection of each 
option.
    In addition to these options, we are also proposing amendments that 
would apply regardless of which option we select. These amendments are 
described in section III.C.

A. What is the non-mercury technology option (Option 1)?

1. Summary of Non-Mercury Technology Option
    This proposed option would amend the 2003 Mercury Cell NESHAP by 
prohibiting mercury emissions from existing mercury cell chlor-alkali 
plants. This would make the standard for existing sources the same as 
the current standard for new and reconstructed sources, which is 
codified at 40 CFR 63.8190(a)(1).
    Since we believe it is improbable that a mercury cell chlor-alkali 
plant can be operated without mercury emissions, we believe that this 
proposal would effectively require existing mercury cell chlor-alkali 
plants either to convert to a non-mercury technology or to cease 
production of chlorine with their current mercury cell production 
methods. However, if there are circumstances where the elimination of 
mercury emissions from an operating mercury cell plant could be 
achieved, we are interested in data and supporting information 
regarding technologies that would eliminate mercury emissions from an 
operating mercury cell facility.
    This proposed option would provide a three-year period from the 
date the final rule is published in the Federal Register to comply. To 
demonstrate compliance, each owner or operator would have to submit a 
report certifying that all mercury emissions have been eliminated 
permanently. This report would have to be submitted no later than 120 
days following the applicable compliance date.
2. Technical Information and Analyses for the non-Mercury Technology 
Option
a. Background on the 2008 Proposal and Costs Analysis
    Section 112(d)(2) of the CAA provides that emission standards for 
new or existing sources of hazardous air pollutants (HAP) shall require 
the maximum degree of reduction in emissions (including a prohibition 
on such emissions, where achievable) that EPA, 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 through application of measures, 
processes, methods, systems or techniques. These may include, but are 
not limited to, measures which (A) Reduce the volume of or eliminate 
emissions 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 emission point; (D) are design, 
equipment, work practice, or operational standards; or (E) are a 
combination of the above.
    One of the claims presented in NRDC's petition for reconsideration 
of the 2003 Mercury Cell NESHAP was that EPA had not adequately 
considered non-mercury technology as a ``beyond-the-floor'' MACT 
control measure for existing sources in the original rulemaking for the 
Mercury Cell NESHAP (see section II.D.3). Further, NRDC claimed that 
the cost-effectiveness of such a requirement, in terms of the 
annualized costs of control per pound of mercury eliminated, would be 
less than EPA previously indicated was warranted for mercury emissions 
from the mercury cell subcategory.
    In response to this comment, we performed an analysis in 2008 to 
determine the capital and annual costs of requiring non-mercury 
technology (Docket Item EPA-HQ-OAR-2002-0017-0088). Specifically, this 
analysis estimated the costs and the cost-effectiveness of converting 
the existing mercury cell chlor-alkali plants to membrane cells.
    In a chlor-alkali process, an electric current is passed through a 
salt solution or brine (sodium chloride or potassium chloride), causing 
the dissociation of salt to produce chlorine gas and an alkaline 
solution (sodium hydroxide or potassium hydroxide). Hydrogen gas is 
also produced as a by-product. This dissociation occurs in chlor-alkali 
``cells,'' where the chloride ions stripped from the brine flow to the 
anode to form the chlorine product, and the sodium/potassium ions flow 
to the cathode, where they form the hydroxide product and hydrogen. In 
a mercury cell, the cathode is a flowing layer of liquid mercury. The 
sodium/potassium ions form an amalgam with the mercury, which is routed 
to a decomposer. In the decomposer, the amalgam is reacted with water 
to form the hydroxide product and hydrogen. The mercury is then 
recycled.
    In a membrane process, a polymer membrane is used to separate the 
anode products from the cathode products. The chloride ions (at the 
anode) and the hydrogen (at the cathode) are kept apart by this 
membrane, which allows the sodium ions to pass into the cathodic 
compartment and react to form the hydroxide.
