[Federal Register Volume 81, Number 69 (Monday, April 11, 2016)]
[Proposed Rules]
[Pages 21295-21308]
[FR Doc No: 2016-08278]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 261

[EPA-HQ-RCRA-2016-0040; FRL9944-67-OLEM]

Hazardous Waste Management System; Tentative Denial of Petition
To Revise the RCRA Corrosivity Hazardous Characteristic

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notification of tentative denial of petition for rulemaking.

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SUMMARY: The Environmental Protection Agency (EPA or the Agency) is
responding to a rulemaking petition (``the petition'') requesting
revision of the Resource Conservation and Recovery Act (RCRA)
corrosivity hazardous waste characteristic regulation. The petition
requests that the Agency make two changes to the current corrosivity
characteristic regulation: revise the regulatory value for defining
waste as corrosive from the current value of pH 12.5, to pH 11.5; and
expand the scope of the RCRA corrosivity definition to include
nonaqueous wastes in addition to the aqueous wastes currently
regulated. After careful consideration, the Agency is tentatively
denying the petition, since

the materials submitted in support of the petition fail to demonstrate
that the requested regulatory revisions are warranted, as further
explained in this document. The Agency's review of additional materials
it identified as relevant to the petition similarly did not demonstrate
that any change to the corrosivity characteristic regulation is
warranted at this time.
    The Agency is also soliciting public comment on this tentative
denial and the questions raised in this action.

DATES: Comments must be received on or before June 10, 2016.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
RCRA-2016-0040, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. The EPA may publish any
comment received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e. on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit http://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Gregory Helms, Materials Recovery and
Waste Management Division, Office of Resource Conservation and
Recovery, (5304P), Environmental Protection Agency, 1200 Pennsylvania
Avenue NW., Washington, DC 20460; telephone number:<PHONE_NUMBER>; email
address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. General Information
    A. Does this action apply to me?
    B. What action is EPA taking?
    C. What is EPA's authority for taking this action?
    D. What are the incremental costs and benefits of this action?
III. Background
    A. Who submitted a petition to the EPA and what do they seek?
    B. What is corrosivity and why are corrosive wastes regulated as
hazardous?
    C. What approaches are used in testing and evaluation of
materials for corrosivity?
IV. Review and Evaluation of the Petition and Relevant Information
    A. Review of Requested Regulatory Revisions and Supporting
Information
    1. Request to Lower RCRA's Corrosivity Characteristic pH
Threshold to 11.5
    a. History of RCRA's Corrosivity Regulation
    b. Other Corrosivity Standards
    2. Request To Include Nonaqueous Corrosive Materials Within the
Scope of RCRA's Corrosivity Vharacteristic
    a. Exposure to World Trade Center 9/11 Dust
    b. Exposure to Concrete Dust
    c. Exposure to Cement Kiln Dust
    B. Wastes That May Be Newly Regulated Under Requested Revisions
    C. Determining What Waste is ``aqueous''
    D. Other Potentially Relevant Incidents
V. EPA's Conclusions and Rationale for Tentative Denial of the
Petition
VI. Request for Public Comment on EPA's Tentative Denial of the
Petition
VII. References

I. Executive Summary

    This action responds to a rulemaking petition requesting revision
of the Resource Conservation and Recovery Act (RCRA) corrosivity
hazardous waste characteristic regulation (see 40 CFR 261.22). The
petition requests that the Agency make two changes to the current
corrosivity characteristic regulation: (1) Revise the regulatory value
for defining waste as corrosive from the current value of pH 12.5, to
pH 11.5; and (2) expand the scope of the RCRA corrosivity definition to
include nonaqueous wastes in addition to the aqueous wastes currently
regulated. The petition argues that the regulatory pH value should be
revised to pH 11.5 because information supporting this value was, in
the petitioners' view, inadequately considered in developing the
regulation and because petitioners allege that this value is widely
used as a threshold for identifying corrosive materials. The petition
further argues that corrosive properties of inhaled dust caused injury
to first responders and others at the World Trade Center (WTC) disaster
of September 11, 2001, and that such dusts should be regulated as
corrosive hazardous waste under RCRA.
    After careful consideration, and as described in greater detail
below, the Agency is tentatively denying the petition, since the
materials submitted in support of the petition fail to demonstrate that
the requested regulatory revisions are warranted. Where used in other
regulatory frameworks, the pH 11.5 value is either optional or a
presumption that may be rebutted by other data, a use very different
than the way pH is used in the RCRA corrosivity regulation.
    Moreover, the dust to which 9/11 first responders and others were
exposed was a complex mixture of pulverized concrete, gypsum, metals,
organic and inorganic fibers, volatile organic compounds, and smoke
from the fires at the site. No single property of the dust can be
reliably identified as the cause of the adverse health effects in those
exposed to the WTC dust. In addition, the injuries that were suffered
by those exposed to the WTC dust did not appear to include corrosive
injuries--i.e., the serious destruction of human skin or other tissues
at the point of contact. Persons exposed to simpler dusts of concern to
the petition (Cement Kiln Dust and concrete dust) similarly did not
appear to experience corrosive injuries. Finally, the petition does not
show that waste management activities resulted in the exposures of
concern, nor does it identify how the proposed regulatory changes would
address these exposures. The Agency's evaluation of additional
materials it identified as relevant to the petition similarly did not
demonstrate that any change to the corrosivity characteristic
regulation is warranted at this time. The Agency is therefore
tentatively denying the petition, and is also soliciting public comment
on this tentative denial and the questions raised in this action.

II. General Information

A. Does this action apply to me?

    The Agency is not proposing any regulatory changes at this time.
Persons that may be interested in this tentative denial of the
rulemaking petition include any facility that manufactures, uses, or
generates as waste, any materials (either aqueous or nonaqueous) with a
pH 11.5 or greater, or 2 or lower.

B. What action is EPA taking?

    Under Subtitle C of RCRA, the EPA has developed regulations to
identify solid wastes that must then be classified as hazardous waste.
Corrosivity is one of four characteristics of wastes that may cause
them to be classified as RCRA hazardous. The Agency defines which
wastes are hazardous because of their corrosive properties at 40 CFR
261.22. On September 8, 2011, the non-governmental organization (NGO)
Public Employees for Environmental Responsibility (PEER) and Cate
Jenkins, Ph.D.,\1\ submitted a rulemaking petition to the EPA seeking
changes to the current regulatory definition of

corrosive hazardous wastes under RCRA. The petitioners express concerns
about potentially dangerous exposures to workers and the general public
from dusts that may potentially be corrosive. In particular, the
petition is concerned about inhalation exposures, primarily to concrete
or cement dust, which may occur in the course of manufacturing or
handling of cement, and during building demolitions. To address these
concerns, the petition urges the Agency to make two changes to the
current regulatory definition of corrosive hazardous waste: (1) Revise
the pH regulatory value for defining waste as corrosive from the
current value of pH 12.5, to pH 11.5; and (2) expand the scope of the
RCRA corrosivity definition to include nonaqueous wastes in addition to
the aqueous wastes currently regulated.
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    \1\ Dr. Jenkins is an EPA employee.
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    With this action, the Agency is responding to requests in the
petition by publishing its evaluation of the petition and supporting
materials, and by requesting public comment on the topics raised by the
petition. A detailed discussion of the petition and the issues
identified by the Agency on which we are soliciting public input are
discussed later in this document. The Agency is soliciting information
and other input on issues related to the scope of the changes proposed
in the petition. This may include information on the adverse health
effects, if any, that may be avoided if the Agency were to grant the
requested regulatory changes. It may also include information on
changes in the universe of waste (including type of waste and volume)
that may become regulated as corrosive hazardous waste if the Agency
were to make the requested changes, including potentially affected
industries and the possible impact of such regulatory changes.

C. What is EPA's authority for taking this action?

    The corrosivity hazardous waste characteristic regulation was
promulgated under the authority of Sections 1004 and 3001 of the RCRA,
as amended by the Hazardous and Solid Waste Amendments of 1984 (HSWA),
42 U.S.C. 6903 and 6921. The Agency is responding to this petition for
rulemaking pursuant to 42 U.S.C. 6903, 6921 and 6974, and implementing
regulations 40 CFR parts 260 and 261.

D. What are the incremental costs and benefits of this action?

    As this action proposes no regulatory changes, this action will
have neither incremental costs nor benefits.

III. Background

A. Who submitted a petition to the EPA and what do they seek?

    On September 8, 2011, petitioners PEER and Cate Jenkins, Ph.D.,
sent the EPA a rulemaking petition seeking revisions to the RCRA
hazardous waste corrosivity characteristic definition (see 40 CFR
261.22). On September 9, 2014, the petitioners filed a petition for
Writ of Mandamus, arguing that the Agency had unduly delayed in
responding to the 2011 petition, and asking the Court to compel the
Agency to respond to the petition within 90 days. The Court granted the
parties' joint request for a stay of all proceedings until March 31,
2016.
    The petition seeks two specific changes to the 40 CFR 261.22(a)
definition of a corrosive hazardous waste:
    1. Reduction of the pH regulatory value for alkaline corrosive
hazardous wastes from the current standard of pH 12.5 to pH 11.5; and
    2. Expansion of the scope of the RCRA hazardous waste corrosivity
definition to include nonaqueous wastes, as well as currently regulated
aqueous wastes.
    The Agency is responding to this RCRA rulemaking petition in
accordance with 40 CFR 260.20(c) and (e).

