these benefits and costs would have on the estimated monetized total annualized benefits and costs in this
  table.

                     Table 68--Annualized Quantified National Costs and Benefits, Option 1b
                                 [PFOA and PFOS MCLs of 5.0 ppt; Million $2021]
----------------------------------------------------------------------------------------------------------------
                                                  3% Discount rate                     7% Discount rate
                                       -------------------------------------------------------------------------
                                            5th                     95th         5th                     95th
                                         Percentile   Expected   Percentile   Percentile   Expected   Percentile
                                            \1\        value        \1\          \1\        value        \1\
----------------------------------------------------------------------------------------------------------------
Total Annualized Rule Costs \2\ \3\...      $558.71    $611.01      $674.32      $864.74    $942.28    $1,035.56
Total Annualized Rule Benefits \3\....       553.37   1,046.91     1,706.81       398.21     773.33     1,292.96
                                       -------------------------------------------------------------------------
    Total Net Benefits................        -5.34     435.90     1,032.49      -466.53    -168.95       257.40
----------------------------------------------------------------------------------------------------------------
Notes:
Detail may not add exactly to total due to independent rounding.
\1\ The 5th and 95th percentile range is based on modeled variability and uncertainty described in section
  XIII.I of this preamble and Table 71 and Table 72. This range does not include the uncertainty described in
  Table 41 for costs and Table 60 for benefits.
\2\ PFAS-contaminated wastes are not considered hazardous wastes at this time and therefore total costs reported
  in this table do not include costs associated with hazardous waste disposal of spent filtration materials. To
  address stakeholder concerns about potential costs for disposing PFAS-contaminated wastes as hazardous should
  they be regulated as such in the future, EPA conducted a sensitivity analysis with an assumption of hazardous
  waste disposal for illustrative purposes only. See Appendix N, Section 2 of the Economic Analysis (USEPA,
  2023i) for additional detail.
\3\ See Table 70 for a list of the nonquantifiable benefits and costs, and the potential direction of impact
  these benefits and costs would have on the estimated monetized total annualized benefits and costs in this
  table.

                     Table 69--Annualized Quantified National Costs and Benefits, Option 1c
                                 [PFOA and PFOS MCLs of 10.0 ppt; Million $2021]
----------------------------------------------------------------------------------------------------------------
                                                  3% Discount rate                     7% Discount rate
                                       -------------------------------------------------------------------------
                                            5th                     95th         5th                     95th
                                         Percentile   Expected   Percentile   Percentile   Expected   Percentile
                                            \1\        value        \1\          \1\        value        \1\
----------------------------------------------------------------------------------------------------------------
Total Annualized Rule Costs \2\ \3\...      $269.36    $292.57      $320.76      $396.22    $430.87      $472.20
Total Annualized Rule Benefits \3\....       280.42     584.80     1,030.56       208.71     436.24       784.59
                                       -------------------------------------------------------------------------
    Total Net Benefits................        11.06     292.23       709.80      -187.51       5.36       312.39
----------------------------------------------------------------------------------------------------------------
Notes:
Detail may not add exactly to total due to independent rounding.
\1\ The 5th and 95th percentile range is based on modeled variability and uncertainty described in section
  XIII.I of this preamble and Table 71 and Table 72. This range does not include the uncertainty described in
  Table 41 for costs and Table 60 for benefits.
\2\ PFAS-contaminated wastes are not considered hazardous wastes at this time and therefore total costs reported
  in this table do not include costs associated with hazardous waste disposal of spent filtration materials. To
  address stakeholder concerns about potential costs for disposing PFAS-contaminated wastes as hazardous should
  they be regulated as such in the future, EPA conducted a sensitivity analysis with an assumption of hazardous
  waste disposal for illustrative purposes only. See Appendix N, Section 2 of the Economic Analysis (USEPA,
  2023i) for additional detail.
\3\ See Table 70 for a list of the nonquantifiable benefits and costs, and the potential direction of impact
  these benefits and costs would have on the estimated monetized total annualized benefits and costs in this
  table.

    The benefit-cost analysis reported dollar figures presented above
reflect benefits and costs that could be quantified for each regulatory
alternative given the best available scientific data. EPA notes that
the quantified benefit-cost results above are not representative of all
benefits and costs anticipated under the proposed NPDWR. Due to
occurrence, health, and economic data limitations, there are several
adverse health effects associated with PFAS exposure and costs
associated with treatment that EPA could not estimate in a quantitative
manner.
    PFAS exposure is associated with a wide range of adverse health
effects including reproductive effects such as decreased fertility;
increased high blood pressure in pregnant women; developmental effects
or delays in children, including low birth weight, accelerated puberty,
bone variations, or behavioral changes; increased risk of some cancers,
including prostate, kidney, and testicular cancers; reduced ability of
the body's immune system to fight infections, including reduced vaccine
response; interference with the body's natural hormones; and increased
cholesterol levels and/or risk of obesity. Based on the available data,
EPA is only able to quantify three PFOA- and PFOS-related health
endpoints in this analysis. All regulatory alternatives are expected to
produce substantial benefits that have not been quantified. Treatment
responses implemented to remove PFOA and PFOS under Options 1a-c are
likely to remove some amount of additional PFAS contaminants where they
co-occur. Co-occurrence among PFAS compounds has been observed
frequently as discussed in the PFAS Occurrence Technical Support
Document (USEPA, 2023e). The proposed option is expected to produce the
greatest reduction in exposure to PFAS compounds because it includes
PFHxS, HFPO-DA, PFNA, and PFBS in the regulation. Inclusion of the HI
will trigger more systems into treatment (as shown in Section 4.4.4 of
the Economic

Analysis) and provides enhanced public health protection by ensuring
reductions of these additional compounds when present above the HI of
1.0. EPA conducted a sensitivity analysis to evaluate the additional
benefits anticipated due to regulating PFAS compounds beyond PFOA and
PFOS. Specifically, EPA's sensitivity analysis demonstrates the
potential significant quantified benefits associated with infant birth
weight expected to result from reductions in PFNA under the proposed
rule. For further discussion of the quantitative and qualitative
benefits associated with the proposed rule, see Section 6.2 of the
Economic Analysis.
    EPA also expects that the proposed option will result in additional
nonquantifiable costs in comparison to Options 1a-c. As noted above,
the HI is expected to trigger more systems into more frequent
monitoring and treatment. Due to occurrence data limitations, EPA has
quantified the national treatment and monitoring costs associated with
the HI for PFHxS only and has not quantified the cost impacts
associated with HI exceedances resulting from HFPO-DA, PFNA, and PFBS.
In instances when concentrations of HFPO-DA, PFNA, and PFBS are high
enough to cause or contribute to an HI exceedance when the
concentrations of PFOA, PFOS, and PFHxS would not have already
otherwise triggered treatment, the modeled costs may be underestimated.
If these PFAS occur in isolation at levels that affect treatment
decisions, or if these PFAS occur in combination with PFHxS when PFHxS
concentrations were otherwise below the HI in isolation (i.e., <9.0
ppt) then the quantified costs underestimate the impacts of the
proposed rule. As such, EPA conducted a semi-quantitative analysis of
the anticipated incremental costs associated with regulating HFPO-DA,
PFNA, and PFBS (for additional detail, please see USEPA (2023i)).
    Table 70 provides a summary of the likely impact of nonquantifiable
benefit-cost categories. In each case, EPA notes the potential
direction of the impact on costs and/or benefits. For example, benefits
are underestimated if the PFOA and PFOS reductions result in avoided
adverse health outcomes that cannot be quantified and valued. Sections
5.7 and 6.8 of the Economic Analysis identify the key methodological
limitations and the potential effect on the cost or benefit estimates,
respectively. Additionally, Table 71 summarizes benefits and costs that
are quantified and nonquantifiable under the proposed rule.

