[Federal Register Volume 65, Number 138 (Tuesday, July 18, 2000)]
[Proposed Rules]
[Pages 44491-44506]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-18103]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 261

[FRN-6838-1]
RIN 2050-AE07


Hazardous Waste Identification Rule (HWIR): Identification and 
Listing of Hazardous of Hazardous Wastes; Notice of Data Availability 
and Request for Comments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of data availability and request for comment; extension 
of the public comment period.

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SUMMARY: The Environmental Protection Agency (EPA) is making available 
for public comment human health and ecological risk data and 
information relating to an exemption from hazardous waste management 
that we discussed in a Federal Register notice published on November 
19, 1999 (64 FR 63382).
    That exemption, also known as the Hazardous Waste Identification 
Rule (HWIR) exemption, would exempt listed hazardous wastes that meet 
chemical-specific exemption levels from hazardous waste management 
requirements. We plan to develop these exemption levels based on 
results from the Multimedia, Multipathway and Multireceptor Risk 
Assessment (3MRA) Model. The model evaluates simultaneous chemical 
exposures across several environmental media and multiple exposure 
pathways to human and ecological receptors in order to estimate the 
health and ecological effects in the vicinity of waste disposal units 
that may receive exempt listed hazardous waste.
    We presented the underlying methodology and assumptions for the 
3MRA Model in the Federal Register (64 FR 63382, November 19, 1999). 
However, because of technical difficulties, we were unable to propose 
exemption levels in that notice. Since then, we have made numerous 
revisions to correct and improve the model. On April 12, 2000, we 
provided an updated version of the 3MRA Model (beta Version 0.98) and 
results for five chemicals in Docket number F-99-WH2P-FFFFF. On April 
19, 2000 (65 FR 20934), we also extended the original deadline of May 
17, 2000 for public comment on the modeling methodology to August 15, 
2000 to allow additional time for review and comment.
    Today's notice makes available the results for 36 chemicals, 
including the five already in the docket, using an updated version of 
the model (Version0.98r). In addition, today's notice again extends the 
comment period for the November 19, 1999 HWIR exemption discussion 
until October 16, 2000, to coincide with the comment period for today's 
notice.
    Before using a revised risk assessment to support a final 
regulatory action, we would propose the HWIR exemption. Comments on the 
1999 HWIR discussion and on today's notice will be helpful to us in 
developing such a proposal.
    Please note that today's notice does not re-open the comment period 
on the revisions to the mixture and derived-from rules that were 
proposed in the November 19, 1999 Federal Register notice (64 FR 63382, 
Sections I-IV, Sections XXI-XVI (as applicable) of the preamble and the 
proposed regulatory language amending 40 CFR Part 261).

DATES: We will accept comments through October 16, 2000 on: (1) The 
concentration-based HWIR exemption discussed in the November 19, 1999 
Federal Register notice; (2) the possible revisions to the Land 
Disposal Restriction (LDR) treatment standard which were also discussed 
in the November 19, 1999 Federal Register notice; and (3) the 
additional data presented today. The discussions of the HWIR exemption 
and possible LDR treatment standard revisions are in Sections V-XX and 
Sections XXI-VVCI (as applicable) of the preamble, 64 FR 63382 
(November 19, 1999).

ADDRESSES: Commenters must send an original and two copies of their 
comments referencing docket number F-2000-WH2A-FFFFF to: (1) If using 
regular U.S. Postal Service mail: RCRA Docket Information Center, 
Office of Solid Waste (5305G), U.S. Environmental Protection Agency 
Headquarters (EPA, HQ), 1200 Pennsylvania Avenue, NW, Washington, DC 
20460-0002, or (2) if using special delivery, such as overnight express 
service: RCRA Docket Information Center (RIC), Crystal Gateway One, 
1235 Jefferson Davis Highway, First Floor, Arlington, VA 22202. 
Comments may also be submitted electronically through the Internet to: 
[email protected]. Comments in electronic format should also be 
identified by the docket number

