[Federal Register Volume 76, Number 200 (Monday, October 17, 2011)]
[Rules and Regulations]
[Pages 64022-64037]
[FR Doc No: 2011-23534]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 372

[EPA-HQ-TRI-2009-0844; FRL-9463-5]
RIN 2025-AA27

Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release
Reporting

AGENCY: Environmental Protection Agency (EPA).

ACTION: Lifting of Administrative Stay for Hydrogen Sulfide.

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SUMMARY: EPA is announcing that it is lifting the Administrative Stay
of the Emergency Planning and Community Right-to-Know Act (EPCRA)
section 313 toxic chemical release reporting requirements for hydrogen
sulfide (Chemical Abstracts Service Number (CAS No.) 7783-06-4).
Hydrogen sulfide was added to the EPCRA section 313 list of toxic
chemicals in a final rule published in the Federal Register on

December 1, 1993. However, on August 22, 1994, EPA issued an
Administrative Stay of the reporting requirements for hydrogen sulfide
in order to evaluate issues brought to the Agency's attention after
promulgation of the final rule concerning the human health effect basis
for the listing and the Agency's use of exposure analysis in EPCRA
section 313 listing decisions. Although the final rule listing hydrogen
sulfide under section 313 of EPCRA remained in force, the stay deferred
the reporting requirements for hydrogen sulfide while EPA completed
this further evaluation. EPA completed its further evaluation of
additional information that has become available since the stay was put
in place regarding the human health and environmental effects of
hydrogen sulfide, and the Agency published a position that the stay
should be lifted in the February 26, 2010, Federal Register document
``Intent to Consider Lifting Administrative Stay; Opportunity for
Public Comment.'' Based on EPA's further evaluation and the
consideration of the public comments received on the notice of intent,
EPA continues to believe that the Administrative Stay should be lifted.
By this current action, EPA is not revisiting the original listing
decision, which was accomplished by final rule on December 1, 1993.
Rather, EPA is lifting the Administrative Stay of the reporting
requirements for hydrogen sulfide.

DATES: This action is effective on October 17, 2011, such that the
first reports on hydrogen sulfide will be due on July 1, 2013 for
reporting year 2012.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-TRI-2009-0844. All documents in the docket are listed in the
http://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, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the OEI Docket, EPA/
DC, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC.
This Docket Facility 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<PHONE_NUMBER>, and the telephone number for the
OEI Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Daniel R. Bushman, Environmental
Analysis Division, Office of Information Analysis and Access (2842T),
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone number:<PHONE_NUMBER>; fax number: 202-
566-0677; e-mail<EMAIL_ADDRESS>for specific information on
this document. For general information on EPCRA section 313, contact
the Emergency Planning and Community Right-to-Know Hotline, toll free
at<PHONE_NUMBER> or<PHONE_NUMBER> in Virginia and Alaska or toll
free, TDD<PHONE_NUMBER>, http://www.epa.gov/epaoswer/hotline/.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this action apply to me?

    You may be potentially affected by this action if you manufacture,
process, or otherwise use hydrogen sulfide. Potentially affected
categories and entities may include, but are not limited to:

----------------------------------------------------------------------------------------------------------------
                  Category                                 Examples of potentially affected entities
----------------------------------------------------------------------------------------------------------------
Industry....................................  Facilities included in the following NAICS manufacturing codes
                                               (corresponding to SIC codes 20 through 39): 311*, 312*, 313*,
                                               314*, 315*, 316, 321, 322, 323*, 324, 325*, 326*, 327, 331, 332,
                                               333, 334*, 335*, 336, 337*, 339*, 111998*, 211112*, 212324*,
                                               212325*, 212393*, 212399*, 488390*, 511110, 511120, 511130,
                                               511140*, 511191, 511199, 512220, 512230*, 519130*, 541712*, or
                                               811490*.
                                              *Exceptions and/or limitations exist for these NAICS codes.
                                              Facilities included in the following NAICS codes (corresponding to
                                               SIC codes other than SIC codes 20 through 39): 212111, 212112,
                                               212113 (correspond to SIC 12, Coal Mining (except 1241)); or
                                               212221, 212222, 212231, 212234, 212299 (correspond to SIC 10,
                                               Metal Mining (except 1011, 1081, and 1094)); or 221111, 221112,
                                               221113, 221119, 221121, 221122, 221330 (Limited to facilities
                                               that combust coal and/or oil for the purpose of generating power
                                               for distribution in commerce) (correspond to SIC 4911, 4931, and
                                               4939, Electric Utilities); or 424690, 425110, 425120 (Limited to
                                               facilities previously classified in SIC 5169, Chemicals and
                                               Allied Products, Not Elsewhere Classified); or 424710
                                               (corresponds to SIC 5171, Petroleum Bulk Terminals and Plants);
                                               or 562112 (Limited to facilities primarily engaged in solvent
                                               recovery services on a contract or fee basis (previously
                                               classified under SIC 7389, Business Services, NEC)); or 562211,
                                               562212, 562213, 562219, 562920 (Limited to facilities regulated
                                               under the Resource Conservation and Recovery Act, subtitle C, 42
                                               U.S.C. 6921 et seq.) (correspond to SIC 4953, Refuse Systems).
Federal Government..........................  Federal facilities.
----------------------------------------------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
action. Some of the entities listed in the table have exemptions and/or
limitations regarding coverage, and other types of entities not listed
in the table could also be affected. To determine whether your facility
would be affected by this action, you should carefully examine the
applicability criteria in part 372 subpart B of Title 40 of the Code of
Federal Regulations. If you have questions regarding the applicability
of this action to a particular entity, consult the person listed in the
preceding FOR FURTHER INFORMATION CONTACT section.

II. Introduction

    Section 313 of EPCRA, 42 U.S.C. 11023, requires certain facilities
that manufacture, process, or otherwise use listed toxic chemicals in
amounts above reporting threshold levels to report their environmental
releases and other waste management quantities of such chemicals
annually. These facilities must also report pollution prevention and
recycling data for such chemicals, pursuant to section 6607 of the
Pollution Prevention Act (PPA), 42 U.S.C. 13106. EPCRA section 313
established an initial list of toxic chemicals composed of more than
300 chemicals and 20 chemical categories.
    EPCRA section 313(d) authorizes EPA to add or delete chemicals from
the list and sets forth criteria for these actions. Specifically, EPCRA
section 313(d)(2) states that EPA may add a chemical to the list if
``there is sufficient evidence to establish any one'' of the listing
criteria. Therefore, to add a chemical, EPA must demonstrate that at
least one criterion is met, but need not determine whether any other
criterion is met. Conversely, EPCRA section 313(d)(3) states that to
remove a chemical from the list, EPA must determine that ``there is not
sufficient evidence to establish any'' of

the Section 313(d)(2) criteria. Therefore, to remove a chemical, EPA
must demonstrate that none of the criteria are met. The EPCRA section
313(d)(2) criteria are:
    (A) The chemical is known to cause or can reasonably be anticipated
to cause significant adverse acute human health effects at
concentration levels that are reasonably likely to exist beyond
facility site boundaries as a result of continuous, or frequently
recurring, releases.
    (B) The chemical is known to cause or can reasonably be anticipated
to cause in humans--
    (i) Cancer or teratogenic effects, or
    (ii) Serious or irreversible--
    (I) Reproductive dysfunctions,
    (II) Neurological disorders,
    (III) Heritable genetic mutations, or
    (IV) Other chronic health effects.
    (C) The chemical is known to cause or can be reasonably anticipated
to cause, because of
    (i) Its toxicity,
    (ii) Its toxicity and persistence in the environment, or
    (iii) Its toxicity and tendency to bioaccumulate in the
environment, a significant adverse effect on the environment of
sufficient seriousness, in the judgment of the Administrator, to
warrant reporting under this section.
    EPA often refers to the section 313(d)(2)(A) criterion as the
``acute human health effects criterion;'' the section 313(d)(2)(B)
criterion as the ``chronic human health effects criterion;'' and the
section 313(d)(2)(C) criterion as the ``environmental effects
criterion.''
    Under EPCRA section 313(e)(1), any person may petition EPA to add
chemicals to or delete chemicals from the list. EPA issued a statement
of petition policy and guidance in the Federal Register of February 4,
1987 (52 FR 3479) to provide guidance regarding the recommended content
and format for submitting petitions under EPCRA section 313(e). EPA
also issued guidance in the Federal Register of May 23, 1991 (56 FR
23703) regarding the recommended content of petitions to delete
individual members of the section 313 metal compound categories. In
addition, EPA published in the Federal Register of November 30, 1994
(59 FR 61432) a statement clarifying its interpretation of the section
313(d)(2) and (d)(3) criteria for modifying the section 313 list of
toxic chemicals.

III. Background Information

A. What is the history of the listing of hydrogen sulfide under EPCRA
section 313?

    In response to a petition from the Natural Resources Defense
Council and the Governor of New York, hydrogen sulfide, along with 20
other chemicals and two chemical categories, was added to the EPCRA
section 313 list of toxic chemicals as part of a 1993 final rule
(December 1, 1993, 58 FR 63500). Hydrogen sulfide was listed under the
criteria of EPCRA section 313(d)(2)(B) (chronic human health effects)
based on chronic neurotoxic effects in humans and under EPCRA section
313(d)(2)(C) (environmental effects) based on acute aquatic toxicity.
However, on August 22, 1994 (59 FR 43048), EPA issued an Administrative
Stay of the EPCRA section 313 reporting requirements for hydrogen
sulfide. Although the final rule listing hydrogen sulfide under section
313 of EPCRA remained in force, the stay deferred the reporting
requirements for hydrogen sulfide. On February 26, 2010, EPA issued a
document in the Federal Register entitled ``Intent to Consider Lifting
Administrative Stay; Opportunity for Public Comment'' (75 FR 8889).
That document provided the public with the opportunity to comment on
EPA's review of the currently available data on the human health and
environmental effects of hydrogen sulfide--specifically, chronic
respiratory effects, chronic neurotoxic effects, and acute, chronic and
early-life stage aquatic toxicity--and EPA's belief that the
Administrative Stay should be lifted based on that data.

B. What was the basis for the administrative stay?

    After the final rule was issued adding hydrogen sulfide to the
EPCRA section 313 list of toxic chemicals, some members of the
regulated community expressed a concern that the ``chronic human health
effects'' basis for listing hydrogen sulfide under EPCRA section
313(d)(2)(B) had changed between the proposed rule (September 8, 1992,
57 FR 41020) and the final rule (December 1, 1993, 58 FR 63500), and
that commenters on the proposed rule therefore did not have an
opportunity to comment on that individual basis for the listing.
Specifically, although the Agency cited the same acute aquatic toxicity
as an ``environmental effects'' basis for the listing under EPCRA
section 313(d)(2)(C) in both the proposed and final rules, the Agency
also cited chronic respiratory effects as a ``chronic human health
effects'' basis under EPCRA section 313(d)(2)(B) in the proposed rule,
but chronic neurotoxic effects as a ``chronic human health effects''
basis under that same provision in the final rule. In addition, after
issuance of the final rule, some members of the regulated community
expressed concern that EPA's decision not to include an exposure
analysis in deciding to list hydrogen sulfide on the basis of chronic
human health effects was inconsistent with past Agency practice.
    Although EPA did not agree that it had been inconsistent in its use
of exposure analyses, and notwithstanding the fact that the listing
decision was appropriate based on the acute aquatic toxicity finding
alone under EPCRA section 313(d)(2)(C), the Agency issued an
Administrative Stay of the reporting requirements for hydrogen sulfide
in order to review the concerns raised after issuance of the final rule
by some members of the regulated community.