    Conversion from mercury cells to membrane cells is technically 
possible at all existing mercury cell chlor-alkali plants, although the 
amount of significant changes will vary for each individual situation. 
There are parts of the mercury cell plant that could be re-used after 
conversion to the membrane cells. It could be possible to use the 
existing cell room building for the new

[[Page 13857]]

membrane cells, provided that the building is in good condition. 
However, constructing a new membrane cell room building would reduce 
the production losses as the mercury cells could continue to operate 
longer throughout the conversion process. Other equipment and processes 
that possibly could be retained include the rectifiers, the hydrogen 
treatment system, and the chlorine compression and liquefaction 
process.
    The mercury cells themselves (and associated decomposers) would 
have to be replaced by membrane cells. Membrane cells need purer brine 
than mercury cells, so a completely new brine purification system would 
likely be needed. Other equipment that would commonly need to be 
totally replaced include the sodium/potassium hydroxide concentration 
unit and evaporation system, the chlorine gas drying and chlorine gas 
absorption units, the power supply unit (excluding the rectifiers), 
pumps, instruments, and much of the piping.
    In performing the cost analysis, we used data from readily-
available sources of information. In our 2008 proposal, we estimated 
that the average cost-effectiveness associated with conversion to non-
mercury technology would be approximately $14,000 per pound of mercury 
emissions eliminated. Further, our 2008 analysis estimated the average 
capital cost of conversion for one mercury cell chlor-alkali facility 
in the U.S. to be approximately $68 million per plant. The average 
annualized facility costs for this conversion were estimated to be 
approximately $7.5 million per plant. Nationwide, the capital cost was 
estimated to be nearly $340 million and the annual costs around $38 
million for the five facilities in operation at the time. We estimated 
that this cost impact would be approximately 11 percent of revenues. As 
a result of these analyses, we proposed in 2008 to reject conversion to 
non-mercury technology as a beyond-the-floor control requirement.
b. Summary of Comments Received on the 2008 Cost Analysis
    One environmental organization disagreed with both our technical 
analysis and resulting conclusions in the 2008 proposal, and claimed 
that the switch to non-mercury technology would be economical. The 
commenter said that, in the 2008 analysis, EPA considered only the 
costs associated with the conversion, without considering the net cost 
or economic benefit. The commenter maintained that it is likely that 
any plant that converts will experience substantial benefits, including 
an increase in energy efficiency between 25 and 35 percent. The 
commenter claimed that this increased energy efficiency could amount to 
substantial savings. Furthermore, the commenter pointed out that 
membrane cells are smaller than mercury cells, which would allow plants 
to increase their chlorine capacity, leading to increased sales and 
additional energy savings due to the additional capacity. The commenter 
submitted a report that it prepared which provided individualized cost 
analyses for each of the remaining mercury cell chlor-alkali plants 
(Docket Item EPA-HQ-OAR-2002-0017-0094.3). According to the commenter, 
its report proves that conversion would pay for the majority of its 
cost in five years. Thus, the commenter concluded that EPA's proposal 
was incorrect to suppose a ``high cost impact'' of conversion to non-
mercury technology, and claimed that EPA should heed the evidence that 
conversion is not only economically feasible but beneficial and mandate 
conversion to non-mercury technology as a beyond-the-floor control 
requirement.
c. 2009 Revised Cost Analyses
    In the second quarter of 2009, we performed a revised beyond-the-
floor cost analysis to address comments received on the 2008 proposed 
amendments described above. The impacts, particularly the savings and 
benefits, of a forced conversion to membrane cells might not be 
universally applicable since the conditions and benefits are not the 
same at every facility. We do agree, however, that these facilities 
would achieve some savings associated with lower electricity and the 
elimination of environmental compliance costs for water treatment, 
waste disposal, and mercury monitoring, and that items should be added 
to the EPA cost analyses. Therefore, without assuming that a uniform 
energy savings would accrue to every facility currently operating, we 
updated our analysis to consider the energy costs savings. We also 
amended our analysis to include savings from the elimination of waste 
treatment, waste disposal, and mercury monitoring. On June 5, 2009, we 
developed a revised and updated analysis of conversion costs for the 
industry. This analysis was posted as a memorandum in the docket 
(Docket Item EPA-HQ-OAR-2002-0017-0098).