                    Table 70--Potential Impact of Nonquantifiable Benefits (B) and Costs (C)
----------------------------------------------------------------------------------------------------------------
             Source                (Proposed option)       Option 1a           Option 1b           Option 1c
----------------------------------------------------------------------------------------------------------------
Nonquantifiable PFOA and PFOS     B: underestimate..  B: underestimate..  B: underestimate..  B: underestimate.
 health endpoints.
Limitations with available        C: underestimate..  n/a...............  n/a...............  n/a.
 occurrence data for HFPO-DA,
 PFNA, and PFBS.
Nonquantifiable HI (HFPO-DA,      B: underestimate..  n/a...............  n/a...............  n/a.
 PFNA, PFHxS and PFBS) health
 endpoints.
Limitations with available        B+C: underestimate  B+C: underestimate  B+C: underestimate  B+C:
 occurrence data for additional                                                                underestimate.
 PFAS compounds.
Removal of co-occurring non-PFAS  B+C: underestimate  B+C: underestimate  B+C: underestimate  B+C:
 contaminants.                                                                                underestimate.
POU not in compliance forecast..  C: overestimate...  C: overestimate...  C: overestimate...  C: overestimate.
Unknown future hazardous waste    C: underestimate..  C: underestimate..  C: underestimate..  C: underestimate.
 management requirements for
 PFAS (including HI).
----------------------------------------------------------------------------------------------------------------

                      Table 71--Summary of Quantified and Nonquantified Benefits and Costs
----------------------------------------------------------------------------------------------------------------
                                                                               Methods (economic analysis report
              Category                    Quantified        Non-quantified         section where analysis is
                                                                                detailed)
----------------------------------------------------------------------------------------------------------------
Costs:
    PWS treatment costs \1\.........                  X                       Section 5.3.1.
    PWS sampling costs..............                  X                       Section <IP_ADDRESS>.
    PWS implementation and                            X                       Section <IP_ADDRESS>.
     administration costs.
    Primacy agency rule                               X                       Section 5.3.2.
     implementation and
     administration costs.
    Hazardous waste disposal for                                          X   Section 5.6.
     treatment media.
    POU not in compliance forecast..                                      X   Section 5.6.
Benefits:
    PFOA and PFOS birth weight                        X                       Section 6.4.
     effects.
    PFOA and PFOS cardiovascular                      X                       Section 6.5.
     effects.
    PFOA and PFOS RCC...............                  X                       Section 6.6.
    Health effects associated with                    X                       Section 6.7.
     disinfection byproducts.
    Other PFOA and PFOS health                                            X   Section <IP_ADDRESS>.
     effects.
    Health effects associated with                                        X   Section 6.2.
     HI compounds (HFPO-DA, PFNA,
     PFBS, PFHxS).
    Health effects associated with                                        X   Section 6.2.
     other PFAS.
----------------------------------------------------------------------------------------------------------------
Notes:
\1\ Due to occurrence data limitations, EPA quantified the national treatment and monitoring costs associated
  with the HI for PFHxS only and has not quantified the national cost impacts associated with HI exceedances
  resulting from PFNA, PFBS, and HFPO-DA.

I. Quantified Uncertainties in the Economic Analysis

    EPA characterized sources of uncertainty in its estimates of costs
expected to result from the proposed PFAS NPDWR. EPA conducted Monte-
Carlo based uncertainty analysis as part of SafeWater MCBC. With
respect to the cost analysis, EPA modeled the sources of uncertainty in
Table 72.

      Table 72--Quantified Sources of Uncertainty in Cost Estimates
------------------------------------------------------------------------
              Source                     Description of uncertainty
------------------------------------------------------------------------
TOC concentration.................  The TOC value assigned to each
                                     system is from a distribution
                                     derived from the SYR4 ICR database
                                     (see Section <IP_ADDRESS> in Economic
                                     Analysis).
Compliance technology unit cost     Cost curve selection varies with
 curve selection.                    baseline PFAS concentrations and
                                     also includes a random selection
                                     from a distribution across feasible
                                     technologies (see Section <IP_ADDRESS>
                                     in Economic Analysis), and random
                                     selection from a triangular
                                     distribution of low-, mid-, and
                                     high-cost equipment (25%, 50%, and
                                     25%, respectively).
------------------------------------------------------------------------

    For each iteration, SafeWater MCBC assigned new values to the four
sources of modeled uncertainty as described in Table 72, and then
calculated costs for each of the model PWSs. This was repeated 4,000
times to reach an effective sample size for each parameter. At the end
of the 4,000 iterations, SafeWater MCBC outputs the expected value as
well as the 90% confidence interval for each cost metric (i.e., bounded
by the 5th and 95th percentile estimates for each cost component).
Detailed information on the data used to model uncertainty is provided
in Appendix L to USEPA (2023i).
    Additionally, EPA characterized sources of uncertainty in its
analysis of potential benefits resulting from changes in PFAS levels in
drinking water. The analysis reports uncertainty bounds for benefits
estimated in each health endpoint category modeled for the proposed
rule. Each lower (upper) bound value is the 5th (95th) percentile of
the category-specific benefits estimate distribution represented by
4,000 Monte Carlo draws.
    Table 73 provides an overview of the specific sources of
uncertainty that EPA quantified in the benefits analysis. In addition
to these sources of uncertainty, reported uncertainty bounds also
reflect the following upstream sources of uncertainty: baseline PFAS
occurrence, affected population size and demographic composition, and
the magnitude of PFAS concentration reductions. These analysis-specific
sources of uncertainty are further described in Appendix L to USEPA
(2023i).

