TIFA data are available since implementation of the new HOS rules at
the start of 2004, the trend is encouraging.

E. Regulatory Analyses and Notices

Executive Order 12866

    FMCSA has determined that this action is an economically
significant regulatory action within the meaning of Executive Order
12866. As such, the Agency has prepared an RIA analyzing the costs and
benefits of this final rule. A copy of the RIA is included in the
docket referenced at the beginning of this final rule. However, a brief
summary of the RIA results is provided

in this section. The Office of Management and Budget (OMB) has reviewed
this document.

Introduction to the RIA

    This analysis considers and assesses the potential consequences of
two potential regulatory options:
    Option 1 is the current rule. It allows up to 11 hours of driving,
allows a new 7- or 8-day period to begin after a 34-hour restart break,
and some splitting of off-duty periods using sleeper berths. The option
constrains the use of sleeper berths, however, to ensure that the main
sleeper berth period is at least 8 hours long, supplemented by an
additional 2-hour break that may be taken outside the sleeper berth.
    Option 2 is more stringent than Option 1, limiting driving to 10
(rather than 11) hours in a tour of duty, and eliminating the 34-hour
restart provision. The sleeper-berth provisions are the same as in
Option 1, and both options retain the short-haul provision contained in
the 2005 rule. That provision allows operators of short-haul vehicles
that do not require a commercial driver's license (CDL)--typically
those of less than 26,000 lbs gross vehicle weight rating (GVWR)--and
that remain within a 150 mile radius of their base, to keep timecards
in lieu of logbooks and be on-duty up to 16 consecutive hours two days
during a seven-day work week.

Overview of the RIA Analysis

    The simulation model used to estimate the costs for implementing
Options 1 and 2 was first loaded with data representative of shipping
patterns and carrier cost structures, and tested to ensure that it
could realistically simulate typical lengths of haul, empty mile
ratios, and productivity. The model was then set up to cover the most
important cases, under certain constraints (that is, daily driving hour
limits, minimum restart hours) represented under each option, and used
to simulate carrier operations under different conditions and HOS rule
options. FMCSA then analyzed the data representing the simulated
operations, using changes in miles driven as a measure of productivity
impacts. Output measures from individual runs were weighted to give a
realistic representation of the affected industry, including the
drivers' use of the most important provisions of the options. The
weighted changes in productivity from this procedure were then used to
estimate the cost increases imposed on the industry by each option,
using an analysis of the changes in wages and other costs likely to
result from changes in productivity. These productivity-related costs
were combined with transition costs associated with shifting to new
regulations to produce estimates of total social costs.
    Safety impacts were measured by feeding the on-duty and driving
schedules from the carrier simulation model into an operator fatigue
model (known as the SAFTE/FAST Model) to project driver performance
levels under different schedules allowed under each HOS option. Then,
the fatigue model results were used to estimate the resulting changes
in crash risks under each HOS option and for the different operations
cases. Changes in fatigue-related crash risks, calibrated to match
realistic levels, were then multiplied by the value of all affected
crashes to yield estimates of total benefits.
    The approaches used to estimate the costs and benefits of this
final rule have not changed since the 2007 HOS IFR. However, several
inputs to the RIA were updated between the IFR and this final rule in
order to reflect the most recent data available. Specifically, these
updates include the following: dollar values are now expressed in 2005
dollars rather than 2004 dollars; the industry population has been
updated to account for growth in numbers of long-haul drivers over the
past six years, when the data were originally collected for the 2003
rule; estimated changes in productivity and crashes have been corrected
slightly to include effects on the less-than-truckload sector; and the
value of crash reductions has been updated using newer crash
information and a revised value of a statistical life. These updates
were made either because of comments submitted to the docket regarding
the outdated inputs used in the cost/benefit estimation, or, in the
case of a higher value of a statistical life, due to new guidance
issued by the DOT in Spring 2008.

RIA Results

    The weighted productivity impacts from implementing Option 2 (that
is, 10 hours driving, no restart) results in a 7.30 percent reduction
in driver (labor) productivity compared to the current IFR. From
research conducted for the 2003 Rule RIA (contained in the docket),
FMCSA analysts showed that each one percent change in driver
productivity is associated with just under $300 million in costs using
a population estimate based on the year 2000 and cost figures expressed
in 2004 dollars. Updating to a more recent and larger 2005 estimate for
the long-haul driver population and expressed in terms of 2005 dollars
raises the cost of each one percent change in productivity to $335
million. Multiplying the weighted average productivity impacts by the
costs per percent decrease in productivity yields $2,443 million in
annual costs associated with implementing Option 2 (relative to Option
1, which obviously showed no change in costs relative to the current
operating environment).
    The reduction in crash risk from implementing Option 2 instead of
Option 1 was estimated to be approximately 0.63 percent. This change in
risk was valued by multiplying it by an estimate of the total annual
damage associated with heavy-duty long-haul truck crashes, updated to
account for a slight increase in total crashes, and re-estimated
damages per crash using a higher value of a statistical life. This
total was multiplied by the percentage of total damages that were
caused by the long-haul segment, yielding just over $34 billion. The
reduction in risk attributable to Option 2, given this total value, is
about 0.63 percent x $34 billion or about $214 million per year.
    In summary, the total annual costs from implementing Option 2 are
roughly $2,443 million and the total annual safety benefits are roughly
$214 million, resulting in a net annual cost from implementing Option 2
of approximately $2,229 million (in 2005 dollars).
    The Agency conducted a series of sensitivity analyses, where it
``stress tested'' various assumptions related to elimination of the
11th hour of driving. Specifically, the Agency revised its assumptions
with regard to several important inputs to the RIA, including the
percent of all large truck crashes that are fatigue related (increasing
it from 7 percent to 15 percent), the value of a statistical life
(increasing it from $5.5 million to more than $10 million), and raising
the relative risk of a fatigue-related crash in the 11th hour of
driving (by 1.3 times the value used in the revised TOT multiplier).
Each change improved the safety benefits relative to costs from
eliminating the 11th hour of daily driving, but none of these changes
in individual assumptions made elimination of the 11th driving hour
cost beneficial. Although it is unlikely that FMCSA mis-specified these
three assumptions in its initial analysis, the Agency nonetheless
combined all of the new assumptions in a way that makes elimination of
the 11th daily driving hour more favorable from a benefit-cost analysis
perspective. This exercise still generated net annual costs of $71
million, meaning that eliminating the 11th hour is unlikely to be cost-
effective under any reasonable set of