C. What is EPA's rationale for lifting the administrative stay for
hydrogen sulfide?

    EPA's technical evaluation of hydrogen sulfide, as discussed in
detail in the February 26, 2010 Federal Register document (75 FR 8889),
shows that it can reasonably be anticipated to cause chronic health
effects in humans. The chronic health effects have been observed in
laboratory animals at concentrations as low as 28 milligrams per cubic
meter (mg/m\3\) (20 parts per million (ppm)) for neurotoxicity and 41.7
mg/m\3\ (30 ppm) for upper respiratory toxicity. In addition, EPA's
technical evaluation of hydrogen sulfide also shows that it can
reasonably be anticipated to cause, because of its toxicity,
significant adverse effects in aquatic organisms. Examples of hydrogen
sulfide's ecological toxicity include acute toxicity (96-hour
LC50 (i.e., the concentration that is lethal to 50% of test
organisms)) values for freshwater fish that ranged from 0.0149
milligrams per liter (mg/L) (fathead minnow) to 0.0448 mg/L (bluegill),
indicating high aquatic toxicity. Examples of hydrogen sulfide's
chronic ecological toxicity include freshwater fish values that ranged
from a 6-week lowest-observed-effect-concentration (LOEC) (growth rate)
of 0.0005 mg/L in a tropical fish (Mystus nemurus) to a 430-day LOEC
(final weight) of 0.009 mg/L for goldfish, also indicating high aquatic
toxicity.
    Based on the above findings, EPA believes that there is no basis
for continuing the Administrative Stay of the reporting requirements
for hydrogen sulfide, and that the Administrative

Stay should therefore be lifted. As an aside, EPA notes also that it
believes that the above findings clearly demonstrate the correctness of
the Agency's final decision in December 1993 to list hydrogen sulfide
on the EPCRA section 313 toxic chemicals list based on the listing
criteria in EPCRA sections 313(d)(2)(B) and (C).
    Finally, in accordance with EPA's stated policy on the use of
exposure assessments (59 FR 61432), EPA does not believe that an
exposure assessment is appropriate for determining whether hydrogen
sulfide meets the criteria of EPCRA section 313(d)(2)(B) or (C), and
therefore the Administrative Stay should not be continued for lack of
an exposure analysis. As EPA explained in the Intent to Lift the Stay
(and as explained in Unit IV.A.1.c. of this Notice):

    EPA has determined that hydrogen sulfide can reasonably be
anticipated to cause serious or irreversible chronic human health
effects at relatively low doses and thus is considered to have
moderately high to high chronic toxicity. EPA does not believe that
it is appropriate to consider exposure for chemicals that are
moderately high to highly toxic based on a hazard assessment when
determining if a chemical can be listed for chronic effects pursuant
to EPCRA section 313(d)(2)(B) (see 59 FR 61432, 61433, 61440-61442).
Hydrogen sulfide has also been determined to cause ecotoxicity at
relatively low concentrations, and thus is considered to have high
ecotoxicity. EPA believes that chemicals that induce death or
serious adverse effects in aquatic organisms at relatively low
concentrations (i.e., they have high ecotoxicity) have the potential
to cause significant changes in the population of fish and other
aquatic organisms, and can therefore reasonably be anticipated to
cause a significant adverse effect on the environment of sufficient
seriousness to warrant reporting. EPA does not believe that it is
required to consider exposure for chemicals that have high
ecotoxicity based on a hazard assessment when determining if a
chemical can be listed for effects pursuant to EPCRA section
313(d)(2)(C) (see 59 FR 61432, 61433, 61440-61442). (75 FR 8889,
8893 (Feb. 26, 2010)).

D. What is the purpose of this document?

    The purpose of this document is to respond to the public comments
received on EPA's February 26, 2010, Federal Register document ``Intent
to Consider Lifting Administrative Stay; Opportunity for Public
Comment'' (75 FR 8889), and to give notice that EPA is lifting the
Administrative Stay of the EPCRA section 313 toxic chemical release
reporting requirements for hydrogen sulfide. With the lifting of this
stay, pursuant to Section 313 of EPCRA, certain facilities that
manufacture, process, or otherwise use hydrogen sulfide in amounts
above reporting threshold levels must now comply with the reporting
requirements that have been in place since hydrogen sulfide was added
to the EPCRA section 313 list in 1993. The first reports on hydrogen
sulfide will be due on July 1, 2013 for reporting year 2012.

IV. What comments did EPA receive on the intent to consider lifting the
administrative stay and what are EPA's responses to those comments?

    EPA received fifteen comments on the Federal Register document
``Intent to Consider Lifting Administrative Stay; Opportunity for
Public Comment'' (75 FR 8889). The comments represented 6 individuals,
32 environmental groups, one state agency, and 10 industry groups.
Environmental groups that commented included the Food & Water Watch,
National Association of Clean Water Agencies, Natural Resources Defense
Council, Waterkeeper Alliance and one comment submitted by 28 other
environmental organizations. The comments from the individuals,
environmental groups, and state agency were supportive of EPA's intent
to lift the Administrative Stay. Many of these groups provided
additional information to support EPA's action as well as requesting
other actions such as listing additional industry sectors that have
significant releases of hydrogen sulfide. The most extensive comments
came from the Hydrogen Sulfide Consortium, whose members are: American
Coke and Coal Chemicals Institute, American Forest and Paper
Association, American Petroleum Institute, Asphalt Institute, Carbon
Disulfide Coalition, Corn Refiners Association, National Petrochemical
and Refiners Association, and The Sulphur Institute. The most
significant opposing comments are summarized and responded to below.
The complete set of comments and EPA's responses can be found in the
response to comment document in the docket for this action (Ref. 1).

A. Comments From the Hydrogen Sulfide Consortium

    1. Scope of Comments. Commenters claim that ``EPA cannot properly
limit comments to whether or not EPA should lift its Administrative
Stay of EPCRA section 313 reporting requirements,'' but rather must
revisit the original listing decision accomplished by final rule in
1993. In support of this argument, commenters assert that: (1) EPA
stated, when it issued the Administrative Stay in 1994, that it would
revisit the original listing decision; (2) EPA cited chronic
respiratory effects as one of the bases for listing under EPCRA section
313(d)(2)(B) in the proposed rule, but chronic neurotoxic effects as a
basis under that same provision in the final rule; (3) EPA adopted its
current policy regarding exposure analyses subsequent to the 1993
listing of hydrogen sulfide; and (4) EPA ``must make a new listing
determination before it may lift [the stay].''
    For the reasons stated below, EPA disagrees with commenters that
EPA must revisit the original listing decision in the context of EPA's
consideration of lifting the Administrative Stay of the EPCRA reporting
requirements for hydrogen sulfide. Based upon our current review of the
science, as presented in EPA's technical evaluation of hydrogen
sulfide, which is discussed in detail in the February 26, 2010 Federal
Register document (75 FR 8889) and summarized in Unit III.C. of this
document, EPA has determined that there is no need to re-visit the
existing listing determination. Before addressing each of the
commenter's arguments in turn, however, a brief reiteration of the
factual background is useful.
    As described in detail below, EPCRA section 313(d)(2) states that
EPA may add a chemical to the list if ``there is sufficient evidence to
establish any one'' (emphasis added) of the listing criteria specified
in section 313(d)(2). Therefore, to add a chemical, EPA must
demonstrate that at least one criterion is met, but need not determine
whether any other criterion is met.
    EPA proposed to add hydrogen sulfide to the EPCRA section 313 list
of toxic chemicals on September 8, 1992 (57 FR 41020) based on a
determination that there was sufficient evidence establishing both
chronic human health effects per EPCRA section 313(d)(2)(B)
(specifically, chronic respiratory effects) and environmental effects
per EPCRA section 313(d)(2)(C) (specifically, acute aquatic toxicity).
On December 1, 1993, EPA promulgated a final rule adding hydrogen
sulfide to the EPCRA section 313 list of toxic chemicals (58 FR 63500)
(effective January 1, 1994). In the final rule, the listing decision
was based on a determination that there was sufficient evidence
establishing environmental effects per EPCRA section 313(d)(2)(C)
(specifically, the same acute aquatic toxicity as identified in the
proposed rule) and chronic human health effects per EPCRA section
313(d)(2)(B). In the final rule, however, the chronic human health
effects finding was based on chronic neurotoxic effects, instead of
chronic respiratory effects as stated in the proposed rule.
    After the final rule was issued adding hydrogen sulfide to the
EPCRA section 313 list, and notwithstanding the fact

that the Agency cited the same acute aquatic toxicity as an
``environmental effects'' basis for the listing under EPCRA section
313(d)(2)(C) in both the proposed rule and the final rule, some members
of the regulated community expressed a concern that the Agency cited
chronic respiratory effects as a ``chronic human health effects'' basis
under EPCRA section 313(d)(2)(B) in the proposed rule, but chronic
neurotoxic effects as a ``chronic human health effects'' basis under
that same provision in the final rule. In addition, after issuance of
the final rule, some members of the regulated community expressed
concern that EPA's decision not to include an exposure analysis in
deciding to list hydrogen sulfide on the basis of chronic human health
effects was inconsistent with past Agency practice. As a result of
these concerns, some commenters threatened to bring legal action
challenging the final rule.
    In response to the post-promulgation comments and concerns raised
by some in the regulated community, and notwithstanding the fact that
the listing decision was appropriate based on the acute aquatic
toxicity finding alone under EPCRA section 313(d)(2)(C), EPA issued an
Administrative Stay of the EPCRA section 313 reporting requirements for
hydrogen sulfide on August 22, 1994 (59 FR 43048) in order to review
those post-promulgation comments and concerns.
    The stay issued on August 22, 1994 made clear that: ``The effect of
this stay is to defer reporting on [hydrogen sulfide] while the Agency
reviews new data and information made available subsequent to the
promulgation of the final rule'' (59 FR 43048 (Aug. 22, 1994) (emphasis
added)). As a result, while the subsequent stay deferred reporting
requirements, the stay did not remove hydrogen sulfide from the EPCRA
section 313 list or alter that final listing determination, which
remained in effect as of January 1, 1994. The listing determination was
never administratively or judicially challenged.
    On February 26, 2010, EPA issued a notice announcing its ``Intent
to Consider Lifting [the hydrogen sulfide] Administrative Stay;
Opportunity for Public Comment.'' 75 FR 8889 (hereinafter Intent to
Lift the Stay). That document stated: ``The purpose of this document is
to provide the public with the opportunity to comment on EPA's review
of the currently available data on the human health and environmental
effects of hydrogen sulfide * * * and EPA's belief that the
Administrative Stay should be lifted based on that data* * *. In
addition, this document addresses the concerns raised regarding use of
exposure analyses.'' Id. at 8891. The Intent to Lift the Stay notice
clearly explained: ``By this current action, EPA is not revisiting the
original listing decision, which was accomplished by final rule on
December 1, 1993. Rather, EPA is merely presenting its rationale for
why the Administrative Stay of the reporting requirements for hydrogen
sulfide should be lifted.'' Id. at 8889 (emphasis added).
    a. EPA Statements when Issuing the Stay. Commenters first argue
that EPA cannot now limit comment to whether or not to lift the stay
because the Agency stated, when it issued the Administrative Stay in
1994, that it intended, at some point in the future, to ``seek comment
on the Agency's initial determination for [hydrogen sulfide].'' 59 FR
at 43049. Specifically, the Administrative Stay stated:

    [T]he Agency will be issuing a forthcoming Federal Register
notice which will seek comment on the Agency's initial determination
for [hydrogen sulfide], * * * procedural issues concerning the
initial final rule, and generally, comments (and any supporting
data) on whether the Agency should either propose to delete
[hydrogen sulfide] or affirm its initial determination and dissolve
today's Administrative Stay. (59 FR at 43049).

    Hydrogen sulfide was listed under section 313 of EPCRA by final
rule on December 1, 1993. The stay did not remove hydrogen sulfide from
the EPCRA section 313 list or alter that final listing determination.
The 1993 listing decision was appropriate based on the acute aquatic
toxicity finding alone under EPCRA section 313(d)(2)(C), which was
included in both the proposed and final rules and never questioned.
Therefore, EPA does not believe it is necessary or appropriate to
revisit the 1993 final listing of hydrogen sulfide in order to lift the
stay of reporting requirements.
    Further, the Agency believes that its action in taking comment on
its intent to lift the stay is substantially in accord with the course
of action it described in issuing the stay in 1994. In the Intent to
Lift the Stay notice, the Agency discussed and invited comment on the
data underlying its consideration of the matter and EPA's application
of its policy regarding exposure assessment to the listing decision. As
described in the Intent to Lift the Stay notice, EPA's planned course
of action arises out of EPA's review of the currently available data,
which clearly demonstrate both chronic health effects in humans (upper
respiratory tract toxicity and neurotoxicity) and significant adverse
effects in aquatic organisms (acute, chronic, and early life stage).
Further, EPA's consideration of these effects is fully consistent with
its policy on exposure assessment. Based on these findings, EPA
believes that there is no basis for continuing the Administrative Stay
of the reporting requirements for hydrogen sulfide, and that the
Administrative Stay should therefore be lifted.
    Moreover, these findings also demonstrate that there is no basis to
consider delisting hydrogen sulfide. EPCRA section 313(d)(3) states
that to remove a chemical from the list, EPA must determine that
``there is not sufficient evidence to establish any'' of the Section
313(d)(2) criteria (emphasis added). Therefore, to remove a chemical,
EPA must demonstrate that none of the criteria are met. As EPA's review
of the currently available data in the context of its consideration of
lifting the Administrative Stay demonstrates, EPA cannot show that none
of the criteria are met. Indeed, the Agency believes that the only
course available is to dissolve the stay, which it is doing through
notice-and-comment, and which is substantially in accord with at least
one of the alternative courses anticipated in 1994.
    Finally, to the extent that the commenters are suggesting that EPA
is legally prohibited from now limiting comment to the issue of whether
or not to lift the Administrative Stay based on the statements in the
preamble the Agency made (excerpted above) when issuing the
Administrative Stay, EPA respectfully notes that these preamble
statements do not create such a legal obligation. See, e.g., Natural
Resources Defense Council v. EPA, 559 F.3d 561, 564-65 (D.C. Cir.
2009).
    b. Proposed and Final Chronic Human Health Effects. Second,
commenters argue that EPA cannot now limit comment to whether or not to
lift the stay because EPA cited chronic respiratory effects as one of
the bases for listing under EPCRA section 313(d)(2)(B) in the proposed
rule, but chronic neurotoxic effects as a basis under that same
provision in the final rule.
    EPCRA section 313(d) authorizes EPA to add or delete chemicals from
the list and sets forth criteria for these actions. The EPCRA section
313(d)(2) criteria are:

    (A) The chemical is known to cause or can reasonably be
anticipated to cause significant adverse acute human health effects
at concentration levels that are reasonably likely to exist beyond
facility site boundaries as a result of continuous, or frequently
recurring, releases.