B. What is corrosivity and why are corrosive wastes regulated as
hazardous?

    The term ``corrosivity'' describes the strong chemical reaction of
a substance (a chemical or waste) when it comes into contact with an
object or another material, such that the surface of the object or
material is irreversibly damaged by chemical conversion to another
material, leaving the surface with areas that appear eaten or worn
away. That is, the corrosive substance chemically reacts with the
material such that the surface of the contacted material is dissolved
or chemically changed to another material at the contact site. Chemical
reaction and damage at the contact site may continue as long as some
amount of the unreacted corrosive substance remains in contact with the
material. In situations in which corrosive substances are being handled
by people, key risks of corrosive damage are injury to human tissue,
and the potential to damage metal storage containers (primarily steel)
that may hold chemicals or wastes. Corrosive substances cause obvious
damage to the surface of living human tissue by chemically reacting
with it, and in the process, destroying it. The strength of the
corrosive material and the duration of exposure largely determine the
degree or depth of injury. Corrosive injury is at the extreme end of a
continuum of effects of dermal and ocular chemical exposure, and
results in serious and permanent damage to skin or eyes.\2\ Corrosive
injury is distinguished from irritation of the skin or eyes based on
the severity and permanence of the injury, with irritation generally
being reversible (see Globally Harmonized System for the Classification
and Labelling of Chemicals (``GHS'' or ``GHS guidance'') Chapters 3.2
and 3.3; Organization for Economic Cooperation and Development (OECD)
Test Methods 404 (rev. 2015) and 405 (rev. 2012); Grant and Kern 1955).
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    \2\ As with thermal burns, chemical burns may heal over time,
but will typically leave scarring, or in more severe cases, may
affect the function of the exposed body part. Ocular corrosive
injury may lead to blindness or other vision problems.
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    In 1980, EPA identified ``corrosivity'' as a characteristic of
hazardous waste because it determined that improperly managed corrosive
wastes pose a substantial present or potential danger to human health
and the environment (see Background Document for Corrosivity, May 1980;
hereafter referred to as Background Document, 1980). While other
international and domestic regulatory programs address corrosivity in
other contexts (e.g. exposure to non-waste hazardous substances), RCRA
is the United States' primary law governing the management of solid and
hazardous waste from cradle to grave. Consideration of RCRA's
corrosivity characteristic therefore requires consideration of whether
a particular threat of harm is one that would be addressed within
RCRA's waste management framework.
    When in contact with steel, corrosive substances (primarily acids)
can react with the iron to change its chemical form and weaken it,
potentially leading to a hole in the container and a release of the
corrosive substance to the environment. In a waste management setting,
extreme pH substances may also mobilize toxic metals, react with other
co-disposed wastes (e.g., reaction of acids with cyanides, to form
hydrogen cyanide gas), or change the pH of surface water bodies,
causing damage to fish or other aquatic populations. However, the
Agency focused primarily on the potential for injury to humans when it
initially developed the corrosivity regulation:

    ``Corrosion involves the destruction of both animate and
inanimate surfaces.'' (Background Document page 3, 1980)
    . . .
    ``Wastes exhibiting very high or low pH levels may cause harm to
persons who come

in contact with the waste. Acids cause tissue damage by coagulating
skin proteins and forming acid albuminates. Strong base or alkalis,
on the other hand, exert chemical action by dissolving skin
proteins, combining with cutaneous fats, and severely damaging
keratin.'' (Background Document page 5, 1980)
    . . .
    ``The Agency has determined that corrosiveness, the property
that makes a substance capable of dissolving material with which it
comes in contact, is a hazardous characteristic because improperly
managed corrosive wastes pose a substantial present or potential
danger to human health and the environment.'' (Background Document
page 1, 1980)

    In the previous discussion, the corrosivity regulation background
document describes corrosives as having a severe effect on human
tissue. Dissolving of skin or other tissue proteins by chemicals, and
chemically combining with fats (stored body fat in adipose or other
human tissue) are chemical processes which clearly destroy the surface
of human tissue and may penetrate beyond surface layers of skin. These
adverse effects on skin have also been described by the term ``chemical
burns'' because of their similarity to burns caused by fire or other
sources of intense heat.
    Highly acidic and alkaline (basic) substances comprise a large part
of the universe of corrosive chemicals. The strength of acids and
alkalies is measured by the concentration of hydrogen ions, usually in
a water solution of the acid or alkali. The hydrogen ion concentration
is expressed as ``pH'', which is a logarithmic scale with values
generally ranging from zero to 14. On the pH scale, pH 7 is the mid-
point, and represents a neutral solution. That is, it is neither acidic
nor basic. Solutions having pH values of less than 7 are acidic while
solutions with pH greater than 7 are basic. As pH values move toward
the extremes of the scale (i.e., 0 and 14), the solution becomes
increasingly acidic or alkaline.
    Under current RCRA regulations, aqueous wastes having pH 2 or
lower, or 12.5 or higher, are regulated as hazardous waste. Liquid
wastes that corrode steel above a certain rate are also classified as
corrosive under RCRA. These values were set in consideration of wastes'
potential to cause injury to human tissue as well as waste management
issues, as discussed in greater detail in section IV below (Background
Document, 1980).
    Federal regulatory agencies other than the EPA also regulate human
exposure to corrosive materials. These include the Occupational Safety
and Health Administration (OSHA), the Department of Transportation
(DOT), and the Consumer Product Safety Commission (CPSC). Further,
international organizations have also made recommendations about
controlling human exposure to corrosive chemicals or wastes. These
include the United Nations Guidance on the Transport of Dangerous Goods
(UNTDG), the GHS, the International Labor Organization (ILO), and the
Basel Convention on the Transboundary Movement of Hazardous Waste
(Basel, or the Basel Convention).

C. What approaches are used in testing and evaluation of materials for
corrosivity?

    Before 1944, there was no systematic method for evaluating the
dermal toxicity and corrosive or irritating properties of chemicals on
human tissue. Advances in chemistry and medicine in the mid-20th
century led to development of a broader range of therapeutic, cosmetic,
and personal care products (e.g., soaps, shampoo, hair conditioner) and
prompted the need to move beyond an anecdotal collection of largely
qualitative information on corrosivity to a systematic approach for
determining the potential for irritation or corrosivity. Scientists
working for the U.S. Food and Drug Administration (FDA) were the first
investigators to develop an approach that tried to be objective and
quantitative, so that differences in the impact of different chemicals
or formulations could be systematically identified (Draize et al. 1944,
Draize 1959). Their testing approach involved application of chemicals
or formulations directly to animal skin or eyes (primarily rabbits),
with the results graded by the severity of the adverse effect and the
duration of exposure required to produce those adverse effects.\3\ The
skin and eyes of the test animals were assumed to be similar to that of
humans, and results were either used directly to classify chemicals or
sometimes, for less irritating materials, were confirmed by testing on
human subjects. The pH of chemicals or formulations was also correlated
with the occurrence of adverse effects on test animals in much of the
basic research that occurred during this time period (Hughes, 1946;
Friedenwald et al., 1946; Grant and Kern, 1955; Grant, 1962). Testing
for pH is a routine and easily performed test for many materials
(although it does require the presence of water or another source of
hydrogen ions in the sample). However, pH testing of very high
concentration acids or alkalies can be problematic, and high
concentrations of sodium ions in solution can cause analytical
interferences (Lowry et al., 2008).
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    \3\ Testing on live animals is described as in vivo testing.
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    The animal testing approach described above evolved to become the
standard method for assessing the corrosivity of chemicals to humans
(Weltman et al., 1965; Balls et al., 1995; OECD Methods 404 and 405).
Variability in test results and some differences in effects on humans
were identified as the tests were further developed and refined.
Sources of variability included different results when chemicals were
applied to different areas of skin, and different reactions of animal
eyes as compared with those of humans, among others (Weil and Scala,
1971; Phillips et al., 1972; Vinegar, 1979). One key approach to
facilitating greater reproducibility (precision) in testing was a
standardized grading scheme published by the FDA (Marzulli, 1965). A
version of this testing approach has also been adopted as guidance by
the OECD to provide an international approach to chemical
classification, with the goal of facilitating international commerce
(see OECD Methods 404 \4\ and 405). Over the intervening time,
significant amounts of animal test data have been collected and used
for classifying chemicals or formulations as corrosive.
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    \4\ OECD Methods 404 and 405 continue to rely on live animal
testing as the definitive test method for assessing corrosivity and
irritation potential of chemicals and formulations. The current
version of Method 404 (2015) and Method 405 (2012) allow for use of
other tests in a weight-of-evidence approach. However, if results
are inconclusive, live animal testing is used as a last resort.
Dermal corrosion is defined as ``. . . visible necrosis through the
epidermis and into the dermis. . .''. For corrosivity to the eye,
``A substance that causes irreversible tissue damage to the eye . .
.''
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    However, concern about testing for corrosivity on live animals has
been expressed within the scientific community (Balls et al., 1995) and
by non-government animal welfare advocacy organizations (Animal
Justice, ``Medical Testing on Animals: A Brief History'' retrieved from
http://www.animaljustice.ca/blog/medical-testing-animals-brief-history/
). The result of this concern has been the development of alternative,
in vitro testing approaches,\5\ intended to reduce reliance on in vivo
animal testing. Among the first such tests was a commercially developed
test named the ``Corrositex[supreg]'' test in 1993 (InVitro
International, ``What is Corrositex?'' 2007, retrieved from http://
www.invitrointl.com/products/

corrosit.htm). In this test, a ``bio-barrier'' material is placed in a
tube such that it blocks the tube, which contains an indicator
solution. The test material is placed on the collagen plug, and
breakthrough to the indicator solution is timed.\6\ Other somewhat
similar testing approaches have also been developed, which use cultured
human skin cells or skin from a laboratory animal that has been
euthanized. Extensive work to validate these new testing approaches
against the existing data has been done (Barratt et al., 1998; Kolle et
al., 2012; Deshmukh et al., 2012; Vindarnell and Mitjans, 2008), and
several are now considered validated to some degree (see OECD Tests
430, 431, 435, 437, 438). A number of studies applying chemical
quantitative structure/activity relationships (QSAR) to assessing
chemical corrosivity have also been published (Hulzebos, et al., 2003;
Verma and Matthews, 2015a; Verma and Matthews, 2015b). However, these
new tests are not yet fully integrated into the evaluation and
classification guidance and regulations used in the U.S. and
internationally, and most guidance and regulations rely first on
existing animal and human data. The new testing approaches and QSAR
analysis are primarily used as alternatives to reduce to a minimum the
use of live animal testing on new, untested chemicals or formulations.
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    \5\ In vitro, literally translated means ``in glass''. In this
context it means testing in a laboratory vessel, rather than using a
live animal.
    \6\ The Agency has added this test to its analytical chemistry
technical guidance for evaluating waste, as Method 1120. While at
one time the Agency considered revising the corrosivity regulation
to rely on this test, no regulatory proposal was ever published.
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IV. Review and Evaluation of the Petition and Relevant Information