circumstances. This represents a brief summary of the contents of the
RIA accompanying this final rule. Readers are encouraged to review the
full contents of the stand-alone 2008 HOS RIA contained in the docket
to this rulemaking.

Regulatory Flexibility Act

    Under the Regulatory Flexibility Act (RFA), as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996 (Pub. L. 104-121,
110 Stat. 857), FMCSA is not required to prepare a final regulatory
flexibility analysis under 5 U.S.C. 604(a) for this final rule because
the Agency has not issued a notice of proposed rulemaking prior to this
action. However, FMCSA believes the RFA impacts of this final rule were
adequately described by the 2005 rule; there are no changes here.

Unfunded Mandates Reform Act of 1995

    This final rule will not impose an unfunded Federal mandate, as
defined by the Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1532, et.
seq.), that will result in the expenditure by State, local, and tribal
governments, in the aggregate, or by the private sector, of $128.1
million or more in any one year.

Paperwork Reduction Act

    This final rule does not alter the existing information collection
requests for HOS recordkeeping.

Environmental Justice

    FMCSA evaluated the environmental effects of this final rule in
accordance with Executive Order 12898 and determined that there are no
environmental justice issues associated with its provisions or any
collective environmental impact resulting from its promulgation.
Environmental justice issues would be raised if there were
``disproportionate'' and ``high and adverse impact'' on minority or
low-income populations. None of the alternatives analyzed in the
Agency's environmental assessment, discussed under National
Environmental Policy Act, would result in high and adverse
environmental impacts.

National Environmental Policy Act

    FMCSA prepared an environmental assessment (EA) of the IFR in
accordance with the National Environmental Policy Act of 1969 (NEPA)
(42 U.S.C. 4321, et seq., as amended), the FMCSA's NEPA Implementing
Procedures and Policy for Considering Environmental Impacts (FMCSA
Order 5610.1),\21\ the Council on Environmental Quality Regulations
(CEQ) regulations implementing NEPA (40 CFR parts 1500-1508), the DOT
Order 5610.C (September 18, 1979, as amended on July 13, 1982 and July
30, 1985), entitled ``Procedures for Considering Environmental
Impacts,'' and other pertinent environmental regulations, Executive
Orders, statutes, and laws for consideration of environmental impacts
of FMCSA actions. The Agency relies on all of the authorities noted in
this paragraph to ensure that it actively incorporates environmental
considerations into informed decision-making on all of its actions,
including rulemaking.
---------------------------------------------------------------------------

    \21\ FMCSA's environmental procedures were published on March 1,
2004 (69 FR 9680), FMCSA Order 5610.1, National Environmental Policy
Act Implementing Procedures and Policy for Considering Environmental
Impacts, and effective on March 30, 2004.
---------------------------------------------------------------------------

    As shown in the EA that accompanied the IFR, none of the
alternatives considered would have had a significant adverse impact on
the human environment. Subsequently, FMCSA determined that the IFR and
this final rule will not significantly affect the quality of the human
environment and that a comprehensive Environmental Impact Statement is
not required. The EA for the IFR, as well as the Agency's finding of no
significant impact (FONSI), are contained in the docket referenced at
the beginning of this notice.

Executive Order 13132 (Federalism)

    This action has been analyzed in accordance with the principles and
criteria contained in Executive Order 13132. FMCSA has determined this
rule does not have a substantial direct effect on States, nor would it
limit the policymaking discretion of the States. Nothing in this
document preempts any State law or regulation.

Executive Order 12372 (Intergovernmental Review)

    The regulations implementing Executive Order 12372 regarding
intergovernmental consultation on Federal programs and activities do
not apply to this program.

Executive Order 12630 (Taking of Private Property)

    This rule will not effect a taking of private property or otherwise
have taking implications under Executive Order 12630, Governmental
Actions and Interference with Constitutionally Protected Property
Rights.

Executive Order 12988

    This regulation meets the applicable standards set forth in
sections 3(a) and 3(b)(2) of Executive Order 12988, Civil Justice
Reform.

