facilities that plate base materials such as brass, steel, aluminum, or
plastic with layers of copper and nickel, followed by a relatively thin
layer of chromium to provide a bright, tarnish- and wear-resistant
surface. Decorative chromium electroplating is used for items such as
automotive trim, metal furniture, bicycles, hand tools, and plumbing
fixtures.
    The Chromium Anodizing source category consists of facilities that
use chromic acid to form an oxide layer on aluminum to provide
resistance to corrosion. The chromium anodizing process is used to coat
aircraft parts (such as wings and landing gears), as well as
architectural structures that are subject to high stress and corrosive
conditions.
    The HAP emission sources subject to the Chromium Electroplating
NESHAP are the tanks in which the chromium deposition takes place. For
hard chromium and decorative chromium electroplating facilities, the
emission sources are electroplating tanks. For the Chromium Anodizing
source category, the emission sources are anodizing tanks.
    The primary emission controls used by the facilities in these
source categories include packed bed scrubbers, mesh pad mist
eliminators, composite mesh pad (CMP) systems, high efficiency
particulate air (HEPA) filters, and wetting agent/fume suppressants
(WAFS). Most decorative chromium electroplating plants comply with the
MACT standards by using WAFS in the tank bath to control surface
tension, which in turn reduces emissions. Some plants use a combination
of WAFS and add-on control to meet the MACT emission limits. If a
facility controls emissions using an add-on control device, the tank is
generally equipped with a hood and duct work to exhaust emissions
through the control device and out the stack. However, when WAFS are
used as the only means of emission control, the tanks often are not
equipped with exhaust hoods. In such cases, emissions from the tank are
fugitive and are exhausted to the outside using wall-mounted exhaust
fans.
    We estimate that there are approximately 1,770 plants that are
currently subject to the Chromium Electroplating MACT standards. Of
these, we estimate that there are 790 hard chromium electroplating
plants, 740 decorative chromium electroplating plants, and 240 chromium
anodizing plants. A detailed description of how the number of each type
of plant was estimated can be found in the Estimated Number of Chromium
Electroplating Plants document available in the docket for this action.
Some facilities perform more than one type of chromium electroplating
or anodizing. For purposes of our estimates, we classified facilities
as hard chromium, decorative chromium, or chromium anodizing based on
the primary type of electroplating operation performed at the facility.
Some chromium

electroplating facilities electroplate items that are used internally
in the manufacturing process at the same facility or within the same
company. For example, some large printing facilities electroplate their
printing rollers in house, and the chromium electroplating processes
are located at the same site as the printing and publishing processes.
2. What data were used in our risk analyses?
    For the Chromium Electroplating source categories, we compiled a
preliminary data set using data in the 2005 NEI. A review of the NEI
resulted in the identification of data for 122 chromium electroplating
facilities. These data were reviewed and the data for eight hard
chromium and six decorative chromium electroplating plants were revised
based on information in the facilities' permits or permit applications.
Additional data were available for 44 facilities through responses to a
CAA section 114 information request that was sent to facilities for the
Plating and Polishing Area Source rule. The data for these facilities
were added to the NEI data set, and, as with the original data,
represent actual emission levels for these electroplating and anodizing
facilities. Most of these facilities have low emissions, which are
generally less than 2 pounds per year (lbs/yr). These 166 facilities
now included in the 2005 NEI comprise approximately 9 percent of the
estimated 1,770 facilities covered by the MACT standards, and include
63 hard chromium electroplating, 96 decorative chromium electroplating,
and 7 chromium anodizing facilities.\25\ This data set of 166
facilities was modeled to determine the maximum individual cancer risk,
the population cancer risk, the cancer incidence, and the maximum
chronic non-cancer risk for the three source categories based on actual
emissions. The maximum individual cancer risk and the maximum chronic
non-cancer risk estimated from this data set were also compared to the
maximum individual cancer risk and the maximum chronic non-cancer risk
estimated from MACT-allowable emissions for the three source
categories.\26\
---------------------------------------------------------------------------

    \25\ The National Association of Surface Finishers provided OMB
with data for 15 plants. We have placed this information in the
docket for this rulemaking.
    \26\ The Occupational Safety and Health Administration adopted a
lower permissible exposure limit for hexavalent chromium in 2006.
---------------------------------------------------------------------------

    To address the possibility that the small number of facilities
included in the 166-facility data set might not be fully representative
of the source categories and their risks, we developed an additional
data set. In the development of this data set, we used ``model plants''
developed for the original MACT standard to represent the individual
facilities. For hard and decorative chromium electroplating, we used
three model plants (large, medium, and small) that represent average
characteristics for each of these groups. For each of these plant
sizes, there is an annual emissions rate (lbs/yr) that is derived from
the design and operating parameters, and is specific to the size and
type of model plant. For chromium anodizing, we have two model plants
(large and small). The model plants were based on data collected during
development of the original MACT standards from 1988 to 1993 from more
than 100 facilities that responded to an Information Collection Request
(ICR) for the chromium electroplating and anodizing industry. Data from
site visits and other information also were used in developing the
model plants. A complete description of the model plants developed for
the MACT standard is provided in the Background Information Document
(BID) for the original MACT standard (Chromium Electroplating BID).
    The basis for this additional data set is 1,629 chromium
electroplating facilities with known addresses.\27\ For about half of
these facilities, the type of electroplating performed is known, but
the size of the facility is not known. For the remaining facilities,
neither the type of chromium electroplating process or processes, nor
the facility size is known.
---------------------------------------------------------------------------

    \27\ There is some overlap between the 1,629 facilities with
known addresses and the 166 facilities for which we have emissions
data based on the NEI and the data collection request.
---------------------------------------------------------------------------

    For use in the risk analysis, the limited available data were used
to divide these facilities into six groups. Facilities in three of the
six groups were assigned to be hard chromium electroplating facilities.
Those groups include: hard chromium facilities; facilities with
combined hard chromium operations and other electroplating or
anodizing; and facilities with unknown processes. Together, these three
groups yielded a total of 1,219 plants, all of which we modeled as hard
chromium electroplating facilities. This total, in addition to the 63
hard chromium electroplating facilities in the 2005 NEI data set,
yields a total of 1,282 facilities, which is substantially higher than
the 790 hard chromium facilities that we estimate exist in the United
States. However, because hard chromium facilities have the highest
emissions among the three source categories, we made these selections
as a conservative or health-protective assumption.
    To represent the decorative chromium electroplating facilities, we
combined two of the six groups of facilities; decorative chromium
facilities and facilities that perform both decorative chromium and
chromium anodizing. This results in 319 decorative chromium facilities
in this data set, which, even when combined with the 96 decorative
chromium electroplating facilities in the 2005 NEI data set, is less
than the 740 facilities that we believe exist in the industry. Because
we modeled all of the unknown electroplating type facilities as the
highest-emitting hard chromium electroplating facilities, we consider
this assessment to be conservative, even though it appears to under-
represent decorative chromium facilities.
    Similarly, the last of the six groups are all known chromium
anodizing facilities. This group includes 73 facilities, and, when
combined with the 7 chromium anodizing facilities in the 2005 NEI data
set, still represents only about a third of the 240 facilities chromium
anodizing facilities. Again, we believe this is conservative because
those facilities not modeled as chromium anodizing plants were modeled
as the higher emitting hard chromium facilities in the analysis.
    To estimate the risks for this assessment, we needed to establish
estimated emissions for each of the electroplating and anodizing types.
To ensure that we did not underestimate cancer risk to the most exposed
individual, we originally planned to use the large plant emission
factors that we had developed for the original MACT standard to
represent all model plants for each type of chromium electroplating
processing. In reviewing available emissions data, we found that, while
the large plant emission factors adequately represent the average
chromium emissions from known large decorative chromium electroplating
and large chromium anodizing facilities, they are not representative of
the average chromium emissions from large hard chromium electroplating
facilities.
    The emission factor for large hard chromium electroplating
developed for the original MACT standard was 35.3 lbs/yr. However, in
comparing this emission factor to available emissions data for
individual facilities, we find that this emissions factor is
unrealistically high and does not represent the average level of
emissions for large facilities as we would expect to see under the
current MACT standard. As explained more fully in the Model Plant Data
Used to Estimate Risk from

Chromium Electroplating Sources document available in the docket for
this action, based on the large model plant design flow rate and
operating hours, a large hard chromium model plant operating at the
MACT emission limit of 0.015 milligrams per dry standard cubic meter
(mg/dscm) would emit a maximum of only 23.6 lbs/yr of chromium
compounds. Moreover, the available data on actual emissions for hard
chromium electroplating plants indicate there are only 4 plants with
annual emissions greater than 10 lbs/yr. As a result, we determined
that the large size model plant emissions factor, as defined for the
original MACT standard, is not representative of existing large hard
chromium electroplating facilities on a nationwide basis. On the other
hand, the emission factor associated with a medium size hard chromium
electroplating model plant (9.26 lbs/yr) falls between the 90th
percentile (8.04 lbs/yr) and the 95th percentile (11.6 lbs/yr) of the
available emissions data for hard chromium electroplating facilities.
Because this emission factor, which was originally developed for medium
sized facilities at the time the MACT standard was developed, is
representative of the emissions from large facilities, the emissions
factor of 9.26 lbs/yr was used to represent current large hard chromium
electroplating facilities. Thus, for purposes of this residual risk
review, we refer to 9.26 lbs/yr as the emissions factor for a ``large''
hard chromium electroplating facility.
    We believe the approach of using the ``large'' facility emissions
factor to represent all facility sizes is reasonable to ensure that we
did not underestimate maximum individual cancer risk. Although we
believe that only a small percentage of the facilities are large, we
recognize that we do not have emissions data for approximately 90
percent of the sources. Thus, by assuming all sources are large, we
have ensured that we will not underestimate the maximum individual
risk.
    For hard chromium electroplating, the model plant emission factors
for small, medium, and large facilities range from 0.55 to 9.26 lbs/yr.
While we expect only 10 percent of the facilities to be large, based on
the distribution of model plant sizes developed for the MACT standard,
we used the emissions factor for a large facility (9.26 lbs/yr) for all
of the 1,219 facilities that we considered as hard chromium
electroplating facilities. Similarly, for decorative chromium
electroplating, the emission factors for small, medium, and large
facilities are 0.065, 0.27, and 2.65 lbs/yr, respectively, and the
large facility emissions factor was used in the risk assessment for
decorative chromium. For the Decorative Chromium category, we estimate
that only 5 percent of the facilities are large, based upon the
distribution of decorative chromium plants nationwide when the original
NESHAP were developed. Finally, for chromium anodizing, the emission
factor for small facilities is 0.036 lb/yr, and for large facilities,
is 0.44 lb/yr. The large facility emissions factor (0.44 lb/yr) was
used in the conservative analysis for all of the anodizing facilities
even though we estimate that only 25 percent are large.
    Population risk indicators can be greatly overstated when highly
conservative emission estimates are applied to every facility in the
source category. Recognizing this fact, we performed a supplemental
analysis to better address nationwide average emission levels and
assess the sensitivity of our population risk estimates. Thus, as
described further below, the supplemental analysis was performed to
understand the degree to which the risk might be overstated, and, thus,
how much weight to attach to the conservative analysis. The
conservatism of this risk assessment is one factor that we consider in
determining whether the risk is acceptable within the meaning of the
Benzene NESHAP.
    For the supplemental analysis, we assigned unique emission factors
to each of the 6 groups of facilities in our 1,629 facility data set.
These emission factors were developed to better estimate the average
emissions for all of the sources within each group. The new emission
factors are:
     2.24 lbs/yr for known hard chromium electroplating
facilities,
     0.225 lb/yr for known decorative chromium electroplating
facilities,
     0.137 lb/yr for known chromium anodizing facilities,
     1.23 lbs/yr for facilities with combinations of hard
chromium electroplating and either decorative electroplating or
anodizing,
     0.181 lb/yr for facilities with combinations of decorative
electroplating and anodizing, and
     1.11 lbs/yr for facilities where the type of process
(electroplating or anodizing) is unknown.
    A detailed explanation for how these emission factors were derived
can be found in the Model Plant Data Used to Estimate Risk from
Chromium Electroplating Sources available in the docket for this
action. These weighted average emission factors account for the plant
type (hard chromium electroplating, decorative chromium electroplating,
or chromium anodizing) and the distribution of plant sizes (large,
medium, or small). For example, the average emissions factor for hard
chromium electroplating (2.24 lbs/yr) is the weighted average of the
model plant emission factors for large plants (10 percent of plants at
9.26 lbs/yr per plant), medium plants (20 percent of plants at 4.63
lbs/yr per plant, and small plants (70 percent of plants at 0.55 lb/yr
per plant). This distribution of plant sizes is based on actual data
collected during development of the original MACT rule. We have no
reason to believe the distribution of facility sizes has changed
significantly since then.
    The uncertainties associated with both the conservative analysis
and the supplemental analysis include the estimated distribution of
plant types and sizes as well as the facility emissions factors.
Although the type of plants used in the NEI analysis is based on a
variety of reliable sources, including ICR responses for the Plating
and Polishing NESHAP, trade association data, data from State agencies,
and information from Web sites, we were unable to identify the plant
type for nearly half of the data set. For those plants of unknown type,
we used the highest emissions factor, which corresponds to a large hard
chromium plant, in the conservative analysis. For the supplemental
analysis, we developed an emissions factor using a weighted average
across all plant types and sizes. For all plants that were modeled, we
are soliciting additional information on actual and MACT-allowable
emissions, plant type, and plant size. More information about the
development of the model plants can be found in the Model Plant Data
Used to Estimate Risk from Chromium Electroplating Sources document
available in the docket for this action.
    In all the data sets, chromium compounds account for all the HAP
emissions from the Chromium Electroplating and Chromium Anodizing
source categories. For the Hard Chromium Electroplating source
category, in the NEI-based data set, chromium VI compounds account for
98 percent of the emissions, with chromium III and chromium trioxide
compounds comprising the remaining HAP. In both the NEI and model plant
emission estimates, we made the conservative assumption that 100
percent of the emissions are chromium VI compounds. For the Decorative
Chromium Electroplating source category, in the NEI-based data set,
chromium VI compounds account for 94 percent of the emissions, with
chromium III and chromium trioxide compounds comprising the remaining
HAP. In both emission estimates, we