A. Review of Requested Regulatory Revisions and Supporting Information

    This action is based on the petition and its supporting
materials,\7\ the Agency's review and evaluation of this information,
information submitted by other stakeholders, and relevant information
compiled by the Agency. All materials and information that form the
basis for this decision are available in the public docket supporting
this action.
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    \7\ In reviewing the petition the Agency identified a number of
statements and/or assertions that are factually incorrect or
inaccurate or are otherwise misstatements. The Agency has not
responded to all such statements, but rather has limited its
responses to those related to the substantive discussion of the
petition's requests and supporting arguments in the petition. The
petition also alleges certain instances of fraud; while the Agency
denies all such allegations, the Agency is not addressing those
allegations in this document because they are not relevant to
considerations about whether a regulatory change to the current RCRA
corrosivity characteristic is warranted.
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    The petition presents a number of arguments and information
supporting the requested revisions to the RCRA corrosivity regulation.
The petition's arguments and supporting information are summarized and
discussed below.
    The petition seeks two specific changes to the 40 CFR 261.22(a)
definition of a corrosive hazardous waste:
    1. Reduction of the pH regulatory value for alkaline corrosive
hazardous wastes from the current standard of pH 12.5 to pH 11.5; and
    2. Expansion of the scope of the RCRA hazardous waste corrosivity
definition to include nonaqueous wastes, as well as currently regulated
aqueous wastes.
    In evaluating the petition, the Agency considered whether these
specific changes are warranted based on the evidence in the petition
and additional, relevant information compiled by the Agency.\8\
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    \8\ While the petition requests the inclusion of nonaqueous
wastes in the corrosivity characteristic regulation, the petition
does not provide any information regarding nonaqueous acidic wastes
having pH 2 or lower. The petition appears to only be alleging harm
from nonaqueous wastes in the upper pH, alkaline range. As such, the
Agency has similarly focused its analysis. To the extent that
petitioners allege the need to include nonaqueous acidic wastes
having pH 2 or lower as part of the RCRA corrosivity characteristic
regulation, additional information should be submitted in the
comment period for the Agency's evaluation.
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1. Request To Lower RCRA's Corrosivity Characteristic pH Threshold to
11.5
    The current RCRA corrosivity regulation classifies aqueous waste
having pH 12.5 or higher as corrosive hazardous waste (40 CFR
261.22(a)(1)). The petition seeks revision of the pH regulatory value
for alkaline corrosive hazardous wastes from the current standard of pH
12.5 to pH 11.5.\9\
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    \9\ The corrosivity characteristic potentially applies to any
aqueous RCRA solid waste, unless exempted from hazardous waste
regulation. In 2011, more than 8 million tons of waste were
regulated as corrosive hazardous waste (see RCRA Biennial Report for
2011, Exhibit 1.8).
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    In urging the Agency to make this regulatory change, the petition
argues that a pH value of 11.5 is widely used in other U.S. regulatory
programs and guidances, as well as in global guidance. The petition
also argues that in promulgating the final regulation in 1980, the EPA
did not give appropriate weight to guidance by the ILO on corrosivity
that the petition considers definitive for identifying corrosive
materials; and therefore expresses the belief that the current standard
is not adequately protective of human health and the environment.\10\
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    \10\ Petitioners allege that EPA misrepresented the pH levels
cited in a 1972 ILO encyclopedia. As mentioned above at footnote 7,
the Agency denies all such allegations. However, the Agency is not
addressing those allegations in this document because they are not
relevant to considerations about whether a regulatory change to the
current RCRA corrosivity characteristic is currently warranted.
While the petitioners place great weight on the mention of a pH of
11.5 in the 1972 ILO encyclopedia, that encyclopedia was one among
multiple factors considered in developing the regulation and it is
in no way binding on the Agency. No challenge to the 1980 regulation
was filed, and the statute of limitations to challenge that 1980
regulation has long since passed.
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a. History of RCRA's Corrosivity Regulation
    The corrosivity regulation was promulgated on May 19, 1980 as part
of a broad hazardous waste regulatory program that was finalized that
day (45 FR 33084, 33109, and 33122). As no timely challenges to the
final corrosivity regulation were filed in the appropriate court
pursuant to 42 U.S.C. 6976(a), the rule, including the regulatory
thresholds used to define solid waste as exhibiting the hazardous
characteristic of corrosivity, has been in effect since 1980.
    The record supporting the May 19, 1980 rulemaking for the
corrosivity hazardous characteristic includes three Federal Register
actions (an Advanced Notice of Proposed Rulemaking (ANPRM), a Proposed
Rule and a Final Rule), draft and final technical background documents,
and comments from and Agency responses to a range of stakeholders.
Review of these materials identifies the Agency's proposed and final
approaches to this regulation, as well as public views on the proposed
regulation.
    In the 1977 ANPRM, the Agency discussed waste corrosivity only with
regard to the potential for waste to damage storage containers, which
could result in waste release to the environment. The Agency solicited
public comments on this approach to regulation of corrosive wastes (42
FR 22332, May 2, 1977).
    Following publication of the ANPRM, the Agency released several
draft versions of the regulations under development, including the
corrosivity regulation. Draft documents dated September 14, 1977,
November 17, 1977, and September 12, 1978 can be found in the
rulemaking docket for the 1980 regulation, as well as several comments
on these drafts. The September 1977 draft included a preliminary
corrosivity definition based on pH values outside the range of pH 2-12,
applied to liquid waste or a

saturated solution of non-fluid waste. The November 1977 draft would
have defined as hazardous those wastes having a pH outside the range of
pH 3-12, and would have potentially applied to aqueous wastes and
nonaqueous wastes when the latter was mixed with an equal weight of
water. In a September 1978 draft, corrosive wastes would have been
defined as aqueous wastes having a pH outside the range of pH 3-12.
    In the 1978 proposed regulations, the Agency proposed to identify
corrosive hazardous waste based on the pH of aqueous solutions, and an
evaluation of the rate at which a liquid waste would corrode steel.
Waste aqueous solutions having a pH less than or equal to pH 3, or
greater than or equal to pH 12 were proposed to be classified as RCRA
corrosive hazardous waste (43 FR 58956, December 18, 1978). Concerns
identified by the Agency in the proposal included the ability of
corrosives to mobilize toxic metals, corrode waste storage containers,
corrode skin and eyes, and cause damage to aquatic life (by changing
the pH of waterbodies). The background support document for the
proposal elaborated on EPA's concerns about corrosion to skin, noting
that the regulation was intended to include as corrosive those waste
``. . . substances that cause visible destruction or irreversible
alteration in human skin tissue at the site of contact.'' (Draft
Background Document on Corrosiveness page 5, December 15th, 1978;
hereafter referred to as ``Draft Background Document, 1978''). The pH
of wastes was used as the basis of the regulation because it could be
used to evaluate both skin damage and toxic metal mobility (see Draft
Background Document pages 13 and 14, 1978). The Agency also expressed
some concern about solid corrosives, and requested that the public
provide information on the potential hazards of solids that may be
corrosive.
    The Agency received many comments on the regulatory proposals made
that day, as significant parts of the RCRA program were proposed. The
comments received addressed a number of topics raised by the proposal,
including the proposed corrosivity regulation.
    The majority of public comments urged expanding the range of pH
values that would not be classified as corrosive. For example, some
commenters urged the Agency to raise the alkaline range pH regulatory
value to either pH 12.5 or 13, in part, because they believed the
proposed pH value would have resulted in lime-stabilized wastes, which
when treated were otherwise non-hazardous, being classified as
hazardous because of their pH. These commenters also believed treatment
to de-characterize these wastes (i.e., make them less corrosive) would
potentially allow the mobilization of toxic metals that were stable in
the waste at the higher pH. The Agency generally agreed with these
concerns and set a final alkaline range pH value of 12.5 and above for
defining corrosive hazardous waste.\11\ The petition reflects concern
about this as part of the basis for the pH regulatory value, and argues
that it is no longer necessary or a valid basis for the regulation
because of other changes in the regulations of wastewater treatment
sludges in particular. However, there is no documentation in the
petition supporting these assertions. High alkalinity materials
continue to be used as an important option in the treatment of metal-
bearing wastes to reduce metal mobility (see LDR Treatment Technology
BDAT Background Document pages 101-109, January 1991; Chen et al.,
2009; Malvia and Chaudhary, 2006).
---------------------------------------------------------------------------

    \11\ The pH of wastes is determined using EPA Method 9040.
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b. Other Corrosivity Standards
    Among the arguments made by the petition is the assertion that a pH
value of 11.5 is widely used in other U.S. regulatory programs and
guidances, as well as in global guidance.\12\ This assertion, however,
is largely inaccurate and fails to support a regulatory change for
several reasons. As discussed in more detail below, the classification
of materials as corrosive and use of pH 11.5 in this process is far
more complicated than portrayed by the petition. Moreover, even where
pH 11.5 is incorporated as a presumptive benchmark in other regulatory
programs or guidance (for example, pH 11.5 is identified by the 1972
ILO Encyclopedia of Occupational Safety and Health (``1972 ILO
Encyclopedia'')), that fact alone is insufficient to demonstrate that
the same benchmark is appropriate for regulation of hazardous waste
under RCRA. While it is useful to consider information on how
corrosivity is measured and regulated by other organizations, EPA is
not bound under RCRA to rely on voluntary standards or the decisions of
other regulatory agencies, or even regulations or guidance developed by
EPA under other statutory authorities.
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    \12\ Use of a pH value of 11.5 was apparently suggested by
Hughes (1946) and Grant (1962) based on empirical observations of
the effects of sodium hydroxide solutions on the eyes of test
animals. It is not clear whether the 11.5 value was systematically
assessed to determine its applicability to other alkaline solutions
or to dermal exposures.
---------------------------------------------------------------------------

    The corrosive potential of materials is addressed by a number of
national and international organizations. Among the organizations that
address corrosivity, the following rely on information from human
exposure, animal tests, or other tests (as discussed previously) as the
primary determinative factor in classifying a material as corrosive,
rather than relying on pH: The UNTDG, the GHS, the DOT, the OSHA, the
U.S. National Institute for Occupational Safety and Health (NIOSH), the
CPSC and U.S. EPA regulations of pesticides under the Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA).13 14
---------------------------------------------------------------------------

    \13\ These organizations rely primarily on human experience
(reported case studies) and the results of animal testing, including
test results that may be reported in scientific publications or from
other sources. Recently developed in-vitro tests are beginning to
replace animal testing.
    \14\ The FDA does not directly regulate cosmetics and related
products based on their corrosive potential. FDA does require that
the safety of cosmetic products be adequately substantiated before
they are sold, unless they bear a warning label noting that the
safety of the product has not been determined (see 21 CFR 740.10)
While the original protocol for testing on animals resulted from its
needs, and was developed by FDA scientists (Draize et al., 1944,
1959), the FDA does not specify required testing for cosmetics.
---------------------------------------------------------------------------