F. List of References

    American Transportation Research Institute (ATRI), ``Safety and
Health Impacts of the New Hours-of-Service Rules,'' 2006.
    Balkin, A.T., Thome, D., Sing, H., Thomas, M., Redmond, D.,
``Title Effects of Sleep Schedules on Commercial Motor Vehicle
Driver Performance'', Walter Reed Army Institute of Research, May
2000.
    Belenky, G., McKnight, A.J., Mitler, M.M., Smiley, A., Tijerina,
L., Waller, P.F., Wierwille, W.W., and Willis, D.K., ``Potential
Hours-of-Service Regulations for Commercial Drivers: Report of the
Expert Panel,'' 1998.
    Belenky, G., and Wu, L.J., ``Literature Review on Fatigue and
Health Issues Associated with Commercial Motor Vehicle Driver Hours
of Service: Update from 2004,'' Washington State University, 2008.
    Caruso, C.C., Hitchcock, E.M., Dick, R.B., Russo, J.M., and
Schmit, J.M., ``Overtime and Extended Work Shifts: Recent Findings
on Illnesses, Injuries, and Health Behaviors,'' April 2004.
    Dick, V., Knipling, R., and Hendrix, J, ``Safety and Health
Impacts of the New Hours-of-Service Rules,'' American Transportation
Research Institute (ATRI), March 2006.
    Friswell, R., and Williamson, A., ``Exploratory study of fatigue
in light and short haul transport drivers in NSW, Australia,''
Accident Analysis Prevention. January 2008; 40(1):410-7. Aug 2007.
    Hall, R.W. and Mukherjee, A., ``Bounds on effectiveness of
driver hours-of-service regulations for freight motor carriers,''
Elsevier Ltd. Transportation Research Part E 44, 2008, pp. 298-312.
    Hanowski, R.J., Dingus, T.A., Sudweeks, J.D., Olson, R.L., and
Fumero, M.C., ``Assessment of the Revised Hours-of-Service
Regulations: Comparison of the 10th and 11th Hour of Driving Using
Critical Incident Data and Measuring Sleep Quantity Using Actigraphy
Data,'' Virginia Tech Transportation Institute, June 2005.
    Hanowski, R.J., Olson, R.L., Bocanegra, J., Hickman, J.S.,
Dingus, T.A., and Sudweeks, J.D. ``Critical incidents that occur in
the 10th and 11th hour of driving in commercial vehicle operations:
Does risk increase in the 11th hour?,'' Arlington, VA: American
Transportation Research Institute. November, 2007.
    Hanowski R.J., Olson R.L., Bocanegra, J., and Hickman, J.S.,
``Analysis of Risk as a Function of Driving-Hour: Assessment of
Driving Hours 1 Through 11'' Virginia Tech Transportation Institute,
December 2007.
    Hursh, S.R., Redmond, D.P., Johnson, M.L., Thorne, D.R.,
Belenky, G., Balkin, T.L., Storm, W.F., Miller, J.C., and Eddy,
D.R., ``Fatigue models for Applied Research in Warfighting'',
Aviation Space and Environmental Medicine, Vol. 75, Number 3,
Supplement 2004.
    Jovanis, P.P., Park, S-W., Gross, F., and Chen, K-Y., ``Crash
Risk and Hours Driving: Interim Report, FMCSA,'' Pennsylvania
Transportation Institute, Penn State University, February 2005.

    Laden, Francine; Hart, Jaime E.; Smith, Thomas J.; Davis, Mary
E.; and Garshick, Eric. ``Cause-Specific Mortality in the Unionized
U.S. Trucking Industry,'' Environmental Health Perspectives, Vol.
115, No. 8, August, 2007, pp. 1192-1196.
    O'Neil, T.R., Krueger, G.P., Van Hemel, S.B., and McGowan, A.L.,
``Effects of Operating Practices on Commercial Driver Alertness,''
1999.
    Orris, P., Buchanan, D., Smiley, A., Davis, D., Dinges, D., and
Bergoffen, G., ``Literature Review on Health and Fatigue Issues
Associated with Commercial Motor Vehicle Driver Hours of Work,''
Transportation Research Board, 2005
    Park, S., Mukherjee, A., Gross, F., Jovanis, P.P., ``Safety
Implications of Multi-day Driving Schedules for Truck Drivers:
Comparison of Field Experiments and Crash Data Analysis,'' 2005.
    Saltzman G.M., and Belzer, M.H., ``Truck Driver Occupational
Safety and Health: 2003 Conference Report and Selective Literature
Review,'' February 2007.
    Wylie, C.D., Shultz, T., Miller, J.C., Mitler, M.M., and Mackie,
R.R., ``Commercial Motor Vehicle Driver Fatigue and Alertness Study
(DFAS),'' 1996.

G. Removal of Rescission Provision

    In view of the events following the 2003 HOS rule--a legal
challenge resulting in an adverse decision by the DC Circuit, which
Congress temporarily suspended to allow time for further Agency action,
culminating in a new rule--FMCSA thought it appropriate to highlight
that the pre-2003 rule had been entirely superseded. It did so by
promulgating Sec.  395.0 in the 2005 rule, which provided that ``[a]ny
regulations on hours of service of drivers in effect before April 28,
2003, which were amended or replaced by the final rule adopted on April
28, 2003 [69 FR 22456] are rescinded and not in effect.'' As there is
no longer a question that the pre-2003 rule is superseded, and further
absent any amendment of specific provisions of the Code of Federal
Regulations, the provision may not be consistent with the Federal
Register Act. FMCSA is therefore removing Sec.  395.0.

List of Subjects

49 CFR Part 385

    Administrative practice and procedure, Highway safety, Motor
carriers, Motor vehicle safety, Reporting and recordkeeping
requirements.

49 CFR Part 395

    Highway safety, Motor carriers, Reporting and recordkeeping
requirements.

0
In consideration of the foregoing, FMCSA adopts as final the interim
final rule published at 72 FR 71247, December 17, 2007, with the
following change:

PART 395--HOURS OF SERVICE OF DRIVERS

0
1. The authority citation for part 395 continues to read as follows:

    Authority: 49 U.S.C. 504, 14122, 31133, 31136, 31502; Sec. 229,
Pub. L. 106-159, 113 Stat. 1748; Sec. 113, Pub. L. 103-311, 108
Stat. 1673, 1676; and 49 CFR 1.73.

Sec.  395.0  [Removed]

0
2. Remove Sec.  395.0.