    (B) The chemical is known to cause or can reasonably be
anticipated to cause in humans--
    (i) Cancer or teratogenic effects, or
    (ii) Serious or irreversible--
    (I) Reproductive dysfunctions,
    (II) Neurological disorders,
    (III) Heritable genetic mutations, or
    (IV) Other chronic health effects.
    (C) The chemical is known to cause or can be reasonably
anticipated to cause, because of
    (i) Its toxicity,
    (ii) Its toxicity and persistence in the environment, or
    (iii) Its toxicity and tendency to bioaccumulate in the
environment,

a significant adverse effect on the environment of sufficient
seriousness, in the judgment of the Administrator, to warrant
reporting under this section.

    EPA often refers to the section 313(d)(2)(A) criterion as the
``acute human health effects criterion;'' the section 313(d)(2)(B)
criterion as the ``chronic human health effects criterion;'' and the
section 313(d)(2)(C) criterion as the ``environmental effects
criterion.''
    While it is true that the Agency cited chronic respiratory effects
as a ``chronic human health effects'' basis under EPCRA section
313(d)(2)(B) in the proposed rule, but chronic neurotoxic effects as a
``chronic human health effects'' basis under that same provision in the
final rule, it bears emphasizing once again that the Agency also
separately cited the same acute aquatic toxicity as an ``environmental
effects'' basis for the listing under EPCRA section 313(d)(2)(C) in
both the proposed and final rules. As a result, and in light of the
fact that EPCRA section 313(d)(2) expressly allows EPA to add a
chemical to the list if ``there is sufficient evidence to establish any
one'' of the listing criteria (emphasis added), the 1993 listing
decision was appropriate based on the acute aquatic toxicity finding
alone under EPCRA section 313(d)(2)(C). That basis for the listing was
never questioned and was and continues to be supported by the data
relied upon by EPA in determining that the stay should be lifted. Any
procedural error that may have occurred regarding the section
313(d)(2)(B) ``chronic human health effects'' finding was harmless in
light of the unchallenged section 313(d)(2)(C) ``environmental
effects'' finding presented in both the proposed and final rules. This
analysis also played directly into EPA's decision to proceed in the
manner it has, as opposed to rigidly following its stated intentions in
1994.
    EPA is currently lifting the stay of hydrogen sulfide reporting
requirements--a substance that has been and remains listed under EPCRA
since promulgation of the final rule on December 1, 1993--based on
EPA's review of the currently available data, which clearly demonstrate
both chronic health effects in humans (upper respiratory tract toxicity
and neurotoxicity) and significant adverse effects in aquatic organisms
(acute, chronic, and early life stage). EPA is not revisiting the
original listing determination, and comments on the original listing
decision are beyond the scope of this action.
    c. EPA's Exposure Analysis Policy. Third, commenters argue that EPA
cannot now limit comment to whether or not to lift the stay because EPA
adopted its current policy regarding exposure analysis subsequent to
the 1993 listing of hydrogen sulfide.
    EPA did not ``adopt a new policy'' on its use of exposure analysis
for listing chemicals under EPCRA section 313 subsequent to the listing
of hydrogen sulfide in 1993. Instead, the Agency's then-existing
position on the use of exposure analyses in listing decisions under
EPCRA section 313 was presented in a proposed rule in the Federal
Register of January 12, 1994 (59 FR 1788). That proposed rule provided
the public with the opportunity to comment on the Agency's then-
existing interpretation of the statutory listing criteria as it relates
to the use of exposure considerations. After considering the comments
received, EPA published in the Federal Register of November 30, 1994
(59 FR 61432) a ``chemical expansion'' final rule, including a
statement clarifying its interpretation of the statutory requirements
regarding how exposure is considered in listing decisions. Subsequent
to that final rule, EPA's interpretation of the statutory listing
criteria as it relates to the consideration of exposure was upheld in
National Oilseed Processors Ass'n. v. Browner, 924 F. Supp. 1193
(D.D.C. 1996), aff'd in part & remanded in part, Troy Corp. v. Browner,
120 F.3d 277 (D.C. Cir. 1997).
    As stated in the chemical expansion final rule:

    Through this rulemaking, EPA is clarifying its position
regarding the use of hazard, exposure, and risk in listing decisions
under EPCRA section 313. EPA will consider exposure factors when
making determinations under section 313(d)(2)(A) (acute human
toxicity). In addition, EPA has discretion to consider exposure
factors where appropriate for determinations under sections
313(d)(2)(B) (chronic human toxicity) and (C) (environmental
toxicity), and that there is a broader range of circumstances in
which exposure will be considered under section 313(d)(2)(C) than
under (B).
    EPA has reviewed its past listing decisions in light of this
clarification, and believes that its prior listing determinations
have been consistent in the consideration of exposure in 31 of the
32 listing/delisting determinations previous to this action* * *(59
FR 61442 (Nov. 30, 1994) (emphasis added)).

    In Troy Corp. v. Browner, the DC Circuit agreed with EPA, finding:

    Were the EPA to abandon a long-held exposure policy and take a
new direction we would, as urged, require a thorough explanation of
its reasons for doing so. Yet, the EPA's pronouncement in its
preamble of its exposure policy is not a change in course. With one
exception, the EPA has consistently stated, as it does in this
rulemaking, that it will consider exposure under subsection (B) only
when the chemical was of ``low to moderately low'' toxicity. * * *
[T]he agency has long maintained that it would consider exposure
under subheading (B) only for low toxicity chemicals. The inorganic
fluorides petition was denied over ten years ago. Since that time,
the agency has made several dozen listing and delisting decisions
under EPCRA. The inorganic fluorides case was the only instance in
which the agency articulated a policy contrary to the one explicated
in this rulemaking. Under these circumstances we cannot say that the
agency has departed from prior practice in a way that requires more
explanation than was provided. (Troy Corp. v. Browner, 120 F.3d at
287 (emphasis added) (citation omitted)).

    Thus, EPA did not subsequently adopt a new exposure policy as
Commenters suggest. Rather, the Agency simply clarified the existing
exposure policy. Further, the 31 of 32 previous cases, noted by the
court in Troy Corp., in which the Agency had been consistent with this
exposure policy included the listing of hydrogen sulfide. Therefore,
EPA had applied this same exposure policy to the listing of hydrogen
sulfide, and need not, as Commenters suggest, provide a new notice and
opportunity to comment on the use of exposure analyses in listing
hydrogen sulfide under section 313 of EPCRA.
    As EPA explained in the Intent to Lift the Stay:

    EPA has determined that hydrogen sulfide can reasonably be
anticipated to cause serious or irreversible chronic human health
effects at relatively low doses and thus is considered to have
moderately high to high chronic toxicity. EPA does not believe that
it is appropriate to consider exposure for chemicals that are
moderately high to highly toxic based on a hazard assessment when
determining if a chemical can be listed for chronic effects pursuant
to EPCRA section 313(d)(2)(B) (see 59 FR 61432, 61433, 61440-61442).
Hydrogen sulfide has also been determined to cause ecotoxicity at
relatively low concentrations, and thus is considered to have high
ecotoxicity. EPA believes that

chemicals that induce death or serious adverse effects in aquatic
organisms at relatively low concentrations (i.e., they have high
ecotoxicity) have the potential to cause significant changes in the
population of fish and other aquatic organisms, and can therefore
reasonably be anticipated to cause a significant adverse effect on
the environment of sufficient seriousness to warrant reporting. EPA
does not believe that it is required to consider exposure for
chemicals that have high ecotoxicity based on a hazard assessment
when determining if a chemical can be listed for effects pursuant to
EPCRA section 313(d)(2)(C) (see 59 FR 61432, 61433, 61440-61442).
(75 FR 8889, 8893 (Feb. 26, 2010)).

    d. EPA Must Make a New Listing Determination. Finally, Commenters
argue that EPA cannot now limit comment to whether or not to lift the
stay because EPA ``must make a new listing determination before it may
lift [the stay].''
    This argument merely restates Commenters' first three arguments in
support of Commenters' ultimate position that EPA must revisit the 1993
listing decision. For the reasons already discussed above, the Agency
disagrees with Commenters' arguments.
    2. Implementation of EPA's Exposure Policy. Commenters state that
EPA may not implement its policy on the use of exposure analysis in
EPCRA section 313 listing decisions in an arbitrary manner. Commenters
claim that EPA has not identified the specific criteria it utilizes in
determining whether a substance causes chronic human health effects at
relatively low doses or ecotoxicity at relatively low concentrations.
Commenters noted that EPA stated in its intent to lift the
Administrative Stay that it is applying the interpretation of the
statutory listing criteria and the policy on the use of exposure
analyses adopted by the EPA in its November 30, 1994, final rule
listing other substances. Commenters cited EPA's statements from the
rule that exposure considerations are appropriate in making listing
determinations under EPCRA section 313(d)(2)(B) for chemicals with low
to moderately low toxicity based on hazard assessment and under EPCRA
section 313(d)(2)(C) for chemicals that are low or moderately ecotoxic.
Commenters claim that they were unable to identify or locate in the
docket for this action any objective criteria that EPA uses in making a
determination of whether a substance may cause ``serious or
irreversible chronic health effects'' or has ``low to moderately low
toxicity.'' Commenters state that they were unable to find any
explanation of the criteria that EPA uses in deciding whether a
substance has ``low to moderately low ecotoxicity.'' Commenters noted
that EPA stated that its interpretation of the statutory listing
criteria that supports the 1994 policy statement was sustained during
subsequent judicial review.
    Commenters state that even if EPA has discretion to select a policy
concerning the circumstances in which exposure analysis will be part of
the EPCRA section 313(d)(2) listing decision, it does not mean the EPA
has unfettered discretion to apply that policy in an arbitrary manner.
Commenters state that if EPA is to have a rational policy that can be
applied in a fair and equitable manner, the scientists conducting a
hazard assessment under EPCRA section 313(d)(2) should not be permitted
to make qualitative judgments concerning potential toxicity in the
absence of objective criteria or guidance concerning what these terms
mean. However, as discussed below, this is precisely the question at
issue in National Oilseed Processors Ass'n. v. Browner, 924 F. Supp.
1193 (D.D.C. 1996), aff'd in part & remanded in part, Troy Corp. v.
Browner, 120 F.3d 277 (D.C. Cir. 1997), where those Courts held that
EPA's exposure analysis policy, including the determination of when a
toxic chemical has ``moderately high to high toxicity'' based on
adverse effects at ``low'' or ``moderate'' dose levels and thus does
not require an exposure analysis in order to be listed, was not
arbitrary or capricious.
    EPA has identified the criteria that it uses in making a
determination of whether a substance that may cause ``serious or
irreversible chronic health effects'' has ``low to moderately low
toxicity,'' and has not applied its policy on the use of exposure
analysis in EPCRA section 313 listing determinations in an arbitrary
manner. To the contrary, in the preamble to the 1994 chemical expansion
final rule, EPA explained that two types of chemicals are considered to
exhibit moderately high to high toxicity:
     Where a review of the scientific data provides a high
level of confidence that the chemical causes an adverse effect at
relatively low dose levels, and
     Where a review of the scientific data indicates that the
chemical will cause various adverse effects at moderate dose levels.

(59 FR 61432, 61433 (Nov. 30, 1994).
    Thus, EPA has in fact articulated criteria for its determination
whether or not exposure considerations will be taken into account in
its chemical listing decisions.