made the conservative assumption that 100 percent of the emissions are
chromium VI compounds. For the Chromium Anodizing source category, in
the NEI-based data set, chromium VI compounds account for 99 percent of
the emissions with chromium III compounds comprising the remaining HAP.
In both emission estimates, we made the conservative assumption that
100 percent of the emissions are chromium VI compounds.
3. What are the results of the risk assessments and analyses?
    We conducted an inhalation risk assessment for each of the three
source categories: Hard Chromium Electroplating, Decorative Chromium
Electroplating, and Chromium Anodizing. Also, for each source category,
we conducted an assessment of facility-wide risk, and performed a
demographic analysis of population risks. As noted above, we developed
two data sets for these source categories, one based primarily on NEI
data for 166 sources, and one based on model plant data for 1,629
sources.
    The following tables present the combined results from the data
sets. Table A.1 provides an overall summary of the maximum individual
inhalation risk assessment results, and Table A.2 provides population
risk assessment results for the Hard Chromium Electroplating,
Decorative Chromium Electroplating, and Chromium Anodizing source
categories.

                         Table A.1--Chromium Electroplating and Anodizing Maximum Individual Inhalation Risk Assessment Results*
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Maximum individual     Maximum chronic non-cancer
                                                              cancer risk (in 1              TOSHI \3\
                                              Number of         million) \2\       ----------------------------
              Source category                 facilities --------------------------                             Maximum off-site acute non-cancer HQ \4\
                                              (NEI/model     Actual     Allowable      Actual       Allowable
                                              plant) \1\   emissions    emissions     emissions     emissions
                                                             level        level         level         level
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hard Chromium Electroplating...............     63/1,219           70           90         0.06          0.09   Not applicable \5\.
Decorative Chromium Electroplating.........       96/337           70           70         0.06          0.06   Not applicable \5\.
Chromium Anodizing.........................         7/73            5            5         0.004         0.004  Not applicable \5\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* All results are for impacts out to 50 km from each source in the categories.
\1\ Number of facilities evaluated in the risk analysis: the first number refers to the NEI data set, and the second number applies to the conservative
  emission estimate.
\2\ Maximum individual excess lifetime cancer risk.
\3\ Maximum TOSHI. The target organ with the highest TOSHI for the Hard Chromium Electroplating, Decorative Chromium Electroplating, and Chromium
  Anodizing source categories is the respiratory system.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values
  shown use the lowest available acute threshold value, which, in most cases, is the REL. When HQ values exceed 1, we also show HQ values using the next
  lowest available acute threshold. See section IV.A. of this preamble for explanation of acute threshold values.
\5\ NA = not applicable. There are no HAP with acute dose-response benchmark values, so no acute HQ were calculated for these source categories. See
  section IV.A of this preamble for an explanation of acute threshold values.

                           Table A.2--Chromium Electroplating and Anodizing Population Risk Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Conservative assessment      Conservative       Supplemental assessment      Supplemental
                                             Number of          population at risk         annual cancer        population at risk         annual cancer
             Source category                facilities   --------------------------------    incidence   --------------------------------    incidence
                                            (NEI/model       >= 1-in-1      >= 10-in-1      (cases per       >= 1-in-1      >= 10-in-1       (case per
                                              plant)          million         million          year)          million         million          year)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hard Chromium Electroplating............        63/1,219      14,200,000          71,000           0.8           360,000           5,100           0.1
Decorative Chromium Electroplating......          96/337         390,000           4,000           0.08           30,000           1,300           0.01
Chromium Anodizing......................            7/73           2,700               0           0.003             540               0           0.001
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As shown in Table A.1, the results of the inhalation risk
assessment for the Hard Chromium Electroplating source category
indicate the maximum lifetime individual cancer risk could be as high
as 70-in-1 million, based on actual emissions, and as high as 90-in-1
million based on allowable emissions. This maximum individual cancer
risk is based on the highest risk facility out of the 63 actual
facilities and the 1,219 model plants. The highest risk facility is one
for which we have design and operating data, and we believe it is also
both the largest and highest emitting hard chromium electroplating
facility in the United States. Thus, we believe this level accurately
reflects the maximum individual exposure. The maximum chronic non-
cancer TOSHI value could be 0.06, based on the actual emissions level,
and up to 0.09 based on allowables. This value is also based on known
emission levels from the largest facility in the nation. A non-cancer
TOSHI of one or less is not of human health concern.
    The total estimated national cancer incidence from hard chromium
electroplating facilities based on actual emission levels is 0.8 excess
cancer cases per year, or one case in every 1.25 years for the
conservative assessment. Our risk assessment shows 14.2 million people
exposed to a cancer risk greater than 1-in-1 million and 71,000 people
exposed to a cancer risk of at least 10-in-1 million.
    As noted above, we conducted a supplemental analysis to determine
the weight to give to the conservative risk analysis. That supplemental
analysis estimates 0.1 excess cancer cases per year, or one case in
every 10 years. Additionally, it estimates a population exposure of
360,000 people at 1-in-1 million cancer risk. For a cancer risk of at
least 10-in-1 million, the population exposed decreases to 5,100.
    Based on the 2005 NEI data set for the Decorative Chromium
Electroplating

source category, the maximum lifetime individual cancer risk could be
as high as 70-in-1 million, and the maximum chronic non-cancer TOSHI
value could be up to 0.06, based on the actual emissions level.\28\ We
do not believe the maximum lifetime individual cancer risk and the
maximum chronic non-cancer TOSHI value would be any higher than this
based on allowable emissions. The total estimated population risks from
the conservative risk assessment of the decorative chromium
electroplating facilities based on actual emission levels is 390,000
people exposed to a cancer risk greater than 1-in-1 million and 0.08
excess cancer cases per year, or one case in every 12 years.\29\
---------------------------------------------------------------------------

    \28\ There is uncertainty regarding the operating status of the
facility (reported to be closed) associated with the maximum
lifetime individual cancer risk. Prior to any final rulemaking
action, we will investigate this situation and revise the risk
analysis and results accordingly.
    \29\ Based on our conservative risk assessment, we believe the
risks are low, and, as explained further below, are proposing that
the risks are acceptable for the Decorative Chromium source
category. Although we did not need to consider the supplemental
analysis that we conducted for Decorative Chromium to help guide our
conclusion about the uncertainty of the risk assessment results, we
note that the supplemental assessment shows 30,000 people exposed to
a cancer risk greater than 1-in-1 million and 0.01 excess cancer
case per year, or one case in every 100 years.
---------------------------------------------------------------------------

    Based on the 2005 NEI data set for the Chromium Anodizing source
category, the maximum lifetime individual cancer risk could be as high
as 5-in-1 million and the maximum chronic non-cancer TOSHI value could
be up to 0.004, based on the actual emissions level. The total
estimated population risks from the conservative assessment of the
chromium anodizing facilities based on actual emission levels is 2,700
people exposed to a cancer risk greater than 1-in-1 million and 0.003
excess cancer cases per year, or one case in every 333 years.\30\
---------------------------------------------------------------------------

    \30\ Based on our conservative risk assessment, we believe the
risks are low, and, as explained further below, are proposing that
the risks are acceptable for the Chromium Anodizing source category.
Although we did not need to consider the supplemental analysis that
we conducted for Chromium Anodizing to help guide our conclusion
about the uncertainty of the risk assessment results, we note that
the supplemental assessment shows 540 people exposed to a cancer
risk greater than 1-in-1 million and 0.001 excess cancer case per
year, or one case in every 1,000 years.
---------------------------------------------------------------------------

    Also, as there were no reported emissions of PB-HAP for these three
source categories, we do not expect the potential for human health
multipathway risks or adverse environmental impacts.
    Our analyses of potential differences between actual emission
levels and emissions allowable under the MACT standards are based on
emissions test data from specific facilities. A comparison of these
test results to allowable emissions at these facilities indicates that
the ratio of MACT-allowable to actual emissions varies considerably
from facility to facility. As a result, a uniform factor was not
available to apply to all facilities. However, for the Hard Chromium
Electroplating source category, we did evaluate the facility that was
modeled as having the highest maximum individual lifetime cancer risk
(70-in-1 million) based on actual emissions. Our analysis indicates
that this facility, if operated at the allowable emissions limit, could
have a maximum individual lifetime cancer risk as high as 90-in-1
million. Furthermore, the available data indicate that no other hard
chromium electroplating facility would have a cancer risk that high if
operated at the allowable emissions limit.
    For the Decorative Chromium Electroplating source category, we
performed a similar analysis of the available data and concluded that
the maximum individual lifetime cancer risk would not exceed 70-in-1
million for any facility that operated at the allowable emissions
limit. As stated earlier, because most chromium anodizing facilities
use WAFS, we believe actual emissions are essentially the same as
allowable emissions. Thus, we believe that the MIR based on allowable
emissions would be the same as that based on actual emissions, i.e., 5-
in-1 million.
    Table A.3 displays the results of the facility-wide risk assessment
for actual emissions of all sources at the facility as reported in the
NEI. We did not perform a facility-wide risk assessment based on
allowable emissions, as explained in the documentation referenced in
section IV.A of this preamble, which is available in the docket for
this action.