    Subsequent to the posting of the June 5, 2009, memorandum, industry 
representatives provided comments on the revised analysis (Docket Items 
EPA-HQ-OAR-2002-0017-0100, 0101, 0102, and 0103). One of the major 
comments raised by industry representatives on our revised analysis 
regarded the 2006 mercury emission levels used to estimate the cost-
effectiveness of conversion to non-mercury technology. The industry 
representatives stated that these data reflected emission levels 
considerably higher than their more recently reported emissions. In 
addition, the industry representatives stated that the capital and 
annual costs in our 2008 analysis were underestimated. The industry 
representatives also believed that the annual energy savings were 
overstated because these savings did not take into account the 
additional energy and fuel that would be needed to concentrate the 
caustic by-product obtained using membrane cells, which is produced at 
33 percent purity, to the 50 percent purity obtained using the mercury 
cell process. The industry representatives also commented that the June 
2009 cost analysis: (1) Underestimated the mercury storage costs; (2) 
used an interest rate that was in practicality too low for calculating 
the capital recovery factor; (3) erroneously used information from a 
European study to estimate the savings due to the elimination of the 
mercury process that were not applicable to the U.S.; and (4) did not 
consider decommissioning costs.
    Consequently, we considered the industry comments and, in instances 
where specific relevant data were provided or available, we 
incorporated the information into another revised cost analysis dated 
September 15, 2009 (Docket Item EPA-HQ-OAR-2002-0017-0105). The 
September 2009 updated cost analysis for conversion to membrane 
technology estimated that the costs to convert the four remaining 
mercury cell plants to be nearly $336 million in total capital costs 
and almost $36 million per year in total annual costs, considering 
electricity and other savings. The cost-effectiveness of conversion 
based on this September 2009 analysis was about $66,000 per pound of 
mercury.
    In this analysis, we did not add certain highly variable costs 
mentioned by the industry commenter that could potentially be incurred 
by a plant when making a change to non-mercury technology. These 
variable costs include losses in production, building replacement, 
plant decommissioning, and many others that are likely to be highly 
variable from facility to facility. We believe that the magnitude of 
these costs, although very likely to occur for most facilities, would 
depend on factors such as the condition of the existing buildings, 
available space on the facility

[[Page 13858]]

site to erect a new cell room building to avoid production losses, and 
possibly other unknown factors. We also received comments on the 
revised 2009 cost analyses from the same environmental organization 
that provided comments on the 2008 cost analysis. The complete comments 
can be found in the docket (Docket EPA-HQ-OAR-2002-0017). The 
environmental organization commenter stated that the capital costs 
estimated by EPA are too high and the EPA analysis did not uniformly 
account for expansion during conversion. In addition, the commenter 
stated that the regression formula of cost vs. capacity used to 
establish an equation is incorrect since there is no relationship 
between capital costs and capacity when considering the full set of 
relevant data rather than just recent U.S. facilities. Also, the 
commenter stated that the capital costs should be annualized over a 
longer period than the 15 years used in the analysis since 30 years is 
a more likely useful life.
    The environmental commenter also made the following points: The 
energy savings estimated by EPA are too low, since higher reductions in 
electricity consumption are common place; the EPA cost estimate for 
producing steam double-counted the cost associated with concentrating 
caustic and did not account for the fact the steam could be obtained 
on-site without expense; the cost savings for environmental compliance 
avoided are underestimated; and the decommissioning costs are already 
included in estimates of conversion since many factories include the 
cost of dismantling and decommission in the reported cost of 
conversion.