    Table 73--Quantified Sources of Uncertainty in Benefits Estimates
------------------------------------------------------------------------
              Source                     Description of uncertainty
------------------------------------------------------------------------
Health effect-serum PFAS slope      The slope factors that express the
 factors.                            effects of serum PFOA and serum
                                     PFOS on health outcomes (birth
                                     weight, CVD,\1\ and RCC) are based
                                     either on EPA meta-analyses or high-
                                     quality studies that provide a
                                     central estimate and a confidence
                                     interval for the slope factors. EPA
                                     assumed that the slope factors
                                     would have a normal distribution
                                     within their range.
RCC risk reduction cap............  EPA implemented a cap on the
                                     cumulative RCC risk reductions due
                                     to reductions in serum PFOA based
                                     on the population attributable
                                     fraction (PAF) estimates for a
                                     range of cancers and environmental
                                     contaminants. This parameter is
                                     treated as uncertain; its
                                     uncertainty is characterized by a
                                     log-uniform distribution with a
                                     minimum set at the smallest PAF
                                     estimate identified in the
                                     literature and a maximum set at the
                                     largest PAF estimate identified in
                                     the literature. The central
                                     estimate for the PAF is the mean of
                                     this log-uniform distribution.
------------------------------------------------------------------------
Note:
\1\ The slope factors contributing to the CVD benefits analysis include
  the relationship between total cholesterol and PFOA and PFOS, the
  relationship between HDLC and PFOA and PFOS, and the relationship
  between blood pressure and PFOS.

J. Cost-Benefit Determination

    When proposing an NPDWR, the Administrator shall publish a
determination as to whether the benefits of the MCL justify, or do not
justify, the costs based on the analysis conducted under paragraph
1412(b)(3)(C). With this proposed rule, the Administrator has
determined that the quantified and nonquantifiable benefits of the
proposed PFAS NPDWR justify the costs.
    Sections XIII.A to XIII.I of this preamble summarize the results of
this proposed rule analysis. As indicated in section XIII.H of this
preamble, EPA discounted the estimated monetized cost and benefit
values using both 3 and 7 percent discount rates. In Federal regulatory
analyses, EPA follows OMB Circular A4 (OMB, 2003) guidance which
recommends using both 3 percent and 7 percent is intended to account
for the different streams of monetized benefits and costs affected by
regulation. The 7 percent discount rate represents the estimated rate
of return on capital in the U.S. economy, to reflect the opportunity
cost of capital when ``the main effect of a regulation is to displace
or alter the use of capital in the private sector.'' Regulatory
effects, however, can fall on both capital and private consumption.\10\
In 2003, Circular A-4 estimated the rate appropriate for discounting
consumption effects at 3 percent. The estimated monetized costs and
benefits of this rulemaking result in expected annual net benefits
(total monetized annual benefits minus total monetized annual costs) of
$461.21 million at a 3 percent discount rate and -$296.50 at a 7
percent discount rate. There are a variety of considerations with
respect to the capital displacement in this particular proposal. For
example, a meaningful number of PWSs may not be managed as profit-
maximizing private sector investments, which could impact the degree to
which the rate of return on the use of capital in the private sector
applies to PWS costs. Federal funding is expected to defray many such
PWS

costs; \11\ where that occurs, such costs are transferred to the
government. Additionally, to the extent that the benefits extend over a
long time period into the future, including to future generations,
Circular A-4 advises agencies to consider conducting sensitivity
analyses using lower discount rates. Regardless, the impacts in this
rulemaking are such that costs are expected to occur in the nearer
term, and in particular that larger one-time capital investments are
expected to occur in the near term; and public health benefits are
expected to occur over the much longer term. Discounting across an
appropriate range of rates can help explore how sensitive net benefits
are to assumptions about whether effects fall more to capital or more
to consumption.
---------------------------------------------------------------------------

    \10\ Private consumption is the consumption of goods and
services by households for the direct satisfaction of individual
needs (rather than for investment).
    \11\ As noted above in this preamble, ``Infrastructure
Investment and Jobs Act, also referred to as the Bipartisan
Infrastructure Law (BIL), invests over $11.7 billion in the Drinking
Water State Revolving Fund (SRF); $4 billion to the Drinking Water
SRF for Emerging Contaminants; and $5 billion to Small, Underserved,
and Disadvantaged Communities Grants.''
---------------------------------------------------------------------------

    EPA has followed Circular A-4's default recommendations to use 3
and 7 percent rates to represent the range of potential impacts
accounting for diversity in stakeholders' time preferences. The Agency
views the 3 to 7 percent range of costs and benefits as characterizing
a significant portion of the uncertainty in the discount rate and views
the quantified endpoint values as demonstrating a range of monetized
costs and benefits which encompass a significant portion of the
uncertainty associated with discount rates. Material unquantified
benefits expected as a result of this proposed rulemaking are discussed
in greater detail later in this section.
    The quantified analysis is limited in its characterization of
uncertainty. In Section XIII.H, Table 66 of this preamble, EPA provides
5th and 95th percentile values associated with the 3 and 7 percent
discounted expected values for net benefits. These values represent the
quantified, or modeled, potential range in the expected net benefit
values associated with the variability in system characteristics and
the uncertainty resulting from the following variables; the baseline
PFAS occurrence; the affected population size; the compliance
technology unit cost curves, which are selected as a function of
baseline PFAS concentrations and population size, the distribution of
feasible treatment technologies, and the three alternative levels of
treatment capital costs; the concentration of TOC in a system's source
water which impacts GAC O&M costs; the demographic composition of the
systems population; the magnitude of PFAS concentration reductions; the
health effect-serum PFOA and PFOS slope factors that quantify the
relationship between changes in PFAS serum level and health outcomes
for birth weight, CVD, and RCC; and the cap placed on the cumulative
RCC risk reductions due to reductions in serum PFOA. These modeled
sources of uncertainty are discussed in more detail in section XIII.I
of this preamble. What the quantified 5th and 95th percentile values do
not include are a number of factors which impact both costs and
benefits but for which the Agency did not have sufficient data to
include in the quantification of uncertainty. The factors influencing
the proposed rule cost estimates that are not quantified in the
uncertainty analysis are detailed in section XIII.C.j and Table 41 of
this preamble. These uncertainty sources include: the specific design
and operating assumptions used in developing treatment unit cost; the
use of national average costs that may differ from the geographic
distribution of affected systems; the possible future deviation from
the compliance technology forecast; and the degree to which actual TOC
source water values differ from EPA's estimated distribution. EPA has
no information to indicate a directional influence of the estimated
costs with regard to these uncertainty sources. To the degree that
uncertainty exists across the remaining factors it would most likely
influence the estimated 5th and 95th percentile range and not
significantly impact the expected value estimate of costs. Section
XIII.D and Table 60, of this preamble, discuss the sources of
uncertainty affecting the estimated benefits not captured in the
estimated 5th and 95th reported values. The modeled values do not
capture the uncertainty in: the exposure that results from daily
population changes at NTNCWSs or routine population shifting between
PWSs, for example spending working hours at a NTNCWS or CWS and home
hours at a different CWS; the exposure-response functions used in
benefits analyses assume that the effects of serum PFOA/PFOS on the
health outcomes considered are independent, additive, and that there
are no threshold serum concentrations below which effects do not occur;
the distribution of population by size and demographics across entry
points within modeled systems and future population size and
demographic changes; and the Value of Statistical Life reference value
or income elasticity used to update the VSL. Given information
available to the Agency four of the listed uncertainty sources would
not affect the benefits expected value but the dispersion around that
estimate. They are the unmodeled movements of populations between PWS
which potentially differing PFAS concentrations; the independence and
additivity assumptions with regard to the effects of serum PFOA/PFOS on
the health outcomes; the uncertainty in the population and demographic
distributions among entry points within individual systems; and the VSL
value and the income elasticity measures. Two of the areas of
uncertainty not captured in the analysis would tend to indicate that
the quantified benefits numbers are overestimates. First, the data
available to EPA with regard to population size at NTNCWs while likely
capturing peaks in populations utilizing the systems does not account
for the variation in use and population and would tend to overestimate
the exposed population. The second uncertainty, which definitionally
would indicate overestimates in the quantified benefits values is the
assumption that there are no threshold serum concentrations below which
health effects do not occur. One factor not accounted for in the
quantified analysis associated with the underestimation of benefits is
the impact of general population growth over the extended period of
analysis.
    In addition to the quantified cost and benefit expected values, the
modeled uncertainty associated within the 5th and 95th percentile
values, and the un-modeled uncertainty associated with a number of
factors listed above, there are also significant nonquantifiable costs
and benefits which are important to the overall weighing of costs and
benefits. Table 70 provides a summary of these nonquantifiable cost and
benefit categories along with an indication of the directional impact
each category would have on total costs and benefit. Tables 41 and 60
also provide additional information on a number of these
nonquantifiable categories.
    On the nonquantifiable costs side of the equation EPA had
insufficient nationally representative data to precisely characterize
occurrence of HFPO-DA, PFNA, and PFBS at the national level and
therefore could not include complete treatment costs associated with;
the co-occurrence of these PFAS at systems already required to treat as
a result of estimated PFOA, PFOS, or PFHxS levels, which would shorten
the filtration media life and therefore increase operation costs; and
the occurrence of HFPO-DA, PFNA,