             Table A.3--Chromium Electroplating and Anodizing Facility-Wide Risk Assessment Results
----------------------------------------------------------------------------------------------------------------
                                                                     Source                           Source
                                                                    category                         category
                                                     Maximum      contribution                     contribution
                                                  facility-wide      to this         Maximum          to this
                Source category                    individual        maximum      facility-wide       maximum
                                                   cancer risk    facility-wide    chronic non-    facility-wide
                                                 (in 1 million)    individual      cancer TOSHI    chronic non-
                                                                   cancer risk                     cancer TOSHI
                                                                       \1\                              \1\
----------------------------------------------------------------------------------------------------------------
Hard Chromium Electroplating...................              90            < 1%              2              < 1%
Decorative Chromium Electroplating.............              90              7%              0.8            < 1%
Chromium Anodizing.............................              20             75%              0.2            < 1%
----------------------------------------------------------------------------------------------------------------
\1\ Percentage shown reflects source category contribution to the maximum facility-wide risks at the facility
  with the maximum risk value shown.

    As shown in Table A.3, the maximum individual cancer risks from all
HAP emissions at facilities that perform hard chromium electroplating,
decorative chromium electroplating, and chromium anodizing are
estimated to be 90-in-1 million, 90-in-1 million, and 20-in-1 million,
respectively. For the facilities where these maximum risk values occur,
the estimated proportion of the cancer risk attributable to the hard
chromium electroplating, decorative chromium electroplating, and
chromium anodizing processes is less than 1 percent, 7 percent, and 75
percent, respectively. The highest facility-wide cancer risk for a
facility that includes a hard chromium electroplating source is
primarily driven by chemical production processes. We are currently
developing a chemical manufacturing sector project \31\ and plan to
address risk from these chemical production processes as part of that
action. The highest facility-wide cancer risk for a facility that
includes a decorative chromium electroplating

source is primarily driven by aerospace processes that will be
addressed in a future residual risk review for the Aerospace
Manufacturing and Rework Facilities source category. The highest
facility-wide cancer risk for a facility that includes a chromium
anodizing source is primarily driven by the chromium anodizing
processes. The facility-wide maximum chronic non-cancer TOSHI values
for facilities that include Hard Chromium Electroplating, Decorative
Chromium Electroplating, and Chromium Anodizing source category
processes are estimated to be 2, 0.8, and 0.2, respectively. At the
facilities where these maximum risk values occur, the estimated
proportion of the non-cancer risk attributable to the Hard Chromium
Electroplating, Decorative Chromium Electroplating, and Chromium
Anodizing source category processes is less than 1 percent for each
source category.
---------------------------------------------------------------------------

    \31\ This is one of several projects EPA is undertaking to
establish and implement national emission-control measures for
specific sectors of the economy by taking an integrated
multipollutant approach to assessing and implementing additional
emission controls using our existing regulatory frameworks.
---------------------------------------------------------------------------

    The results of the demographic analyses performed to investigate
the distribution of risks above 1-in-1 million, based on actual
emissions levels for the population living within 5 km of the
facilities, among various demographic groups are provided in a report
available in the docket for this action and summarized in Tables A.4,
A.5, and A.6 below. These estimates of total population with risk
exceeding 1-in-1 million differ from the risk estimates presented above
because the demographic analysis uses a 5 km radius and the risk
assessment results provided above reflect use of a 50 km radius around
all chromium electroplating facilities.

                                         Table A.4--Hard Chrome Electroplating Demographic Risk Analysis Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Population with risk greater than 1-in-1 million
                                       Maximum   -------------------------------------------------------------------------------------------------------
          Emissions basis            risk  (in 1                                          Other and                              Below the   Over 25  w/
                                       million)      Total     Minority  %    African    multiracial  Hispanic or     Native      poverty      o a  HS
                                                   (millions)                American %       %         Latino %    American %    level %     diploma %
--------------------------------------------------------------------------------------------------------------------------------------------------------
Nationwide.........................          n/a          285           25           12           12           14          0.9           13           13
Source Category....................           70         13.1           52           23           29           34          0.6           22           20
Facility-wide......................           90         13.1           52           23           29           34          0.6           22           20
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                     Table A.5--Decorative Chromium Electroplating Demographic Risk Analysis Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Population with risk greater than 1-in-1 million
                                       Maximum   -------------------------------------------------------------------------------------------------------
          Emissions basis            risk  (in 1                                          Other and                              Below the   Over 25  w/
                                       million)      Total      Minority %    African    multiracial  Hispanic or     Native      poverty      o a  HS
                                                   (millions)                American %       %         Latino %    American %    level %     diploma %
--------------------------------------------------------------------------------------------------------------------------------------------------------
Nationwide.........................          n/a          285           25           12           12           14          0.9           13           13
Source Category....................           70         0.35           50           18           32           47          0.8           24           23
Facility-wide......................           90         0.43           54           21           32           48          0.7           24           25
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                             Table A.6--Chromium Anodizing Demographic Risk Analysis Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Population with risk greater than 1-in-1 million
                                       Maximum   -------------------------------------------------------------------------------------------------------
          Emissions basis            risk  (in 1                                          Other and                              Below the   Over 25  w/
                                       million)      Total      Minority %    African    multiracial  Hispanic or     Native      poverty      o a  HS
                                                   (millions)                American %       %         Latino %    American %    level %     diploma %
--------------------------------------------------------------------------------------------------------------------------------------------------------
Nationwide.........................          n/a          285           25           12           12           14          0.9           13           13
Source Category....................            5       0.0027           36           16            0            0          0.4           25           19
Facility-wide......................           20       0.0079           22           10           12           13          0.8           19           16
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The results of the demographic analysis show that, for the
population located within 5 km of Hard Chromium Electroplating source
category, there are about 13.1 million people with cancer risks greater
than 1-in-1 million for both the source category and facility-wide. Of
this population at risk, 52 percent could be classified as a
``Minority,'' 34 percent are included in the ``Hispanic or Latino''
demographic group, 29 percent are included in the ``Other and
Multiracial'' demographic group, 23 percent are included in the
``African-American'' demographic group, 22 percent are included in the
``Below Poverty Level'' demographic group, and 20 percent are included
in the ``Over 25 Without a High School Diploma'' demographic group. The
percentage of the population within 5 km of a hard chromium
electroplating facility and with a cancer risk greater than 1-in-1
million is higher than the typical distribution of these demographic
groups across the United States. These demographic analyses are based
on the conservative assessment results.
    For the Decorative Chromium Electroplating source category, there
are about 350,000 people with cancer risks greater than 1-in-1 million
for the source category and 430,000 people with

cancer risks greater than 1-in-1 million facility-wide. Of this
population at risk, 50 percent could be classified as a ``Minority,''
47 percent are included in the ``Hispanic or Latino'' demographic
group, 32 percent are included in the ``Other and Multiracial,''
demographic group, 18 percent are included in the ``African-American''
demographic group, 24 percent are included in the ``Below Poverty
Level'' demographic group, and 23 percent are included in the ``Over 25
Without a High School Diploma'' demographic group. The percentage of
the population within 5 km of a decorative chromium electroplating
facility and with a cancer risks greater than 1-in-1 million is higher
than the typical distribution of these demographic groups across the
United States. The results of the demographic analysis for facility-
wide emissions are similar to the results for the source category.
    For the Chromium Anodizing source category, there are about 2,700
people with cancer risks greater than 1-in-1 million and 7,900 people
with cancer risks greater than 1-in-1 million facility-wide. Of the
population with cancer risks greater than 1-in-1 million, 36 percent
could be classified as a ``Minority,'' 16 percent are included in the
``African-American'' demographic group, 25 percent are included in the
``Below Poverty Level'' demographic group, and 19 percent are included
in the ``Over 25 Without a High School Diploma'' demographic group. The
percentage of the population within 5 km of a chromium anodizing
facility and with a cancer risk greater than 1-in-1 million is higher
than the typical distribution of these demographic groups across the
United States. The results of the facility-wide demographic analysis
are higher than the typical distribution of risks to the demographic
groups across the United States, for the ``Below Poverty Level'' and
the ``Over 25 Without a High School Diploma'' demographic groups, but
are lower than these levels for the other demographic groups.
    Details of these assessments and analyses can be found in the
residual risk documentation as referenced in section IV.A of this
preamble, which is available in the docket for this action.
4. What are our proposed decisions on risk acceptability and ample
margin of safety?
a. Risk Acceptability
    The risk analysis we performed for this proposal indicates that for
the Hard Chromium Electroplating source category, the cancer risks to
the individual most exposed is 70-in-1 million based on actual
emissions and 90-in-1 million based on MACT-allowable emissions. The
maximum non-cancer risk level, which is low, is a TOSHI of 0.06 based
on actual emissions and 0.09 based on allowable emissions. These risks
are due to estimated emissions of hexavalent chromium, which EPA
describes as a known human carcinogen by the inhalation route of
exposure. As explained above, both the MIR and the maximum non-cancer
risk levels are based on emissions from what we believe is the highest
risk hard chromium facility operating in the United States.
    We further estimate that the excess cancer incidence could be as
high as 0.8 cases per year, and that over 14 million people could be
exposed to a cancer risk of 1-in-1 million or greater. These risk
levels are based on a highly conservative risk assessment as described
above. In summary, in this assessment we used (1) actual emissions data
for 63 facilities and (2) emissions estimates that are reflective of
average emissions for the highest emitting facilities for each one of
an additional 1,219 facilities not in the original dataset. Because
there are only 790 hard chromium facilities, and because only ten
percent of the facilities would have this high an emissions rate, we
believe that these conservative risk assessment results overstate
cancer incidence and population exposure.
    As noted above, we performed a supplemental analysis to assess the
degree to which the conservative risk assessment may overstate risks,
and, thus, to determine how heavily to weigh those risks in determining
whether to find the risks acceptable. In this supplemental analysis we
assessed these risks based on (1) the emissions data used in the
conservative assessment for the 63 facilities for which we have actual
facility emission information, and (2) revised emission data that
better represent nationwide average emission levels for the 1,219
facilities. The supplemental assessment indicates that the excess
cancer risks from hard chromium electroplating facilities is 0.1 cancer
cases per year and 360,000 people exposed to a cancer risk of 1-in-1
million or more, which is substantially less than we found with the
conservative assessment. These results indicate that the estimated
risks are uncertain and are highly sensitive to input assumptions and
that the conservative assessment may substantially overstate risks.
    The results of our demographic analysis indicate that minorities
face disproportionate risks \32\ from exposure to emissions from this
category (Tables A.4-A.6). Although the demographic analysis was based
on our conservative risk assessment modeling, we have no reason to
believe that the results would be substantially different were we to
re-run that analysis using the assumptions underlying the supplemental
assessment. This is because the disparate impacts identified through
our demographic analysis are reflective of the fact that many chrome
facilities are located in inner city urban areas, and in or near
residential neighborhoods more likely to be inhabited by minority and
low income persons. We are concerned about the potential
disproportionate health risks from these urban facilities on minorities
and those below the poverty level. We solicit comment on whether there
may be pollution prevention efforts or other HAP emission reduction
approaches that could mitigate the impacts that these facilities have
on their immediate surroundings. We also recognize that, in addition to
whatever controls are required in the final rulemaking for the Hard
Chromium Electroplating source category, there may be other approaches,
such as facility-specific compliance assistance, that could mitigate
the impacts that these facilities have on their immediate surroundings.
We solicit comment and supporting information to assist EPA in
identifying measures to mitigate these disproportionate risks.
---------------------------------------------------------------------------