    In addition, the commenter recommended that in evaluating the 
costs, EPA should use the average sales per establishment instead of 
the average sales per ton of chlorine capacity because the commenter 
believes that the latter term grossly underestimates sales. The 
commenter also stated that societal costs of conversion to non-mercury 
technology should be considered (Docket Item EPA-HQ-OAR-2002-0017-
0104). The commenter also believed that the industry-supplied emission 
estimates are not reliable and are likely underestimated, thus 
overestimating the costs per pound of mercury emissions prevented. 
Finally, the commenter stated that EPA's overall conclusion does not 
reflect the real world since over 100 plants have made the conversion 
globally and at least five chlor-alkali facilities expected or received 
a complete repayment from their investment within five years.
d. Revised Cost Analysis for This Proposal
    Many of the comments we received on the September 2009 cost 
analysis were considered and used to estimate costs that represent the 
outcome of a potential conversion to non-mercury technology. In this 
revised analysis, we recognize that there are significant uncertainties 
in estimating these costs, and consider ranges of the potential costs 
(and savings) associated with each cost element. For each element, we 
do select a ``best estimate'' to allow the estimation of capital and 
annual costs of conversion for each facility. The results of this 
analysis are summarized below in section III.A.2.a of this document, 
and a memorandum that documents the details of this cost analysis can 
be found in the docket. We are specifically requesting comment on our 
analysis, along with additional facility-specific data, to allow a 
refinement of the analysis.
3. Estimated Impacts of the Non-Mercury Technology Option
a. Environmental and Energy Impacts
    We estimate that the total mercury emissions from the four mercury 
cell operating facilities to be around 640 pounds per year. The non-
mercury technology option would reduce mercury emissions by this 
amount. These four facilities reported almost 2,000 additional pounds 
per year of on-site and off-site mercury releases to non-air media. 
These releases, which are primarily in the form of hazardous wastes, 
would be eliminated in the longer term, with consequential benefits for 
non-air quality related health and environmental values. The potential 
problems associated with the handling and continuous management of over 
1,200 tons of virgin mercury that is used in the cells at these four 
chlor-alkali plants would also be eliminated. In addition, 
approximately two tons of this mercury was reported by the industry as 
``unaccounted'' in 2008. This non-mercury technology option would 
eliminate the unaccounted mercury as well.
    The membrane cell chlor-alkali process requires less energy than 
the mercury cell process. Therefore, assuming that all four existing 
mercury cell chlor-alkali plants convert to membrane cells, there would 
be a savings in energy. We estimate that this savings would be around 
350,000 megawatt hours per year, which is approximately equivalent to 
the energy produced annually by a 40 megawatt power plant. The emission 
reductions associated with this reduced electricity generation are 
estimated to be 68 tons per year of fine particulate matter 
(PM2.5), 5 tons per year of volatile organic compounds 
(VOC), 0.1 tons per year of ammonia (NH3) 0.008 tons per 
year of mercury, and 287,000 tons per year of carbon dioxide 
(CO2). Since nitrogen oxide (NOx) and sulfur dioxide 
(SO2) are covered by capped emissions trading programs, we 
are only estimating PM2.5 emission reductions from reduced 
electricity demand.
    In the short term, the conversion of these facilities would result 
in the need to dispose of mercury-contaminated wastes. While there is 
considerable uncertainty in quantifying the amount of these wastes, we 
estimate that there could be around 7,000 cubic meters of mercury 
contaminated waste generated that could contain around 6 tons of 
mercury.
    As stated above, over 1,200 tons of virgin or process mercury from 
the facilities would need to be dealt with whether the facilities close 
or convert to non-mercury technology. The Mercury Export Ban Act of 
2008, discussed earlier, would prohibit this mercury from being 
exported. Therefore, this mercury would need to be stored or sold 
domestically. Since mercury is a hazardous substance, it cannot be 
stored without a permit; hence, DOE is planning to build a Federal 
facility to accommodate the excess mercury that results from the export 
ban.