    Issued on: November 13, 2008.
David H. Hugel,
Deputy Administrator.
[FR Doc. E8-27437 Filed 11-18-08; 8:45 am]

BILLING CODE 4910-EX-P


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 UNREASONABLE RISK DETERMINATION

TSCA section 6(b)(4) requires EPA to conduct a risk evaluation to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified by EPA as relevant to this Risk Evaluation, under the conditions of use.

EPA has determined that HBCD presents an unreasonable risk of injury to health and the environment under the conditions of use. This determination is based on the information in previous sections of this Risk Evaluation, the appendices and supporting documents of Cyclic Aliphatic Bromide Cluster (HBCD), in accordance with TSCA section 6(b), as well as TSCA's best available science (TSCA section 26(h)) and weight of  scientific evidence standards (TSCA section 26(i)), and relevant implementing regulations in 40 CFR part 702.

The full list of conditions of use evaluated for the HBCD TSCA risk evaluation are listed in Table 8-1 of the risk evaluation: https://www.epa.gov/sites/default/files/2020-09/documents/1._risk_evaluation_for_cyclic_aliphatic_bromide_cluster_hbcd_casrn25637-99-4_casrn_3194-5_casrn_3194-57-8.pdf. EPA's unreasonable risk determination for HBCD is driven by risks associated with the following conditions of use, considered singularly or in combination with other exposures:

 Import
 Processing: Incorporated into a Formulation, Mixture, or Reaction Products
 Processing: Incorporation into Article
 Processing: Recycling (of XPS and EPS foam, resin, and panels containing HBCD
 Commercial/Consumer Use: Building/Construction Materials (Installation)
 Disposal (Demolition)
EPA will initiate risk management for HBCD by applying one or more of the requirements under TSCA section 6(a) to the extent necessary so that HBCD no longer presents an unreasonable risk. Under TSCA section 6(a), EPA is not limited to regulating the specific activities found to drive unreasonable risk and may select from among a suite of risk management options related to manufacture, processing, distribution in commerce, commercial use, and disposal in order to address the unreasonable risk. For instance, EPA may regulate upstream activities (e.g., processing, distribution in commerce) in order to address downstream activities driving unreasonable risk (e.g., use) even if the upstream activities are not unreasonable risk drivers.
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Background

Background on Policy Changes Relating to the Whole Chemical Risk Determination and Assumption of PPE Use by Workers

      From June 2020 to January 2021, EPA published risk evaluations on the first ten chemical substances, including for HBCD in September 2020. The risk evaluations included individual unreasonable risk determinations for each condition of use evaluated. The determinations that particular conditions of use did not present an unreasonable risk were issued by order under TSCA section 6(i)(1).

	In accordance with Executive Order 13990 ("Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis") and other Administration priorities (Refs. 1, 2, 3, and 4), EPA reviewed the risk evaluations for the first ten chemical substances to ensure that they meet the requirements of TSCA, including conducting decision-making in a manner that is consistent with the best available science.

	As a result of this review, EPA announced plans to revise specific aspects of certain of the first ten risk evaluations in order to ensure that the risk evaluations appropriately identify unreasonable risks and thereby can help ensure the protection of health and the environment (https://www.epa.gov/newsreleases/epa-announces-path-forward-tsca-chemical-risk-evaluations). To that end, EPA is reconsidering two key aspects of the risk determinations for HBCD published in September 2020. First, EPA proposes that the appropriate approach to these determinations is to make an unreasonable risk determination for HBCD as a whole chemical substance, rather than making unreasonable risk determinations separately on each individual condition of use evaluated in the risk evaluation. Second, EPA proposes that the risk determination should be explicit that it does not rely on assumptions regarding the use of personal protective equipment (PPE) in making the unreasonable risk determination under TSCA section 6; rather, the use of PPE would be considered during risk management. Further discussion of the rationale for the whole chemical approach is found in the Federal Register notice in the docket accompanying this revised HBCD unreasonable risk determination and further discussion of the proposed decision to not rely on assumptions regarding the use of PPE is provided in the Federal Register Notice and in section <IP_ADDRESS> below. With respect to the HBCD risk evaluation, EPA does not intend to amend, nor does a whole chemical approach require amending, the underlying scientific analysis of the risk evaluation in the risk characterization section of the risk evaluation.

      With regard to the specific circumstances of HBCD, as further explained below, EPA proposes that a whole chemical approach better aligns with TSCA's objective of protecting health and the environment. For HBCD, EPA favors the whole chemical approach based in part on the benchmark exceedances for multiple conditions of use (spanning across most aspects of the chemical lifecycle - from manufacturing (import), processing, commercial and consumer use, and disposal) for both health and the environment and considering the physical-chemical properties of HBCD as a persistent, bioaccumulative and toxic substance, and the irreversible health effects associated with HBCD exposures. Since the chemical-specific properties cut across the conditions of use within the scope of the risk evaluation, the Agency's risk findings and conclusions encompass the majority of those conditions of use, and the Agency is better positioned to achieve its TSCA objectives for HBCD when issuing a whole chemical determination for HBCD, EPA concludes that the Agency's risk determination for HBCD is better characterized as a whole chemical risk determination rather than condition-of-use-specific risk determinations. As explained in the Federal Register Notice, the revisions to the unreasonable risk determination (section 5 of the risk evaluation) would be based on the existing risk characterization section of the risk evaluation (section 4 of the risk evaluation) and would not involve additional technical or scientific analysis. The discussion of the issues in this draft revision to the risk determination would supersede any conflicting statements in the prior HBCD risk evaluation and the response to comments document (Summary of External Peer Review and Public Comments and Disposition for Cyclic Aliphatic Bromide Cluster (HBCD), September 2020). In addition, in making this risk determination, EPA does not assume the use of PPE. EPA also views the peer reviewed hazard and exposure assessments and associated risk characterization as robust and upholding the standards of best available science and weight of the scientific evidence, per TSCA sections 26(h) and (i).