and/or PFBS at levels high enough to cause systems to exceed the HI and
have to install PFAS treatment. EPA expects that the quantified
national costs are marginally underestimated as a result of this lack
of sufficient nationally representative occurrence data for purposes of
model integration. In an effort to better understand the costs
associated with treatment of potentially co-occurring HFPO-DA, PFNA,
and PFBS at systems already required to treat and the potential costs
resulting from an HI exceedance associated with the same chemicals EPA
estimated the potential unit treatment costs for model systems under
both scenarios for differing assumed HI PFAS concentrations. The
analysis is discussed in section <IP_ADDRESS> and Appendix N of the Economic
Analysis (USEPA, 2023j; USEPA, 2023i). Two additional nonquantifiable
cost impacts stemming from insufficient co-occurrence data could also
potentially shorten filtration media life and increase operation costs.
The co-occurrence of other PFAS and other non-PFAS contaminants not
regulated in the proposed rule could both increase costs to the extent
that they reduce media life. EPA did not include POU treatment in the
compliance technology forecast because current POU units are not
certified to remove PFAS to the standards required in the proposed
rule. Once certified this technology may be a low-cost treatment
alternative for some subset of small systems. Not including POU
treatment in this analysis has resulted in a likely overestimate of
cost values. Appendix N of the Economic Analysis (USEPA, 2023j; USEPA,
2023i) contains a sensitivity analysis that estimates there may be a
national annual costs of $30 to $61 million, discounted at 3 and 7
percent, respectively, which would accrue to systems if the waste
filtration media from GAC and IX were handled as hazardous waste. This
sensitivity analysis includes only disposal costs and does not consider
other potential environmental costs associated with the disposal of the
waste filtration media.
    There are significant nonquantifiable sources of benefits that were
not captured in the quantified benefits estimated for the proposed
rule. While EPA was able to monetize some of the PFOA and PFOS benefits
related to CVD, infant birthweight, and RCC effects, the Agency was
unable to quantify additional negative health impacts. EPA did not
quantify PFOA and PFOS benefits related to health endpoints including
developmental, cardiovascular, hepatic, immune, endocrine, metabolic,
reproductive, musculoskeletal, and other types of carcinogenic effects.
See Section XIII.E, of this preamble, for additional information on the
nonquantifiable impacts of PFOA and PFOS. Further, the Agency did not
quantify any health endpoint benefits associated with the potential
reductions in HI PFAS, which include PFHxS, HFPO-DA, PFNA, and PFBS, or
other co-occurring non-regulated PFAS which would be removed by the
installation of required filtration technology at those systems with
PFOA, PFOS, or HI exceedances. The nonquantifiable benefits impact
categories associated with PFHxS, HFPO-DA, and PFBS include
developmental, cardiovascular, immune, hepatic, endocrine, metabolic,
reproductive, musculoskeletal, and carcinogenic effects. In addition,
EPA did not quantify the potential developmental, cardiovascular,
immune, hepatic, endocrine, metabolic, reproductive, musculoskeletal,
and carcinogenic impacts related to the removal of other co-occuring
non-regulated PFAS. See Section XIII.F, of this preamble, for
additional information on the nonquantifiable impacts of PFHxS, HFPO-
DA, PFNA, and PFBS and other non-regulated co-occurring PFAS.
    The treatment technologies installed to remove PFAS can also remove
numerous other non-PFAS drinking water contaminants which have negative
health impacts including additional regulated and unregulated DBPs (the
quantified benefits assessment does estimate benefits associated with
THM4), heavy metals, organic contaminants, and pesticides, among
others. The removal of these co-occurring non-PFAS contaminants could
have significant positive health benefits. In total these
nonquantifiable benefits are anticipated to be significant and are
discussed qualitatively in Section 6.2 of the Economic Analysis (USEPA,
2023j).
    To fully weigh the costs and benefits of the action the Agency
considered the totality of the monetized values, the potential impacts
of the unquantified uncertainties described above, and the
nonquantifiable costs and benefits. The Administrator has determined
that the benefits of this proposed regulation justify the costs.

XIV. Request for Comment on Proposed Rule

    The Agency is requesting comment on this proposed NPDWR for PFAS.
In the proposal, the Agency highlighted numerous areas where specific
public comment will be helpful for EPA in developing a final rule. EPA
specifically requests comment on the following topics within each
section of this preamble.