b. Cost Impacts
    The estimated costs for the non-mercury technology option, assuming 
that all four currently operating mercury cell chlor-alkali plants 
convert to membrane cell technology, include total capital costs of 
approximately $300 million dollars, with individual plant capital costs 
ranging from a low of $28 million to a high of approximately $160 
million. Our analysis does show that, in the hypothetical situation 
that a single plant could incur the lowest possible costs while also 
realizing the highest possible energy and other savings, there could be 
an overall cost savings in the conversion from mercury cells to 
membrane cells. However, we do not believe that this scenario is 
realistic. Using more conservative assumptions, our best estimate is 
that the average annual costs would be between $800,000 and $7 million 
per year per plant. The total annual costs are estimated to be $13 
million per year. Based on these costs and the estimated mercury 
emissions for each facility, the cost-effectiveness, in terms of 
annualized costs per pound of mercury eliminated, is approximately 
$20,000 per pound for the industry, with a range

[[Page 13859]]

of around $13,000 to $31,000 per pound for the individual facilities.
c. Economic Impacts
    In addition to cost analyses, we also conducted an economic 
analysis of the impacts of the option to require non-mercury 
technology. A regulatory impact analysis (RIA) was performed for this 
non-mercury technology option. A report that documents the EIA methods 
and results can be found in the docket (EPA-HQ-OAR-2002-0017).
    Although individual plant information would be the best method to 
assess the true economic impacts of the non-mercury technology option, 
detailed information for this industry was not publicly available. As a 
result, we relied on parent company information provided in company 
annual reports (e.g., form 10-K), local press and industry trade 
publications, and company Web sites.
    There are many aspects of the cost estimate for conversion that are 
unknown or difficult to assess. While we believe that we have evaluated 
the conversion cost information available to us at the time of this 
action, the true costs may vary considerably. However, variation in 
engineering costs is not expected to cause a significant difference in 
the general conclusions of the RIA.
    We performed an analysis that compared the annual conversion costs 
to sales (cost to sales ratio, or CSR). We estimated that the CSR of 
ASHTA, the one small business in this industry, would range from one to 
two percent using the costs presented in this proposal. The other three 
plants are owned by large parent companies with significant company-
wide sales. As a result, the CSRs for these large parent companies are 
below one percent. When single plant sales were considered, the CSRs 
for the mercury cell chlor-alkali plants owned by large parent 
companies ranged from 4 to 9 percent.
    We also analyzed industry profitability effects by comparing the 
annual conversion costs to reported industry margins for a 
representative electrochemical unit. This analysis confirms the results 
of the sales comparisons that plant conversion costs will likely have 
an economically significant effect. Conversion costs could reduce the 
margins by 10 to 20 percent.
    This non-mercury technology option would force owners of mercury 
chlor-alkali plants to make an investment decision based on the costs 
of conversion as opposed to the future benefits of the conversion. This 
non-mercury technology option could lead to plant shutdowns that would 
involve adjustment costs for people working at the affected plants. 
Affected plants may also have strong links with other firms or 
downstream markets; as a result, secondary consequences of the 
regulation are important to consider. We are interested in receiving 
comments related to the downstream impacts of potential mercury cell 
plant shutdowns. In particular, we are interested in the impact on the 
potassium carbonate market and the potential impact on the 
competitiveness of the potassium hydroxide market.
    Many owners have converted from mercury cell chlor-alkali 
technologies in Europe and the U.S., while other mercury cell chlor-
alkali plant owners have concluded the investment decision was 
currently not in their company's interest given their assessment of 
future economic conditions, and have shutdown their mercury cell chlor-
alkali plants instead. Since 2003, three U.S. mercury cell chlor-alkali 
facilities have closed and three have converted. Specifically, the 
Occidental Chemical mercury cell chlor-alkali facilities in Delaware 
City, Delaware, Muscle Shoals, Alabama, and Deer Park, Texas, have 
closed; while the PPG facility in Lake Charles, Louisiana, the ERCO 
facility in Port Edwards, Wisconsin, and the Pioneer chlor-alkali 
facility (now owned by Olin) in St. Gabriel, Louisiana, have converted 
to membrane cells.
