[Federal Register Volume 81, Number 69 (Monday, April 11, 2016)]
[Proposed Rules]
[Pages 21295-21308]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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

[[Page 21296]]

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: 703-308-8855; email 
address: corrosivitypetition@epa.gov.

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

[[Page 21297]]

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

[[Page 21298]]

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/

[[Page 21299]]

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

[[Page 21300]]

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.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \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

[[Page 21301]]

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

[[Page 21302]]

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

[[Page 21303]]

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

[[Page 21304]]

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

[[Page 21305]]

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).

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

[[Page 21306]]

    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,

[[Page 21307]]

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.

[[Page 21308]]

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