Section III--Regulatory Determinations for Additional PFAS

     EPA requests comment on its preliminary regulatory
determination for PFHxS and its evaluation of the statutory criteria
that supports the finding. EPA also requests comment on if there are
additional data or studies EPA should consider that support or do not
support the Agency's preliminary regulatory determination for PFHxS,
including additional health information and occurrence data.
     EPA requests comment on its preliminary regulatory
determination for HFPO-DA and its evaluation of the statutory criteria
that supports the finding. EPA also requests comment on if there are
additional data or studies EPA should consider that support or do not
support the Agency's preliminary regulatory determination for HFPO-DA,
including additional health information and occurrence data.
     EPA requests comment on its preliminary regulatory
determination for PFNA and its evaluation of the statutory criteria
that supports the finding. EPA also requests comment on if there are
additional data or studies EPA should consider that support or do not
support the Agency's preliminary regulatory determination for PFNA,
including additional health information and occurrence data.
     EPA requests comment on its preliminary regulatory
determination for PFBS and its evaluation of the statutory criteria
that supports the finding. EPA also requests comment on if there are
additional data or studies EPA should consider that support or do not
support the Agency's preliminary regulatory determination for PFBS,
including additional health information and occurrence data.
     EPA requests comment on whether there are other peer-
reviewed health or toxicity assessments for other PFAS the Agency
should consider as a part of this action.
     EPA requests comment on its evaluation that regulation of
PFHxS, HFPO-DA, PFNA, PFBS, and their mixtures, in addition to PFOA and
PFOS, will provide protection from PFAS that will not be regulated
under this proposed rule.

Section V--Maximum Contaminant Level Goal

     EPA requests comment on the derivation of the proposed
MCLG for PFOA and its determination that PFOA

is Likely to be Carcinogenic to Humans and whether the proposed MCLG is
set at the level at which there are no adverse effects to the health of
persons and which provides an adequate margin of safety. EPA is also
seeking comment on its assessment of the noncancer effects associated
with exposure to PFOA and the toxicity values described in the support
document on the proposed MCLG for PFOA.
     EPA requests comment on the derivation of the proposed
MCLG for PFOS, its determination that PFOS is Likely to be Carcinogenic
to Humans and whether the proposed MCLG is set at the level at which
there are no adverse effects to the health of persons and which
provides an adequate margin of safety. EPA is also seeking comment on
its assessment of the noncancer effects associated with exposure to
PFOS and the toxicity values described in the support document on the
proposed MCLG for PFOS.
     EPA requests comment on the general HI approach for the
mixture of four PFAS.
     EPA requests comment on the merits and drawbacks of the
target-specific HI or RPF approach.
     EPA requests comment on significant figure use when
calculating both the HI MCLG and the MCL. EPA has set the HI MCLG and
MCL using two significant figures (i.e., 1.0). EPA requests comment on
the proposed use of two significant figures for the MCLG when
considering underlying health information and for the MCL when
considering the precision of the analytical methods.
     EPA requests comment on the derivation of the HBWCs for
each of the four PFAS considered as part of the HI.
     EPA requests comment on whether the HBWCs should instead
be proposed as stand-alone MCLGs in addition to or in lieu of the
mixture MCLGs.

Section VI--Maximum Contaminant Level

     EPA requests comment on its proposed determination to set
MCLs at 4.0 ppt for PFOA and PFOS and whether 4.0 ppt is the lowest PQL
that can be achieved by laboratories nationwide.
     EPA seeks comment on its PFOA and PFOS evaluation of
feasibility for the proposal, including analytical measurement and
treatment capability, as well as reasonable costs, as defined by SDWA.
     EPA seeks comment on its evaluation of feasibility for the
proposed HI MCL finding, including analytical measurement and treatment
capability, as well as reasonable costs, as defined by SDWA.
     EPA requests comment on implementation challenges and
considerations for setting the MCL at the PQLs for PFOA and PFOS,
including on the costs and benefits related to this approach.
     EPA requests comment on the underlying assumptions that
sufficient laboratory capacity will be available with the proposed
MCLs; that demand will be sufficiently distributed during rule
implementation to allow for laboratory capacity; and on the cost
estimates related to these assumptions.
     EPA requests comment on its proposal of using an HI
approach for PFHxS, HFPO-DA, PFNA, and PFBS, including whether it can
be clearly implemented and achieves the goal of protecting against dose
additive noncancer health effects.
     EPA requests comment on its proposed decision to establish
stand-alone MCLs for PFOA and PFOS in lieu of including them in the HI
approach.
     EPA requests comment on whether establishing a traditional
MCLG and MCL for PFHxS, HFPO-DA, PFNA, and PFBS instead of, or in
addition to, the HI approach would change public health protection,
improve clarity of the rule, or change costs.

Section VII--Occurrence

     EPA requests comment on the number of systems estimated to
solely exceed the HI (but not the PFOA or PFOS MCLs) according to the
approach outlined in USEPA (2023e).

Section IX--Monitoring and Compliance Requirements

     EPA requests comment on the proposed monitoring
flexibility for groundwater systems serving 10,000 or fewer to only
collect two samples at each EPTDS to satisfy initial monitoring
requirements.
     EPA requests comment on monitoring-related flexibilities
that should be considered to further reduce burden while also
maintaining public health protection including a rule trigger level at
different values than the currently proposed values of 1.3 ppt for PFOA
and PFOS and 0.33 for the HI PFAS (PFHxS, HFPO-DA, PFNA, and PFBS),
specifically alternative values of 2.0 ppt for PFOA and PFOS and 0.50
for the HI PFAS. EPA also requests comment other monitoring
flexibilities identified by commenters.
     EPA requests comment on the proposed allowance of a water
system to potentially have each EPTDS on a different compliance
monitoring schedule based on specific entry point sampling results
(i.e., some EPTDS being sampled quarterly and other EPTDS sampled only
once or twice during each three-year compliance period), or if
compliance monitoring frequency should be consistent across all of the
system's sampling points.
     EPA requests comments on whether water systems should be
permitted to apply to the primacy agency for monitoring waivers.
Specifically, EPA is requesting comment on the allowance of monitoring
waivers of up to nine years if after at least one year of sampling
results are below the proposed rule trigger level. Similarly, EPA also
requests comment on whether allowance of monitoring waivers of up to
nine years should be permitted based on previously acquired monitoring
data results that are below the proposed rule trigger level.
Additionally, EPA is also requesting comment on the identification of
possible alternatives to traditional vulnerability assessments that
should be considered to identify systems as low risk and potentially
eligible for monitoring waivers.
     EPA requests comment on if all water systems, regardless
of system size, be allowed to collect and analyze one sample per three-
year compliance period if the system does not detect regulated PFAS in
their system at or above the rule trigger level.
     EPA requests comment on its proposal to allow the use of
previously acquired monitoring data to satisfy initial monitoring
requirements including the data collection timeframe requirements and
if other QA requirements should be considered.
     EPA requests comment on whether EPA should consider an
alternative approach to what is currently proposed when calculating
compliance with proposed MCLs. Specifically, in the case where a
regulated PFAS is detected but below its proposed PQL, rather than
using zero for the measurement value of the specific PFAS in the
running annual average compliance calculation, that the proposed rule
trigger levels (1.3 ppt for PFOA and PFOS and 0.33 of each of the HI
PFAS PQLs (i.e., PFHxS=1.0, HFPO-DA=1.7, PFNA=1.3, and PFBS=1.0)) be
used as the values in calculating the running annual average for
compliance purposes.
     EPA requests comment on other monitoring related
considerations including laboratory capacity and QA/QC of drinking
water sampling.
     EPA seeks comment on the Agency's proposed initial
monitoring timeframe, particularly for NTNCWS or all systems serving
3,300 or fewer.