    More specifically, EPA has provided guidance concerning how it
evaluates chemicals to determine whether they meet the EPCRA section
313 listing criteria, including information on the factors EPA
considers in determining whether a chemical is sufficiently toxic that
exposure need not be considered in the listing decision. The specific
criteria EPA uses to determine whether a chemical has moderately high
or high toxicity, and thus does not have low to moderately low
toxicity, were explained in detail in the 1994 chemical expansion rule:

    3. Hazard evaluation. After completing the screening phase, EPA
conducted a thorough hazard assessment for each of the addition
candidates that resulted from the above analyses and determined
based on the weight-of-the evidence if there was sufficient evidence
to establish that the candidate chemical met the statutory criteria
for addition to EPCRA section 313. To make this determination, EPA
senior scientists reviewed readily available toxicity information on
each chemical for each of the following effect areas: acute human
health effects; cancer; other chronic human effects; and
environmental effects. In addition, EPA reviewed, where appropriate,
information on the environmental fate of the chemical.
    The hazard assessment was conducted in accordance with relevant
EPA guidelines for each adverse human health or environmental effect
(e.g., the appropriate guidelines for hazard evaluation of chemical
carcinogens and for the type of evidence required to substantiate a
determination of carcinogenicity are the Assessment Guidelines for
Carcinogen Risk (Ref. 4)). During this assessment the number,
severity, and significance of the effects induced by the chemical,
the dose level causing the effect, and the quality and quantity of
the available data, including the nature of the data (e.g., human
epidemiological, laboratory animal, field or workplace studies) and
confidence level in the existing data base, were all considered.
Where a careful review of the scientific data for a particular
chemical results in a high level of confidence that the chemical
causes an adverse effect at relatively low dose levels, EPA believes
that this evidence is sufficient for listing the chemical under
section 313. EPA also believes that where a review of the scientific
data indicates that the chemical will cause various adverse effects
at moderate dose levels, the total weight-of-the-evidence indicates
that there is sufficient evidence for listing the chemical under
EPCRA section 313. EPA believes that both types of chemicals
described above exhibit moderately high to high toxicity based on a
hazard assessment.
    EPA also conducted an analysis of exposure for each chemical or
chemical category proposed for listing under EPCRA section
313(d)(2)(A) (i.e., based on adverse acute human health effects),
and, where appropriate, under section 313(d)(2)(C) (i.e., based on
adverse ecological effects). For chemicals listed under EPCRA
section 313(d)(2)(A), this analysis included estimated
concentrations of the chemical at or beyond

the facility site boundary through the use of estimated releases and
modeling techniques. EPA did not conduct an analysis of exposure for
the chemicals proposed for listing under section 313(d)(2)(B)
because these chemicals exhibit moderately high to high toxicity
based on a hazard assessment (see Unit IV.B. for a discussion of the
use of exposure). As discussed more thoroughly in Unit IV.B. of this
preamble, EPA does not believe that it is appropriate to factor
exposure into the listing decisions for the chemicals being listed
pursuant to section 313(d)(2)(B) in this rulemaking.
    Following a review and analysis of the information available
about each chemical in this final rule (including information
provided through public comment) by senior Agency scientists, the
Agency concludes that for each of the chemicals listed one or more
of the EPCRA section 313 listing criteria are met. Moreover, the
adverse effects associated with each of the chemicals being listed
today are serious and significant. In some cases the effects are
extreme, such as cancer or death. In others, the effects are serious
and lasting, including, for example, impairment of a fetus' or an
offspring's physical development, neurological effects inhibiting
motor abilities or mental processes or impairing the ability to
reproduce, or the sustainability of a fragile ecosystem such as an
estuary. For a number of chemicals in the final rule, there is more
than one adverse effect.
    It is important to understand that although an adverse effect is
known or can be reasonably anticipated to be caused by a chemical on
the section 313 list, a release of a chemical into a community does
not necessarily mean that the effect will occur. Exposure and dose
are also important factors in determining whether an adverse effect
occurs and how serious the manifestation will be. The listing of a
chemical on the section 313 list does not mean that a particular
community will experience these adverse effects. Instead the purpose
for listing a chemical is to ensure that the public gets information
about releases of such chemicals. Thus, EPA believes that for
chemicals that typically do not affect solely one or two species but
rather affect changes across a whole ecosystem and for which there
is well-documented evidence supporting the adverse effects, that
their addition to the EPCRA section 313 list is warranted even
though the severity of the adverse effects that they induce will be
dependent upon site-specific characteristics. Once EPA makes release
data available through TRI, the community may then make its own
determination on the importance of these releases (and their
potential adverse effects). (59 FR at 61433, 11/30/1994 (emphasis
added)).

EPA went on to state in the chemical expansion rule that:

    Through this rulemaking, EPA is clarifying its position
regarding the use of hazard, exposure, and risk in listing decisions
under EPCRA section 313. EPA will consider exposure factors when
making determinations under section 313(d)(2)(A) (acute human
toxicity). In addition, EPA has discretion to consider exposure
factors where appropriate for determinations under sections
313(d)(2)(B) (chronic human toxicity) and (C) (environmental
toxicity), and that there is a broader range of circumstances in
which exposure will be considered under section 313(d)(2)(C) than
under (B).
    EPA has reviewed its past listing decisions in light of this
clarification, and believes that its prior listing determinations
have been consistent in the consideration of exposure in 31 of the
32 listing/delisting determinations previous to this action,
including a number of deletions of low toxicity chemicals that
Congress placed on the initial EPCRA section 313 list. EPA is
currently reviewing the one exception, inorganic fluorides, to
determine if additional action is warranted. EPA will continue to
evaluate petitions according to this clarification and will delete
chemicals that do not meet the statutory criteria. (59 FR at 61442,
11/30/1994).

    EPA's exposure analysis policy, as set forth in the chemical
expansion Final Rule, was judicially challenged in National Oilseed
Producers Ass'n v. Browner, 924 F. Supp. 1193 (D.D.C. 1996). There, the
plaintiffs presented precisely the same argument that the Hydrogen
Sulfide Consortium now raises. In National Oilseed, the court stated
that ``Plaintiffs * * * claim that EPA has not adequately explained
when it will consider exposure under Section 313(d)(2)(B).'' National
Oilseed, 924 F. Supp. at 1203. The court squarely rejected that
argument, holding:

    The Agency argues generally that, in the exercise of its
discretion, it has elected to consider exposure only in limited
circumstances. Specifically, when EPA's hazard assessment shows that
a chemical exhibits only low or moderately low toxicity, EPA will
consider the potential for exposure in making a listing decision.
Conversely, where EPA's hazard assessment reveals that a chemical's
toxicity is high or moderately high, EPA does not consider exposure,
and will list the chemical based solely on its toxic effect.
* * * * *
    Moreover, EPA asserts that it explained adequately on the record
that it chose to not consider exposure in this rulemaking because
all of the chemicals proposed for listing under Section 313(d)(2)(B)
were of ``high to moderately-high'' toxicity and therefore
consideration of exposure was not appropriate.
    After consideration of the extensive arguments on both sides of
this issue, the Court concludes that the Agency did not act
arbitrarily and capriciously in declining to consider exposure in
the listing decisions for this rulemaking. * * * While a more
clearly and fully articulated policy would be preferable, the Court
cannot conclude that EPA was unreasonable in exercising its
discretion by continuing to exclude consideration of exposure when
chemicals are of high to moderately-high toxicity.
* * * * *
    What is significant is that EPA stated what its policy for
consideration of exposure would be, and then described its
application to the chemicals considered in this rulemaking.
    Because EPA's decision to not consider exposure in this
rulemaking was consistent with its policy of using exposure data
only in particular circumstances, i.e., where chemicals are of low
toxicity, the Court concludes that the Agency was not arbitrary and
capricious.

    National Oilseed, 924 F. Supp. at 1203-04 (citations and footnotes
omitted).

    On appeal to the U.S. Court of Appeals for the D.C. Circuit, the
plaintiffs again raised this same argument. There, the court stated:
``* * * [Plaintiffs] argue that the EPA abused its discretion and acted
arbitrarily and capriciously by failing to establish criteria for the
consideration of exposure * * *.'' Troy Corp. v. Browner, 120 F.3d 277,
282 (D.C. Cir. 1997). On this point, the D.C. Circuit rejected the
plaintiffs' argument and affirmed the judgment of the D.C. District
Court in National Oilseed. Troy Corp., 120 F.3d at 293.
    Just as EPA did in the 1994 chemical expansion rule and other
previous listing decisions, upheld by the Courts in National Oilseed
and Troy Corp.--including application of the Agency's exposure analysis
policy in conducting such hazard assessments--EPA conducted a hazard
assessment of the human health and ecological effects of hydrogen
sulfide, upon which the determinations that hydrogen sulfide has
moderately high to high human toxicity were based. Based on the data
from the hazard assessment, as presented in the Federal Register notice
and supporting documents, EPA determined that hydrogen sulfide has
moderately high to high toxicity to humans and is highly toxic to
aquatic organisms. EPA discussed these determinations in detail in the
notice of Intent to Lift the Stay in the Federal Register (75 FR 8889,
2/26/2010). Human health toxicity was discussed in detail beginning on
page 8891, with references, and ecological effects were discussed in
detail beginning on page 8893, with references.
    In the section of the Federal Register document that discussed the
rationale for lifting the stay, EPA provided the following summary of
the hazard data:

    EPA's technical evaluation of hydrogen sulfide shows that it can
reasonably be anticipated to cause chronic health effects in humans.
The chronic health effects have been observed in laboratory animals
at concentrations as low as 28 mg/m\3\ (20 ppm) and 41.7 mg/m\3\ (30
ppm). In addition, EPA's technical evaluation of hydrogen sulfide
also shows that it can reasonably be anticipated

to cause, because of its toxicity, significant adverse effects in
aquatic organisms. Examples of hydrogen sulfide's ecological
toxicity include acute toxicity (96-hour LC50) values for
freshwater fish that ranged from 0.0149 mg/L (fathead minnow) to
0.0448 mg/L (bluegill), indicating high aquatic toxicity. Examples
of hydrogen sulfide's chronic ecological toxicity include freshwater
fish values that ranged from a 6-week LOEC (growth rate) of 0.0005
mg/L in a tropical fish (Mystus nemurus) to a 430-day LOEC (final
weight) of 0.009 mg/L for goldfish, also indicating high aquatic
toxicity. (75 FR 8893, 2/26/2010).

    As the language above clearly shows, EPA did identify the
information and the rationale for why hydrogen sulfide was determined
to have moderately high to high human toxicity and high ecotoxicity.
    3. EPA's Rationale for Hydrogen Sulfide's Toxicity Level.
Commenters claim that EPA has not given its rationale for why hydrogen
sulfide causes chronic human health effects at relatively low levels
and ecotoxicity at relatively low concentrations. Commenters contend
that EPA has not provided any rationale for the determinations that no
exposure assessment is needed for hydrogen sulfide. Commenters noted
that EPA provided a description of the chronic human health effects and
ecological toxicity of hydrogen sulfide. Commenters also noted that EPA
asserted that it had made the requisite determinations concerning the
relative magnitude of the toxicity of hydrogen sulfide for both human
health and ecological effects. Commenters contend, however, that EPA's
statements are wholly conclusory and that the docket does not appear to
contain any explanations of the relation between the hazard assessments
prepared by EPA scientists and these determinations. Commenters state
that they do not believe that the effect levels cited by EPA will be
caused by the releases reportable under EPCRA section 313. Commenters
state that they believe that the effect levels cited by EPA as
``relatively low'' are actually very high. Commenters stated that the
chronic health effect levels cited by EPA are 2,000 to 3,000 times
greater than the odor detection threshold (10 parts per billion (ppb))
for hydrogen sulfide. Commenters claim that while releases may result
in ambient hydrogen sulfide concentrations that exceed the odor
detection threshold, the concentrations will always be far below the
lowest levels for chronic effects in animals cited by EPA. Commenters
cited a 1990 EPA study on oil and natural gas extraction and a 1999
Public Health Service study for one city near hydrogen sulfide sources
as evidence that hydrogen sulfide levels are low. Commenters also cited
established state air standards that range from 83 to 200 ppb noting
that these are 100 to 150 times less than the lowest levels EPA cited
for chronic effects in animals.
    In discussing the data EPA cited as supporting its evaluation that
hydrogen sulfide is toxic to aquatic organisms at relatively low
concentrations, the commenters stated that while the levels may seem
relatively low in the abstract, they believe they are actually quite
high when viewed in the context of data that clearly establish that
hydrogen sulfide will rapidly oxidize to less toxic chemical forms when
released to surface waters. Commenters cited the EPA Water Quality
Criteria Gold Book as support for their position:

    The fact that H2S is oxidized in well-aerated water
by natural biological systems to sulfates or is biologically
oxidized to elemental sulfur has caused investigators to minimize
the toxic effects of H2S on fish and other aquatic life.
(EPA Gold Book, May 1, 1986, page 268 (Ref. 2)).