    \32\ Using census data on race and ethnicity, we estimated the
percentage of people in the United States that are minority. We also
estimated the percentage of people that live within 5 km of each
facility and have cancer risks greater than 1-in-1 million that are
minority. Where the percentage of people at risk is higher than the
percentage nationwide, those minorities face disproportionate risks.
---------------------------------------------------------------------------

    In accordance with the approach established in the Benzene NESHAP,
EPA weighed all health risk measures and information, including the
maximum individual cancer risk, the cancer incidence, the number of
people exposed to a risk greater than 1-in-1 million, the distribution
of risks in the exposed population, and the uncertainty of our risk
calculations in determining whether the risk posed by emissions from
hard chromium facilities is acceptable.
    As an initial matter, we note that the 90-in-1 million risk based
on allowable emissions is approaching the ``presumptive limit on
maximum individual lifetime risk of approximately 1-in-10 thousand
[100-in-1 million]'' recognized in the Benzene NESHAP (54 FR 38045). We
also note

that, based on our conservative analysis, there is a high level of
cancer incidence of 0.8 excess cancer cases per year nationwide, and a
very large number (14.2 million) of people potentially exposed to a
cancer risk greater than 1-in-1 million.\33\ However, we also recognize
that our supplemental assessment based on alternative input assumptions
concerning emissions (that better represent nationwide average
emissions) indicate that the results of the conservative assessments
are substantially overstated. Thus, there is great uncertainty about
both the cancer incidence and the number of people exposed.
---------------------------------------------------------------------------

    \33\ These comparisons refer to estimates of incidence and
populations from risk assessments performed for other source
categories previously covered by RTR risk assessments.
---------------------------------------------------------------------------

    On the one hand, we acknowledge that the cancer incidence and
number of people exposed to cancer risks of 1-in-1 million or greater
are high based on our conservative analysis. On the other hand, we
recognize the significant uncertainty of these risk estimates and the
likelihood that they are overstated, based on the conservative nature
of the assessment. The supplemental analysis highlights the sensitivity
of our risk analysis to highly uncertain input assumptions and supports
a determination that the population exposure and cancer incidence risk
numbers are overstated. It shows substantially lower cancer incidence
(0.1 excess cases per year nationwide as opposed to 0.8) and number of
people potentially exposed to a cancer risk of 1-in-1 million or more
(360 thousand as opposed to 14.2 million). In addition, the
distribution of risks in the exposed population shows the number of
people exposed to a cancer risk greater than 10-in-1 million is 71,000
for the conservative assessment and 5,100 for the supplemental
analysis.
    In determining whether risk is acceptable, we focus on the results
of all aspects of the risk assessment. Because the MIR is less than
100-in-1 million, and because of the significant uncertainty of the
cancer incidence and number of people exposed, which we believe are
overstated based on the fact that our risk analysis was highly
conservative, at this time, we are proposing that the risks from the
Hard Chromium Electroplating source category are acceptable. We are
proposing that the risks are acceptable, in large part, because we
believe that the assumptions underlying the supplemental analysis may
present a more realistic estimate of the emissions from hard chromium
facilities.
    However, we are very concerned by the results of our conservative
risk analysis, especially the large number of people (including
disproportionately affected populations) estimated to be exposed at a
cancer risk above 1-in-1 million. We are also concerned about the level
of uncertainty with our analysis given that we have very limited
information as to the number (and size) of the facilities. While our
current proposal is supported by recognizing the uncertainty associated
with the high risk levels from our conservative assessment and, as
explained above, that uncertainty (as demonstrated by the supplemental
analysis) points in the direction of an overstatement of risk, we would
prefer to base a final rule on more complete and reliable information.
The purpose of the residual risk standards under CAA section 112(f) is
to ensure protection of public health and the environment. Thus, we
believe it is important to develop a conservative risk analysis and err
on the side of potential overestimation of risk analyses where we are
missing data. In this case, we recognize that the assessment may be
overly conservative, and we are considering additional methods for
performing a conservative analysis. However, we believe additional
information and data regarding the location, type and size of
facilities will be important to performing any additional analysis that
would err on the side of protectiveness without being overly
conservative. At this time, we are not certain that we would take final
action finding the risk to be acceptable based on the limited
information currently available to the Agency.
    The comments and information that we receive on this proposal will
be critical in making a final decision on acceptability. We are
soliciting comment and data to help the Agency make an informed
decision as it moves forward with this rulemaking. Specifically, with
regard to each of the facilities listed in Appendix A to this preamble,
we are seeking to identify (1) the actual annual emissions, if known;
(2) which of the three source categories it falls within; and (3)
whether, for hard chromium, it is a ``large'' or ``small'' facility
within the definitions in 40 CFR 63.341(a). In particular, we are
encouraging the States to provide EPA with better inventory data for
sources within their States. Moreover, we are encouraging States to
help identify sources that may be located near sensitive populations or
other populations of concern, such as located near schools or that may
be located in communities with a significant minority population. To
feel comfortable with a final decision finding the risk acceptable, we
believe it is important to reduce the level of uncertainty associated
with our current analyses. Thus, in light of the comments and any
additional data (or lack thereof) that we receive during the comment
period, we may determine that it is appropriate to issue a supplemental
proposal in which we propose to find the risk unacceptable. If we issue
a supplemental proposal in which we propose to find the risk
unacceptable, we would be required to propose emissions standards or
work practices that reduce risk to a level that is acceptable and
provides an ample margin of safety.
    For the Decorative Chromium Electroplating source category, the
cancer risks to the individual most exposed is 70-in-1 million, based
on both actual and MACT-allowable emissions. Based on this cancer risk
level and in consideration of other health measures and factors,
including the cancer incidence (one case in every 12.5 years) and the
low maximum non-cancer risk level (TOSHI of 0.06 based on both actual
and MACT-allowable emissions), we propose that the risks from the
Decorative Chromium Electroplating source category are acceptable.
    For the Chromium Anodizing source category, the cancer risks to the
individual most exposed is 5-in-1 million, based on both actual and
allowable emissions. Based on this low cancer risk level and in
consideration of other health measures and factors, including the
cancer incidence (one case in every 250 years) and the low maximum non-
cancer risk level (TOSHI of 0.004 based on actual emissions), we
propose that the risks from the Chromium Anodizing source category are
acceptable.
b. Ample Margin of Safety
    Although we are proposing that the risks from these source
categories are acceptable, risk estimates for individuals in the
exposed population are above 1-in-1 million. Consequently, we
considered whether the MACT standard provides an ample margin of
safety. As part of this analysis, we investigated available emissions
control options that might reduce the risk associated with chromium
compound emissions from the nationwide estimated 1,770 hard chromium
electroplating, decorative chromium electroplating, and chromium
anodizing operations. Once we identified the available emissions
control options, we estimated the cost of these options and

estimated the emission reduction associated with each control option.
To determine controlled baseline emissions nationwide, assumptions were
made about the numbers and types of emission control technologies in
use, and the control efficiencies achieved by those technologies. The
distribution of emission control methods among the various types of
chromium electroplating plants and plant sizes was estimated based on
general knowledge of the industry. Table A.7 summarizes the nationwide
costs and cost-effectiveness of these regulatory control options.

                                             Table A.7--Costs of Control Options for Chromium Electroplating
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Annualized      Cost-
                                                                           Number of     Emission     Capital       costs     effectiveness   MIR after
           Type of facility                      Control option             affected    reduction      costs      ($million/    ($million/   control (in-
                                                                           facilities     (TPY)      ($million)      yr)           ton)       1-million)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Large hard chromium electroplating....  HEPA filter retrofit............          132          1.0         35.1         18.4          36.3             6
Small hard chromium electroplating....  HEPA filter retrofit............          658          0.4         66.0         33.9          59.3             6
                                        CMP retrofit....................          392          0.2         36.6         11.1          33.1            10
Decorative chromium electroplating....  HEPA filter retrofit............          740          0.1        109.0         47.8           486             4
                                        CMP retrofit....................          644     \1\ 0.05         63.1         17.1           367            10
Chromium anodizing....................  HEPA filter retrofit............          240         0.02         43.9         17.9           895           < 1
                                        CMP retrofit....................          198    \1\ 0.009         22.9          5.6           649             2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on an estimated control efficiency of 99.9 percent.

    For large hard chromium electroplating facilities, we evaluated the
costs and emissions reductions associated with retrofitting existing
tanks with HEPA filters. For small hard chromium electroplating
facilities, we evaluated the same HEPA filter retrofit option, and also
the option of retrofitting CMP systems on all tanks currently
controlled with packed bed scrubbers. Retrofitting HEPA filters on
existing tanks at large hard chromium electroplating plants would
reduce nationwide emissions of chromium compounds by an estimated 1.0
TPY from the estimated baseline level of 1.10 TPY. The estimated
capital and annualized costs for this option would be $35,100,000 and
$18,430,000, respectively. The cost-effectiveness would be $36,300,000
per ton of HAP emissions reduced. Retrofitting HEPA filters on existing
tanks at small hard chromium electroplating plants would reduce
nationwide emissions of chromium compounds by an estimated 0.40 TPY
from the estimated baseline level of 0.42 TPY. The estimated capital
and annualized costs for this option would be $65,980,000 and
$33,860,000, respectively. The cost-effectiveness would be $59,300,000
per ton of HAP emissions reduced. Retrofitting CMP systems on all tanks
currently controlled with packed bed scrubbers at small hard chromium
electroplating plants would reduce nationwide emissions of chromium
compounds by an estimated 0.19 TPY from the estimated baseline level of
0.37 TPY. The estimated capital and annualized costs for this option
would be $36,640,000 and $11,050,000, respectively. The cost-
effectiveness would be $33,100,000 per ton of HAP emissions reduced.
The Benzene NESHAP emphasize the need to consider ``costs and the
economic impacts of control,'' which implies some knowledge of
affordability (54 FR 38046). The cost of the control options for hard
chromium electroplating would impact over half of these facilities with
estimated cost to sales ratios ranging from 8 percent to 22 percent. A
cost to sales ratio greater than 3 percent may have a significant
impact, including plant closure for many of these facilities.
    These additional control requirements would reduce the maximum
lifetime individual cancer risk from the Hard Chromium Electroplating
source category to approximately 4-in-1 million, based on actual
emissions. We estimate that, considering MACT-allowable emissions
levels, the maximum lifetime individual cancer risk from the Hard
Chromium Electroplating source category would be reduced to
approximately 6-in-1 million. The cancer incidence would be reduced to
approximately 0.05 and the estimated number of people exposed higher
than 1-in-1 million would be about 1 million.
    For decorative chromium electroplating, we evaluated the options of
retrofitting HEPA filters on all existing tanks and the option of
retrofitting CMP systems on the existing tanks that currently are not
equipped with add-on control devices. Retrofitting HEPA filters on all
existing decorative chromium electroplating tanks would reduce
nationwide emissions of chromium compounds by an estimated 0.098 TPY
from the estimated baseline level of 0.10 TPY. The estimated capital
and annualized costs for this option would be $108,970,000 and
$47,800,000, respectively. The cost-effectiveness would be $486,000,000
per ton of HAP emissions reduced. Retrofitting CMP systems on all
decorative chromium electroplating tanks that currently do not have
add-on controls would reduce nationwide emissions of chromium compounds
by an estimated 0.05 TPY from the estimated baseline level of 0.10 TPY.
The estimated capital and annualized costs for this option would be
$63,100,000 and $17,100,000, respectively. The cost-effectiveness for
this option would be $367 million per ton of HAP emissions reduced. The
additional control requirements for HEPA filters would reduce the
maximum lifetime individual cancer risk from the Decorative Chromium
Electroplating source category to approximately 4-in-1 million, based
on actual emissions. Because we believe the actual emissions are
essentially the same as the MACT-allowable emissions for the Decorative
Chromium Electroplating source category, we estimate no difference
between the risks from the allowable emission level and the actual
emission level.
    For chromium anodizing, we evaluated the options of retrofitting
HEPA filters on all existing tanks and the option of retrofitting CMP
systems on the existing tanks that currently are not equipped with add-
on control devices. Retrofitting HEPA filters on all existing chromium
anodizing tanks