Section X--Safe Drinking Water Right to Know

     EPA requests comment on its proposal to designate
violations of the proposed MCLs as Tier 2.
     EPA requests comment on what may be needed for water
systems to effectively communicate information about the PFAS NPDWR to
the public.

Section XI--Treatment Technologies

     EPA requests comment on whether PWSs can feasibly treat to
4.0 ppt or below.
     EPA requests additional information on PFAS removal
treatment technologies not identified in the proposed rule that have
been shown to reduce levels of PFAS to the proposed regulatory
standard.
     EPA requests comment on the co-removal of the HI chemicals
(PFHxS, PFBS, PFNA, and HFPO-DA) when GAC, IX, or RO are used in the
treatment of PFOA and/or PFOS.
     EPA requests comment on whether there are additional
technologies which are viable for PFAS removal to the proposed MCLs as
well as any additional costs which may be associated with non-treatment
options such as water rights procurement.
     EPA estimates GAC treatment will be sufficiently available
to support cost-effective compliance with this proposed regulation, and
requests comment on whether additional guidance on applicable
circumstances for GAC treatment is needed.
     EPA is seeking comment on the benefits from using
treatment technologies (such as reverse osmosis and GAC) that have been
demonstrated to co-remove other types of contaminants found in drinking
water and whether employing these treatment technologies are sound
strategies to address PFAS and other regulated or unregulated
contaminants that may co-occur in drinking water.
     EPA requests comment on the estimates for disposing of
drinking water treatment residuals or regenerating drinking water
treatment media including assumptions related to the transport distance
to disposal sites and other costs that arise out of disposal of PFAS
contaminated drinking water treatment residuals.
     EPA requests comment on the availability of facilities to
dispose of or regenerate drinking water treatment media that contains
PFAS. EPA requests comment on whether there will be sufficient capacity
to address the increased demand for disposal of drinking water
treatment residuals or to regenerate media for reuse by drinking water
treatment facilities.
     EPA requests comment on the impacts that the disposal of
PFAS contaminated treatment residuals may have in communities adjacent
to the disposal facilities.
     EPA requests comment on the type of assistance that would
help small public water systems identify laboratories that can perform
the required monitoring, evaluate treatment technologies and determine
the most appropriate way to dispose of PFAS contaminated residuals and
waste the systems may generate when implementing the rule.

Section XII--Rule Implementation and Enforcement

     EPA is seeking comment as to whether there are specific
conditions that should be mandated for systems to be eligible for
exemptions under 1416 to ensure that they are only used in rare
circumstances where there are no other viable alternatives and what
those conditions would be.

Section XIII--HRRCA

     EPA requests comment on all components of the HRRCA for
the proposed NPDWR.
     In the Economic Analysis, EPA presented estimated costs
and benefits of regulatory alternatives for PFOA and PFOS if setting
MCLs at 5.0 ppt and 10.0 ppt. EPA is requesting comment on its
evaluation of these alternatives within the Economic Analysis.
     EPA requests comment on the methodology used to estimate
national costs for the proposed rule and regulatory alternatives. EPA's
cost analysis can be found in Chapter 5 of the Economic Analysis.
     EPA is requesting comment on the WBS models, including the
range of component levels assumed in the input to the models, and the
range of cost estimates for GAC, IX, and centralized RO.
     EPA requests comment on Table 26 which provides the
initial treatment technology compliance forecast, presented in
percentages of systems adopting GAC, PFAS-selective IX, centralized RO,
system interconnection, and use new wells across system design flows
and TOC levels. This information is used in EPA's cost and benefit
modeling. Please also comment on the potential for point-of-use
devices, including those using RO or activated carbon as a compliance
option.
     EPA requests comment on the cost of treatment when
additional co-occurring but not targeted PFAS chemicals are found in
source water.
     EPA requests comment generally on its estimation of
sampling costs. The Agency is also specifically requesting comment on
the ability of systems to demonstrate they are reliably and
consistently below 1.3 ppt for PFOA and PFOS and 0.33 ppt for PFAS
regulated by the HI in order to qualify for reduced monitoring.
     EPA requests comment on the underlying assumptions that,
under UCMR 5, individual water systems would be able to request the
full release of data from the labs for use in determining their
compliance monitoring frequency and that PWSs may be able to use these
lab analyses to demonstrate a ``below trigger level'' concentration
using the UCMR 5 analyses by following up with the lab for a more
detailed results report.
     EPA requests comment on the costs associated with the
storage, transportation and underground injection of the brine
concentrate residuals from the RO/NF process.
     EPA requests comment on the small system affordability
analysis, including both the national affordability determination using
EPA's existing 2.5% of MHI methodology and the supplemental analyses
using use of alternative metrics (i.e., expenditure margins at 1% of
MHI and 2.5% of lowest quintile income). EPA's national small system
affordability determination can be found in Section 9.12.1 of the
Economic Analysis. EPA's supplementary affordability analyses can be
found in Section 9.12.2 of the Economic Analysis.
     EPA requests comment on the discussion of estimated PN
costs provided in the proposed rule.
     EPA requests comment on the assumption that exceedances of
HI PFAS not included in the national cost analyses (HFPO-DA, PFBS, and
PFNA) will not significantly impact overall compliance costs and
national costs estimates are, therefore, unlikely to be substantially
underestimated.
     EPA requests comments on the approaches we used to
estimate each of the health impacts of exposure to the PFAS chemicals
covered in this proposed rule, including the transparency of the
assumptions we made and the impact of these assumptions on the
magnitude of the risks avoided by the proposed regulatory action.
     EPA requests comment on whether factors such as
anticipated Federal funding, the structure of PWSs relative to private
enterprises, or the nature of the public health benefits should be
further explored in the final rule analysis, including as it relates to
the estimated range of impacts under the applied discount rates.

Section XV--Statutory and Executive Order Reviews

     EPA requests comment on all aspects of its EJ analysis,
particularly its choice of comparison groups to determine potential
demographic disparities in anticipated PFAS exposure and its use of
thresholds against which to examine anticipated exposures. For more
information, please see section XV.J of this preamble.