Background on Unreasonable Risk Determination
In each Risk Evaluation under TSCA section 6(b), EPA determines whether a chemical substance presents an unreasonable risk of injury to health or the environment, under the conditions of use. The unreasonable risk determination does not consider costs or other non-risk factors. In making the unreasonable risk determination, EPA considers relevant risk-related factors, including, but not limited to: the effects of the chemical substance on health and human exposure to such substance under the conditions of use (including cancer and non-cancer risks); the effects of the chemical substance on the environment and environmental exposure under the conditions of use; the population exposed (including any potentially exposed or susceptible subpopulations (PESS)); the severity of hazard (including the nature of the hazard, the irreversibility of the hazard); and uncertainties. EPA takes into consideration the Agency's confidence in the data used in the risk estimate. This includes an evaluation of the strengths, limitations, and uncertainties associated with the information used to inform the risk estimate and the risk characterization. This approach is in keeping with the Agency's final rule, Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (82 FR 33726, July 20, 2017).

This section describes the draft revised unreasonable risk determination for HBCD, under the conditions of use in the scope of the Risk Evaluation for the cyclic aliphatic bromide cluster chemicals. EPA evaluated two of the three chemicals in the cluster: CASRN 25637-99-4 and CASRN 3194-55-6. In this document, the use of "HBCD" refers to either or both chemicals. No conditions of use were identified for the third chemical, CASRN 3194-57-8. This draft revised unreasonable risk determination is based on the risk estimates in the final Risk Evaluation, which may differ from the risk estimates in the draft Risk Evaluation due to peer review and public comments.

Unreasonable Risk to Human Health

Human Health

EPA's HBCD risk evaluation identified non-cancer adverse effects from acute and chronic inhalation and dermal exposures to HBCD. The most sensitive and robust endpoint for acute exposure is offspring loss, and for chronic exposure, it is thyroid effects. Risks were estimated for all human receptors following both acute and chronic exposure for representative endpoints from every hazard domain carried through to dose-response analysis. The health risk estimates for all conditions of use are in Tables 4-14 through 4-24 of this Risk Evaluation.

EPA accounted for PESS in risk estimation by providing risk conclusions based on the most sensitive receptor or lifestage (i.e., female workers of reproductive age for occupational risk, the youngest relevant lifestage for general population and consumer risk) and consideration of high end exposures (Section 4.5.2 and Table 4-11 of this Risk Evaluation).

EPA evaluated exposures to workers, occupational non-users (ONUs), consumer users, and the general population using reasonably available monitoring and modeling data for inhalation, dermal, and ingestion exposures, as applicable. The description of the data used for human health exposure is in Section 4.2 of this Risk Evaluation. Uncertainties in the analysis are discussed in Section 4.3.2 of this Risk Evaluation and are considered in the unreasonable risk determination including that EPA was unable to model the potential effects of bioaccumulation in human tissues over time, EPA was unable to quantify ONU exposure due to lack of adequate data or relevant models, and estimated fish ingestion exposure is highly dependent on the selected Bioaccumulation Factor (BAF) value.

EPA quantitatively evaluated inhalation, ingestion and dermal exposures to the general population via exposure to indoor and ambient air; dermal contact with soil and dust; and oral exposures via ingestion of food, breast milk, soil, dust and fish. While HBCD is released to surface water, EPA determined during problem formulation that no further analysis beyond what was presented in the problem formulation document would be done for the drinking water exposure pathway in this Risk Evaluation. While this exposure pathway remains in the scope of this Risk Evaluation, EPA  does not find the unreasonable risk determination for HBCD to be driven by general population exposure to HBCD in drinking water, based on a qualitative assessment of the physical chemical properties and fate of HBCD in the environment as well as the absence of any detection of HBCD in monitored water samples (Section <IP_ADDRESS> of the Problem Formulation; Section <IP_ADDRESS> of this Risk Evaluation).
Non-Cancer Risk Estimates

The risk estimates of non-cancer effects (expressed as margins of exposure or MOEs) refer to adverse health effects associated with health endpoints other than cancer, including to the body's organ systems, such as thyroid effects, liver effects, and reproductive/developmental effects. The MOE is the point of departure (POD) (an approximation of the no-observed adverse effect level (NOAEL) or benchmark dose level (BMDL)) and the corresponding human equivalent concentration (HEC) for a specific health endpoint divided by the exposure concentration for the specific scenario of concern. Section 3.2.5 presents the PODs for acute and chronic non-cancer effects for HBCD and Section 4.2 presents the MOEs for acute and chronic non-cancer effects.

The MOEs are compared to a benchmark MOE. The benchmark MOE accounts for the total uncertainty in a POD, including, as appropriate: (1) the variation in sensitivity among the members of the human population (i.e., intrahuman/intraspecies variability); (2) the uncertainty in extrapolating animal data to humans (i.e., interspecies variability); (3) the uncertainty in extrapolating from data obtained in a study with less-than-lifetime exposure to lifetime exposure (i.e., extrapolating from subchronic to chronic exposure); and (4) the uncertainty in extrapolating from a lowest observed adverse effect level (LOAEL) rather than from a NOAEL. A lower benchmark MOE (e.g., 30) indicates greater certainty in the data (because fewer of the default uncertainty factors (UFs) relevant to a given POD as described above were applied). A higher benchmark MOE (e.g., 1000) would indicate more uncertainty for specific endpoints and scenarios. However, these are often not the only uncertainties in a risk evaluation. The benchmark MOE for the most robust and sensitive acute non-cancer risks for HBCD is 100 (accounting for intraspecies and interspecies variability). The benchmark MOE for the most robust and sensitive chronic non-cancer risks for HBCD is 300 (accounting for interspecies and intraspecies variability as well as subchronic to chronic extrapolation). Additional information regarding the benchmark MOE is in Section 3.2.6.