    The UNTDG guidelines include criteria for classifying materials as
corrosive, and reference the OECD test methods for applying the UNTDG
corrosivity criteria. Classification as corrosive under the UNTDG
guidelines is based on full thickness destruction of intact skin.
(UNTDG Model regulations Chapter 2.8, Rev. 18, 2013, and UNTDG test
methods Section 37, Rev. 5 2009).
    In 2003, the UN published its GHS guidance, which addresses
corrosivity, among other chemical hazards. The 2013 version of GHS
(Rev. 5, 2013) addresses chemical corrosivity to skin and eyes in
separate sections of the guidance. For classification as corrosive to
skin (GHS Chapter 3.2), a material must result in skin tissue
destruction. The GHS tiered evaluation approach (Figure 3.2.1) relies
primarily on available human data (case studies) for making a
corrosivity determination, then animal data, and references the use of
material pH in the third tier of the evaluation.
    The UN expert groups responsible for developing the UNTDG and GHS
guidances have been working for a number of years (since at least 2010)
to harmonize the corrosivity definitions of the two guidance documents.
As of April 2015, there was no consensus on how to define corrosivity,
and work of the two groups is ongoing (see: UN

working document ST/SG/AC.10/C.3/2015/21 and ST/SG/AC.10/C.4?2015/2,
April 2015, retrieved from: http://www.unece.org/fileadmin/DAM/trans/doc/2015/dgac10c3/ST-SG-AC.10-C.3-2015-21e-ST-SG-AC.10-C.4-2015-2e.pdf).
    Current ILO guidance in the ILO Encyclopedia of Occupational Safety
and Health urges reliance on international agreements, and the UNTDG
guidance in particular for chemicals and the Basel Convention for waste
(see ILO Encyclopedia, freely available at http://www.ilo.org/safework/info/publications/WCMS_113329/lang-en/index.htm). As discussed
previously, the UNTDG guidance does not refer to either pH in general
or to a particular pH range.
    Finally, the Basel Convention also has a physical and chemical
hazard classification system for waste that addresses corrosivity and
which is described in several Annexes to the Convention. The Basel
Convention does not rely on the 11.5 pH value in defining corrosive
waste as a general matter in Annex III, but does rely on it as a
rebuttable presumptive value for corrosive solutions in the Annex IX
(non-hazardous) waste listings. Under the Basel Convention, listed
hazardous waste can be delisted by showing that it exhibits no Annex
III characteristics.
    Unlike many of the other regulatory frameworks that the petitioners
cite, the Basel Convention classification system, like RCRA, applies
specifically to hazardous waste management. However, the Basel
Convention and its hazardous waste classification system take into
account the limited capabilities of the developing countries to manage
hazardous waste and other waste (see Preamble to the Basel Convention).
The Basel Convention takes a precautionary approach, broadly
characterizing materials as hazardous out of an abundance of caution.
The U.S., on the other hand, has substantial capacity for proper
management of both hazardous and non-hazardous wastes, and therefore
current RCRA regulations do not incorporate the level of precaution
that the Basel Convention does in classifying waste as hazardous under
RCRA.\15\
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    \15\ A significant purpose of the Basel Convention is to control
the export of hazardous waste from developed to developing
countries, because many developing countries do not have the
capacity to safely manage either hazardous or non-hazardous waste.
Most Basel hazardous waste listings do not include concentration
values for hazardous constituents below which the waste would be
considered non-hazardous, because many developing nations do not
have adequate capacity to safely manage even non-hazardous waste.
Basel listings are written so wastes posing any degree of hazard may
be subject to the Basel notice and consent provisions, thereby
enabling developing countries to refuse waste shipments they are
unable to safely manage.
---------------------------------------------------------------------------

    Additionally, the EPA considers degrees of risk in classifying
waste as hazardous, taking into account the comprehensive nature of the
U.S. waste management system. The United States has extensive
regulatory and physical capacity for environmentally sound waste
management, including capacity for management of both hazardous and
non-hazardous waste. Many forms of mismanagement that may occur in
developing nations are already illegal in the U.S., and so any such
mismanagement would not be considered a basis for revising or
developing new hazardous waste regulations (that is, types of waste
mismanagement that are already illegal under RCRA would be addressed as
enforcement/compliance issues, rather than as the basis for new
regulations). Further, the structure of the Basel hazardous waste
classification system is different from that of RCRA. While the
presumption of corrosiveness at pH 11.5 under Basel is rebuttable using
the Annex III criteria, the RCRA corrosivity definition is a hard
value, and there is no opportunity in the RCRA regulations to show that
a waste is non-corrosive despite its exceedance of the regulatory
criteria. Seen in this light, the degree of precaution incorporated in
Basel's use of pH 11.5 may not be warranted in U.S. waste regulations.
    In the U.S., the DOT hazardous materials regulatory definition of
``corrosive material'' is a narrative that does not reference the pH of
materials. Rather, corrosive material is defined as ``. . . a liquid or
solid that causes full thickness destruction of human skin at the site
of contact within a specified period of time'' (see 49 CFR 173.136(a)).
DOT referenced the 1992 OECD testing guideline #404, among other
international guidances, when it updated its regulations to harmonize
with the UNTGD Guidance (59 FR 67390, 67400 and 67508, December 29,
1994). The OECD Testing Guideline #404 is based on results of live
animal testing or other direct experience with the chemical, although
testing on live animals is being phased out where possible.
    OSHA identifies the hazards of chemicals to which workers may be
exposed, including corrosivity hazards. OSHA recently harmonized its
Hazard Communication Standard (HCS) with the GHS classification
criteria, including a modified version of the GHS criteria for
corrosivity (GHS Revision 3, 2009; see: 77 FR 17574, 17710, and 17796
March 26, 2012). The CPSC implements the Federal Hazardous Substances
Act (FHSA), and includes corrosives as hazardous substances in its
implementing regulations. Under FHSA regulations, ``Corrosive means any
substance which in contact with living tissue will cause destruction of
tissue by chemical action . . .'' 16 CFR 1500.3(b)(7). This definition
is further elaborated at 16 CFR 1500.3(c)(3), where a corrosive
substance is one that, ``. . . causes visible destruction or
irreversible alterations in the tissue at the site of contact.''
    The petitioners also argue that EPA pesticides regulations rely on
a pH value of 11.5 to define corrosivity. However, that
characterization misunderstands the regulatory framework for product
pesticides. EPA regulation of pesticides under the FIFRA require
evaluation of the potential for chemicals to cause primary eye or
dermal irritation as part of the required toxicology evaluation (see 40
CFR 158.500). Test guidelines (EPA 1998a, b) describe live animal
testing as the basis for dermal or ocular irritation, although pre-test
considerations note that substances known (based on existing data) to
be corrosive or severely irritating, or that have been assessed in
validated in vitro tests, or have a pH of 11.5 or greater (with
buffering capacity accounted for) may be considered irritants and need
not be tested in live animals, if the applicant so chooses. As noted in
the preamble to the relevant rule, the Agency considered the importance
of minimizing animal testing, and stated that it would consider data
from validated in vitro tests as a way to reduce animal testing
requirements (see 72 FR 60934, October 26, 2007). Because pH 11.5 may
be used as an optional presumption for toxicity categorization, the
regulatory framework contemplates that chemicals having pH 11.5 may not
be corrosive, and it allows the applicant to submit live animal testing
data demonstrating that a particular pesticide is not a dermal or
ocular irritant.
    While the pH of a material can play some role in corrosivity
determinations in these other regulatory frameworks, pH 11.5 is not the
primary means of identifying corrosive materials except in the Basel
Convention. In FIFRA, it may be used as part of the basis for
precautionary labeling of pesticides, if the registrant elects to rely
on it. It is a third-tier criteria in the GHS system, but is not
referenced by the regulations of DOT or by the UNTDG guidance. Further,
the experts of GHS and UNTDG are continuing work to harmonize

model regulations for corrosive materials, illustrating the fact that
corrosivity assessment methods and criteria are not well settled
matters.
    In fact, historically, in vivo animal test data has been the
primary basis for classification, and because of increasing animal
welfare concerns with live animal testing, development of new methods
for evaluating the corrosivity of materials has been an active research
area, involving the development of new in vitro tests and structure-
activity relationship models. Alternative test development has been
driven largely by the desire to reduce the use of live animals, in
particular, for making corrosivity determinations for chemicals. These
alternatives to animal testing have been validated in some cases
(Barratt et al., 1998; Kolle et al., 2012), and incorporated into the
corrosivity evaluations of the OECD testing framework (see OECD tests
430, 431, 435, 437, and 438, in particular). A number of studies
attempting to correlate chemical structure with corrosive potential, or
QSAR evaluations have also been published in recent years. These have
focused primarily on the corrosivity potential of organic chemicals,
and attempt to address both corrosivity and irritation potential.
(Hulezebos et al., 2005)
    In addition, the pH 11.5 value in these other frameworks is used
only as an optional approach or a rebuttable presumption of
corrosiveness. That is, chemical manufacturers or waste generators have
in all cases the opportunity to conduct additional testing if they
believe their product or waste is not corrosive despite exhibiting pH
11.5 or higher.\16\ However, as used in the RCRA corrosivity
regulation, the pH of an aqueous waste determines whether that waste is
a corrosive hazardous waste as a legal matter, and there is no
opportunity to rebut this classification for an aqueous waste that
exhibits pH 12.5 or higher. Thus, lowering the pH in RCRA has far-
reaching implications that are not present in other regulatory systems.
---------------------------------------------------------------------------

    \16\ A number of researchers have identified solutions
exhibiting pH values higher than pH 11.5 that are nonetheless not
classified as corrosive. Murphy, et al., (1982) found that none of
the test rabbits exposed to 0.1% and 0.3% NaOH solution (pH 12.3 and
pH 12.8 respectively) developed corneal opacity (i.e., 0/6) even
when the eyes were not washed after exposure. Young et al. (1988)
identified a 1% KOH solution, with pH 13.3 as an irritant but not
corrosive. The following solutions were also classified either as
irritants or as not dangerous: 1% NaOH, with pH 13.4; 10%
NH3, with pH 12.2; Na2CO3, with pH
11.6; and Na3PO4, with pH 12.3. Similarly,
Oliver, et al., (1988) and Barratt et al. (1998) identified several
materials exhibiting pH values higher than pH 11.5 that were
nonetheless not classified as corrosive.
---------------------------------------------------------------------------