would reduce nationwide emissions of chromium compounds by an estimated
0.020 TPY from the estimated baseline level of 0.021 TPY. The estimated
capital and annualized costs for this option would be $43,860,000 and
$17,900,000, respectively. The cost- effectiveness would be
$895,000,000 per ton of HAP emissions reduced. Retrofitting CMP systems
on all chromium anodizing tanks that currently do not have add-on
controls would not significantly reduce emissions. The estimated
capital and annualized costs for this option would be $22,900,000 and
$5,600,000, respectively. The cost-effectiveness for this option would
be $649 million per ton of HAP emissions reduced. The additional
control requirements for HEPA filters would reduce the maximum lifetime
individual cancer risk from the Chromium Anodizing source category to
less than 1-in-1 million, based on actual emissions. Because we believe
the actual emissions are essentially the same as the MACT-allowable
emissions for the Chromium Anodizing source category, we estimate the
risk reduction based on allowable emissions to be the same as that for
the actual emissions.
    Our risk analysis results show cancer risks to the individual most
exposed of 70-in-1 million and 5-in-1 million based on actual and MACT-
allowable emissions, respectively, for the Decorative Chromium
Electroplating and Chromium Anodizing source categories. For both of
these categories, the cancer incidence is less than 0.01 cases per
year. For decorative chromium electroplating, the number of people
exposed to a cancer risk of 1-in-1 million or more is approximately
390,000. For chromium anodizing, the number of people exposed to a
cancer risk of 1-in-1 million or more is approximately 2,700.
    For the Hard Chromium Electroplating source category, our risk
analysis shows cancer risks to the individual most exposed are 70-in-1
million based on actual emissions levels and 90-in-1 million based on
MACT-allowable emissions. The cancer incidence for this source category
could be as high as 0.8 cases per year, and could be over 14 million
people exposed to cancer risks of 1-in-1 million or greater due to
emissions from hard chromium electroplating sources using highly
conservative assumptions. As we stated previously, we believe we
overestimated hard chromium electroplating emissions, the number of
plants that perform hard chromium electroplating, and, therefore, that
the risks from the resulting analyses are also overstated. Our
supplemental risk analysis for this source category indicates a cancer
incidence of 0.1 cases per year and 360,000 people exposed to cancer
risks of greater than 1-in-1-million. This analysis indicates that the
risk levels in the assessment are highly uncertain and err on the side
of being conservative.
    Our analyses also show that, for these source categories, there is
no potential for an adverse environmental effect or human health
multipathway effects, and that acute and chronic non-cancer health
impacts are unlikely. Our additional analysis of facility-wide risks
showed that the maximum facility-wide cancer risk is 90-in-1 million,
and that the maximum chronic non-cancer risks are unlikely to cause
health impacts. Our additional analysis of the demographics of the
exposed population shows that minorities face disproportionate risk
from exposure to emissions from this category
    We do not believe there is a significant risk reduction from the
housekeeping measures we are proposing under CAA section 112(d)(6).
However, we are requesting information on any risk reductions from
these housekeeping practices and whether we should consider adopting
these practices under CAA section 112(f)(2).
    We considered all these factors in our ample margin of safety
decision, and concluded that the costs of the options analyzed are not
reasonable considering the emissions reductions and cancer health
benefits potentially achievable with the controls. As a result, we
propose that the existing MACT standard provides an ample margin of
safety (considering cost, technical feasibility, and other factors) to
protect public health for all three of these source categories. Thus,
we are proposing to re-adopt the existing MACT standard to satisfy
section 112(f) of the CAA.
    While we propose that the existing MACT standard for the Hard
Chromium Electroplating source category is acceptable and provides an
ample margin of safety, we are proposing additional requirements under
CAA section 112(d)(6), as discussed below. Notwithstanding our proposal
that the risks are acceptable, we remain concerned that up to 14.2
million people may be exposed to cancer risks of 1-in-1 million or
greater, and that there are disparities in risks for some demographic
groups. While we are rejecting the option of adding HEPA filters or CMP
as not cost-effective, we are specifically requesting comment on
whether there are any cost-effective controls that may be able to
reduce these risks. In particular, we are requesting States to identify
any controls they have already required for these facilities, any
controls they are currently considering, or any other controls of which
they may be aware. We are also soliciting comment on whether our cost
estimates for these options are accurate and whether these controls may
be more cost-effective.
    In summary, we propose that the risks posed by these source
categories are acceptable. We are also proposing that the current MACT
standard provides an ample margin of safety to protect public health
based on our conclusion that the controls available are not cost-
effective in light of the additional health protection the controls
would provide. Thus, we are proposing to re-adopt the existing MACT
standard to satisfy section 112(f) of the CAA.
5. What is our proposed decision on the technology review?
    To evaluate developments in practices, processes, and control
technologies for the chromium electroplating source categories, several
activities were performed. Public comments received on the proposed
2002 amendments to the Chromium Electroplating MACT standards (67 FR
38810, June 5, 2002) were reviewed to determine whether they identified
any developments in practices, processes, or control technologies that
warrant further consideration. A review was performed of the supporting
documentation for the 2007 amendments to California's Airborne Toxic
Control Measure (ATCM) for Chromium Plating and Chromium Anodizing
Facilities. Finally, searches of the RBLC and the Internet were
conducted to identify other practices, processes, or control
technologies that could be applied to chromium electroplating.
    The 2004 amendments to the Chromium Electroplating MACT standards
addressed three specific technology developments that occurred
following promulgation of the original MACT standard: The use of WAFS
for hard chromium electroplating emission control; instrumental
differences in surface tension measurements for demonstrating
compliance with electroplating bath surface tension limits; and
enclosing hoods for electroplating tanks. Because those technology
developments have already been addressed and we are not aware of any
improvements to them, they are not discussed further. The following
paragraphs describe all developments in practices, processes, and
control technologies that we identified and that

were thus considered for the technology review, along with our
conclusions.
a. Emission Elimination Device
    An emission elimination device (EED), which is also referred to as
a ``Merlin cover,'' consists of a tank cover that includes a porous
membrane that allows gases to escape, but captures droplets and mist
emanating from the electroplating tank. While these tank covers are
available, we do not believe any chromium electroplating or anodizing
facilities are currently using an EED due to the impracticality of
covering the electroplating tank while plating is underway. Because
these devices are not known to be used in this industry and because it
is unclear that they are feasible for these operations, we concluded
that it is not necessary to revise the MACT standard to require this
control under section 112(d)(6). However, we request comment on tanks
or processes in which an EED could practicably be used by chromium
electroplating or anodizing facilities.
b. HEPA Filters
    Although HEPA filters have been on the market for decades, they
were not considered to be a practical control method for electroplating
tank emissions when the MACT standards were developed due to potential
problems with clogging and the availability of several other types of
mist eliminator technologies that had been proven to be effective in
reducing emissions from electroplating tanks. However, in the past
decade, facilities in California have increasingly used HEPA filters to
meet the emission limits of the State's ATCM for Chromium Plating and
Chromic Acid Anodizing Facilities. In October 2007, the California Air
Resources Board (CARB) amended the ATCM to further tighten emission
limits and to require HEPA filters on all new chromium electroplating
and anodizing tanks. In those applications, HEPA filters act as a
second stage of control, with the first stage generally consisting of a
mesh pad mist eliminator or other device that removes large particles
from the exhaust stream prior to the HEPA filter. Discussions with
State and local agency staff in California indicate no technological
problems with using HEPA filters for chromium electroplating emissions
control. As part of this technology review, HEPA filters have been
considered as a possible control option for sources subject to the
Chromium Electroplating MACT standards. The costs of requiring HEPA
filters were estimated, and are discussed above in section V.A.4.b of
this preamble. In light of the high cost of this option as compared
with the risk reductions it would achieve, we are proposing that it is
not necessary to revise the MACT standard under section 112(d)(6) to
require HEPA filters. However, we request comment on whether we should
require HEPA filters for new source MACT.
c. Wetting Agent Fume Suppressants (WAFS)
    The MACT standard allows the use of WAFS as a compliance
alternative for meeting the applicable emission limit. WAFS are used in
most decorative chromium electroplating and chromium anodizing tanks
and in many hard chromium electroplating tanks for emission control.
Historically, the most effective types of WAFS have been based on
perfluorooctyl sulfonate (PFOS). The PFOS-based WAFS used in the
chromium electroplating industry are part of a family of chemical
compounds categorized as long-chain perfluorinated chemicals (PFC). As
noted in a 2010 California Office of Health Hazard Assessment report,
Perfluorooctane sulfonate (PFOS) and Its Salts and Transformation and
Degradation Precursors,\34\ these compounds have persistent,
bioaccumulative, and toxic characteristics and are a particular concern
for children's health.
---------------------------------------------------------------------------

    \34\ This report is available at http://www.oehha.org/prop65/
CRNR_notices/pdf_zip/070910_PFOS_CIC.pdf.
---------------------------------------------------------------------------

    Over the last several years there have been developments associated
with the use of WAFS as a compliance alternative. There are now several
types of WAFS on the market that do not include PFOS chemicals and have
been proven effective for use in hard chromium and decorative chromium
electroplating baths that we believe are cost-effective. Furthermore,
these non-PFOS WAFS are not associated with any known adverse health
effects. Although the non-PFOS WAFS have not been used extensively in
the chromium anodizing industry, we are not aware of any technical
reasons to preclude their use and effectiveness for chromium anodizing
baths. However, we seek comment on this, as well as on our assessment
that their use is cost-effective. Because of the adverse non-air
quality health and environmental impacts associated with using PFOS-
based WAFS (i.e., the increasing concern over the presence of long-
chain PFC in the environment), we are proposing under CAA section
112(d)(6) to revise the scope of the compliance alternative to no
longer allow the addition of PFOS-based WAFS to tanks as a control
method for these source categories. We solicit comment on all aspects
of this change, including the non-air quality health and environmental
impacts associated with using PFOS based WAFS.
    For new sources, we are proposing that no PFOS-based WAFS could be
used upon startup. For existing sources, we are proposing that no PFOS-
based WAFS could be added to the electroplating or anodizing tanks
beginning 3 years after promulgation of the final amendments; however,
the tanks may continue operating with the remaining PFOS-based WAFS in
them after that date until it is depleted. Under these amendments,
these requirements would be specified in 40 CFR 63.342(c)(1)(iv) and
(2)(vi) for hard chromium electroplating tanks, 40 CFR 63.342(d)(3) for
decorative chromium electroplating and chromium anodizing tanks, and 40
CFR 63.342(e)(2) for decorative chromium electroplating tanks that use
a trivalent chromium bath. A definition of PFOS-based fume suppressants
also would be added to 40 CFR 63.341.
d. Housekeeping Procedures
    We are also proposing under CAA section 112 (d)(6) to incorporate
several housekeeping requirements into 40 CFR 63.342(f). In our review
of the 2007 amendments to California's ATCM for Chromium Plating and
Chromic Acid Anodizing Facilities, we found this rule required several
housekeeping procedures that were not included in the housekeeping
procedures required by the Chromium Electroplating MACT standards.
These measures would potentially reduce fugitive chromium emissions
from chromium electroplating and anodizing operations. In view of the
implementation of these procedures in California and the potential for
fugitive emissions reductions, we are proposing to add these procedures
to the Chromium Electroplating MACT standards. The proposed
housekeeping procedures would include storage requirements for any
substance that contains hexavalent chromium as a primary ingredient;
controls for the dripping of bath solution resulting from dragout;
splash guards to minimize overspray and return bath solution to the
electroplating or anodizing tank; a requirement to promptly clean up or
contain all spills of any substance containing hexavalent chromium;
requirements for the routine cleaning or stabilizing of storage and
work surfaces, walkways, and other surfaces potentially contaminated
with hexavalent chromium; a requirement to