    We do not have sufficient data to predict whether individual 
companies would choose to convert or close the affected mercury cell 
chlor-alkali plants. However, the data obtained in this study suggests 
that plant closure may be a preferred alternative to meet the 
requirements of the non-mercury technology option for one or more of 
the mercury cell chlor-alkali plants.
    As noted above, individual plant information was not available to 
perform a refined analysis of whether these mercury cell plants would 
likely convert to non-mercury technology or close. We are specifically 
requesting comment on our analysis, along with facility-specific data, 
to allow a refinement of the analysis for this non-mercury technology 
option.
d. Benefits
    Mercury is a highly neurotoxic contaminant that enters the food web 
as a methylated compound, methylmercury (U.S. EPA, 2008c). The 
contaminant is concentrated in higher trophic levels, including fish 
eaten by humans. Mercury is emitted to the air from various man-made 
and natural sources. These emissions transport through the atmosphere 
and eventually deposit to land or water bodies. This deposition can 
occur locally, regionally, or globally, depending on the form of 
mercury emitted and other factors such as the weather. The form of 
mercury emitted from these sources is estimated to be about 98 percent 
elemental and two percent divalent mercury. Gaseous elemental mercury 
can be transported very long distances, even globally, to regions far 
from the emissions source (becoming part of the global ``pool'') before 
deposition occurs. Inorganic ionic (divalent) mercury has a shorter 
atmospheric lifetime and can deposit to land or water bodies closer to 
the emissions source. Furthermore, elemental mercury in the atmosphere 
can undergo transformation into ionic mercury, providing a significant 
pathway for deposition of emitted elemental mercury.
    This source category emitted about 640 pounds of mercury in the air 
in 2008 in the U.S. Based on the EPA's National Emission Inventory, 
about 103 tons of mercury were emitted from all anthropogenic sources 
in the U.S. in 2005. Moreover, the United Nations has estimated that 
about 2,100 tons of mercury were emitted worldwide by anthropogenic 
sources in 2005. We believe that total mercury emissions in the U.S. 
and globally in 2008 were about the same magnitude in 2005. Therefore, 
we estimate that in 2008, these sources emitted about 0.3 percent of 
the total anthropogenic mercury emissions in the U.S. and about 0.02 
percent of the global emissions. Overall, the non-mercury technology 
option (Option 1) would directly reduce mercury emissions by about 640 
pounds per year from current levels as well as an estimated 16 pounds 
per year indirectly through reduced electricity generation, and, 
therefore, contribute to reductions in mercury exposures and health 
effects. Due to data, time, and resource limitations, we were unable to 
model mercury dispersion, deposition, methylation, bioaccumulation in 
fish tissue, and human consumption of mercury-contaminated fish that 
would be needed in order to estimate the human health benefits from 
reducing mercury emissions.
    Potential exposure routes to mercury emissions include both direct 
inhalation and consumption of fish containing methylmercury. For 
elemental mercury, inhalation is the most direct exposure route of 
potential concern. Effects on the nervous system appear to be the most 
sensitive toxicological endpoint and can include tremors, nervousness, 
insomnia, neuromuscular changes (such as weakness, muscle atrophy, and 
muscle

[[Page 13860]]

twitching), and headaches.\b\ In the U.S., the primary route of human 
exposure to mercury emissions from industrial sources is generally 
indirectly through the consumption of fish containing methylmercury. As 
described above, mercury that has been emitted to the air eventually 
settles into water bodies or onto land where it can either move 
directly or be leached into waterbodies. Once deposited, certain 
microorganisms can change it into methylmercury, a highly toxic form 
that builds up in fish, shellfish and animals that eat fish. 
Consumption of fish and shellfish are the main sources of methylmercury 
exposure to humans. Methylmercury builds up more in some types of fish 
and shellfish than in others. The levels of methylmercury in fish and 
shellfish vary widely depending on what they eat, how long they live, 
and how high they are in the food chain. Most fish, including ocean 
species and local freshwater fish, contain some methylmercury. For 
example, in recent studies by EPA and the U.S. Geological Survey (USGS) 
of fish tissues, every fish sampled from 291 streams across the country 
contained some methylmercury (Scudder, 2009).\c\
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    \b\ Integrated Risk Information System (IRIS). U.S. 
