Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting, 64022-64037 [2011-23534]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 76, Number 200 (Monday, October 17, 2011)]
[Rules and Regulations]
[Pages 64022-64037]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[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

[[Page 64023]]

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 
https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in https://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 (202) 566-1744, and the telephone number for the 
OEI Docket is (202) 566-1752.

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: 202-566-0743; fax number: 202-
566-0677; e-mail: bushman.daniel@epa.gov, 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 (800) 424-9346 or (703) 412-9810 in Virginia and Alaska or toll 
free, TDD (800) 553-7672, https://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:

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                  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.
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    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

[[Page 64024]]

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

[[Page 64025]]

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

[[Page 64026]]

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.

[[Page 64027]]

    (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

[[Page 64028]]

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

[[Page 64029]]

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

[[Page 64030]]

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 mod