install a barrier between all buffing, grinding, or polishing
operations and electroplating or anodizing operations; and requirements
for the storage, disposal, recovery, or recycling of chromium-
containing wastes. The proposed housekeeping procedures would be listed
in a new Table 2 to 40 CFR 63.342. In addition, this proposed action
would require owners and operators to incorporate these housekeeping
procedures in the facility Operation and Maintenance Plan specified in
section 40 CFR 63.342(f)(3) and implement them, and a new definition
would be added to 40 CFR 63.341(a) to clarify what is meant by the term
``contains hexavalent chromium as a primary ingredient.'' The proposed
compliance date for implementing the housekeeping procedures would be 6
months after promulgation of the final amendments.
6. What are the other actions we are proposing?
a. SSM Provisions
    Consistent with Sierra Club v. EPA, EPA is proposing that standards
in this rule would apply at all times. The existing MACT standards for
these three source categories already specifies that the emission
limitations apply ``during periods of startup and shutdown'' but not
during malfunctions. We are proposing to revise this paragraph to
remove the sentence indicating that the emission limitations do not
apply during malfunctions. We are maintaining the malfunction-
associated reporting and recordkeeping requirements in 40 CFR 63.346
and 40 CFR 63.347 with minor revisions. We are proposing to add
language to 40 CFR 63.344(a) to clarify the conditions during which
performance tests shall be conducted and to specify in Table 1 that the
performance test specifications in 40 CFR 63.7(e)(1) of the General
Provisions do not apply. We are also proposing to add a general duty
provision to minimize emissions into 40 CFR 63.342(a)(1). In addition,
we are proposing to promulgate an affirmative defense against civil
penalties for exceedances of emission standards caused by malfunctions,
as well as criteria for establishing the affirmative defense. EPA has
attempted to ensure that we have not incorporated into the proposed
regulatory language any provisions that are inappropriate, unnecessary,
or redundant in the absence of the SSM exemption. We are specifically
seeking comment on whether there are any such provisions that we have
inadvertently incorporated or overlooked.
b. Rule Improvements
    In addition, we identified the need for revisions of the standards
to correct editorial errors, make clarifications, or address issues
with implementation or determining compliance with the rule provisions.
    Monitoring and Testing Requirements. We are proposing to revise 40
CFR 63.344(e), which addresses compliance provisions for multiple
sources controlled by a common add-on air pollution control device.
This section of the MACT standard references testing by Method 306,
without any mention of Method 306A. Since Method 306A is an alternative
to Method 306, we are proposing to revise section 40 CFR 63.344(e) to
clarify that testing can be performed by either Method 306 or Method
306A.
    To correct inconsistencies between the amendments made to 40 CFR
part 63, subpart N in 2004 (69 FR 42885) and Method 306B, we are
proposing to revise Method 306B, which specifies procedures for
measuring the surface tension of chromium electroplating and anodizing
baths. In addition, the proposed amendments would help to ensure that
surface tension measurements made using stalagmometers are accurate.
Under the proposed amendments, section 1.2 of Method 306B would be
revised to clarify that the method also applies to hard chromium
electroplating tanks. Section 11.1 would be revised to include
procedures for checking the accuracy of, and cleaning, a stalagmometer
before using the stalagmometer to measure surface tension. The proposed
revisions to section 11.1 are consistent with the CARB ATCM for
Hexavalent Chromium for Decorative and Hard Chrome plating and Chromic
Acid Anodizing Facilities. Maintaining surface tension measuring
devices is critical for obtaining accurate measurements. Method 306B
currently references standard procedures for the use of tensiometers
(ASTM Method D 1331-89), but not for the use of stalagmometers. The
proposed amendment to section 11.1 would help to ensure that
stalagmometers used to demonstrate compliance with surface tension
limits are maintained and used properly. Finally, section 11.2 would be
revised to account for the differences in surface tension limits,
depending on the type of instrument used (tensiometer or
stalagmometer).
    Rule Corrections. To eliminate a discrepancy between the Chromium
Electroplating MACT standards in subpart N of part 63 and the General
Provisions in subpart A of part 63, this proposed action would also
revise the trigger for semiannual compliance reports specified in 40
CFR 63.347(h)(2)(A) to be consistent with the trigger specified in the
General Provisions. Subpart N currently provides that a semiannual
report must be submitted if both the duration of excess emissions
exceeds 1 percent of the source operating time and the duration of air
pollution control device malfunctions exceeds 5 percent of the source
operating time during the reporting period; however, 40 CFR
63.10(e)(3)(viii) of the General Provisions requires submitting a
semiannual report if either condition occurs. We are proposing to
revise 40 CFR part 63, subpart N to require semiannual reports to be
submitted if either condition occurs.

B. What are the results and proposed decisions for the Group I Polymers
and Resins Production source categories?

    The National Emission Standards for Hazardous Air Pollutant
Emissions: Group I Polymers and Resins were promulgated on September 5,
1996 (62 FR 46925), and codified at 40 CFR part 63, subpart U. The
Polymers and Resins I MACT standard applies to major sources and
regulates HAP emissions from nine source categories: Butyl Rubber
Production, Epichlorohydrin Elastomers Production, Ethylene Propylene
Rubber Production, Hypalon\TM\ Production, Neoprene Production, Nitrile
Butadiene Rubber Production, Polybutadiene Rubber Production,
Polysulfide Rubber Production, and Styrene Butadiene Rubber and Latex
Production.
    The Polymers and Resins I MACT standards regulate HAP emissions
resulting from the production of elastomers (i.e., synthetic rubber).
An elastomer is a synthetic polymeric material that can stretch to at
least twice its original length and then return rapidly to
approximately its original length when released. Elastomers are
produced via a polymerization/copolymerization process, in which
monomers undergo intermolecular chemical bond formation to form a very
large polymer molecule. Generally, the production of elastomers entails
four processes: (1) Raw material (i.e., solvent) storage and refining;
(2) polymer formation in a reactor (either via the solution process,
where monomers are dissolved in an organic solvent, or the emulsion
process, where monomers are dispersed in water using a soap solution);
(3) stripping and material recovery; and (4) finishing (i.e., blending,
aging, coagulation, washing, and drying).

    Sources of HAP emissions from elastomers production include raw
material storage vessels, front-end process vents, back-end process
operations, wastewater operations, and equipment leaks. The ``front-
end'' processes include pre-polymerization, reaction, stripping, and
material recovery operations; and the ``back-end'' process includes all
operations after stripping (predominately drying and finishing).
Typical control devices used to reduce organic HAP emissions from
front-end process vents include flares, incinerators, absorbers, carbon
adsorbers, and condensers. In addition, hydrochloric acid formed when
chlorinated organic compounds are combusted are controlled using
scrubbers. Emissions from storage vessels are controlled by floating
roofs or by routing them to a control device.
    While emissions from back-end process operations can be controlled
with control devices such as incinerators, the most common method of
reducing these emissions is the pollution prevention method of reducing
the amount of residual HAP that is contained in the raw product going
to the back-end operations. Emissions from wastewater are controlled by
a variety of methods, including equipment modifications (e.g., fixed
roofs on storage vessels and oil water separators; covers on surface
impoundments, containers, and drain systems), treatment to remove the
HAP (steam stripping, biological treatment), control devices, and work
practices.
    Emissions from equipment leaks are typically reduced by leak
detection and repair work practice programs, and in some cases, by
equipment modifications. Each of the seven Group I Polymers and Resins
Production source categories addressed in this proposal are discussed
further below.
1. Epichlorohydrin Elastomers Production
    Epichlorohydrin Elastomers Production is one of the source
categories for which we proposed RTR decisions on October 10, 2008.
a. Overview of the Source Category
    Epichlorohydrin elastomers are prepared from the polymerization or
copolymerization of epichlorohydrin or other monomers. Epichlorohydrin
elastomers are produced by a solution polymerization process, typically
using toluene as the solvent in the reaction. The main epichlorohydrin
elastomers are polyepichlorohydrin, epi-ethylene oxide (EO) copolymer,
epi-allyl glycidyl ether (AGE) copolymer, and epi-EOAGE terpolymer.
Epichlorohydrin elastomers are widely used in the automotive industry.
    We identified one currently operating epichlorohydrin elastomers
production facility subject to the Polymers and Resins I MACT standard.
Toluene accounts for the majority of the HAP emissions from the
epichlorohydrin elastomers production processes at this facility
(approximately 44 TPY and 99 percent of the total HAP emissions by
mass). This facility also reported relatively small emissions of
epichlorohydrin and ethylene oxide. The majority of HAP emissions are
from back-end process vents (approximately 82 percent of the total HAP
by mass). We estimate that the MACT-allowable emissions (i.e., the
maximum emission levels allowed if in compliance with the MACT
standard) from this source category are approximately equal to the
reported, actual emissions. For more detail about this estimate of the
ratio of actual to MACT-allowable emissions, see the memo in the docket
for this action describing the estimation of MACT-allowable emission
levels and associated risks and impacts.
b. What data were used in our risk analyses?
    We initially created a preliminary data set for the Epichlorohydrin
Elastomers Production source category using information we collected
directly from industry on emissions data and emissions release
characteristics. We also reviewed the emissions and other data to
identify data anomalies that could affect risk estimates. On March 29,
2007, we published an ANPRM (72 FR 29287) for the express purpose of
requesting comments on and updates to this data set, as well as to the
data sets for the other source categories addressed in that ANPRM.
Comments received in response to the ANPRM were reviewed and
considered, and we made adjustments to the data set where we concluded
the comments supported such adjustment. After making appropriate
changes to the data set based on this public data review process, the
data set on which we based the initial proposal was created. This data
set was used to conduct the risk assessment and other analyses for the
Epichlorohydrin Elastomers Production source category that formed the
basis for the proposed RTR included in the October 10, 2008, proposal.
    We have continued to scrutinize the existing data set and have
evaluated any additional data that became available subsequent to the
October 10, 2008, proposal. Specific questions we had concerning
current operations led us to develop a questionnaire and ask for
updated emissions and emissions release characteristics information.
This information was requested from the facility in May 2010 using the
authority of section 114 of the CAA. We updated our data set for this
source category based on the information received through this request.
c. What are the results of the risk assessments and analyses?
    We have conducted a revised inhalation risk assessment for the
Epichlorohydrin Elastomers Production source category. We have also
conducted an assessment of facility-wide risk, and performed a
demographic analysis of population risks. Table B.1.1 provides an
overall summary of the results of the revised inhalation risk
assessment.