Cancer Risk Estimates

Usually, EPA determines cancer risk estimates to represent the incremental increase in probability of an individual in an exposed population developing cancer over a lifetime (excess lifetime cancer risk (ELCR)) following exposure to the chemical. EPA did not evaluate cancer risk from exposure to HBCD because there is indeterminate evidence to make a conclusion of genotoxicity of HBCD and therefore inadequate information to assess the carcinogenic potential of HBCD. The only experimental animal study to examine cancer endpoints concluded that HBCD was not carcinogenic, however, this study was only available as an incomplete report (Kurokawa et al. 1984). Therefore, according to the U.S. EPA Guidelines for Carcinogen Risk Assessment (U.S. EPA 2005), there is "inadequate information to assess the carcinogenic potential" of HBCD. Despite the limited evidence, it is unlikely that the results of any potential additional studies would significantly alter the conclusions about the hazard due to the mixed results and the negative incomplete report. As a result, this hazard was not carried forward for dose-response analysis or risk estimation (Section <IP_ADDRESS> of this Risk Evaluation).
Determining Unreasonable Risk of Injury to Health

Calculated non-cancer risk estimates (MOEs) can provide a risk profile of HBCD by presenting a range of estimates for different health effects for different conditions of use. A calculated MOE that is less than the benchmark MOE supports a determination of unreasonable risk of injury to health, based on noncancer effects.These calculated risk estimates alone are not bright-line indicators of unreasonable risk. Whether EPA makes a determination of unreasonable risk for the chemical substance depends upon other risk-related factors, such as the endpoint under consideration, the reversibility of effect, exposure-related considerations (e.g., duration, magnitude, or frequency of exposure, or population exposed), and the confidence in the information used to inform the hazard and exposure values.

In the HBCD risk characterization, offspring loss was identified as the most robust and sensitive endpoint for non-cancer adverse effects from acute exposures for all conditions of use. For chronic exposures, thyroid effects were identified as the most robust and sensitive endpoint for noncancer adverse effects for all conditions of use. However, additional risks associated with other adverse effects (e.g., liver effects, reproductive effects, and other developmental effects) were also identified for acute and chronic exposures. The HBCD unreasonable risk determination uses offspring loss and thyroid effects as driving endpoints.

When making a determination of unreasonable risk for the chemical substance, the Agency has a higher degree of confidence where uncertainty is low. For example, EPA has high confidence in the hazard and exposure characterizations when the basis for characterizations is measured or monitoring data or a robust model and the hazards identified for risk estimation are relevant for conditions of use. This Risk Evaluation discusses the major assumptions and key uncertainties by major topic: physical-chemical properties and toxicokinetics, hazard, occupational exposure, general population/consumer exposure, and historical production volumes and activities. For the human health risk estimation, key assumptions and uncertainties are related to the toxicokinetics of HBCD, including high-end assumptions about dermal absorption and uncertainty whether existing UFs sufficiently account for bioaccumulation in human tissues. Additional sources of uncertainty related to human health hazard include the application of adult rodent thyroid hormone changes to humans in a developmental context and the absence of reliable dose-response information for developmental neurotoxicity endpoints. Important assumptions and key sources of uncertainty in the risk characterization are described in more detail in Section 4.3.2 of this Risk Evaluation.

When determining the unreasonable risk for a chemical substance, EPA considers the central tendency and high-end exposure levels in occupational settings and in environmental media. Risk estimates based on high-end exposure level scenarios (e.g., 95th percentile) are generally intended to cover individuals or sub-populations with greater exposure (i.e., PESS) as well as to capture individuals with sentinel exposure, and risk estimates at the central tendency exposure levels are generally estimates of average or typical exposure (p. 38).

As shown in Section 4 of this Risk Evaluation, when characterizing the risk to human health from occupational exposures during risk evaluation under TSCA, EPA believes it is appropriate to evaluate the levels of risk present in baseline scenarios where no mitigation measures are assumed to be in place. This approach considers the risk to potentially exposed or susceptible subpopulations of workers who may not be covered by Occupational Safety and Health Administration (OSHA) standards, such as self-employed individuals and public sector workers who are not covered by a State Plan. In addition, EPA believes it is appropriate to evaluate the levels of risk present in scenarios considering applicable OSHA requirements (e.g., chemical-specific permissible exposure limits (PELs) and/or chemical-specific PELs with additional substance-specific standards) as well as scenarios considering industry or sector best practices for industrial hygiene that are clearly articulated to the Agency. By characterizing risks using scenarios that reflect different levels of mitigation, EPA risk evaluations can help inform potential risk management actions by providing information that could be used during risk management to tailor risk mitigation appropriately to address any unreasonable risk identified.

 When undertaking unreasonable risk determinations as part of TSCA risk evaluations, EPA cannot assume as a general matter than an applicable OSHA requirement or industry practice is consistently and always properly applied or would automatically lead EPA to conclude that any unreasonable risk for a chemical substance is not driven by occupational scenarios. Mitigation scenarios included in the HBCD risk evaluation (e.g., scenarios considering use of various personal protective equipment (PPE)) likely represent what is happening already in some facilities. However, the Agency cannot assume that all facilities will have adopted these practices for the purposes of making the TSCA risk determination.