    Moreover, many of the standards discussed above are concerned with
product chemicals and formulations, not waste. As products are
manufactured to a certain specification, they can be evaluated for
safety once, and typically that evaluation can be relied on going
forward (unless the formulation changes or there is some indication the
initial evaluation was flawed). However, waste is not manufactured to a
specification, but rather may vary from batch-to-batch, sometimes
widely. Therefore, the more careful, thorough evaluation, as described
in OECD Method 404, for example, is not practical for use on each
separate batch of waste generated. The simpler approach of relying on
pH value was therefore used by the EPA in developing the corrosivity
regulation, as pH is a useful indicator of hazard potential, and
testing for pH is reasonable to perform for many wastes.
    Finally, the petitioners argue that the RCRA corrosivity
characteristic regulation should be changed because other regulatory
frameworks rely on it (see petition at 12 (discussing DOT and the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) regulations' cross references to RCRA)). However, to the
extent that petitioners are concerned about shortcomings in DOT or
CERCLA regulations, the appropriate avenue for changes in those
frameworks is to seek changes directly to those frameworks. The RCRA
regulatory framework is focused on management of hazardous waste, and
should not be amended solely on the basis of perceived shortcomings in
other regulatory frameworks.
    In sum, while other regulatory frameworks may use pH 11.5 as part
of their corrosivity determinations, the use of pH 11.5 in these
frameworks is fundamentally different from the use of pH in the RCRA
corrosivity characteristic regulation, and such use, therefore, should
not set a precedent for RCRA regulation.
2. Request To Include Nonaqueous Corrosive Materials Within the Scope
of RCRA's Corrosivity Characteristic
a. Exposure to World Trade Center 9/11 Dust
    In seeking to expand the scope of the corrosivity characteristic to
include nonaqueous wastes in addition to revising the regulatory value
to pH 11.5, the petition argues that injury to 9/11 first responders,
other workers, and potentially members of the public, was caused by
corrosive properties of airborne cement dust present in the air as a
result of the buildings' collapse. Further, the petition argues that
regulation of these airborne dusts as RCRA hazardous wastes would have
prompted wide-spread respirator use and prevented first responder lung
injury, and can prevent such injury to demolition workers and the
general public present at future building demolitions.
    However, after a thorough review of the information currently
before the Agency,\17\ the Agency has tentatively concluded that
petitioners' arguments to include nonaqueous wastes within the scope of
the corrosivity characteristic are not supported by the events of the
World Trade Center (WTC) for at least three reasons: (1) It is not
possible to establish a causal connection between the potential
corrosive properties of the dust and the resultant injuries to those
exposed; (2) the injuries documented at the WTC in connection with
potentially harmful dust are not consistent with injuries caused by
corrosive material; and (3) nothing submitted by petitioners
demonstrates that injury to human health or the environment was related
to improper treatment, storage, transport, or disposal of solid waste
(i.e. the petition does not demonstrate how RCRA would or could address
the potential exposures alleged to be hazardous). The Agency is seeking
comment on these tentative conclusions.
---------------------------------------------------------------------------

    \17\ While the Agency has reviewed numerous studies, and we
believe we have considered key studies, the body of literature
published on the events of 9/11/01 is voluminous. As part of
soliciting public comments the Agency is interested in any
additional key studies that should be considered as relevant to the
issues considered in this document.
---------------------------------------------------------------------------

    While there is a substantial body of research and broad consensus
that exposure to the 9/11 atmosphere for the first hours after the
collapse of the towers, and for some time thereafter, caused adverse
health effects in first responders and others, this atmosphere was a
complex combination of dust, fibers, smoke, and gases. As reported by
the New York Fire Department Bureau of Health Services (FDNY 2007; p.
24), ``[w]hen the towers collapsed, an enormous dust cloud with a high
concentration of particulate matter consumed lower Manhattan.''
Analysis of the settled dust from samples collected in the days
following September 11 shows that it consisted of a number of
materials, including concrete dust, toxic metals, silica, asbestos,
wood fiber, fiberglass, and smoke particulates from the fires (EPA

2002, Chen and Thurston, 2002; Landrigan et al., 2004; Lorber et al.,
2007; Lioy et al., 2002; Lioy et al., 2006).
    Further, while initial exposures are known to be very high for
those near the towers when they collapsed, the distribution of
exposures is not well documented nor quantitated (Lioy et al., 2006;
Lorber et al., 2007). Because of the complex nature of the ambient
atmosphere on 9/11, and lack of exposure data (although exposures were
clearly very significant for many people), it is not possible to
establish a causal connection between the potential corrosive
properties of the dust and the resultant injuries to those exposed, to
the exclusion of other co-occurring exposures. These co-occurring
exposures include glass fiber, silica, cellulose, metals, wood fiber
and fiberglass, a number of minerals (calcite, gypsum, quartz) and a
wide range of organic polyaromatic hydrocarbons (PAHs) and dioxin (see
docket for OSHA Sampling Results Summary; Lippy, 2001 (NIEHS); EPA,
2002; Lioy, 2002; Chen & Thurston, 2002).
    Other factors also argue against the use of the 9/11 disaster as an
event that would support changing the RCRA corrosivity regulation.
Most, but not all, outdoor dust samples tested for pH were below pH 11,
and so would not be classified as corrosive hazardous waste under the
regulatory changes proposed by the petition. These include data in
studies by EPA, 2002; USGS, 2001; ATSDR, 2002; McGee et al., 2003; and
Lorber et al., 2007. Some indoor dust samples had pH values as high as
pH 11.8 (USGS, 2001). While the petition discounts these data as not
representing actual exposures to the 9/11 airborne dust, and expresses
concern that the samples were evaluated using several different
protocols,\18\ they are nonetheless the only pH data known to the
Agency.
---------------------------------------------------------------------------

    \18\ Water must be added to a dust in order to test its pH, as
in EPA Method 9045. Dust pH was evaluated by different investigators
using methods they believed appropriate for the particular studies
being conducted. Investigators used different liquid/solid ratios,
and for one data set, pH was tested in the course of running a
deionized water leaching test (initial pH of the water approximately
pH 5.5).
---------------------------------------------------------------------------

    The pH values found for the WTC dust are generally consistent with
pH testing of waste concrete fine aggregates being recycled, for which
pH values are often less than pH 11.5 (Poon, 2006). This is supported
by information from Material Safety Data Sheets (MSDS) for crushed
concrete aggregate, which reported pH 7 for this material (LaFarge
MSDS, revised 3/1/2011), although Gotoh et al. (2002) found pH values
ranging from 11.6-12.6 for five samples of concrete dust generated by
building demolition resulting from an earthquake.
    In addition, numerous studies of exposed workers and laboratory
test animals fail to identify the gross damage to human tissue used as
a benchmark in defining corrosive materials as an effect resulting from
exposure to WTC dust. The 1980 RCRA background document supporting the
corrosivity regulation notes that ``[s]trong base or alkalis . . .
exert chemical action by dissolving skin proteins, combining with
cutaneous fats, and severely damaging keratin.'' Typical injury
endpoints used in guidance for defining a material as corrosive
describe ``. . .visible necrosis through the epidermis and into the
dermis . . .''. ``Corrosive reactions are typified by ulcers, bleeding,
bloody scabs . . . .'' (GHS 3.2.1).
    In reviewing the published literature describing injury to 9/11
exposed workers and residents, none describe gross respiratory tissue
destruction or other injuries of the severity identified in definitions
of corrosivity. Rather, adverse effects in various studies describe
respiratory irritation and other adverse effects. Chen & Thurston
(2002) identified ``World Trade Center Cough'', and noted that exposure
to the larger particles cause temporary nose, throat, and upper airway
symptoms. In a review of exposure and health effects data, Lioy et al.
(2006) identified the major health consequences of WTC exposure as
``aerodigestive and mental health related illnesses.'' The WTC
aerodigestive syndrome is identified as consisting of ``. . . WTC
cough, irritant asthma or reactive airways dysfunction syndrome and
gastroesophageal reflux disorder.'' In September of 2011, The Lancet
published a series of articles reviewing and updating the research on
adverse health effects suffered by those exposed to the WTC atmosphere.
Perlman et al. (2011) identified upper and lower respiratory effects,
including asthma, wheezing, tightness in the chest, and reactive airway
dysfunction syndrome, as well as gastroesophageal reflux symptoms.
Wesnivesky et al. (2011) identified updated occurrence rates of the
adverse effects described by Perelman through a longitudinal cohort
study, and it found a 42% incidence of spirometric abnormalities nine
years after the exposures. Jordan et al. (2011) studied mortality among
those registered in the World Trade Center Health Registry. No
significantly increased mortality rates (SMR) for respiratory or heart
disease were found, although increased mortality from all causes was
found in more highly exposed individuals compared with the low exposure
group. Finally, Zeig-Owens et al. (2011) studied cancer incidence in
New York firefighters, including those exposed to the WTC dust, and
found a modest increase in the cancer rates for the exposed group.
However, the authors remained cautious in their conclusions, as no
specific organs were preferentially affected, and the nine years since
exposure does not represent the full latency period for development of
many cancers. While the WTC-exposed populations in these studies
experienced adverse health effects related to exposures, they are not
effects of the nature and severity that the corrosivity regulation was
intended to prevent.\19\
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    \19\ This may raise the question of whether the Agency should
consider regulating waste dusts that are respiratory irritants as
hazardous waste under RCRA. However, that question is outside the
scope of the petition. As discussed herein, the petition fails to
show how RCRA regulation could address any of the alleged exposures,
and therefore does not support such regulation. Evaluation of
whether the Agency should regulate respiratory irritants as
hazardous waste would require additional information and analysis,
including evaluation of whether ``respiratory irritants'' meet the
statutory and regulatory definition of hazardous waste; and, if so,
which tests or criteria would be appropriate to identify such
irritants.
---------------------------------------------------------------------------