                             Table B.1.1--Epichlorohydrin Elastomers Production Revised Inhalation Risk Assessment Results *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                               Maximum individual                                 Maximum chronic non-
                                                cancer risk (in 1                     Annual        cancer TOSHI \3\
                                                  million) \2\         Population     cancer   --------------------------
          Number of facilities\1\          --------------------------  at risk >=   incidence                               Maximum off-site acute non-
                                               Actual     Allowable      1-in-1     (cases per     Actual     Allowable            cancer HQ \4\
                                             emissions    emissions     million       year)      emissions    emissions
                                               level        level                                  level        level
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.........................................           10           10          800       0.0001          0.1          0.1  HQREL = 0.2 epichlorohydrin
--------------------------------------------------------------------------------------------------------------------------------------------------------
* All results are for impacts out to 50 km from every source in the category.
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk.

\3\ Maximum TOSHI. The target organ with the highest TOSHI for the Epichlorohydrin Elastomer Production source category is the respiratory system.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values
  shown use the lowest available acute threshold value, which, in most cases, is the REL. When HQ values exceed 1, we also show HQ values using the next
  lowest available acute threshold. See section IV.A. of this preamble for explanation of acute threshold values.

    The inhalation risk modeling was performed using actual emissions
level data. As shown in Table B.1.1, the results of the revised
inhalation risk assessment indicated the maximum lifetime individual
cancer risk could be as high as 10-in-1 million, the maximum chronic
non-cancer TOSHI value could be as high as 0.1, and the maximum off-
facility-site acute HQ value could be as high as 0.2, based on the
actual emissions level and the REL value for epichlorohydrin. The total
estimated national cancer incidence from these facilities based on
actual emission levels is 0.0001 excess cancer cases per year, or one
case in every 10,000 years.
    Based on our analysis, we believe that actual emissions approximate
emissions allowable under the MACT standard. Therefore, the risk
results for MACT-allowable emissions are approximately equal to those
for actual emissions. For more detail about the estimate of the ratio
of actual to MACT-allowable emissions, see the memo in the docket for
this action describing the estimation of MACT-allowable emission levels
and associated risks and impacts.
    There were no reported emissions of PB-HAP; therefore, we do not
expect potential for human health multipathway risks or adverse
environmental impacts.
    Table B.1.2 displays the results of the facility-wide risk
assessment. This assessment was conducted based on actual emission
levels.

  Table B.1.2--Epichlorohydrin Elastomers Production Facility-Wide Risk
                           Assessment Results
------------------------------------------------------------------------

------------------------------------------------------------------------
Maximum facility-wide individual cancer risk (in 1                    10
 million)............................................
    Epichlorohydrin Elastomer Production source                     100%
     category contribution to this maximum facility-
     wide individual cancer risk \1\.................
Maximum facility-wide chronic non-cancer TOSHI.......                0.1
    Epichlorohydrin Elastomer Production source                     100%
     category contribution to this maximum facility-
     wide non-cancer TOSHI \1\.......................
------------------------------------------------------------------------
\1\ Percentage shown reflects Epichlorohydrin Elastomer Production
  source category contribution to the maximum facility-wide risks at the
  facility with the maximum risk value shown.

    As shown in Table B.1.2, the maximum individual cancer risk from
all HAP emissions at the one facility that contains epichlorohydrin
elastomers production processes subject to the Group I Polymers and
Resins MACT standard is estimated to be 10-in-1 million, and the
maximum chronic non-cancer TOSHI value is estimated to be 0.1. The
estimated proportion of the risk attributable to Epichlorohydrin
Elastomers Production source category processes at this facility is
approximately 100 percent for cancer risks and 100 percent for chronic
non-cancer risk.
    The results of the demographic analyses performed to investigate
the distribution of risks above 1-in-1 million, based on actual
emissions levels for the population living within 5 km of the
facilities, among various demographic groups are provided in a report
available in the docket for this action and summarized in Table B.1.3
below.

                                        Table B.1.3--Epichlorohydrin Elastomers Demographic Risk Analysis Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Population with risk greater than 1-in-1 million
                                              Maximum   ------------------------------------------------------------------------------------------------
              Emissions basis               risk  (in 1                                       Other and    Hispanic                Below the  Over 25 W/
                                              million)      Total    Minority %    African   multiracial   or Latino    Native      poverty     O a HS
                                                         (millions)              American %       %            %      American %    level %    diploma %
--------------------------------------------------------------------------------------------------------------------------------------------------------
Nationwide................................          n/a         285          25          12           12          14         0.9          13          13
Source Category...........................           10      0.0008          54          53            1           1         0.4          20          11
Facility-wide.............................           10        0.01          52          50            2           1         0.2          23          14
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The results of the demographic analysis show that, for the
Epichlorohydrin Elastomers Production source category, of the
population of 800 people with cancer risk greater than 1-in-1 million,
54 percent could be classified as a ``Minority,'' 53 percent are
included the ``African-American'' demographic group, and 20 percent are
included the ``Below Poverty Level,'' demographic group. The percentage
of the population within 5 km of a epichlorohydrin elastomers
production facility and with a cancer risk greater than 1-in-1 million
is higher than expected for these demographic categories based on the
typical distribution of these demographic groups across the United
States. The table also shows that the results of the demographic
analysis for the facility-wide emissions are similar to the results for
the source category.
    Details of these assessments and analyses can be found in the
residual risk documentation as referenced in section IV.A. of this
preamble, which is available in the docket for this action.
d. What are our proposed decisions on risk acceptability and ample
margin of safety?
    October 2008 Proposed Decision. In our October 10, 2008, proposal,
we proposed that the risks 0f 30-in-1 million were acceptable because
the risks results indicated that cancer risks to the individual most
exposed to emissions from the category were greater than 1-in-1
million, but less than 100-in-1 million. We then analyzed other risk
factors in the ample margin of safety determination. In this analysis,
we proposed that emissions from the source category posed no potential
for

an adverse environmental effect, did not pose potential for human
health multipathway risks, and were unlikely to cause acute or chronic
non-cancer health impacts. We also identified one emissions control
option that would reduce risks. We proposed that such control was not
necessary to protect public health with an ample margin of safety in
light of the high cost and limited addition health protection it would
provide. Therefore, we proposed that the existing standard provided an
ample margin of safety and proposed to re-adopt the existing MACT
standard to satisfy section 112(f) of the CAA.
    Risk Acceptability. The revised risk analysis we performed for this
proposal indicates that the cancer risks to the individual most exposed
is 10-in-1 million based on both actual and MACT-allowable emissions.
The cancer incidence and the number of people exposed to cancer risks
of 1-in-1 million or greater are not significantly changed from the
risk identified in the October 2008 proposal. Similarly, the risk
analysis continued to show no potential for an adverse environmental
effect or human health multipathway effects, and that acute or chronic
non-cancer health impacts are unlikely. Our additional analysis of
facility-wide risks showed that the maximum facility-wide cancer risk
is 10-in-1 million and that the maximum chronic non-cancer risks are
unlikely to cause health impacts. Our additional analysis of the
demographics of the exposed population shows disparities in risks
between demographic groups for the 800 people exposed at risks of 1-in-
1 million. Based on this low cancer risk level and in consideration of
other health measures and factors, including the low cancer incidence
(one case in every 10,000 years) and the low maximum non-cancer risk
level (TOSHI of 0.1), we propose that the risks from the
Epichlorohydrin Elastomers Production are acceptable.
    Ample Margin of Safety. Because we are proposing that the risks are
acceptable, but still above 1-in-1 million, we then reconsidered our
2008 ample margin of safety decision. We have not identified any
additional control options or any changes to the previously analyzed
control option. Our analysis does not indicate a change in the
emissions reductions that could be achieved or the cost of control for
the control option considered in the October 2008 proposal. Therefore,
we continue to propose that the current MACT standard provides an ample
margin of safety to protect public health and the environment, and we
are proposing to re-adopt the existing MACT standard to satisfy section
112(f) of the CAA.
e. What are our proposed decisions on the technology review?
    In the October 10, 2008 proposal, we identified no advancements in
practices, processes, and control technologies applicable to the
emission sources in the Group I Polymers and Resins Production source
categories in our technology review, and we proposed to re-adopt the
existing MACT standard to satisfy section 112(d)(6) of the CAA. In that
review, we examined the regulatory requirements and/or technical
analyses for subsequently promulgated air toxics regulations with
similar types of emissions sources as those in the Group I Polymers and
Resins Production source categories, and we conducted a search of the
RBLC for controls for VOC- and HAP-emitting processes in the Group I
Polymers and Resins Production source categories. We have not
identified any additional developments in practices, processes, and
control technologies since the proposal date for the Epichlorohydrin
Elastomers Production source category. Thus, we are proposing that it
is not necessary to revise the MACT standard pursuant to section
112(d)(6) of the CAA.
f. What other actions are we proposing?
    SSM Provisions. We are proposing to eliminate the SSM exemption in
the Group 1 Polymers and Resins MACT standard. Consistent with Sierra
Club v. EPA, EPA is proposing that standards in this rule would apply
at all times. We are proposing several revisions to 40 CFR part 63,
subpart U. Specifically, we are proposing to revise Table 1 to indicate
that the requirements of 40 CFR 63.6(e) of the General Provisions do
not apply. The 40 CFR 63.6(e) requires owner or operators to act
according to the general duty to ``operate and maintain any affected
source, including associated air pollution control equipment and
monitoring equipment, in a manner consistent with safety and good air
pollution control practices for minimizing emissions.'' We are
separately proposing to incorporate this general duty to minimize into
40 CFR 63.483(a). The 40 CFR 63.6(e) also requires the owner or
operator of an affected source to develop a written SSM plan. We are
proposing to remove the SSM plan requirement. We are proposing to
remove the explanation of applicability of emissions standards during
periods SSM in 40 CFR 63.480(j); remove the malfunction plan from 40
CFR 63.482 and revise the definition of initial start-up to remove
references to malfunctions in this section; clarify that representative
conditions do not include periods of SSM throughout the rule; remove
references to periods of SSM in monitoring; and revise the SSM-
associated recordkeeping and reporting requirements in 40 CFR 63.506 to
require reporting and recordkeeping for periods of malfunction. We are
also proposing to revise Table 1 to indicate that SSM-related
provisions in 40 CFR 63.6(f)(1), 40 CFR 63.7(e)(1), and 40 CFR
63.10(d)(5)(i) of the General Provisions do not apply. In addition, we
are proposing to promulgate an affirmative defense against civil
penalties for exceedances of emission standards caused by malfunctions,
as well as criteria for establishing the affirmative defense.
    EPA has attempted to ensure that we have not incorporated into
proposed regulatory language any provisions that are inappropriate,
unnecessary, or redundant in the absence of the SSM exemption. We are
specifically seeking comment on whether there are any such provisions
that we have inadvertently incorporated or overlooked.
    Significant Emission Points Not Previously Regulated Review. We
identified the absence of a limit for a significant emissions source
within the provisions of the Group I Polymers and Resins MACT standard
that apply to the Epichlorohydrin Elastomers Production source
category. Specifically, there are no back-end process operation
emission limits for this source category.\35\ As these processes are
major sources of emissions for the one facility in the source category,
we are proposing to set standards for back-end process operations under
CAA section 112(d)(2) and (d)(3) in this action.
---------------------------------------------------------------------------

    \35\ Note that these uncontrolled emissions were included in the
baseline risk assessment.
---------------------------------------------------------------------------

    As there is only one facility in the source category, the emissions
level currently being achieved by this facility represents the MACT
floor. The annual HAP emissions from the back-end process operations at
this facility are approximately 36 TPY of toluene. There are two
separate dryer vents, one emitting around 24 TPY of toluene, and the
other emitting around 12 TPY of toluene. Neither of these vents is
controlled. Therefore, we have determined that the MACT floor for these
processes is 36 TPY based on the current level of HAP stripping and
recovery, given current production levels, but which would fluctuate
proportionally with an increase or decrease in production levels.
    As part of our beyond-the-floor analysis, we considered
alternatives

more stringent than the MACT floor option. We identified one option
using add-on emission controls that would require the ducting of
emissions from the back-end process operations to a control device,
such as an incinerator. This option would also require an initial
performance test of the incinerator and continuous parameter monitoring
averaged daily. The capital costs of this option are estimated to be
approximately $600,000 and the total annual costs are estimated to be
approximately $1,100,000. We estimate that an incinerator would achieve
an emissions reduction of 98 percent, resulting in a HAP decrease of
approximately 35 TPY, with a cost- effectiveness of approximately
$31,000/ton. Table B.2.4 summarizes the cost and emission reduction
impacts of the proposed options. Because the reduction in HAP would be
due to toluene, no reduction of cancer risk would result from this
control option.