Therefore, EPA conducts baseline assessments of risk and makes its determination of unreasonable risk from a baseline scenario that does not assume compliance with OSHA standards, including any applicable exposure limits or requirements for use of respiratory protection or other PPE. Making unreasonable risk determinations based on the baseline scenario should not be viewed as an indication that EPA believes there are no occupational safety protections in place at any location or that there is widespread non-compliance with applicable OSHA standards. Rather, it reflects EPA's recognition that unreasonable risk may exist for subpopulations of workers that may be highly exposed because they are not covered by OSHA standards, such as self-employed individuals and public sector workers who are not covered by a State Plan, or because their employer is out of compliance with OSHA standards, or because EPA finds unreasonable risk for purposes of TSCA notwithstanding existing OSHA requirements.

Unreasonable Risk to the Environment

EPA's Risk Evaluation identified adverse effects resulting from acute and chronic exposures to HBCD for both aquatic and terrestrial organisms for all conditions of use, as summarized in Section 3.1. The environmental hazard threshold is calculated for both aquatic and terrestrial organisms. The hazard threshold for aquatic organisms takes into account an assessment factor that represents uncertainties explained in Section 3.1.5, therefore allowing a concentration of concern (COC) to be derived. Limitations in data availability regarding HBCD toxicity to terrestrial organisms do not allow for an assessment factor to be used to derive a COC, therefore the hazard threshold is based on reported hazard effect concentrations reported by key studies summarized in Section 3.1.5. The description of the data used for environmental exposure is in Section 2.3. The environmental concentration is determined based on the levels of the chemical released to the environment (e.g., surface water, sediment, soil, biota) under the conditions of use, based on the fate properties, release potential, and reasonably available environmental monitoring data. Section 4.1. provides more detail regarding the risk quotient derivationsfor HBCD.

EPA calculated a risk quotient (RQ) to compare environmental concentrations against an effect level. The environmental risk quotient from exposure to HBCD via water (e.g., surface water and sediment) and air (e.g., soil) releases are characterized in Section 4.1 (Table 4-3 through Table 4-7). Uncertainties in the analysis are discussed in Section 4.3 and considered in the risk determination below, including the fact that despite HBCD being a PBT, exposure to HBCD across and within media types were not aggregated to estimate risk (as explained in Section 4.1.3), therefore environmental risk may be underestimated for aquatic and terrestrial organisms.

Determining Unreasonable Risk of Injury to the Environment

Calculated risk quotient (RQs) can provide a risk profile by presenting a range of estimates for different environmental hazard effects for different conditions of use. An RQ equal to 1 indicates that the exposures are the same as the concentration that causes effects. An RQ less than 1, when the exposure is less than the effect concentration, generally indicates that there is not risk of injury to the environment that would support a determination of unreasonable risk for the chemical substance. An RQ greater than 1, when the exposure is greater than the effect concentration, generally indicates that there is risk of injury to the environment that would support a determination of unreasonable risk for the chemical substance. Consistent with EPA's human health evaluations, the RQ is not treated as a bright line and other risk-based factors may be considered (e.g., confidence in the hazard and exposure characterization, duration, magnitude, uncertainty) for purposes of making an unreasonable risk determination.

EPA evaluated the effects of exposure to HBCD on aquatic and terrestrial organisms. HBCD is a persistent, bioaccumulative, and toxic (PBT) substance. EPA found that there were exceedances of benchmarks for pelagic and benthic aquatic organisms (Section <IP_ADDRESS> of this Risk Evaluation). There were no exceedances of benchmarks for terrestrial organisms (Section <IP_ADDRESS> of this Risk Evaluation). In the HBCD risk characterization, delayed hatching and reduced growth of offspring were identified as the most robust and sensitive endpoints for pelagic organisms due to acute and chronic exposures of HBCD, respectively. EPA evaluated algae risk separately from the categorization of an acute or chronic exposure, and risk of reduced algae growth was evaluated. The most robust and sensitive endpoint identified for benthic organisms due to chronic HBCD exposure was reduced reproduction. EPA also identified reduced reproduction and survival of soil organisms due to chronic exposure to HBCD as being the most robust and sensitive endpoint. EPA provides estimates for environmental risk in Section 4.5.1 of this Risk Evaluation.

EPA may make an unreasonable risk determination when the risk affects organisms that are identified as being relevant (Section 3.1). Based on the available hazard data for aquatic and terrestrial organisms, EPA based environmental risk for conditions of use on predicted media-specific HBCD concentrations. Although EPA acknowledges that due to the physical-chemical properties of HBCD that dietary exposure is likely, HBCD release information cannot be directly used to extrapolate tissue concentrations of prey of either aquatic or terrestrial organisms; monitoring data was primarily used for the trophic transfer estimation of HBCD (Section 3.1.3), and that is used to evaluate the potential for HBCD to undergo trophic transfer due to all activities and releases that likely contribute to HBCD background exposures. Due to the lack of HBCD hazard information regarding terrestrial organism exposure, terrestrial organism risk resulting from HBCD exposure is limited to that for soil organisms (e.g., earthworms), and EPA acknowledges this uncertainty (Section 4.3.1).

When making a determination of unreasonable risk, EPA has a higher degree of confidence where uncertainty is low. For example,  EPA has high confidence in the hazard and exposure characterizations when the basis for the characterizations is measured or monitoring data or a robust model and the hazards identified for risk estimation are relevant for conditions of use. Where EPA has made assumptions in the scientific evaluation, whether or not those assumptions are protective is also a consideration. Additionally, EPA considers the central tendency and high-end scenarios when determining the unreasonable risk. High-end risk estimates (e.g., 90th percentile) are generally intended to cover organisms or populations with greater exposure (those inhabiting ecosystems near industries) and central tendency risk estimates are generally estimates of average or typical exposure.