    The petition identifies several particular studies that the
petitioners believe demonstrate corrosive effects of the WTC dust, and
it cites to several passages, apparently taken from these studies as
supporting the petition (see page 30; the referenced publications are
identified in footnotes (FN) to the petition).
    The first passage identifies papers by Weiden et al. (2010; FN 88)
and Aldrich, et al. (2010; FN 89) as the source of information. The
petition extracts a quotation from the Weiden (2010) paper's discussion
section that noted, ``The WTC collapse produced a massive exposure to
respirable particulates, with the larger size dust fractions having a
pH ranging from 9 to11, leading to an alkaline ``burn'' of mucosal
surfaces.'' However, this publication presented research on pulmonary
capacity, and it states its primary conclusion in the paper's abstract
as follows: ``Airways obstruction was the predominant physiological
finding underlying the reduction in lung function post September 11,
2001, in FDNY WTC rescue workers presenting for pulmonary evaluation.''
The idea of an alkaline ``burn'' is at best inferred; it is not an
effect directly observed or evaluated by the researchers, nor is it one
of the findings of the study. The Aldrich et al. (2010; FN89) study
similarly conducted spirometry (lung function) studies of exposed
firefighters

and others. This abstract of this study reported that, ``Exposure to
World Trade Center dust led to large declines in FEV1 (1-second forced
expiratory volume) for FDNY rescue workers during the first year.
Overall, these declines were persistent . . .''. The paper found there
was no association between time of first responder/worker arrival at
the WTC site and chronic effects. The paper discussion did note that
the intensity of initial exposure was linked to acute lung
inflammation, although there was no reference to ``chemical burns'' or
other possible descriptors of chemical corrosive effects on workers'
tissues.
    The petition also cites an October 2009 poster presentation/
abstract (Kim et al., 2009; FN90) from an American College of Chest
Physicians meeting providing the results of a study of asthma
prevalence in WTC responders. The petition is generally accurate in
reflecting the researchers' conclusion that asthma in WTC responders
doubled over the study period 2002-2005, and in noting exposures to
dust and toxic pollutants following the 9/11 attacks. There was no
report in the paper of corrosive injuries to the workers.
    Footnote 91 references a New York Times newspaper article of April
7, 2010, reporting on the pending publication of the paper by Aldrich
et al. (2010; FN89) in the New England Journal of Medicine. The
petition quotes from the New York Times article, noting that, ``The
cloud contained pulverized glass and cement, insulation fibers,
asbestos and numerous toxic chemicals. It caused acute inflammation of
the airways and the lungs. Dr. Prezant said.'' The article also noted,
``This was not a regular fire,'' Dr. Prezant said. ``There were
thousands of gallons of burning jet fuel and an immense, dense
particulate matter cloud that enveloped these workers for days.'' This
article again illustrates the complex nature of the exposures to first
responders and others at the WTC site, and does not include corrosive
injury when noting the acute effects of this exposure.
    The petition next quotes from a NY Fire Department, Bureau of
Health Services report (FDNY, 2007; FN 92) which reports on upper
respiratory symptoms in firefighters (cough, nasal congestion, sore
throat) from the day of the attacks as well as at intervals up to 2-4
years in the future. The report notes that ``Particulate matter
analysis has shown a highly alkaline pH of WTC dust (like lye), which
is extremely irritating to the upper and lower airways.'' Earlier
discussion in the report (p.24) notes that firefighters were exposed to
``. . . an enormous dust cloud with a high concentration of particulate
matter consumed lower Manhattan.'' The WTC dust not only had very high
particulate concentrations, but was also a complex mixture of
materials.
    Finally, the petition cites a portion of the discussion in a paper
published by Reibman, et al., (2009; FN 94), which notes that,
``[m]easurements of settled dust documented that these particles were
highly alkaline (pH 11), and this property alone has been shown to be
associated with respiratory effects. Occupational exposure to inhaled
alkaline material induces chronic cough, phlegm, and dyspnea, as well
as upper respiratory tract symptoms.'' This paper presented the results
of spirometry (lung function) testing, and concluded that the exposed
population had, ``. . . persistent respiratory symptoms with lung
function abnormalities 5 or more years after the WTC destruction.'' As
in describing the results of other research on the WTC exposed
populations, these studies identify a number of adverse effects
attributable to WTC exposures from the day of the towers' collapse, as
well as subsequent exposures occurring during site rescue and
demolition and clean-up activities. While the adverse effects
identified represent serious injuries to many workers, these injuries
do not appear to include the type of gross tissue destruction of skin
or the respiratory tract that is the underlying basis for defining
materials as corrosive (i.e., destroying tissue by dissolving or
coagulating skin proteins). Rather, these effects are associated with
inflammatory and irritant properties of inhaled materials.
    Similarly, laboratory toxicity studies in which mice were exposed
to collected 9/11 dust samples (PM2.5), adverse effects were
limited to mild to moderate degrees of airway inflammation. The test
animals did experience increased responsiveness to methylcholine
aerosol challenge (EPA, 2002), suggesting an irritant response to the
WTC particulate matter. While these studies again suggest an irritant
response to the 9/11 dust samples, they do not demonstrate corrosive
injury.
    If one were to apply the criteria for classifying dusts as
corrosive, such as GHS (which does provide guidance for identifying
nonaqueous corrosives) to the WTC data, WTC dust would not have been
assessed as corrosive. GHS defines skin corrosion as ``. . . visible
necrosis, through the dermis and into the epidermis . . . Corrosive
reactions are typified by ulcers, bleeding, bloody scabs . . .'' (GHS
3.2.1.). None of these reactions to the WTC dust have been identified
in the published literature cited by the petition, nor in studies
identified in the Agency's review. The background information for the
current RCRA corrosivity characteristic regulation references
dissolution of skin proteins, combination of the corrosive substance
with cutaneous fats, and severe damage to keratin as the adverse
effects the regulation is intended to prevent. These kinds of injuries
have not been reported in the published scientific literature
presenting studies of WTC adverse effects.
    The petition also argues that classification of the 9/11 dust as
RCRA hazardous may have impacted workers' respirator use at the 9/11
site. However, this argument does not appear to have support. OSHA's
regulations govern worker safety (e.g., respirator use) when workers
are handling hazardous substances in emergency response (see 29 CFR
1910.120(a)). While the petitioner is correct that CERCLA regulations
incorporate RCRA hazardous wastes as part of the universe of
``hazardous substances,'' (see petition at 8 (citing 40 CFR 302.4(b)),
the universe of substances that give rise to worker safety regulations
is much broader than RCRA hazardous wastes (see 29 CFR 1910.120(a)).
Petitioners provide no support for the contention that broadening the
universe of waste classified as RCRA-hazardous for corrosivity would
have had any impact on the level of worker safety regulation imposed at
the WTC site.\20\
---------------------------------------------------------------------------

    \20\ Petitioners also argue that regulating nonaqueous wastes
with a pH between 11.5 and 12.5 would have made the first responders
``more motivated'' to wear respirators. Petition at 23. However,
there is no support for this argument, and EPA does not find this
type of unsupported suggestion sufficient to warrant regulation of a
new universe of waste as hazardous.
---------------------------------------------------------------------------

    Finally, nothing submitted by petitioners indicates that injury to
human health or the environment at the WTC was related to improper
treatment, storage, transport, or disposal of solid waste.\21\
Similarly, petitioners fail to explain how the exposures they are
concerned about at the WTC site were related to waste management
activities. The complexity and duration of exposures and the lack of
documentation makes it infeasible to distinguish the ambient air
exposures directly resulting from the initial collapse of the towers
(and ongoing fires) from exposures potentially related to waste
management. Without any

support for the proposition that petitioners' concerns are RCRA
concerns, there is similarly no indication that amending the RCRA
regulations would address similar concerns during future emergency
response events.
---------------------------------------------------------------------------

    \21\ See 42 U.S.C. 6903(5); the definition of hazardous waste
includes, in part, solid wastes that may ``pose a substantial
present or potential hazard to human health or the environment when
improperly treated, stored, transported, or disposed of, or
otherwise managed.''
---------------------------------------------------------------------------