               Table B.1.4--Epichlorohydrin Elastomer Production Facility Back-End Options Impacts
----------------------------------------------------------------------------------------------------------------
                                                                                Cost-
                                                                                effectiveness as
                                                                                compared to
         Regulatory alternatives            HAP emissions     Capital cost       Annual cost        baseline
                                              (TPY HAP)        ($million)       ($million/yr)  -----------------
                                                                                $/Ton HAP
                                                                                Removed
----------------------------------------------------------------------------------------------------------------
Baseline................................                36  ................  ................  ................
1 (MACT floor)..........................                36                 0                 0  ................
2 (Beyond-the-floor)....................                 1               0.6               1.1            31,000
----------------------------------------------------------------------------------------------------------------

    In addition to the cost and emission reduction impacts shown in
Table B.1.4, we estimate that the beyond-the-floor option would result
in increases in criteria pollutant and carbon dioxide emissions (PM-0.2
TPY, SO2-0.03 TPY, NOX-12 TPY, CO-2 TPY, and
CO2-7,000 TPY), and an increase in energy use of
approximately 117,000 million British thermal units (BTU)/year at a
cost of approximately $33,000/year.
    We believe that the costs and other impacts of this beyond-the-
floor option are not reasonable, given the level of emission reduction.
Therefore, we are proposing an emission standard that reflects the MACT
floor option. We are requesting comment on this analysis and these
options.
    As noted above, we are proposing that the MACT standard, prior to
the implementation of the proposed emission limitation to the back-end
process operations discussed in this section, provides an ample margin
of safety to protect public health. Therefore, we maintain that after
the new standard's implementation, the rule will continue to provide an
ample margin of safety to protect public health. Consequently, we do
not believe it will be necessary to conduct another residual risk
review under CAA section 112(f) for this source category 8 years
following promulgation of new back-end process limitations, merely due
to the addition of this new MACT requirement.
2. Polybutadiene Rubber Production
    Polybutadiene Rubber Production is one of the source categories for
which we proposed RTR decisions on October 10, 2008.
a. Overview of the Source Category
    Polybutadiene rubber is a homopolymer of 1,3-butadiene (i.e., 1,3-
butadiene is the only monomer used in the production of this polymer).
While both the solution and emulsion polymerization processes can be
used to produce polybutadiene rubber, all currently operating
facilities in the United States use a solution process. In the solution
process, the reaction is conducted in an organic solvent (hexane,
toluene, or a non-HAP organic solvent), which helps to dissipate heat
generated by the reaction and control the reaction rate. While
polybutadiene rubber is the primary product at these facilities,
styrene-butadiene rubber can also be produced as a minor product by
adding styrene as a monomer. Most of the polybutadiene rubber
manufactured in the United States is used in the production of tires in
the construction of the tread and sidewalls. Polybutadiene rubber is
also used as a modifier in the production of other polymers and resins
(e.g., polystyrene).
    We identified five currently operating polybutadiene rubber
production facilities subject to the Polymers and Resins I MACT
standard. Some of these facilities are located at plant sites that also
have other HAP-emitting sources regulated under separate MACT
standards, which have been or will be addressed in separate regulatory
actions. Three of the polybutadiene rubber production facilities use
hexane as the solvent in their solution process, one facility uses
toluene as its solvent, and the fifth uses a non-HAP organic solvent.
Overall, hexane and toluene account for the majority of the HAP
emissions from this source category (approximately 1,600 TPY hexane,
which represents 70 percent of the total HAP emissions by mass, and 500
TPY toluene, which represents 23 percent). The facilities in this
source category also reported emissions of styrene, 1,3-butadiene,
ethylbenzene, and relatively minor quantities of other HAP. The
majority of HAP emissions are from back-end process operations
(approximately 70 percent of the total HAP by mass). For all emission
sources except the back-end process operations, the actual emissions
level is representative of the MACT-allowable level. For back-end
process operations, we estimate that MACT-allowable emissions from this
source category could be as high as seven times the actual emissions.
Because these back-end limitations are production-based, this estimate
was made by comparing the actual emissions levels to the emissions
calculated using the limitations and production levels. For more detail
about the estimate of the ratio of actual to MACT-allowable emissions,
see the memo in the docket for this action describing the estimation of
MACT-allowable emission levels and associated risks and impacts.
b. What data were used in our risk analyses?
    We initially created a preliminary data set for the Polybutadiene
Rubber Production source category using information we collected
directly from industry on emissions data and emissions release
characteristics. We also reviewed the emissions and other data to
identify data anomalies that could affect risk estimates. On March 29,
2007, we published an ANPRM (72 FR 29287) for the express purpose of
requesting comments on, and updates

to, this data set, as well as to the data sets for the other source
categories addressed in that ANPRM. Comments received in response to
the ANPRM were reviewed and considered. We made adjustments to the data
set where we concluded the comments supported such adjustment. After
making appropriate changes to the data set based on this public data
review process, the data set on which we based the initial proposal was
created. This data set was used to conduct the risk assessment and
other analyses for the Polybutadiene Rubber Production source category
that formed the basis for the proposed actions included in the October
10, 2008, proposal. We have continued to scrutinize the data set and
any additional data that have become available since the October 10,
2008, proposal.
c. What are the results of the risk assessments and analyses?
    We have conducted a revised inhalation risk assessment for the
Polybutadiene Rubber Production source category. We have also conducted
an assessment of facility-wide risk and performed a demographic
analysis of population risks. Table B.2.1 provides an overall summary
of the results of the revised inhalation risk assessment.

                                                         Table B.2.1--Polybutadiene Rubber Revised Inhalation Risk Assessment Results *
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Maximum individual cancer risk                                     Maximum chronic non-cancer TOSHI
                                                       (in 1 million) \2\                           Annual cancer                  \3\
                                               ----------------------------------  Population at      incidence    ----------------------------------
           Number of  facilities\1\                                 Allowable      risk >= 1-in-1     (cases per         Actual         Allowable      Maximum off-site acute  non-cancer HQ \4\
                                                     Actual         emissions         million           year)          emissions        emissions
                                                emissions level       level                                              level            level
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
5.............................................              30               30           24,000            0.003              0.3              0.3   HQREL = 1 toluene
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* All results are for impacts out to 50 km from every source in the category.
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk.
\3\ Maximum TOSHI. The target organ with the highest TOSHI for the Polybutadiene Rubber Production source category is the reproductive system.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values shown use the lowest available acute
  threshold value, which, in most cases, is the REL. When HQ values exceed 1, we also show HQ values using the next lowest available acute threshold. See section IV.A. of this preamble for
  explanation of acute threshold values.

    The inhalation risk modeling was performed using actual emissions
level data. As shown in Table B.2.1, the results of the revised
inhalation risk assessment indicated the maximum lifetime individual
cancer risk could be as high as 30-in-1 million, the maximum chronic
non-cancer TOSHI value could be up to 0.3, and the maximum off-
facility-site acute HQ value could be as high as 1, based on the actual
emissions level and the REL value for toluene. The total estimated
national cancer incidence from these facilities based on actual
emission levels is 0.003 excess cancer cases per year, or one case in
every 333 years.
    Our analysis of potential differences between actual emission
levels and emissions allowable under the MACT standard indicated that
MACT-allowable emission levels are equal to actual emissions for all
emissions sources other than back-end process operations and may be up
to seven times greater than actual emission levels for back-end process
operations. When these ratios of actual to MACT-allowable emissions are
applied to each emission source type, the result is that the cancer
risks at the MACT-allowable level are equal to those at the actual
level shown in Table B.2.1.
    There were no reported emissions of PB-HAP; therefore, we do not
expect potential for human health multipathway risks or adverse
environmental impacts.
    Table B.2.2 displays the results of the facility-wide risk
assessment. This assessment was conducted based on actual emission
levels.

     Table B.2.2--Polybutadiene Rubber Production Facility-Wide Risk
                           Assessment Results
------------------------------------------------------------------------

------------------------------------------------------------------------
Maximum facility-wide individual cancer risk (in 1 million)..         30
    Polybutadiene Rubber Production source category                 100%
     contribution to this maximum facility-wide individual
     cancer risk) \1\........................................
Maximum facility-wide chronic non-cancer TOSHI...............        0.3
    Polybutadiene Rubber Production source category                 100%
     contribution to this maximum facility-wide non-cancer
     TOSHI \1\...............................................
------------------------------------------------------------------------
\1\ Percentage shown reflects Polybutadiene Rubber Production source
  category contribution to the maximum facility-wide risks at the
  facility with the maximum risk value shown.

    The maximum individual cancer risk from all HAP emissions at a
facility that contains polybutadiene rubber production processes
subject to the Group I Polymers and Resins MACT standard is estimated
to be 30-in-1 million, and the maximum chronic non-cancer TOSHI value
is estimated to be 0.3. At the facilities where these maximum risk
values occur, the estimated proportion of the risk attributable to the
Polybutadiene Rubber Production source category processes is 100
percent for both cancer and non-cancer risk.
    The results of the demographic analyses performed to investigate
the distribution of risks above 1-in-1 million, based on actual
emissions levels for the population living within 5 km of the
facilities, among various demographic groups are provided in a report
available in the docket for this action and summarized in Table B.2.3
below.

                                           Table B.2.3--Polybutadiene Rubber Demographic Risk Analysis Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Population with risk greater than 1-in-1 million
                                              Maximum   ------------------------------------------------------------------------------------------------
              Emissions basis                risk (in 1                            African    Other and    Hispanic                Below the  Over 25 W/
                                              million)      Total     Minority    American   multiracial   or Latino    Native      poverty     O a HS
                                                         (millions)       %           %           %            %      American %    level %    diploma %
--------------------------------------------------------------------------------------------------------------------------------------------------------
Nationwide................................          n/a         285          25          12           12          14         0.9          13          13
Source Category...........................           30       0.017          11           6            4           4         0.5          11          13
Facility-wide.............................           30        0.02          12           7            5           4         0.5          12          14
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The results of the Polybutadiene Rubber Production source category
demographic analysis show that the percentage of the population within
5 km of a polybutadiene rubber production facility and with a cancer
risk greater than 1-in-1 million is less than the distribution of these
demographic groups across the United States as displayed in Table
B.2.3, with the exception of those ``Over 25 Without a High School
Diploma'', where the levels are equal to the distribution of these
demographic groups across the United States. The table also shows that
the facility-wide emissions demographic analysis shows similar results.