    As discussed in the previous response, EPA has provided guidance on
how it determines whether a chemical has moderately high to high human
toxicity and high ecotoxicity. In its notice of Intent to Lift the
Stay, EPA provided a detailed hazard assessment of both the human
health effects and the ecological effects of hydrogen sulfide. This
assessment included both the effects caused by hydrogen sulfide and the
doses/concentrations that caused those effects. This information was
discussed in the Federal Register (75 FR 8889, 2/26/2010), and the
details were contained in the hazard assessments and other references
cited by EPA. Specifically, at 75 FR 8889, 8891-8893 (Feb. 26, 2010),
EPA's lengthy and detailed technical review of hydrogen sulfide (Part
IV. of the Federal Register notice, entitled ``What is EPA's Technical
Review of Hydrogen Sulfide?''), including references, can be found (and
need not be reiterated here). EPA then concluded, based on the hazard
assessment:

    EPA has determined that hydrogen sulfide can reasonably be
anticipated to cause serious or irreversible chronic human health
effects at relatively low doses and thus is considered to have
moderately high to high chronic toxicity * * *. Hydrogen sulfide has
also been determined to cause ecotoxicity at relatively low
concentrations, and thus is considered to have high ecotoxicity. EPA
believes that chemicals that induce death or serious adverse effects
in aquatic organisms at relatively low concentrations (i.e., they
have high ecotoxicity) have the potential to cause significant
changes in the population of fish and other aquatic organisms, and
can therefore reasonably be anticipated to cause a significant
adverse effect on the environment of sufficient seriousness to
warrant reporting. (75 FR 8893, 2/26/2010).

    In the section of the Federal Register document that discussed the
rationale for lifting the stay, EPA provided the following summary of
the hazard data:

    EPA's technical evaluation of hydrogen sulfide shows that it can
reasonably be anticipated to cause chronic health effects in humans.
The chronic health effects have been observed in laboratory animals
at concentrations as low as 28 mg/m\3\ (20 ppm) and 41.7 mg/m\3\ (30
ppm). In addition, EPA's technical evaluation of hydrogen sulfide
also shows that it can reasonably be anticipated to cause, because
of its toxicity, significant adverse effects in aquatic organisms.
Examples of hydrogen sulfide's ecological toxicity include acute
toxicity (96-hour LC50) values for freshwater fish that
ranged from 0.0149 mg/L (fathead minnow) to 0.0448 mg/L (bluegill),
indicating high aquatic toxicity. Examples of hydrogen sulfide's
chronic ecological toxicity include freshwater fish values that
ranged from a 6-week LOEC (growth rate) of 0.0005 mg/L in a tropical
fish (Mystus nemurus) to a 430-day LOEC (final weight) of 0.009 mg/L
for goldfish, also indicating high aquatic toxicity. (75 FR 8893, 2/
26/2010).

    The above determinations are based on the human health effects and
ecological effects caused by hydrogen sulfide and the doses/
concentrations that caused those effects. EPA clearly stated why the
hazard assessment supports a finding of moderately high to high human
toxicity and high ecotoxicity. Therefore, EPA has clearly stated how
the hazard assessment data supports a conclusion that hydrogen sulfide
has moderately high to high human toxicity and high ecological
toxicity.
    Regarding the information that the commenter provided on previous
exposure assessments, air standards, etc., none of that information is
relevant to a determination that hydrogen sulfide has moderately high
to high human toxicity or high ecological toxicity. The toxicity of a
chemical is separate from whether there are exposures from facility
releases of that chemical or not. In addition, the information provided
by the commenter does not demonstrate that releases of hydrogen sulfide
could not reach a level of concern from all the types of facilities
that report under EPCRA section 313. EPA notes that the examples of the
very low air standards for hydrogen sulfide of 83-200 parts per billion
support EPA's determination that hydrogen sulfide is highly toxic.
    The commenter's statement that the cited toxic effects of hydrogen
sulfide are 2,000 to 3,000 times greater than the odor detection
threshold for hydrogen

sulfide of 10 ppb is not a basis for discounting the toxic effects of
hydrogen sulfide. As EPA has stated:

    Recent reviews of the health hazards associated with
H2S exposure and subsequent treatment include Milby and
Baselt (1999a) and Guidotti (1996). Earlier reviews of the health
effects were provided by Glass (1990), Reiffenstein et al. (1992),
and Mehlman (1994). Exposure to H2S has been reported to
be an important cause of morbidity and mortality in the workplace
(Snyder et al., 1995) and olfactory dysfunction (Hirsch and Zavala,
1999). These reviews indicate that the typical ``rotten-egg odor''
of H2S is an inadequate warning indicator of exposure
since levels in the range of 100-200 ppm (140-280 mg/m\3\) can lead
to loss of smell followed by olfactory paralysis (Reiffenstein et
al., 1992) (IRIS, 2003, page 10 (Ref. 3)).

    In addition, simply because someone can smell hydrogen sulfide does
not mean they will automatically remove themselves from that exposure.
Individuals that are frequently exposed to hydrogen sulfide may become
less sensitive to the smell and, as indicated in the IRIS assessment,
it is possible to have loss of smell from hydrogen sulfide exposure.
    Commenters further state that:

    EPA bases its evaluation that H2S is ecotoxic at
``relatively low concentrations'' exclusively on potential effects
on aquatic life, noting that toxicity values for aquatic species
include ``numerous values that are well below 1 milligram per liter
(mg/L).'' While the levels cited by EPA may seem ``relatively low''
in the abstract, they are actually quite high when viewed in the
context of data that clearly establish that H2S will be
rapidly oxidized to less toxic chemical forms when released to
surface waters. The EPA Water Quality Criteria Gold Book makes a
similar observation:
    The fact that H2S is oxidized in well-aerated water
by natural biological systems to sulfates or is biologically
oxidized to elemental sulfur has caused investigators to minimize
the toxic effects of H2S on fish and other aquatic life.
    (Footnotes omitted)

    The quote from the water quality criteria document that ``[t]he
fact that H2S is oxidized in well-aerated water by natural
biological systems to sulfates or is biologically oxidized to elemental
sulfur has caused investigators to minimize the toxic effects of
H2S on fish and other aquatic life'' is from the
introductory paragraph of the water quality criteria for hydrogen
sulfide. This statement simply explains what has caused some
investigators in the past to minimize the toxic effects of hydrogen
sulfide. However, in the rationale section, the document goes on to
discuss the toxicity of hydrogen sulfide to aquatic life in detail and
does not dismiss the potential impacts hydrogen sulfide may have on
aquatic life. In fact, the document presents the rationale for setting
a water quality criterion of just 2 micrograms per liter ([mu]g/L)
undissociated hydrogen sulfide for fish and other aquatic life in both
fresh and marine water. Concerning oxidation, the EPA Gold Book states:

    The degree of hazard exhibited by sulfide to aquatic animal life
is dependent on the temperature, pH, and dissolved oxygen. At lower
pH values a greater proportion is in the form of the toxic
undissociated H2S. In winter when the pH is neutral or
below or when dissolved oxygen levels are low but not lethal to
fish, the hazard from sulfide is exacerbated. (EPA Gold Book, May 1,
1986, page 268, (Ref. 2)).

The criteria document also states that:

    Many past data on the toxicity of hydrogen sulfide to fish and
other aquatic life have been based on extremely short exposure
periods. Consequently, these early data have indicated that
concentrations between 0.3 and 0.4 mg/L permit fish to survive (Van
Horn 1958, Boon and Follie 1967, Theede et al., 1969). Recent long-
term data, both in field situations and under controlled laboratory
conditions, demonstrate hydrogen sulfide toxicity at lower
concentrations. (EPA Gold Book, May 1, 1986, page 268, (Ref. 2)).

and concludes that:

    Available data indicate that water containing concentrations of
2.0 [mu]g/L undissociated H2S would not be hazardous to
most fish and other aquatic wildlife, but concentrations in excess
of 2.0 [mu]g/L would constitute a long-term hazard.'' (EPA Gold
Book, May 1, 1986, page 270 (emphasis added) (Ref. 2)).

The conclusion that a concentration of hydrogen sulfide in excess of
just 2.0 [mu]g/L would constitute a long-term hazard to aquatic life
supports a determination that hydrogen sulfide is clearly highly toxic
and a potential hazard to aquatic life despite its fate under certain
environmental conditions. If hydrogen sulfide were not highly toxic to
fish and other aquatic life, then there would be no need for such a
very low water quality criteria value.
    Regarding the two references cited by the commenters concerning
oxidation of hydrogen sulfide in seawater and aqueous solutions (i.e.,
Millero, F.J., Hubinger, Fernandez and Garnett (1987). Oxidation of
H2S in Seawater as a Function of Temperature, pH and Ionic
Strength. Env. Sci. Tech. 21:439-443; Obrien, D.J. and Birkner, F.B.
(1977). Kinetics of Oxygenation of Reduced Sulfur Species in Aqueous
Solutions. Env. Sci. Tech. 11:1114-1120.), the Millero reference was
cited in EPA's hazard assessment (page 8) and the Obrien reference was
cited in the Millero reference (Ref. 4). EPA is thus familiar with the
issue of oxidation of hydrogen sulfide and discussed the topic in its
hazard assessment on page 8 and again on page 17 (Ref. 4). However, the
fact that hydrogen sulfide can be oxidized under certain environmental
conditions does not mean that it is not highly toxic. As was cited
above, the EPA Gold Book stated:

    The degree of hazard exhibited by sulfide to aquatic animal life
is dependent on the temperature, pH, and dissolved oxygen. At lower
pH values a greater proportion is in the form of the toxic
undissociated H2S. In winter when the pH is neutral or
below or when dissolved oxygen levels are low but not lethal to
fish, the hazard from sulfide is exacerbated. (EPA Gold Book, May 1,
1986, page 268 (Ref. 2)).

    If hydrogen sulfide were rapidly oxidized to harmless chemicals
under all environmental conditions, then that would have an impact on
EPA's assessment, but that is certainly not the case. How much damage a
particular release of hydrogen sulfide will cause can depend on a
number of factors including the amount of the release, whether the
release is continuous or infrequent, the pH of the water, the
temperature of the water, the type of water (fresh or seawater), the
time of year, velocity of the body of water, etc. These factors would
be considered in site-specific exposure and risk assessments. While
hydrogen sulfide may be oxidized under certain environmental
conditions, there are many common environmental conditions under which
oxidation will not be significant and thus will not lessen the impact
of a release of hydrogen sulfide. As the aquatic toxicity data shows,
hydrogen sulfide is toxic to many different aquatic species and at
several stages of life with some toxicity values at or below one part
in a billion. Thus, it takes very little hydrogen sulfide to have an
impact on aquatic life. Even under favorable oxidation conditions, the
experimental half-life of hydrogen sulfide is 50 hours in fresh water
and 26 hours in seawater. Considering how low the 48 and 96 hour
LC50 values are for hydrogen sulfide, hydrogen sulfide
toxicity is still a concern even under favorable oxidation conditions.
The potential oxidation of hydrogen sulfide does not lessen the
inherent toxicity of hydrogen sulfide.
    EPA notes that, other than the single quote from the water quality
criteria document and two references concerning oxidation of hydrogen
sulfide in water, the commenters have not questioned or tried to refute
in any way the aquatic toxicity information provided in EPA's hazard
assessment. The summary table of the aquatic

toxicity values presented in the hazard assessment provided over 90
toxicity values from more than a dozen sources. The commenters did not
provide any specific comments on why those data should not be
considered sufficient to support EPA's conclusions.
    With regard to the commenters' statements concerning criteria or
guidance for determining whether a chemical has moderately high to high
human toxicity or high ecological toxicity, it appears that the
commenters may have been looking for some type of numerical cutoffs.
The comments regarding criteria or guidance for determining whether a
chemical has moderately high to high human toxicity or high ecological
toxicity have been addressed in EPA's other responses to the
commenters. With regard to possible numerical cutoffs, EPA does not
agree that numerical cutoffs should be or need to be established in
order to determine whether a chemical has moderately high to high human
toxicity or high ecological toxicity. As EPA explained in the chemical
expansion rule in 1994:

    The hazard assessment was conducted in accordance with relevant
EPA guidelines for each adverse human health or environmental effect
(e.g., the appropriate guidelines for hazard evaluation of chemical
carcinogens and for the type of evidence required to substantiate a
determination of carcinogenicity are the Assessment Guidelines for
Carcinogen Risk (Ref. 4)). During this assessment the number,
severity, and significance of the effects induced by the chemical,
the dose level causing the effect, and the quality and quantity of
the available data, including the nature of the data (e.g., human
epidemiological, laboratory animal, field or workplace studies) and
confidence level in the existing data base, were all considered.
Where a careful review of the scientific data for a particular
chemical results in a high level of confidence that the chemical
causes an adverse effect at relatively low dose levels, EPA believes
that this evidence is sufficient for listing the chemical under
section 313. EPA also believes that where a review of the scientific
data indicates that the chemical will cause various adverse effects
at moderate dose levels, the total weight-of-the-evidence indicates
that there is sufficient evidence for listing the chemical under
EPCRA section 313. EPA believes that both types of chemicals
described above exhibit moderately high to high toxicity based on a
hazard assessment. (59 FR 61433, 11/30/1994).