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F-2000-WH2A-FFFFF and must be submitted as an ASCII file avoiding the 
use of special characters and any form of encryption and should include 
commenter's mailing address and phone number. If comments are not 
submitted electronically, we are asking prospective commenters to 
voluntarily submit one additional copy of their comments on labeled 
personal computer diskettes in ASCII (TEXT) format or a word processing 
format that can be converted to ASCII (TEXT). It is essential to 
specify on the disk label the word processing software and version/
edition as well as the commenter's name and address. This will allow 
EPA to convert the comments into one of the word processing formats 
utilized by the Agency. Please use mailing envelopes designed to 
physically protect the submitted diskettes. We emphasize that the 
submission of comments on diskettes is not mandatory, nor will it 
result in any advantage or disadvantage to any commenter.
    Commenters should not submit electronically any confidential 
business information (CBI). An original and two copies of CBI must be 
submitted under separate cover to: RCRA CBI Document Control Officer, 
Office of Solid Waste (5305W), U.S. EPA, 1200 Pennsylvania Ave., N.W., 
Washington, DC 20460-0002.
    Public comments and supporting materials are available for viewing 
in the RCRA Information Center (RIC), located at Crystal Gateway I, 
First Floor, 1235 Jefferson Davis Highway, Arlington, VA. The RIC is 
open from 9 a.m. to 4 p.m., Monday through Friday, excluding federal 
holidays. To review docket materials, it is recommended that the public 
make an appointment by calling 703-603-9230. The public may copy a 
maximum of 100 pages from any regulatory docket at no charge. 
Additional copies cost $0.15/page. The notice and other material 
associated with this action can be electronically accessed on the 
Internet at http://www.epa.gov/epaoswer/hazwaste/id/hwirwste/index.htm.
    The official record will be kept in paper form. Accordingly, EPA 
will transfer all comments received electronically into paper form and 
place them in the official record, which will also include all comments 
submitted directly in writing. The official record is the record 
maintained at the address in ADDRESSES at the beginning of this 
document. The comments and other documents associated with the November 
19, 1999 HWIR notice (64 FR 63382) are kept in docket Number F-99-WH2P-
FFFFF.
    We will respond to submitted comments, whether written or 
electronic, in a notice in the Federal Register or in a response to 
comments document placed in the official record. We will not 
immediately reply to electronically submitted comments other than to 
seek clarification of comments that may be garbled in transmission or 
during conversion to paper form, as discussed above.

FOR FURTHER INFORMATION CONTACT: For general information, contact the 
RCRA Hotline at 800-424-9346 or TDD 800-553-7672 (hearing impaired). In 
the Washington, DC, metropolitan area, call 703-412-9810 or TDD 703-
412-3323.
    For specific information on the risk modeling, contact David 
Cozzie, (703) 308-0479, [email protected], Stephen Kroner, (703) 
308-0468, [email protected], or Zubair Saleem, (703) 308-0467, 
[email protected], all at: Office of Solid Waste, U.S. 
Environmental Protection Agency (5307W), 1200 Pennsylvania Avenue, NW, 
Washington, DC 20460-0002.

SUPPLEMENTARY INFORMATION:   

Outline

I. How does today's notice relate to the November 19, 1999 notice?
II. How has EPA revised the 3MRA Model since the November 19, 1999 
notice?
III What are the results from the revised 3MRA Model?
IV. What are possible next steps for the HWIR exemption development?

I. How Does Today's Notice Relate to the November 19, 1999 Notice?

    The November 19, 1999 Federal Register notice includes (among other 
things) a discussion of a concentration-based exemption (the ``HWIR 
exemption'') from the definition of hazardous waste (64 FR 63382 and 
docket number F-99-WH2P-FFFFF; see also the web site at: http://www.epa.gov/epaoswer/hazwaste/id/hwirwste/index.htm for accessing the 
background documents electronically). Included in this discussion is an 
extensive explanation of the risk assessment methodology that would 
support this exemption. The version of the 3MRA Model that we discussed 
was beta Version 0.93. However, because of unresolved technical issues, 
we did not have results from the risk assessment modeling, other than 
for acrylonitrile, to include in the Federal Register notice.
    Since then, we have addressed many technical issues and have 
revised the 3MRA Model. Today's notice and materials placed in the 
docket explain the revisions to the 3MRA Model and present results for 
36 chemicals using beta Version 0.98r of the revised model.