Environmental Protection Agency. https://www.epa.gov/ncea/iris/subst/0370.htm.
    \c\ Scudder, B.C., Chasar, L.C., Wentz, D.A., Bauch, N.J., 
Brigham, M.E., Moran, P.W., and Krabbenhoft, D.P. 2009. Mercury in 
fish, bed sediment, and water from streams across the United States, 
1998-2005: U.S. Geological Survey Scientific Investigations Report 
2009-5109, p. 74.
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    The majority of fish consumed in the U.S. are ocean species. The 
methylmercury concentrations in ocean fish species are primarily 
influenced by the global mercury pool. However, the methylmercury found 
in local fish can be due, at least partly, to mercury emissions from 
local sources. Research shows that most people's fish consumption does 
not cause a mercury-related health concern. However, certain people may 
be at higher risk because of their routinely high consumption of fish 
(e.g., Tribal and other subsistence fishers and their families who rely 
heavily on fish for a substantial part of their diet). It has been 
demonstrated that high levels of methylmercury in the bloodstream of 
unborn babies and young children may harm the developing nervous 
system, making the child less able to think and learn. Moreover, 
mercury exposure at high levels can harm the brain, heart, kidneys, 
lungs, and immune system of people of all ages.
    Several studies suggest that the methylmercury content of fish may 
reduce these cardio-protective effects of fish consumption. Some of 
these studies also suggest that methylmercury may cause adverse effects 
to the cardiovascular system. For example, the National Research 
Council (NRC) (2000) review of the literature concerning methylmercury 
health effects took note of two epidemiological studies that found an 
association between dietary exposure to methylmercury and adverse 
cardiovascular effects.\d\ Moreover, in a study of 1,833 males in 
Finland aged 42 to 60 years, Solonen et al. (1995) observed a 
relationship between methylmercury exposure via fish consumption and 
acute myocardial infarction (AMI or heart attacks), coronary heart 
disease, cardiovascular disease, and all-cause mortality.\e\ The NRC 
also noted a study of 917 seven year old children in the Faroe Islands, 
whose initial exposure to methylmercury was in utero although post 
natal exposures may have occurred as well. At seven years of age, these 
children exhibited an increase in blood pressure and a decrease in 
heart rate variability.\f\ Based on these and other studies, NRC 
concluded in 2000 that, while ``the data base is not as extensive for 
cardiovascular effects as it is for other end points (i.e., neurologic 
effects) the cardiovascular system appears to be a target for 
methylmercury toxicity.'' \g\
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    \d\ National Research Council (NRC). 2000. Toxicological Effects 
of Methylmercury. Committee on the Toxicological Effects of 
Methylmercury, Board on Environmental Studies and Toxicology. 
National Academies Press. Washington, DC. pp. 168-173.
    \e\ Salonen, J.T., Seppanen, K. Nyyssonen et al. 1995. ``Intake 
of mercury from fish lipid peroxidation, and the risk of myocardial 
infarction and coronary, cardiovascular and any death in Eastern 
Finnish men.'' Circulation, 91 (3):645-655.
    \f\ Sorensen, N, K. Murata, E. Budtz-Jorgensen, P. Weihe, and 
Grandjean, P., 1999. ``Prenatal Methylmercury Exposure as a 
Cardiovascular Risk Factor at Seven Years of Age'', Epidemiology, 
pp. 370-375.
    \g\ National Research Council (NRC). 2000. Toxicological Effects 
of Methylmercury. Committee on the Toxicological Effects of 
Methylmercury, Board on Environmental Studies and Toxicology. 
National Academies Press. Washington, DC. p. 229.
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    Since publication of the NRC report, there have been some 30 
published papers presenting the findings of studies that have examined 
the possible cardiovascular effe