    EPA provided a hazard assessment that presented the information
used to support the finding that hydrogen sulfide has moderately high
to high human toxicity and high ecotoxicity. As in the 1994 rulemaking,
and subsequent rulemakings, the data presented in the hazard
assessments addressed issues such as the number, severity, and
significance of the effects induced by the chemical, the dose level
causing the effect, and the quality and quantity of the available data,
including the nature of the data (e.g., human epidemiological,
laboratory animal, field or workplace studies) and confidence level in
the existing data base. All commenters had the opportunity to comment
on whether these data support EPA's determinations regarding the
toxicity of hydrogen sulfide in response to EPA's notice of Intent to
Lift the Stay of the reporting requirements for hydrogen sulfide.
Establishing a numerical cutoff would limit EPA's ability to consider
other factors that might increase or decrease the concern for the
toxicity of a chemical. For example, if one chemical causes one serious
effect at 100 milligrams per kilogram per day (mg/kg/day) and another
chemical causes multiple serious effects across multiple organ systems
but at 300 mg/kg/day it would not make sense to discount the latter if
there were some arbitrary numerical cutoff of 200 mg/kg/day. EPA does
not believe that would be the correct way to evaluate chemicals for
listing. Rather, EPA considers all of the toxicity data, including the
doses/concentrations causing the toxic effects, in making
determinations about the toxicity of a chemical. EPA provided this
information in the hazard assessment for hydrogen sulfide and provided
its rationale for lifting the stay based on this information.
    While EPA has not set numerical cutoffs, a quick review of the
chemicals included in the 1994 chemical expansion rule (59 FR 61432,
11/30/1994), the persistent, bioaccumulative, and toxic (PBT) chemicals
rule (64 FR 693, 1/5/1999), and other actions shows that the doses and
concentrations that cause adverse effects for hydrogen sulfide are well
within those of chemicals that EPA has previously determined to have
moderately high to high human toxicity and high ecotoxicity. In fact,
with regard to ecotoxicity, some of the levels at which hydrogen
sulfide causes toxicity are among the lowest that EPA has evaluated.
Even if EPA were to establish numerical cutoffs, based on EPA's
previous listing determinations the levels at which hydrogen sulfide
causes toxicity would be well below any such numerical cutoffs.
    With regard to the phrase ``relatively low doses,'' this simply
refers to doses that are low relative to the body burden they impose.
Dose levels are most often measured as (or converted into) the units
milligrams per kilogram per day (mg/kg/day) where kilogram refers to
each kilogram of body weight. As noted above, EPA has explained that in
determining whether a chemical has moderately high to high chronic
toxicity the dose levels causing the effects along with the number and
severity of the adverse effects are considered (59 FR 61433, 1/30/
1994). While EPA has not set a numerical cutoff for a relatively low
dose, it has provided numerous examples of the dose levels that EPA
considers to be relatively low as well as dose levels that EPA
considers to be relatively high. The 1994 chemical expansion rule alone
contains over 200 examples of relatively low doses (59 FR 1788, 1/12/
1994). Doses in that rule that were considered relatively low were
generally at or below 100 mg/kg/day. EPA has also identified, through
numerous actions, dose levels that are considered to be high or
relatively high. Such dose levels are typically at or above 500 mg/kg/
day, with most examples being in excess of 1,000 mg/kg/day or more (see
for example: 59 FR 49888, 9/30/1994; 60 FR 46076, 9/5/1995, and 64 FR
8769, 2/23/1999). Even in the rulemaking that added hydrogen sulfide to
the TRI list, EPA identified doses of 600 and 1,000 mg/kg/day as
``relatively high doses'' (57 FR 41020, 9/8/1992). These ``relatively
high doses'' were cited by EPA in the determinations that b-
chloronapthalene and isobutyl alcohol were not sufficiently toxic to be
added to the EPCRA section 313 list (57 FR 41033, 9/8/1992). These dose
levels are significantly higher than the less than 15 mg/kg/day doses
(converted from 20-30 ppm) that EPA has cited as being relatively low
for hydrogen sulfide. While EPA has not set a numerical cutoff for
relatively low doses, the Agency has provided, through the listing and
delisting of chemicals, substantial guidance for this terminology.
    As EPA has noted, low dose alone is not the only consideration in
determining whether a chemical has moderately high to high toxicity and
thus should be listed on hazard alone:

    Where a careful review of the scientific data for a particular
chemical results in a high level of confidence that the chemical
causes an adverse effect at relatively low dose levels, EPA believes
that this evidence is sufficient for listing the chemical under
section 313. EPA also believes that where a review of the scientific
data indicates that the chemical will cause various adverse effects
at moderate dose levels, the total weight-of- the-evidence indicates
that there is sufficient evidence for listing the chemical under
EPCRA section 313. EPA believes that both types of chemicals
described above exhibit moderately high to high toxicity based on a
hazard assessment. (59 FR 61433, 1/30/1994).

An example of this concept is the listing of triphenyltin chloride.
This chemical was cited by EPA as causing significant reproductive
toxicity, including adverse effects on the testes, epididymis, sperm
duct, prostate gland, seminal vesicle, Cowper's gland, and accessory
glands, at an oral dose of 380 mg/kg over 19 days. While the dose level
was more moderate, EPA determined that the severity and number of
effects were sufficient for listing (59 FR 1843, 1/12/1994). This is
the kind of flexibility regarding dose levels that is required when
making determinations about the toxicity of chemicals, and is
consistent with the exposure policy EPA has established for EPCRA
section 313 determinations.
    Regarding the phrase ``relatively low concentrations'' used in the
assessment of ecological toxicity, this is similar to the ``relatively
low dose'' terminology in that it focuses on concentrations that result
in low doses to the organisms. Data for aquatic organisms is the most
commonly cited data and typically has the units of milligrams per liter
(mg/L). As EPA has stated, exposure assessments are not used to list a
chemical for ecological effects if it has high toxicity. Based on
concentration, EPA has typically limited its consideration of highly
toxic to those chemicals that cause acute effects at about 1 mg/L or
less and chronic effects at 0.1 mg/L or less (see for example: 57 FR
41020, 9/8/1992 and 59 FR 1788, 1/12/1994). Since the statutory
criteria of EPCRA section 313(d)(2)(C) also includes consideration of
persistence and bioaccumulation, EPA has considered somewhat higher
concentrations as highly toxic for chemicals with those characteristics
(64 FR 696, 1/5/1999). As with chronic human health effects, EPA has
not set a numerical cut off for relatively low concentrations, but has
provided, through the listing and delisting of chemicals, substantial
guidance for this terminology.
    EPA notes that other programs within the Agency that have numerical
cutoffs for aquatic organisms have set numerical cutoffs that are
consistent with the kind of toxicity concentrations that EPA has
identified as being highly toxic in EPCRA section 313 evaluations. For
example, the Office of Pesticide Programs cites the following:

      Ecotoxicity Categories for Terrestrial and Aquatic Organisms
------------------------------------------------------------------------
         Concentration (ppm)                   Toxicity category
------------------------------------------------------------------------
                        Aquatic Organisms: Acute
------------------------------------------------------------------------
< 0.1...............................  very highly toxic.
0.1-1...............................  highly toxic.
>1-10...............................  moderately toxic.
>10-100.............................  slightly toxic.
> 100...............................  practically nontoxic.
------------------------------------------------------------------------
(http://www.epa.gov/oppefed1/ecorisk_ders/toera_analysis_eco.htm#Ecotox).

Under the above numerical cutoffs, not only would hydrogen sulfide be
considered highly toxic, but most of the available data would support a
classification of very highly toxic.
    4. Qualitative Judgment on Exposure Levels. Commenters stated that
the lack of any objective rationale for EPA's determination that
hydrogen sulfide causes health and ecological effects at relatively low
levels suggests that EPA made a qualitative judgment about the
magnitude of the potential exposure without preparing any supporting
exposure analysis. Commenters restated their position that EPA has not
provided any objective criteria for its determination that hydrogen
sulfide causes human health effects and ecological effects at
relatively low levels. Commenters assert that one possibility is that
EPA scientists have simply made a qualitative judgment concerning the
plausibility that hydrogen sulfide exposure might occur at the levels
in question. Commenters stated that such a judgment would be
intrinsically arbitrary when it is possible to do a proper and
defensible exposure analysis. Commenters claim that if an exposure
analysis were conducted they are confident it would show that exposure
levels are below the levels that EPA has identified for human health
effects and ecological effects.
    As discussed in a previous response to this commenter, EPA has
provided the information it used to determine that hydrogen sulfide has
moderately high to high human toxicity and high ecotoxicity and has
explained the methodology by which EPA makes such determinations.
Therefore, EPA disagrees with the commenter's statement that EPA did
not provide an objective rationale for its determinations.
    Commenter asserts that:

    One possibility is that EPA scientists have simply made a
qualitative judgment concerning the plausibility that H2S
exposure might occur at the levels in question. Such a judgment
would be intrinsically arbitrary when it is possible to do a proper
and defensible exposure analysis.

There is nothing in the materials that EPA has provided that even
suggests that EPA made a qualitative judgment about hydrogen sulfide
exposure levels. The determination as to whether or not a chemical has
moderately high to high human toxicity or high ecotoxicity is separate
from any consideration of potential exposures. EPA did not consider or
evaluate the potential exposures to hydrogen sulfide in making its
finding that hydrogen sulfide has moderately high to high toxicity to
humans and is highly toxic to aquatic organisms. The toxicity of a
chemical is an intrinsic property of the chemical that is established
by determining what exposure level (i.e., dose) causes adverse effects
through appropriately conducted toxicological studies; it is not based
on releases that occur at facilities. Consideration of the level of
exposure from releases occurring at facilities is part of a risk
assessment, not a hazard assessment. Unlike the intrinsic toxicity of a
chemical, exposure levels can change depending on many factors such as
release quantities, type of release, changes in weather patterns, etc.
As EPA has stated:

    It is important to understand that although an adverse effect is
known or can be reasonably anticipated to be caused by a chemical on
the section 313 list, a release of a chemical into a community does
not necessarily mean that the effect will occur. Exposure and dose
are also important factors in determining whether an adverse effect
occurs and how serious the manifestation will be. The listing of a
chemical on the section 313 list does not mean that a particular
community will experience these adverse effects. Instead the purpose
for listing a chemical is to ensure that the public gets information
about releases of such chemicals. Thus, EPA believes that for
chemicals that typically do not affect solely one or two species but
rather affect changes across a whole ecosystem and for which there
is well-documented evidence supporting the adverse effects, that
their addition to the EPCRA section 313 list is warranted even
though the severity of the adverse effects that they induce will be
dependent upon site-specific characteristics. Once EPA makes release
data available through TRI, the community may then make its own
determination on the importance of these releases (and their
potential adverse effects). (59 FR 61433, 11/30/1994).

    In upholding EPA's interpretation of EPCRA section 313 listing
decisions as it relates to the use of exposure, the U.S. Court of
Appeals for the District of Columbia itself provided a very good
example of the difference between the toxicity of a chemical and
exposure to that chemical:

    It is not the case that the congressional language mandating
listing of a chemical that `is known to cause or can reasonably be
anticipated to cause in humans' the enumerated adverse effects
unambiguously incorporates the likelihood of contact between humans
and the chemical. A simple analogy quickly refutes NPG's argument
that the language is unambiguous. Consider a herpetologist and a
student contemplating a reptile imprisoned in a glass cage. The
student asks, `Can that snake's bite reasonably be anticipated to
cause death in humans?' The scientist replies, `Yes.' The scientist
is not commenting on the likelihood of the serpent's escape, only
the toxicity of its venom. Concededly, his answer could be taken to
mean, `Yes, it is likely that this creature will escape, bite
someone, and kill them.' But that is certainly not the unambiguous
purport of his words. Even so is the statutory language of Congress.
It is conceivable that Congress may have contemplated release in its
phrasing of the standard, but that is certainly not unambiguously
the case. (Troy Corp. v. Browner, 120 F.3d 277, 285 (D.C. Cir.
1997)).