XV. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is an economically significant regulatory action that
was submitted to the Office of Management and Budget (OMB) for review.
Any changes made in response to OMB recommendations have been
documented in the docket. EPA prepared an analysis of the potential
costs and benefits associated with this action. This analysis, the
Economic Analysis (USEPA, 2023j), is available in the docket and is
summarized in section XIII of this preamble.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the PRA. The Information Collection Request (ICR) document
that EPA prepared has been assigned EPA ICR number 2732.01. You can
find a copy of the ICR in the docket for this rule at https://www.regulations.gov/docket/EPA-HQ-OW-2022-0114, and it is briefly
summarized here.
    The monitoring information collected as a result of the proposed
rule should allow primacy agencies and EPA to determine appropriate
requirements for specific systems and evaluate compliance with the
proposed rule. For the first three-year period following rule
promulgation, the major information requirements concern primacy agency
activities to implement the rule including adopting the NPDWR into
state regulations, providing training to state and PWS employees,
updating their monitoring data systems, and reviewing system monitoring
data and other requests. Compliance actions for drinking water systems
(including monitoring, administration, and treatment costs) would not
begin until after three years due to the proposed effective date of
this rule. More information on these actions is described in Section
XII of this preamble and in Chapter 9 from the Economic Analysis of the
Proposed PFAS NPDWR (USEPA, 2023j).
    The respondents/affected entities are PWSs and primacy agencies.
The collection requirements are mandatory under SDWA (42 U.S.C. 300g-
7). For the first three years after publication of the rule in the FR,
information requirements apply to an average of 38,089 respondents
annually, including 38,033 PWSs and 56 primacy agencies. The burden
associated with the proposed rule over the three years covered by the
ICR is 3.8 million hours, for an average of 1.3 million hours per year.
The total costs over the three-year period is $142.6 million, for an
average of $47.5 million per year (simple average over three years).
The average burden per response (i.e., the amount of time needed for
each activity that requires a collection of information) is 6.6 hours
for PWSs and 1.1 hours for primacy agencies; the average cost per
response is $234.41 for PWSs and $60.89 for primacy agencies. Details
on the calculation of the proposed rule information collection burden
and costs can be found in the ICR for the proposed rule.
    Burden is defined at 5 CFR 1320.3(b) and means the total time,
effort, and financial resources required to generate, maintain, retain,
disclose, or provide information to or for a Federal agency. This
includes the time needed to review instructions; develop, acquire,
install, and utilize technology and systems for the purposes of
collecting, validating, and verifying information, processing and
maintaining information, and disclosing and providing information;
adjust the existing ways to comply with any previously applicable
instructions and requirements; train personnel to be able to respond to
a collection of information; search data sources; complete and review
the collection of information; and transmit or otherwise disclose the
information.
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collected for information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the
accuracy of the provided burden estimates and any suggested methods for
minimizing respondent burden to EPA using the docket identified at the
beginning of this proposed rule. EPA will respond to any ICR-related
comments in the final rule. You may also send your ICR-related comments
to OMB's Office of Information and Regulatory Affairs using the
interface at www.reginfo.gov/public/do/PRAMain. Find this particular
information collected by selected ``Currently under Review--Open for
Public Comments'' or by using the search function. OMB must receive
comments no later than May 30, 2023.

C. Regulatory Flexibility Act (RFA)

    Pursuant to section 603 of the Regulatory Flexibility Act (RFA),
EPA prepared an initial regulatory flexibility analysis (IRFA) that
examines the impact of the proposed rule on small entities along with
regulatory alternatives that could minimize the impact. The complete
IRFA is available in Section 9.3 of the Economic Analysis in the docket
and is summarized here.
    For purposes of assessing the impacts of this proposed rule on
small entities, EPA considered small entities to be water systems
serving 10,000 people or fewer. This is the threshold specified by
Congress in the 1996 Amendments to SDWA for small water system
flexibility provisions. As required by the RFA, EPA proposed using this
alternative definition in the FR (USEPA, 1998c), sought public comment,
consulted with the Small Business Administration (SBA), and finalized
the small water system threshold in the Agency's Consumer Confidence
Report Regulation (USEPA, 1998d). As stated in the document, the
alternative definition would apply to all future drinking water
regulations.
    The SDWA is the core statute addressing drinking water at the
Federal level. Under the SDWA, EPA sets public health goals and
enforceable standards for drinking water quality. As previously
described, the proposed PFAS NPDWR requires water systems to minimize
certain PFAS in drinking water. EPA is proposing to regulate PFAS in
drinking water to improve public health protection by reducing drinking
water exposure to PFAS in drinking water.
    The proposed rule contains provisions that would affect
approximately 62,000 small PWSs. A small PWS serves between 25 and
10,000 people. These water systems include approximately 45,000 CWSs
that serve the year-round residents and approximately 17,000 NTNCWSs
that serve the same persons over six months per year (e.g., a PWS that
is an office park or school). The proposed PFAS NPDWR includes
development of legally enforceable regulatory standards

with requirements for monitoring, PN, and treatment or non-treatment
options for water systems exceeding the regulatory standard. This
proposed rule also include reporting, recordkeeping, and other
administrative requirements. States are required to implement operator
certification (and recertification) programs per SDWA Section 1419 to
ensure operators of CWSs and NTNCWSs, including small water system
operators, have the appropriate level of certification.
    Under the proposed rule requirements, small CWSs and NTNCWs serving
10,000 or fewer people are required to conduct initial monitoring or
demonstrate recent, previously collected monitoring data to determine
the level of certain PFAS in their water system. Based on these initial
monitoring results, systems will be required to conduct ongoing
monitoring at least every three years or as often as four times per
year. Systems that exceed the drinking water standard will be required
to choose between treatment and non-treatment as the compliance option.
Under the proposed rule, EPA estimates that approximately 18,000 small
CWSs (40 percent of small CWSs) could incur annual total PFAS NPDWR
related costs of more than one percent of revenues, and that
approximately 10,000 small CWSs (22 percent of small CWSs) could incur
annual total costs of three percent or greater of revenue. See Section
9.3 of the proposed PFAS NPDWR Economic Analysis for more information
on the characterization of the impacts under the proposed rule.
    As required by section 609 (b) of the RFA, EPA also convened a
Small Business Advocacy Review (SBAR) Panel to obtain advice and
recommendations from small entity representatives (SERs) that
potentially would be subject to the rule's requirements. On May 24,
2022, EPA's Small Business Advocacy Chairperson convened the Panel,
which consisted of the Chairperson, the Director of the Standards and
Risk Management Division within EPA's Office of Ground Water and
Drinking Water, the Administrator of the Office of Information and
Regulatory Affairs within OMB, and the Chief Counsel for Advocacy of
the SBA. Prior to convening the Panel, EPA conducted outreach with SERs
that will potentially be affected by this regulation and solicited
comments from them. Additionally, after the Panel was convened, the
Panel provided additional information to the SERs and requested their
input. In light of the SERs' comments, the Panel considered the
regulatory flexibility issues and elements of the IRFA specified by
RFA/Small Business Regulatory Enforcement Fairness Act (SBREFA) and
developed the findings and discussion summarized in the SBAR report.
For example, the SBAR Panel recommended several flexibilities in
monitoring requirements for small systems, including the use of
existing monitoring data (such as the UCMR 5) for initial monitoring
purposes; as well as reduced compliance monitoring requirements
specifically for small groundwater systems. EPA is including these
flexibilities as a part of the proposed rule requirements. The report
includes a number of other observations and recommendations to meet the
statutory obligations for achieving small-system compliance through
flexible regulatory compliance options. The report was finalized on
August 1, 2022 and transmitted to the EPA Administrator for
consideration. A copy of the full SBAR Panel Report is available in the
rulemaking docket (USEPA, 2022a).