II. How Has EPA Revised the 3MRA Model Since the November 19, 1999 
Notice?

    The details of all the improvements and corrections made to beta 
Version 0.93 of the model and incorporated in beta Version 0.98r of the 
model are presented in the RCRA docket number F-2000-WH2A-FFFFF. 
Selected examples of changes we made are listed below.
    (1) We changed the aerated tank and surface impoundment modules so 
that exceedance of constituent solubility in either the leachate or the 
waste management unit (WMU) causes an error that terminates the model 
instead of issuing a warning that allows the model to continue. We 
changed this because solubility exceedance indicates that the modules 
were not operating within the intended range of simulation; that is, 
the modules were not intended to model concentrations that lead to the 
formation of non-aqueous phase liquids.
    (2) We changed the national data table in the aquifer module so 
that it simulates the effects of fractures and heterogeneities on the 
transport of chemical constituents. We did this to better reflect the 
nature of the subsurface environment in the vicinity of the WMUs.
    (3) We corrected an error in the data transfer between the 
ecological risk module and the exit-level processor (ELP-I). Previously 
the ELP-I misread the ecological receptor group descriptors. In beta 
version 0.98r, the ecological module outputs the ecological receptor 
groups directly to the ELP-I; and
    (4) We changed the exit-level processor (ELP-II) to correct the 
exposure pathway tables to include only those pathways relevant to the 
chemical. The ELP-II now refers to flags in the human health benchmarks 
database to identify appropriate exposure pathways for each chemical. 
This specific change has occurred since Version 0.98.

III. What Are the Results From the Revised 3MRA Model?

    We are presenting the draft chemical-specific results estimated for 
the three waste forms (liquids, solids, and semi-solids) and one WMU 
type (landfill) for the four Protection Groups. The Protection Groups 
are based on five different types of protection criteria: (1) Cancer 
risk level, (2) human health hazard quotient (HQ) for non-cancer risks, 
(3) ecological hazard quotient, (4) population percentile, and (5)

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probability of protection. We summarize below these five risk 
protection criteria, which are explained more fully in the November 19, 
1999 Federal Register notice (see 64 FR 63440-41).
    1. Cancer Risk Level. The cancer risk level refers to an 
individual's increased chance of developing cancer over a lifetime due 
to potential exposure to a specific chemical. A risk of 
1 x 10-\6\ translates as an increased chance of one in a 
million of developing cancer during a lifetime. EPA generally sets 
regulations at risk levels between 10-\6\ and 
10-\4\ (in other words, from one in a million to one in ten 
thousand increased chance of developing cancer during a lifetime). In 
the RCRA hazardous waste listing program, a 10-\6\ risk is 
usually the presumptive ``no list'' level, while 10-\5\ is 
often used to determine which wastes are considered initial candidates 
for listing (see, for example the petroleum listing at 63 FR 42117). We 
present the exemption levels that result from both the 
10-\6\ and 10-\5\ risk levels.
    2. Human Health Hazard Quotient (HQ). The HQ refers to the 
likelihood that exposure to a specific chemical would result in a non-
cancer health problem (for example, neurological effects). The hazard 
quotient is developed by dividing the estimated exposure to a chemical 
by the reference dose (RfD) for oral ingestion pathways or reference 
concentration (RfC) for inhalation pathways. The RfD and RfC are 
estimates of the highest dose or concentration that might be considered 
safe. An HQ of one or lower indicates that the given exposure is 
unlikely to result in adverse health effects. We present the exemption 
levels that result from both an HQ of 0.1 and an HQ of one.
    3. Ecological Hazard Quotient. The ecological hazard quotient is 
analogous to the human health HQ, except that the estimated exposure is 
compared with an ecological toxicity value rather than the human health 
RfD or RfC. For this analysis, we developed two types of toxicity 
values: (1) An ecological benchmark that is calculated as a dose (mg/
kg-day); and (2) a chemical stressor concentration limit (CSCL) that is 
calculated as a concentration in media (for example, mg/l). The 
ecological hazard quotient protects ecological health at the population 
or community level, and, therefore, focuses on reproductive and 
developmental effects, rather than the mortality of individual 
organisms. In developing ecological toxicity values for this risk 
assessment, we used the geometric mean between a No Observed Effects 
Level (NOEL) and a Lowest Observed Effects Level (LOEL). (Human health 
reference doses are based on NOELs.) We present the exemption levels 
that result from an ecological hazard quotient of one and ten.
    4. Population Percentile. The population percentile is the 
percentage of the population protected at the specified risk level and 
hazard quotient for a single environmental setting. A setting is a 
specific WMU at a specific site, and is defined by combining site-based 
information (such as unit size, and unit placement) with variable 
environmental information (such as rainfall and exposure rates) from 
regional and national databases. We present the exemption levels that 
result from population protection percentiles of 99% and 95%.
    5. Probability of Protection. The probability of protection is 
defined as the percentage of WMU settings that meet the population 
percentile criteria. We present the exemption levels that result from 
probability of protection levels of 95% and 90%.
    Four Protection Groups are defined below in Table 1. These four 
groups serve to indicate the potential range of risk decision measures, 
from most conservative (Group 1) to least conservative (Group 4), that 
we could use to determine the final HWIR regulatory exemption levels. 
These groups are not an exhaustive look at all possible combinations of 
potential risk protection criteria; we could choose a different 
combination altogether. An example of how these protection groups are 
interpreted is provided below with respect to the Group 2 criteria for 
cancer and hazard effects, respectively:

--99% of the population are subject to cancer risks of less than 10-6 
across 90% of the environmental settings;
--99% of the population experience exposure levels below an HQ of 1 
across 90% of the environmental settings.

                                      Table 1.--Protection Groups Evaluated
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                                                               Protection   Protection   Protection   Protection
                                                                group 1      group 2      group 3      group 4
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Risk Level..................................................       10-\6\       10-\6\       10-\5\       10-\5\
Human Health HQ.............................................          0.1            1            1            1
Ecological HQ...............................................            1            1            1           10
Population Percentile.......................................           99           99           99           95
Probability of Protection...................................           95           90           90           90
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    In addition to the five risk criteria set forth in the November 19, 
1999 notice and summarized above, we present a sixth risk criterion: 
the distance to human and ecological receptors from the WMU. We 
developed draft chemical-specific waste concentrations for each of the 
36 chemicals that are presented in Tables 2 through 13. These tables 
present results using 3MRA Model beta Version 0.98r for the four 
Protection Groups based on the above five protection criteria and for 
various distances to human receptors corresponding to 500, 1000, 2000 
meters and for a fixed distance of 2000 meters for ecological 
receptors.
    We also are presenting in the RCRA Docket (Docket Number F-2000-
WH2A-FFFFF) the following results for the same 36 chemicals:
    1. Protection Group Results. Draft chemical-specific waste 
concentrations identified for the additional four waste management unit 
types (waste piles, aerated tanks, surface impoundments, and land 
application units);
    2. Sub-Population Results. Risk or hazard quotient estimates for 
each sub-population (residents, gardeners, beef/dairy farmers, and 
fishers) for each Protection Group and the three waste forms and the 
five waste management unit types;
    3. Cohort Results. Risk or hazard quotient estimates for each 
cohort (infants, children 1-12, and adults 13 and older) for each 
Protection Group and the three waste forms and the five waste 
management unit types; and
    4. Exposure Pathway Results. Risk or hazard quotient estimates for 
each exposure pathway (air inhalation, soil ingestion, water ingestion, 
crop ingestion, beef ingestion, milk ingestion, fish ingestion, shower 
inhalation, breast milk, all inhalation, all ingestion, all

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ingestion and inhalation, and groundwater total) for each Protection 
Group for the three waste forms and for the five waste management unit 
types.
    Copies of beta Version 0.98r of the 3MRA Model are in the RCRA 
docket on a CD. Beta Version 0.98r of the 3MRA model can also be 
accessed at: http://www.epa.gov/ceampubl/hwir.htm.

IV. What Are Possible Next Steps for the HWIR Exemption 
Development?

    Since the results of the HWIR risk assessment model presented in 
today's notice are intrinsically related to the discussion of the HWIR 
risk assessment found in the November 19, 1999 Federal Register notice, 
we have harmonized the comment periods for both to end on October 16, 
2000. However, please note that nothing in today's notice changes or 
supersedes the information in the November 19, 1999 Federal Register 
notice. The information available by today's notice specifically 
supplements the information in Sections XV-XIX in the preamble to the 
November 19, 1999 discussion. Please note that today's notice does not 
re-open the comment period on the revisions to the mixture and derived-
from rules that were proposed in the same November 19, 1999 Federal 
Register notice. That comment period ended February 17, 2000.
    We will review the public comments and decide if further revisions 
to the HWIR risk assessment (3MRA) model or other aspects, e.g., 
implementation, of the HWIR exemption are necessary. We also are 
continuing independent testing and external peer review of the HWIR 
risk assessment model. Before we go final with an HWIR exemption, we 
will publish a proposal to allow public comment on a unified package. 
The exact timing of this proposal will depend on the extent of the 
public and peer review comments.

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    Dated: July 7, 2000.
Elizabeth A. Cotsworth,
Director, Office of Solid Waste.
[FR Doc. 00-18103 Filed 7-17-00; 8:45 am]
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