    In sum, it is not possible to establish a causal connection between
the potential corrosive properties of the dust and the resultant
injuries to those exposed. The injuries documented at the WTC in
connection with potentially harmful dust are not consistent with
injuries caused by corrosive material. And finally, nothing submitted
by petitioners demonstrates that injury to human health or the
environment was related to improper treatment, storage, transport, or
disposal of solid waste (i.e. the petition does not demonstrate how
RCRA would or could address the potential exposures alleged to be
hazardous).
b. Exposure to Concrete Dust
    Petitioners also argue that corrosive injury could result from the
corrosive properties of inhaled concrete dust present in the air as a
result of building demolition by implosion. While the petition
illustrates the potential for exposure to concrete dust from several
building demolitions, no documented evidence of corrosive (or other)
injury from building demolition is provided. The petition, therefore,
fails to support the argument that concrete dust should be regulated as
corrosive hazardous waste.
    Concrete is among the most common construction materials used in
the US. It is a mixture of Portland cement (10-15%) and aggregate (60-
75%), with water added (15-20%) to allow hydration of the cement, which
results in its solidification (Portland Cement Association, 2015).
Concrete may include some entrained air, and in some cases, a portion
of the Portland cement may be replaced with combustion fly ash,
particularly coal fly ash. Cement is made when lime (CaO), silica
(SiO2), alumina (Al2O3), iron oxide
(Fe2O3), and sulfate (SO3) are burned
together in a cement kiln at approximately 2600 degrees Fahrenheit
([deg]F). The resulting material, called ``clinker'', which contains
more complex mineral forms of the ingredients, is ground to a fine
powder, and gypsum is added (CaSO4-2 H2O). This
powder is cement; when added to aggregate and hydrated, it becomes
concrete.
    The other key component of concrete is the aggregate. Both fine and
coarse aggregate are used, with their proportions varying depending on
the particular use of the concrete. A variety of materials may be used
as aggregate, with recently increasing emphasis on use of recycled
materials as aggregate (e.g., glass, ceramic scrap, crushed concrete;
Marie and Quaisrawi, 2012; Castro and Brito, 2013). However,
traditional aggregate is sand and gravel from different types of rock.
These include silica sand, quartz, granite, limestone and many others.
There exists a whole field of study dedicated to understanding the
properties and best uses of different kinds of aggregate materials in
making concrete (PCA, 2003). Many of the materials used as concrete
aggregate include silica minerals, and crystalline silica dust exposure
is a significant occupational exposure concern, as it can cause
respiratory injury known as silicosis (see 78 FR 56274, September 12,
2013). In silicosis, inhaled crystalline silica dust can cause fluid
accumulation and scarring of the lungs, which can reduce respiratory
capacity (American Lung Association, ``Learn about Silicosis.''
retrieved from http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/silicosis/learn-about-silicosis.html). Various MSDS for
ready mix concrete (i.e., cement pre-mixed with aggregate; just add
water) identify its crystalline silica content as, in one case, 20-85%,
in another, as 0-90% (MSDS-Ready Mixed Concrete, April 14, 2011; MSDS-
Lafarge Crushed Concrete, March 1, 2011).
    Many of the compounds and oxides present in concrete are already
regulated by OSHA when they occur as airborne dust. These include
calcium silicates, calcium hydroxide, calcium oxide, and silicates.
OSHA sets worker exposure standards for these chemicals, known as
``permissible exposure levels'' (PELs; see 29 CFR 1910.1000, tables Z-1
and Z-3, in particular). The PEL for airborne calcium oxide dust is 5
mg/m\3\; those for calcium hydroxide and calcium silicate are 15 mg/
m\3\ for total dust, and 5 mg/m\3\ for respirable dust; all measured as
8 hour time weighted average (TWA) values.
    There appear to be few studies published in the peer-reviewed
scientific literature that have examined the adverse health effects of
exposure specifically to concrete dust. OSHA includes concrete dust
among the materials that would be covered under their proposed
regulation to revise the PEL for respirable crystalline silica
(September 12, 2013; 78 FR 56274). OSHA's ``Occupational Exposure to
Respirable Crystalline Silica--Review of Health Effects Literature and
Preliminary Quantitative Risk Assessment'' (OSHA, 2013), developed in
support of its proposed regulation, identifies concrete production as
among the industries whose workers are likely to be exposed to
crystalline silica, and notes that several of the health effects
studies OSHA relied on in its assessment consider exposure to brick or
concrete dust as risk factors for cancers caused by silica. The one
study that specifically considered the adverse health effects of
concrete dust exposure to 144 concrete workers identified ``. . . mild
chronic obstructive pulmonary disease at respirable concrete dust
levels below 1 mg/m\3\, with a respirable crystalline silica content of
10% (TWA 8 hr.).'' (Meijer et al., 2001). Neither this report, nor the
OSHA silica rule risk assessment document noted any corrosive effects
in workers exposed to respirable concrete dust. Other OSHA literature
on concrete does identify potential effects from exposure to cement
dust or wet concrete, ranging from moderate irritation to chemical
burns (OSHA Pocket Guide on Concrete Manufacturing; available online at
https://www.osha.gov/Publications/3221_Concrete.pdf). However, neither
the petition nor information gathered through the Agency's independent
review of the literature provides sufficient specificity for the Agency
to analyze whether this ``Pocket Guide'' supports the regulatory
changes requested. For example, it is not clear whether any of the
potential exposures cited in the document involved actual waste
management scenarios. Given the wide range of potential effects cited,
it is also not clear how the pH of the material would relate to that
range of potential effects. Finally, as discussed above, many of the
compounds and oxides present in concrete are already regulated by OSHA,
and, where OSHA evaluated the risks of respirable concrete dust as part
of its silica rule, its studies did not cite potential corrosive
effects of concrete dust as part of the worker health concern the
regulation was focused on controlling.
    OSHA also distinguishes inert, or nuisance dust from fibrogenic
dust, such as crystalline silica or asbestos. Nuisance dust is dust
containing less than 1% quartz, a form of crystalline silica; the PEL
values for nuisance dust are also 15 mg/m\3\ total dust and 5 mg/m\3\
for the respirable fraction, the same PEL values as for calcium
hydroxide and calcium silicate dusts. (OSHA, ``Chapter 1: Dust and its
Control,'' retrieved from https://www.osha.gov/dsg/topics/silicacrystalline/dust/chapter_1.html).\22\
---------------------------------------------------------------------------

    \22\ Some of the exposures that petitioners are concerned about
may also be addressed by the National Ambient Air Quality Standards
(``NAAQS'') for particulate matter (40 CFR pt. 50) and the National
Emission Standards for Hazardous Air Pollutants (``NESHAPs'') for
asbestos (40 CFR pt. 61, subpt. M).

---------------------------------------------------------------------------

    In sum, while the petition alleges harmful exposure to concrete
dust from several building demolitions, no documented evidence of
corrosive (or other) injury from building demolition is provided in the
petition. Similarly, the literature on this topic is limited, and what
limited literature does exist does not demonstrate that the
petitioners' requested regulatory changes are warranted.
c. Exposure to Cement Kiln Dust
    The petition also argues that corrosive injury could result from
the corrosive properties of Cement Kiln Dust (CKD). However, the
petition again fails to provide any evidence demonstrating that CKD
would be appropriately characterized as corrosive under RCRA.
    CKD is an air pollution control residue collected during Portland
cement manufacture. CKD was exempted from regulation as hazardous waste
under RCRA pending completion of a report to Congress providing an
evaluation of CKD properties, potential hazards, current management,
and other information, by the Bevill Amendment to RCRA (see 42 U.S.C.
6921(b)(3)(A)(i) through (iii)). Following completion of the Report,
the EPA was required to determine whether regulation of CKD as
hazardous waste is warranted. EPA published its Report to congress on
CKD in 1993 (see docket for Report to Congress on CKD, 1993), and
published a RCRA regulatory determination in 1995 (60 FR 7366, February
7, 1995). Most CKD is managed on-site in non-engineered landfills,
piles, and ponds, which lack liners, leachate collection and run-on/
runoff controls. Wind-blown CKD was cited as a concern in a number of
the damage cases resulting from CKD management, but the Agency did not
identify any cases of corrosive injury either to workers or the general
public. The risk assessment portion of the Report examined possible
direct exposures to CKD via the air pathway and found:

    ``Quantitative modeling of air pathway risks to people living
near case-study facilities indicated that wind erosion and
mechanical disturbances of on-site CKD piles do not result in
significant risks at nearby residences via direct inhalation (e.g.,
central tendency and high end risks estimates were all less than 1 x
10-11 increased individual cancer risk at all five
facilities modeled). However, fugitive dust from on-site CKD piles
was estimated to be one of two contributors in some cases to higher
risk estimates for indirect exposure pathways (which were primarily
a result of direct surface run-off from the CKD pile reaching an
agricultural field).'' See docket for Report to Congress on CKD,
page 6-51.

    Subsequent screening level modelling found that windblown fugitive
CKD could cause violations of the Clean Air Act fine particulate matter
ambient air quality standard (PM 10) at plant boundaries and
potentially at nearby residences. The Agency's regulatory determination
for CKD concluded that existing fugitive dust controls were ineffective
in preventing fugitive releases to the air, and determined that
additional controls were warranted due to risks from fugitive air
emissions and runoff to surface waters in particular, and also due to
the potential for metals to leach into groundwater. However, no
corrosive injuries were identified.
    EPA published a proposed rule in 1999 (64 FR 45632, August 20,
1999) to address these concerns. The proposal focused in particular on
improving runoff controls from CKD piles, and controlling fugitive dust
releases, as well as performance-based controls on release to
groundwater. Action on this proposed rule has not been finalized.\23\
---------------------------------------------------------------------------

    \23\ While action on RCRA regulation has not yet been finalized,
EPA has established standards for emissions of hazardous air
pollutants from the Portland cement manufacturing industry under
section 112 of the Clean Air Act. See, e.g., 40 CFR pt. 63, subpt.
LLL.
---------------------------------------------------------------------------

    A number of new studies and data reviews have been published since
the 1999 proposal. These include a 2006 review of the effects of
Portland cement dust exposure by the United Kingdom Health and Safety
Executive (2005) and studies published in the scientific literature by
van Berlo et al., (2009); Isikli et al., (2006); Ogunbileje et al.,
(2013); Ogunbileje et al., (2014); Orman et al., (2005); and Fatima et
al., (2001). While several of these studies note that cement dust may
be an irritant, or cause contact dermatitis, none identified corrosive
injury resulting from exposures to CKD or Portland cement dust.
    In sum, while the petition alleges harmful exposure from CKD, the
current record before the Agency fails to support that CKD should be
regulated as corrosive under RCRA.

B. Wastes That May Be Newly Regulated Under the Requested Revisions

    In the process of reviewing and evaluating the petition, the Agency
has focused primarily on understanding and responding to the issues
raised by the petition. While the petition focuses on exposure and
health effects issues, it does not address the issue of the impacts of
the petition's proposed regulatory changes. At this point in its
review, the Agency has not developed a systematic assessment of the
types and volumes of waste that might be newly regulated as hazardous
if the Agency were to make the requested changes to the corrosivity
characteristic regulations. However, interested industry stakeholders
have reviewed the petition and sent the Agency their estimates of the
types and volumes of wastes generated by their industries that might
become RCRA hazardous under the petitioners' proposed regulatory
revisions. The industry stakeholders believe these wastes are currently
managed or reused safely, and that regulating them as hazardous waste
would not produce a corresponding benefit to worker, public or
environmental safety. The Agency has not evaluated their estimates.
While the industry estimates are informal, they may nonetheless provide
at least a qualitative, and, to some degree, a quantitative estimate of
waste that could become newly regulated were the Agency to make the
requested regulatory changes. See Letters of September 30, 2015 and
November 30 2015, from Wittenborn and Green. Also see letter of
September 4, 2015 from Waste Management, and August 28, 2015 letter
from the National Waste and Recycling Association, in the rulemaking
docket for this document.