EPA considered uncertainties in its determination of unreasonable risk for HBCD. Key assumptions and uncertainties in the environmental risk estimation are related to data used for the characterization of environmental exposure (e.g., model input parameters, inability to directly relate monitoring sites to conditions of use) and environmental hazard (e.g., selection of representative organisms, allometric-scaling to estimate hazard thresholds for other organisms). Additionally, the reasonably available environmental monitoring data was limited temporally and geographically. Assumptions and key sources of uncertainty in the risk characterization are detailed in Section 4.3.1. of this Risk Evaluation.

Additional Information regarding the Basis for the Unreasonable Risk Determination

Tables 5-1 and 5-2 summarize the basis for the draft revised determination of unreasonable risk of injury to health and the environment presented by HBCD. In both tables, a checkmark indicates the type of effect and the exposure route to the population evaluated for each condition of use that support the unreasonable risk determination for HBCD. As explained in Section 5.1, for the draft revised unreasonable risk determination, EPA considered the effects on human health and the environment of exposure to HBCD at the central tendency and high-end, the exposures from the condition of use, the risk estimates, and the uncertainties in the analysis. See Sections 4.5.1 and 4.5.2 of this Risk Evaluation for a summary of risk estimates.
Table 5-1. Supporting Bases for the Draft Revised Unreasonable Risk Determination for Human Health

                               Life Cycle Stage
                                 Category [a]
                                Subcategory [b]
                                  Population
                                Exposure Route
                               Human Health Risk

                                     Acute
                                  Non-cancer
                              Chronic Non-cancer

                                   High End
                               Central Tendency
                                   High End
                               Central Tendency

Manufacture
Import

Import
Worker
Inhalation and Dermal
                                       P
                                       P
                                       P
                                      P

Processing
Incorporated into formulation, mixture or reaction product

Flame retardants used in custom compounding of resin (e.g., compounding in XPS masterbatch) and in solder paste
Worker
Inhalation and Dermal
                                       P
                                       P
                                       P
                                       P
Processing
Processing  -
incorporation into article

Flame retardants used in plastics product manufacturing (manufacture of XPS and EPS foam; manufacture of structural insulated panels (SIPS) and automobile replacement parts from XPS and EPS foam)
Worker

Inhalation & Dermal

                                      P
                                       P
                                       P
                                      P

Processing
Recycling
Recycling of XPS and EPS foam, resin, panels containing HBCD

Worker
Inhalation

                                       P

Commercial/
consumer use
Building/
construction materials
 Plastic articles (hard): construction and building materials covering large surface areas (e.g., XPS/EPS foam insulation in residential, public and commercial buildings, and other structures) and solder paste
Worker & ONU

Inhalation & Dermal

                                       P

Disposal
Disposal

Land disposal (e.g., EPS and XPS foam insulation)

Worker &
ONU

Inhalation

                                      P

[a] These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent additional information regarding all conditions of use of HBCD.

[b] These subcategories reflect more specific information regarding the conditions of use of HBCD.

Table 5-2. Supporting Bases for the Draft Revised Unreasonable Risk Determination for the Environment

                               Life Cycle Stage
                                  Category a
                                 Subcategory b

                                  Population
                                Exposure Route
                              Environmental Risk

                                     Acute

                                    Chronic

                                   High End
                               Central Tendency
                                   High End
                               Central Tendency

Manufacture
Import

Import

Aquatic Organisms
Surface Water and Sediment
                                      P
                                       P
                                       P
                                      P

Processing
Incorporated into formulation, mixture or reaction product

Flame retardants used in custom compounding of resin (e.g., compounding in XPS masterbatch) and in solder paste
Aquatic Organisms
Surface Water and Sediment
                                       P
                                       P
                                       P

Processing
Processing  -
incorporation into article

Flame retardants used in plastics product manufacturing (manufacture of XPS and EPS foam; manufacture of structural insulated panels (SIPS) and automobile replacement parts from XPS and EPS foam)
Aquatic Organisms
Surface Water and Sediment
                                      P
                                       P
                                       P
                                       P
                                  Processing
Recycling

Recycling of XPS and EPS foam, resin, panels containing HBCD

Aquatic Organisms
Surface Water and Sediment
                                      P
                                       P
                                       P

Commercial/consumer use
Building/
construction materials
Plastic articles (hard): construction and building materials covering large surface areas (e.g., XPS/EPS foam insulation in residential, public and commercial buildings, and other structures) and solder paste
Aquatic Organisms
Surface Water and Sediment
                                       P
                                       P

Disposal
Disposal

Land disposal (e.g., EPS and XPS foam insulation)

Aquatic Organisms
Surface Water
                                      P
                                       P
                                       P

[a] These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent additional information regarding all conditions of use of HBCD.

[b] These subcategories reflect more specific information regarding the conditions of use of HBCD.

5.3 References
 	1. Executive Order 13985. Advancing Racial Equity and Support for Underserved Communities Through the Federal Government. Federal Register (86 FR 7009, January 25, 2021).

 	2. Executive Order 13990. Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis. Federal Register (86 FR 7037, of January 25, 2021).

 	3. Executive Order 14008. Tackling the Climate Crisis at Home and Abroad. Federal Register (86 FR 7619, February 1, 2021).

 	4. Presidential Memorandum. Memorandum on Restoring Trust in Government Through Scientific Integrity and Evidence-Based Policymaking. Federal Register (86 FR 8845, February 10, 2021).