    The example of a venomous snake in a glass cage provides a perfect
illustration of the difference between exposure and toxicity. Just as
the containment of the venomous snake in a glass cage does not change
the fact that the snake's venom is highly toxic, lack of exposure does
not lessen the intrinsic toxicity of a chemical. Lack of exposure
addresses the issue of the level of risk, not the level of toxicity.
    5. Use of Best Available Science. Commenters claim that EPA did not
properly consider the best available scientific evidence concerning
hydrogen sulfide toxicity and exposure. Commenters cited one clinical
study of potential neurological effects of hydrogen sulfide exposure in
humans that EPA did not consider. Commenters stated that in the
Fieldler et al. study (Ref. 5), 74 healthy male and female volunteers
participated in a clinical study designed to evaluate neurobehavioral
effects of 2-hour controlled chamber exposures to hydrogen sulfide.
Commenters state that neurobehavioral effects were evaluated using a
battery of established tests immediately prior to, and immediately
following, exposure to 0.05, 0.5, and 5.0 ppm hydrogen sulfide in
separate sessions approximately one week apart. Commenters state that
the sequence of exposures was randomly assigned to each subject and
that the investigators reported that no significant changes were found
between pre- and post-exposure performance, and that no dose-response
was found in any of the neurobehavioral or neurosensory data sets.
Commenters contend that although the exposures studied in the Fiedler
et al. study did not constitute chronic exposure, the study is highly
relevant in establishing the levels at which humans might experience
neurological effects from hydrogen sulfide exposure. Commenters claim
that the neurobehavioral endpoints that were evaluated in this study
are likely to be much more effective in capturing subtle neurological
impairments that could not be detected in animal studies.
    Commenters provided an additional primary literature resource for
the evaluation of hydrogen sulfide human health effects. However, the
commenters mistakenly reported no significant changes between pre- and
post-exposure performance. This is inaccurate as the authors identified
significant impairment of verbal learning in all exposure groups (p <=
0.0003). Although the response was not dose dependent, the authors
offer several explanations for this finding including a threshold
effect for hydrogen sulfide as low as 0.05 ppm.
    EPA's Federal Register notice of Intent to Lift the Stay of the
hydrogen sulfide reporting requirements specifically states that the
human health concern for hydrogen sulfide is chronic human health
effects (both upper respiratory and neurotoxic effects) (75 FR 8893,
February 26, 2010). As the commenters correctly pointed out, the
Fiedler et al. study ``Sensory and Cognitive Effects of Acute Exposure
to Hydrogen Sulfide'' evaluated only acute exposures--not chronic
exposures. The study evaluated subjects exposed to hydrogen sulfide for
<=2 hours. Therefore, the study in question is not relevant to the
chronic human health effects or the environmental effects that form the
basis of EPA's cited concerns for hydrogen sulfide.
    While the Fiedler et al. study may be relevant in establishing the
levels at which humans might experience neurological effects from acute
hydrogen sulfide exposure, the Agency does not support the extension to
chronic neurological effects. The Fiedler et al. study was designed to
evaluate cognitive endpoints shown to be responsive in acute studies.
As detailed in the Federal Register (75 FR 8891, February 26, 2010),
hydrogen sulfide neurotoxicity is thought to occur due to hypoxia
induced neuronal cell death. This pathology would not be evidenced in
the short-term human study conducted by Fiedler et al. because the
exposures were acute not chronic. Therefore, we would also conclude
that the neurobehavioral endpoints that were used in the Fiedler et al.
study are not, as the commenters suggest, ``likely to be much more
effective in capturing subtle neurological impairments that could not
be detected in animal studies'' since the effects of chronic exposure
would not be observed. The ability to sacrifice animals to study
neurotransmitters and brain chemistry provides information that is not
available in human studies. These types of studies provide powerful
quantitative data, as evidenced in Skrajny et al. (Ref. 6).
    It should also be noted that the hydrogen sulfide inhalation
exposure in the Fiedler et al. study ranged from 0.05 to 5.0 ppm. This
is far below the lowest observed adverse effect levels (LOAELs) seen in
the animal studies of neurotoxicity cited in EPA's notice of Intent to
Lift the Stay and support materials. The Fiedler et al. study may
indicate that hydrogen sulfide can cause adverse effects in humans at
exposure levels (at least acute exposure levels) much lower than
previously expected.
    6. New Hydrogen Sulfide Dosimetry Data. Commenters state that EPA
has not considered new information on tissue dosimetry in determining
the no observed adverse effect levels for chronic inhalation exposure
to hydrogen sulfide. Commenters cited two studies that, in combination
with the Fiedler et al. study, they contend demonstrate that the
chronic human health effects are not likely at hydrogen sulfide
concentrations of 5 ppm or below. Commenters cited the 2006 Schroeter
et al. study (Ref. 7), in which the authors used computational fluid
dynamics (CFD) modeling to quantitatively correlate hydrogen sulfide
tissue dosimetry in rat and human nasal passages. Commenters state that
assuming that equivalent hydrogen sulfide flux values will induce
similar responses in the olfactory regions of rats and humans, the no
observed adverse effect level-human equivalent concentration (NOAEL-
HEC) was estimated to be 5 ppm. Commenters also cited a 2010 Schroeter
et al. study (Ref. 8) in which the authors investigated interhuman
variability of hydrogen sulfide nasal dosimetry using anatomically
accurate CFD models of the nasal passages of five adults and two
children generated from magnetic resonance imaging (MRI) or computed
tomography (CT) scan data. Commenters state that using allometrically
equivalent breathing rates, the authors simulated steady-state
inspiratory airflow and hydrogen sulfide uptake. Approximate locations
of olfactory epithelium were mapped in each model to compare air :
tissue flux in the olfactory region among individuals. The fraction of
total airflow to the olfactory region ranged from 2 percent to 16
percent. Despite this wide range in olfactory airflow, hydrogen sulfide

dosimetry in the olfactory region was predicted to be similar among
individuals. Differences in the 99th percentile and average flux values
were < 1.2-fold at inhaled concentrations of 1, 5, and 10 ppm.
Commenters contend that these preliminary results suggest that
differences in nasal anatomy and ventilation among adults and children
do not have a significant effect on hydrogen sulfide dosimetry in the
olfactory region.
    The Agency would like to thank the commenters for bringing
additional primary research studies to our attention, enabling us to
make decisions using all available resources. EPA agrees with the
commenters in regard to consideration of the dosimetry information
presented in both papers by Schroeter et al. This type of
pharmacokinetic modeling and the results presented represent the
current state-of-the-science for inhalation dosimetry and are being
reviewed by EPA for its utility in addressing our current reference
concentration (RfC) derivation methods (see http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=212131). However, it is important to note
that the purpose of the papers by Schroeter et al. was to provide a
model-based NOAEL-HEC (5 ppm), not an alternative final RfC which
incorporates the application of uncertainty factors. Thus, the only
part of the EPA's methods in deriving a value that is addressed is the
calculation of an HEC extrapolated from animal data. No judgment is
made by these authors that 5 ppm represents a replacement or
alternative RfC or serves to replace or reduce the application of
uncertainty factors. EPA's human health hazard assessment for hydrogen
sulfide is based on the Agency's current IRIS toxicological profile
(Ref. 3), and while this new dosimetry information and resulting NOAEL-
HEC might be considered in a revaluation of the current RfC, it does
not impact EPA's assessment of the potential for hydrogen sulfide to
cause chronic toxicity.
    The Agency does not concur with the commenter's conclusion that the
Fiedler and Shroeter studies demonstrate that chronic human health
effects are not likely at hydrogen sulfide concentrations of 5 ppm or
below. As noted, the Fiedler study addresses solely acute exposures and
is not relevant to chronic effects. Further, the Schroeter reports only
provide data for use in calculating the NOEAL-HEC based on
pharmacokinetic modeling. Therefore, the commenter's conclusions
regarding chronic human health effects of hydrogen sulfide are not
supported by the studies presented.
    7. No Need for TRI Reporting. Commenters contend that there is no
need to include hydrogen sulfide on the Toxics Release Inventory.
Commenters restated their claim that emissions of hydrogen sulfide
reported under EPCRA section 313 cannot be reasonably anticipated to
cause any of the chronic health effects covered by EPCRA section
313(d)(2)(B). Commenters state that although accidental releases of
hydrogen sulfide can result in serious adverse effects, such releases
are subject to the emergency notification requirements of EPCRA section
304 and by the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) section 103. Commenters state that such
accidental releases are expressly regulated pursuant to Clean Air Act
(CAA) Section 112(r) and hydrogen sulfide is among the substances that
were specifically identified for such regulation by Congress in Section
112(r). Commenters also claim that since there is no evidence that
suggests that routine releases of hydrogen sulfide pose any risk,
nothing would be achieved by adding reporting requirements under EPCRA
section 313. Commenters contend that since emissions of hydrogen
sulfide that would typically be reported under EPCRA Section 313 are
irrelevant to potential chronic health effects of the type addressed by
EPCRA Section 313(d)(2)(B), and accidental releases of hydrogen sulfide
that might be expected to present a potential hazard are well
regulated, reporting under EPCRA Section 313 serves no purpose.
Commenters claim that even if EPA has properly determined that hydrogen
sulfide has ``moderately high to high chronic toxicity,'' EPA is not
required to list hydrogen sulfide in these circumstances.
    Commenters state that in announcing its policy concerning use of
exposure analyses in listing determinations under EPCRA Section
313(d)(2), EPA stated:

    The statute is silent on the issue of exposure considerations
for the section 313(d)(2)(B) and (C) criteria. The language of
section 313 does not prohibit EPA from considering exposure factors
when making a finding under either section 313(d)(2)(B) or section
313(d)(2)(C) (59 FR 61441-61442).

    Commenters state that the reviewing court that reviewed this
construction expressly affirmed this conclusion, stating that
``chemicals of moderate or high toxicity are not necessarily added [to
the list] because of it.'' Troy Corp. v. Browner, 120 F.3d at 287.
    Commenters claim that EPA has not cited any adverse consequence
from the Administrative Stay of reporting requirements under EPCRA
Section 313 that has been in place for over 15 years and that EPA
should exercise its discretion to consider exposure factors in making a
new listing determination for hydrogen sulfide and then rescind its
prior listing determination.
    As EPA stated in response to the commenter's previous comments on
the releases of hydrogen sulfide, EPA does not agree that the
commenters have shown that releases of hydrogen sulfide will not cause
the kinds of health and environmental effects that EPA cited as support
for listing hydrogen sulfide. Most importantly, EPA is not required to
show that the effects that hydrogen sulfide can cause are actually
occurring in order to list it on EPCRA section 313. EPA notes that
other commenters have provided comments alleging that they have
experienced adverse health effects from hydrogen sulfide releases (see
for example: EPA-HQ-TRI-2009-0844-0076, EPA-HQ-TRI-2009-0844-0081 in
the docket for this action).
    Regarding the fact that accidental releases of hydrogen sulfide
that may cause serious adverse health effects including death are
covered by other statutes, this has no impact on the listing of a
chemical under EPCRA section 313. Listing of a chemical under EPCRA
section 313 is separate and apart from any other regulatory actions.
EPCRA section 313 is focused on a community's right-to-know about
releases of toxic chemicals, not emergency reporting requirements for
industrial accidents.
    With regard to the commenter's statements that listing hydrogen
sulfide on EPCRA section 313 serves no purpose, the Agency disagrees.
As EPA has stated:

    It is important to understand that although an adverse effect is
known or can be reasonably anticipated to be caused by a chemical on
the section 313 list, a release of a chemical into a community does
not necessarily mean that the effect will occur. Exposure and dose
are also important factors in determining whether an adverse effect
occurs and how serious the manifestation will be. The listing of a
chemical on the section 313 list does not mean that a particular
community will experience these adverse effects. Instead the purpose
for listing a chemical is to ensure that the public gets information
about releases of such chemicals. Thus, EPA believes that for
chemicals that typically do not affect solely one or two species but
rather affect changes across a whole ecosystem and for which there
is well-documented evidence supporting the adverse effects, that
their addition to the EPCRA section 313 list is warranted even
though the severity of the adverse effects that they induce will be
dependent upon site-specific characteristics. Once EPA makes release
data available through TRI, the community may then make

its own determination on the importance of these releases (and their
potential adverse effects). (59 FR 61433, 11/30/1994 (emphasis
added)).