C. Determining What Waste Is ``Aqueous''

    As a part of the argument regarding regulation of solid corrosives,
the petition asserts that the current corrosivity regulation is
ambiguous, particularly with regard to the definition of the term
``aqueous'' as used in 40 CFR 261.22(a)(1) and that this causes
confusion in implementing the regulation (see page 36 of the petition).
The petition also asserts that inclusion of nonaqueous wastes within
the scope of the characteristic is consistent with the approach taken
by other federal agencies, and would clarify this issue. Method 9040
(in ``Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods,'' also known as SW-846), which is incorporated into the
corrosivity characteristic regulation to test for pH, is used to
evaluate ``aqueous wastes and those multiphase wastes where the aqueous
phase constitutes at least 20% of the total volume of the waste''. A
number of EPA policy letters on determining what wastes are aqueous,
referred to in the paragraph below, do identify more than one approach
to distinguishing aqueous from nonaqueous wastes. However,

while petitioners are correct in noting that the inclusion of
nonaqueous wastes within the scope of the corrosivity characteristic
would address this issue, the Agency currently lacks data demonstrating
that regulation of nonaqueous wastes as corrosive is warranted under
RCRA. Therefore any clarification of the term ``aqueous'' should be
appropriately tailored and narrower than the change the petition
recommends.
    The Agency did address this issue when developing the corrosivity
characteristic definition in 1980. The background document discusses
how to address the potential for analytical interference in testing
wastes that may be suspensions or gel type material. At least one
commenter urged the Agency to define the term ``aqueous''; however, the
Agency considered it as a testing issue, and part of the waste
generator's obligation to determine whether their waste is RCRA
hazardous (see 40 CFR 262.11). In 1985, the Agency published the
``paint filter liquids test'' (PFT) for identifying wastes containing
free liquids (Method 9095; 50 FR 18372, April 30, 1985), and
recommended its use for distinguishing aqueous from nonaqueous wastes.
However, a year later, EPA expressed concern about the reliability and
precision of the PFT for separating liquids from solids when it
proposed the Toxicity Characteristic Leaching Procedure (TCLP) test,
and instead proposed the use of pressure filtration for separating
solids from liquids in that test (June 13, 1986; 51 FR 21681). In
letters in 1989 (see docket for letter to Mr. Wagner) and 1990 (see
docket for letter to Mr. Wyatt) the Agency urged the use of the EP Tox
test pressure filtration procedure (Step 7.15; Method 1310) for
determining whether wastes contained liquids, but also noted that the
paint filter test could be used to show that a waste was liquid or
aqueous (i.e., a positive determination), but not to show a waste was
not liquid or aqueous (i.e., a negative determination). Letters in 1992
(see docket for letters titled `` `Aqueous' as Applied to the
Corrosivity Characteristic'' and ``Alcohol-Content Exclusion for the
Ignitability Characteristic'') and 1993 (see docket for letter to Mr.
Parsons) noted that aqueous wastes need not be liquid, and identified
suspensions, sols or gels for which pH could be measured as subject to
the corrosivity characteristic. In a 1993 rule proposal updating SW-
846, the Agency stated that method 9095 could be used only to
demonstrate that a waste is aqueous, and that pressure filtration is
necessary to show that a waste is not aqueous (58 FR 46054, August 31,
1993), and proposed to revise the SW-846 guidance for implementing the
hazardous characteristics to reflect this. However, in finalizing these
proposed revisions to SW-846, the Agency considered industry concerns
that the proposed revision to the characteristics implementation
guidance was insufficiently clear and determined not to revise the
guidance. The Agency also reiterated its assessment of PFT use: that
wastes producing no liquid using Method 9095 should be subsequently
subjected to the more definitive method for separating liquids from
solids, pressure filtration, as described in Step 7.2.7 of Method 1311
(the TCLP test; 60 FR 3089 and 3092, January 13, 1995).
    As this issue is tangential to the petitioners' requests for
regulatory change, the Agency is proposing no changes to its guidance
at this time. The Agency may further consider this issue in the course
of revising and updating the SW-846 analytical methods in the future.

D. Other Potentially Relevant Incidents

    The purpose of this analysis is to identify whether currently
unregulated wastes are causing harm that could be effectively addressed
by RCRA regulation (``damage cases.'') The petition presents several
incidents the petitioners consider to be waste-management damage cases.
As explained above, the evidence presented in the petition does not
appear to justify a regulatory change. In addition to the incidents
presented by the petition, the Agency sought to identify incidents of
corrosive injuries (i.e., chemical burns) to workers or others that may
be attributable to exposure to corrosive materials. In support of
revisions to RCRA's regulatory definition of solid waste, the Agency
searched for damage cases involving mishandling of wastes at recycling
facilities. Several of the 208 cases identified mishandling of
``corrosive or caustic wastes'' (primarily at drum reconditioning
operations); no corrosive injuries to individuals were reported, and
the pH of the materials was not identified, so it is not possible to
know whether these wastes were in fact RCRA hazardous (EPA 2007; An
Assessment of Environmental Problems Associated with Recycling of
Hazardous Secondary Materials). A 2015 update of this study similarly
identified incidents at several drum reconditioning operations in which
caustic solutions were mishandled, but no corrosive injuries to workers
were reported (EPA 2015, updating ``An Assessment of Environmental
Problems Associated with Recycling of Hazardous Secondary Materials'').
    The Agency also reviewed a worker accident database compiled by
OSHA (available by using key word ``chemical burn'' at http://osha.gov/pis/imis/accidentsearch.html). While a number of chemical burns were
identified in the database, only a few contained enough detail to know
the pH of the material, and all but one of the cases also involved
heated materials (most at 136-295 [deg]F, and one above 800 degrees
[deg]F), making it difficult to attribute the resultant injuries solely
to the corrosive properties of the materials. In the case that did not
involve heated material, an employee got chemical burns when exposed to
effluent with pH estimated to be 9.9 from a clarifier tank leak,
although the material was not identified. In light of the pH value,
petitioners' proposed regulatory change would still not have captured
this material as characteristic waste.
    The Agency also has information describing a 1999 incident in which
an employee of a pulp and paper plant apparently slipped and fell into
black liquor sludge at the edge of a concrete pad on which it was being
stored (see docket materials related to Mr. Matheny). The employee was
knocked unconscious, and, as he was working an overnight shift, lay in
the material for several hours before being found by co-workers. He
suffered chemical burns on more than 50% of his body, and died from his
injuries. While this material apparently contained enough absorbed
water to cause injury (although the water content was not tested),
subsequent information indicated that it passed the paint filter test,
and so was not considered to be an aqueous waste under the RCRA
corrosivity regulation, and was therefore determined to be outside the
scope of the regulation. This may be an instance in which a high sodium
concentration in the waste interfered with testing its pH, as it showed
a pH reading of 12.45 when tested directly, but with 10% water added to
the sample to reduce the sodium interference, its pH was 12.95. Rather
than providing support for expanding the definition of corrosivity to
include nonaqueous materials however, the Agency believes this damage
case may illustrate the value of clarifying the Agency's approach to
determining what wastes are aqueous. As mentioned above in section
IV.2.C, the Agency may further consider the issue of testing which
wastes are aqueous in the course of revising and updating the SW-846
analytical methods in the future.

V. EPA's Conclusions and Rationale for Tentative Denial of the Petition

    In urging the Agency to expand the scope of the RCRA corrosivity
characteristic, the petition advances a number of arguments. However,
the petition fails in several ways to demonstrate that a regulatory
change is warranted. While the petition demonstrates that there has
been human exposure to materials identified by the petition as being of
concern, such as concrete dust and CKD, it fails to identify injuries
of the type and severity addressed by the RCRA corrosivity
characteristic that have resulted from these exposures. The injuries
that did occur to those exposed to the WTC dust have been attributed to
the dust as a whole, but cannot reliably be attributed to any one
property of the dust. While WTC first responders and demolition workers
clearly have suffered adverse health effects resulting from WTC dust
exposure, none of the published research on this population reviewed by
the Agency has identified gross tissue damage of the kind incorporated
into the RCRA and other regulatory and guidance definitions of
corrosivity (e.g., dissolving of skin proteins, combining with
cutaneous fats, or chemical burns). WTC dust and concrete and cement
dust may be respiratory irritants, but do not appear to be corrosives.
Further, many of the dusts identified as of concern often exhibit pH
values below the pH 11.5 value advocated in the petition. And finally,
the petition fails to demonstrate that the hazards posed by the WTC
site dust could have been reduced or controlled through RCRA
regulation.
    The petition also argues that pH 11.5 is a widely used presumptive
standard for identifying material as corrosive, but fails to identify
that corrosive injury in animal tests remains the fundamental basis for
corrosivity classification, and that pH 11.5 is used as an optional
screening value that may be rebutted by in vivo or various in vitro
test data. The use of pH 11.5 in these regulations and guidances is
fundamentally different from how the pH 12.5 value is used in the RCRA
corrosivity characteristic regulation, and such use does not set a
precedent for defining corrosivity under RCRA. Significant precaution
can be incorporated into these flexible evaluation approaches without
resulting in unwarranted regulation, because the presumption of
corrosivity can be rebutted. RCRA regulations do not include such
flexibility and are not rebuttable; a waste meeting the hazardous waste
characteristics regulatory criteria (and not otherwise excluded from
regulation) is RCRA hazardous, which would trigger the entire RCRA
cradle-to-grave waste management system. As noted in the discussion
previously, the RCRA corrosivity characteristic reflects the particular
concerns of waste management in the United States.
    One of the Agency's tentative conclusions in evaluating the
petition and related materials is that while the dusts identified by
the petition as being of concern are not corrosive materials, they
appear to be irritant materials. This raises the question of whether
the Agency should consider a new hazardous waste characteristic that
would identify and regulate irritant wastes. However, this particular
question falls outside the scope of the current petition. Moreover,
there remain significant questions about whether RCRA waste management
procedures would address any of the exposures identified in the
petition.
    Finally, the hazardous characteristics regulations are not the only
RCRA authority the Agency has for addressing risks related to waste
management. If wastes generated by a particular industry, or a
particular waste generated by a number of industries, were identified
as posing corrosive risks to human health or the environment that could
be effectively addressed by RCRA regulation, the Agency could initiate
a hazardous waste listing rulemaking to regulate that waste. Given the
lack of evidence to demonstrate that a wholesale change of the pH
threshold in the corrosivity regulation is warranted, the listing
approach would effectively address a specifically identified waste
without running the risk of over-including wastes that have a pH
greater than 11.5 without demonstrating corrosive properties.\24\
---------------------------------------------------------------------------

    \24\ In particular instances, RCRA 7003 authority can also be
used to address situations posing threats of imminent and
substantial endangerment from waste mismanagement.
---------------------------------------------------------------------------

VI. Request for Public Comment on EPA's Tentative Denial of the
Petition

    As part of this document, the Agency is soliciting public comment
and data and other information on the issues raised by the petition.
These include information on possible health impacts of the current
corrosivity regulation (if any), as well as health benefits (if any)
that may be anticipated were the Agency to grant the petition's
proposed regulatory changes. Further, the Agency is requesting public
comment on any other issues raised by this tentative decision to deny
the petition, as well as additional information on the types and
amounts of waste that may be newly regulated, and the potential cost of
such management, were the agency to grant the proposed regulatory
changes. Stakeholders intending to provide comments or information to
the Agency in this matter are encouraged to review the petition and its
supporting documents in their entirety to ensure that they identify any
issues not discussed here that they may find of interest.

VII. References

    The full bibliography for references and citations in this action
can be found in the docket as a supporting document.

List of Subjects in 40 CFR Part 261

    Environmental protection, Characteristic of corrosivity, and
Characteristics of hazardous waste.

    Dated: March 30, 2016.
Mathy Stanislaus,
Assistant Administrator, Office of Land and Emergency Management.
[FR Doc. 2016-08278 Filed 4-8-16; 8:45 am]
 BILLING CODE 6560-50-P