    Listing a chemical under EPCRA section 313 allows the public and
governments to track and assess the impacts of chemical releases and
make determinations as to whether or not a risk exists. Without release
data, the public is limited in its ability to determine whether or not
releases of a toxic chemical are impacting their health and/or
environment. Even if releases are low and no adverse impacts are
expected, that information is still of value to the public.
    The listing of hydrogen sulfide on EPCRA section 313 is consistent
with EPA's stated policy on the use of exposure assessments, which does
not include the use of exposure for chemicals such as hydrogen sulfide
that have moderately high to high human toxicity and high ecotoxicity.
The commenter suggests that EPA should exercise its discretion with
regard to the consideration of exposure, citing Troy Corp v. Browner
for the proposition that ``chemicals of moderate or high toxicity are
not necessarily added [to the list] because of it.'' Placed in greater
context, that quotation is as follows:

    The EPA's exposure policy merely informed the public that the
agency would exercise its discretion by considering exposure only
for low toxicity chemicals. The EPA did not thereby curtail this
discretion; it did nothing more than clarify its own position. The
policy does not impose rights or obligations or bind the agency to a
particular result. Chemicals of low toxicity may be added despite
the policy, just as chemicals of moderate or high toxicity are not
necessarily added because of it. (Troy Corp. v. Browner, 120 F.3d at
287).

    As the DC Circuit noted, EPA stated that it would exercise its
discretion by considering exposure only for low toxicity chemicals. If
EPA were to consider exposure for hydrogen sulfide it would be
inconsistent with the Agency's stated policy on the use of exposure
assessments in EPCRA section 313 listing decisions. While EPA does have
discretion to deviate from its policy, the Agency does not believe that
there is any reason to consider exposure in its listing decision for
hydrogen sulfide and thus has no reason to deviate from its stated
exposure policy.

B. Comments From the National Renderers Association

    The commenter stated that they do not support listing hydrogen
sulfide emissions from rendering plants under EPCRA section 313 because
of what they claim are extremely low levels of hydrogen sulfide
potentially emitted from such facilities. The commenter stated that
they agreed with EPA that, at certain concentration levels, exposure to
hydrogen sulfide can cause significant adverse acute and chronic human
health effects and adverse impacts to the environment. The commenters
contend that these potentially harmful concentrations are well
understood, published, and regulated under the Occupational Safety and
Health Administration (OSHA) and the National Institute for
Occupational Safety and Health (NIOSH) standards with which their
facilities comply. The commenter stated that there are safe levels of
hydrogen sulfide exposure and that the fence-line concentration of
hydrogen sulfide at a typical rendering plant would be expected to be
well below these safe levels. The commenter recommended that EPA take
into account the ``concentration levels that are reasonably likely to
exist beyond facility site boundaries as a result of continuous, or
frequently recurring, releases,'' as required under EPCRA section
313(d)(2)(A), and exempt the reporting of hydrogen sulfide as a by-
product of rendering operations.
    The commenter provided information on the natural sources of
hydrogen sulfide and information that hydrogen sulfide degrades rapidly
in the environment. The commenter stated that the typical rendering
plant might emit roughly 400 pounds of hydrogen sulfide per year. The
commenter stated that hydrogen sulfide can be found in very low
concentrations throughout the rendering industry supply and processing
chain as a by-product related to the recycling, collecting, handling
and processing of animal byproduct and used cooking oil. The commenter
claims that hydrogen sulfide releases in the rendering facility
workplace environment tend to be fugitive in nature, inconsistent in
concentration, and irregularly present. The commenter stated that the
presence of hydrogen sulfide, if any, depends on the age of the raw
materials, moisture content, temperature, state of anaerobic bacterial
decay, and other factors. The commenter claimed that ``[h]ydrogen
sulfide concentration emissions from a typical rendering plant likely
result in air concentrations off-site that would be several orders of
magnitude below concentrations that are potentially hazardous to human
health and the environment.'' The commenter claims that as a result of
these characteristics, the hydrogen sulfide that may be present in a
rendering facility is not likely to reach site boundaries at any
measurable or reliably quantifiable concentration. The commenters claim
that through their years of studying potential hydrogen sulfide
emissions in rendering operations, they know that it is difficult to
quantify and report the low levels of emissions that may occur at their
facilities. The commenter suggested that the addition of hydrogen
sulfide to TRI listing must, at a minimum, allow for no TRI
requirements for de minimums sources such as facilities in the
rendering supply and processing chain.
    As EPA discussed in the Notice of Intent to Lift the Stay (75 FR
8893, 8889, February 26, 2010), exposure consideration is not
appropriate for chemicals that have moderately high to high chronic
human health toxicity or high environmental toxicity. Hydrogen sulfide
meets both of these criteria, therefore exposure (or the potential for
exposure) is not a factor in the listing decision. Regarding EPCRA
section 313(d)(2)(A), hydrogen sulfide is not listed under that
criteria, but rather the criteria of EPCRA sections 313(d)(2)(B) and
(C).
    It is well known that hydrogen sulfide is a byproduct of the
rendering process (Ref. 9). EPA has published emission factors for at
least one stage of the rendering process (Ref. 10). The commenter
believes that reporting would be difficult for hydrogen sulfide, yet
they provide an estimate of 400 pounds of releases per year, thus it
appears that these facilities could make at least a reasonable estimate
of releases as required under EPCRA section 313. EPA notes that
rendering plants must already report their release of ammonia, another
gas with variations in production and release. Regarding whether or not
``emissions from a typical rendering plant likely result in air
concentrations off-site that would be several orders of magnitude below
concentrations that are potentially hazardous to human health and the
environment,'' unless the release data is made available the local
communities and governments will not be able to confirm this
conclusion. EPCRA section 313 contains no provisions for de minimis
sources other than the fact that facilities must exceed the reporting
thresholds (25,000 pounds for manufacture and processing and 10,000
pounds for otherwise use). It appears that rendering plants do not use
hydrogen sulfide, thus they would have to manufacture or process 25,000
pounds before they would have to file a report.

C. Comments From the American Meat Institute

    The commenters stated that they agree with the comments submitted
by the National Renderers Association. The commenter stated that in
their members' plants hydrogen sulfide is released primarily in
rendering and waste treatment processes and that the releases are
fugitive, can be widespread and are in concentrations that are
irregular and inconsistent. The commenter stated that to comply with
EPCRA Section 313, their members will have to estimate their releases
to determine if the reporting thresholds are met. The commenter claimed
that because of the ephemeral nature of the releases, standard field
and even more sophisticated laboratory grade measurement devices are
inadequate and unreliable. The commenter claimed that the releases
disperse rapidly, resulting in concentrations below the measurement
capability of some devices and, regardless of the measurement device,
the measurements are not easily replicated. The commenter stated that
meat packing and processing plants do not have a reliable method for
determining compliance. The commenter stated that because of this they
have significant concerns regarding how to implement EPCRA section 313
with respect to hydrogen sulfide and contend EPA should consider such
practical issues before lifting the stay.
    EPA notes that the ability of any one particular industry to be
able to report releases is not a factor in determining whether a
chemical meets the EPCRA section 313 listing criteria. It is well known
that hydrogen sulfide is a byproduct of the rendering process (Ref. 9).
EPA has published emission factors for at least one stage of the
rendering process (Ref. 10). The commenter believes that reporting
would be difficult for hydrogen sulfide, yet the National Renderers
Association provided an estimate of 400 pounds of releases per year,
thus it appears that these facilities could make at least a reasonable
estimate of releases as required under EPCRA section 313. EPA notes
that rendering plants as well as meat packing and processing plants
must already report their release of ammonia, another gas that is also
likely to have variations in production and release as it is also
produced from the decay of organic matter. While EPA would like to
collect the most accurate information possible, EPCRA section 313 only
requires that facilities report a reasonable estimate of releases. EPA
sees no reason why meat packing and processing plants should not be
able to make at least reasonable estimates of the amounts of hydrogen
sulfide manufactured and released.

VI. What are the references cited in this document?

    EPA has established an official public docket for this action under
Docket ID No. EPA-HQ-TRI-2009-0844. The public docket includes
information considered by EPA in developing this action, including the
documents listed below, which are electronically or physically located
in the docket. In addition, interested parties should consult documents
that are referenced in the documents that EPA has placed in the docket,
regardless of whether these referenced documents are electronically or
physically located in the docket. For assistance in locating documents
that are referenced in documents that EPA has placed in the docket, but
that are not electronically or physically located in the docket, please
consult the person listed in the above FOR FURTHER INFORMATION CONTACT
section.

1. USEPA, OEI. Response to Comments Received on the February 26,
2010, Federal Register Document (75 FR 8889): Hydrogen Sulfide;
Community Right-to-Know Toxic Chemical Release Reporting; Intent to
consider lifting the administrative stay; opportunity for public
comment. U.S. Environmental Protection Agency, Office of
Environmental Information, Office of Information Analysis and
Access. July 21, 2011.
2. USEPA, Office of Water Regulations and Standards, Quality
Criteria for Water, EPA 440/5-86-001 (May 1, 1986) (EPA Gold Book),
page 268.
3. U.S. Environmental Protection Agency. ``Toxicological Review of
Hydrogen sulfide, (CAS No. 7783-06-4), In Support of Summary
Information on the Integrated Risk Information System.'' Washington,
DC: Integrated Risk Information System. U.S. Environmental
Protection Agency. June, 2003. http://www.epa.gov/ncea/iris/toxreviews/0061-tr.pdf. Integrated Risk Information Summary for
Hydrogen Sulfide available at: http://www.epa.gov/ncea/iris/subst/0061.htm.
4. U.S. Environmental Protection Agency, Technical Review of
Hydrogen Sulfide: Chemistry, Environmental Fate and Ecological
Toxicity, CAS Registry Number 7783-06-4; Office of Environmental
Information, Office of Information Access and Analysis,
Environmental Analysis Division, Analytical Support Branch; June 22,
2009.
5. Fiedler N., Kipen H., Ohman-Strickland P., Zhang J., Weisel C.,
Laumbach R., Kelly-McNeil K., Olejeme K., and Lioy P., ``Sensory and
Cognitive Effects of Acute Exposure to Hydrogen Sulfide.'' Env.
Health Persp. v. 116(1), (2008), pp. 78-85.
6. Skrajny, B., Hannah, R.S., Roth, S.H., ``Low concentrations of
hydrogen sulphide alter monoamine levels in the developing rat
central nervous system.'' Can. J. Physiol. Pharmacol. v. 70(11),
(1992), pp. 1515-1518.
7. Schroeter J.D., Kimbell J.S., Andersen M.E., and Dorman D.C.,
``Use of a pharmacokinetic-driven computational fluid dynamics model
to predict nasal extraction of hydrogen sulfide in rats and
humans.'' Toxicol. Sci. v. 94(2), (2006), pp. 359-367.
8. Schroeter J.D., Garcia G.J. M., and Kimbell, J.S., ``A
computational fluid dynamics approach to assess interhuman
variability in hydrogen sulfide nasal dosimetry.'' Inhalation
Toxicol. v. 22(4), (2010), pp. 277-286.
9. Emission Factor Documentation for AP-42 Section 9.5.3 Meat
Rendering Plants Final Report. Prepared by Midwest Research
Institute (MRI) for the Office of Air Quality Planning and Standards
(OAQPS), U. S. Environmental Protection Agency (EPA), under EPA
Contract No. 68-D2-0159. September 1995.
10. AP 42, Fifth Edition, January 1995. Compilation of Air Pollutant
Emission Factors, Volume I: Stationary Point and Area Sources.
Chapter 9: Food and Agricultural Industries section 9.5.3 Meat
Rendering Plants. Office of Air Quality Planning and Standards
(OAQPS), Office of Air and Radiation, U.S. Environmental Protection
Agency (EPA).

List of Subjects in 40 CFR Part 372

    Environmental protection, Community right-to-know, Reporting and
recordkeeping requirements, and Toxic chemicals.

    Dated: September 8, 2011.
Lisa P. Jackson,
Administrator.

    Therefore, 40 CFR part 372 is amended as follows:

PART 372--[AMENDED]

0
1. The authority citation for part 372 continues to read as follows:

    Authority:  42 U.S.C. 11023 and 11048.

Sec.  372.65  [Amended]

0
2. Section 372.65 is amended by lifting the stay on hydrogen sulfide
and methyl mercaptan entries and all related dates under paragraph (a)
and under paragraph (b), lifting the stay on the entries for CAS Nos.
74-93-1 and 7783-06-04 and all related dates.

[FR Doc. 2011-23534 Filed 10-14-11; 8:45 am]
BILLING CODE 6560-50-P