D. Unfunded Mandates Reform Act (UMRA)

    This action contains a Federal mandate under the Unfunded Mandates
Reform Act (UMRA), 2 U.S.C. 1531-1538 that may result in expenditures
of $100 million or more for state, local, and tribal governments, in
the aggregate, or the private sector in any one year. Accordingly, EPA
has prepared a written statement required under section 202 of UMRA
that is included in the docket for this action (see Chapter 9 of the
Economic Analysis for the Proposed PFAS NPDWR) and briefly summarized
here.
    Consistent with UMRA section 205, EPA identified and analyzed a
reasonable number of regulatory alternatives to determine the MCL
requirement in the proposed rule. Sections VI, IX, X, and XII of this
preamble describe the proposed options. See section XIII of this
preamble and Chapter 9 of the Economic Analysis for the Proposed PFAS
NPDWR (USEPA, 2023j) for alternative options that were considered.
    Consistent with the intergovernmental consultation provisions of
UMRA section 204, EPA consulted with governmental entities affected by
this rule. EPA describes the government-to-government dialogue and
comments from state, local, and tribal governments in section XV.E
Executive Order 13132: Federalism and section XV.F Executive Order
13175: Consultation and Coordination with Indian Tribal Governments of
this document.
    Consistent with UMRA section 205, EPA identified and analyzed a
reasonable number of regulatory alternatives to determine the
regulatory requirements in the proposed PFAS NPDWR. Section VI of this
preamble describes the proposed option. See section XIII of this
preamble and Section 9.4 in the Economic Analysis of the Proposed PFAS
NPDWR (USEPA, 2023j) for alternative options that were considered.
    This action may significantly or uniquely affect small governments.
EPA consulted with small governments concerning the regulatory
requirements that might significantly or uniquely affect them. EPA
describes this consultation above in the RFA, section XV.C of this
preamble.

E. Executive Order 13132: Federalism

    EPA has concluded that this action has federalism implications
because it imposes substantial direct compliance costs on state or
local governments, and the Federal government will not provide the
funds necessary to pay those costs. However, EPA notes that the Federal
government will provide a potential source of funds necessary to offset
some of those direct compliance costs through the BIL. EPA estimates
that the net change in primacy agency related cost for state, local,
and tribal governments in the aggregate is estimated to be $8 million
(3 percent discount rate) or $9 million (7 percent discount rate).
    EPA provides the following federalism summary impact statement. EPA
consulted with State and local governments early in the process of
developing the proposed action to allow them to provide meaningful and
timely input into its development. EPA held a federalism consultation
on February 24, 2022. EPA invited the following national organizations
representing State and local elected officials to a virtual meeting on
February 24, 2022: The National Governors' Association, the National
Conference of State Legislatures, the Council of State Governments, the
National League of Cities, the U.S. Conference of Mayors, the National
Association of Counties, the International City/County Management
Association, the National Association of Towns and Townships, the
County Executives of America, and the Environmental Council of States.
Additionally, EPA invited the Association of State Drinking Water
Administrators, the Association of Metropolitan Water Agencies, the
National Rural Water Association, the American Water Works Association,
the American Public Works Association, the Western Governors'
Association, the

Association of State and Territorial Health Officials, the National
Association of Country and City Health Officials, and other
organizations to participate in the meeting. In addition to input
received during the meeting, EPA provided an opportunity to receive
written input within 60 days after the initial meeting. A summary
report of the views expressed during federalism consultations is
available in the Docket (EPA-HQ-OW-2022-0114).
    In addition to the federalism consultation, regarding state
engagement more specifically, EPA notes there were multiple meetings
held by the Association of State Drinking Water Administrators where
EPA gathered input from state officials related to the considerations
for the development of the proposed rule. EPA utilized this state input
to inform this rule proposal.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action has tribal implications, it imposes direct compliance
costs on tribal governments, and the Federal government will not
provide funds necessary to pay those direct compliance costs. However,
EPA notes that the Federal government will provide a potential source
of funds necessary to offset some of those direct compliance costs
through the BIL.
    EPA has identified 998 PWSs serving tribal communities, 84 of which
are federally owned. EPA estimates that tribal governments will incur
PWS compliance costs of $5 million per year attributable to monitoring,
treatment or non-treatment actions to reduce PFAS in drinking water,
and administrative costs, and that these estimated impacts will not
fall evenly across all tribal systems. The proposed PFAS NPDWR does
offer regulatory relief by providing flexibilities for all water
systems to potentially utilize pre-existing monitoring data in lieu of
initial monitoring requirements and for groundwater CWSs and NTNCWSs
serving 10,000 or fewer to reduce initial monitoring from quarterly
monitoring during a consecutive 12-month period to only monitoring
twice during a consecutive 12-month period. These flexibilities may
result in implementation cost savings for many tribal systems since 98
percent of tribal CWSs and 94 percent of NTNCWs serve 10,000 or fewer
people.
    Accordingly, EPA provides the following Tribal summary impact
statement as required by section 5(b) of Executive Order 13175.
Consistent with EPA Policy on Consultation and Coordination with Indian
Tribes (May 4, 2011), EPA consulted with Tribal officials and their
representatives early in the process of developing this proposed
regulation to permit them to have meaningful and timely input into its
development. EPA conducted consultation with Indian Tribes beginning on
February 7, 2022 and ending on April 16, 2022. The consultation
included two national webinars with interested tribes on February 23,
2022, and March 8, 2022, where EPA provided proposed rulemaking
information and requested input. A total of approximately 35 tribal
representatives participated in the two webinars. Updates on the
consultation process were provided to the National Tribal Water Council
and EPA Region 6's Regional Tribal Operations Committee upon request at
regularly scheduled monthly meetings during the consultation process.
Additionally, EPA received written comments from the following Tribes
and Tribal organizations: Little Traverse Bay Bands of Odawa Indians,
Sault Ste. Marie Tribe of Chippewa Indians, and National Tribal Water
Council. A summary report of the webinars and views expressed during
the consultation is available in the Docket (EPA-HQ-OW-2022-0114).

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

    This action is subject to Executive Order 13045 because it is an
economically significant regulatory action as defined by Executive
Order 12866, and EPA believes that the environmental health or safety
risk addressed by this action has a disproportionate effect on
children. Additionally, the Agency's 2021 Policy on Children's Health
(https://www.epa.gov/children/epas-policy-evaluating-risk-children) is
to protect children from environmental exposures by consistently and
explicitly considering early life exposures (from conception, infancy,
early childhood and through adolescence) and lifelong health in all
human health decisions through identifying and integrating data when
conducting risk assessments of children's health. Accordingly, EPA has
evaluated the environmental health or safety effects of PFAS found in
drinking water on children and estimated the risk reduction and health
endpoint impacts to children associated with adoption of treatment or
non-treatment options to reduce PFAS in drinking water. The results of
these evaluations are contained in the Economic Analysis of the
Proposed PFAS NPDWR (USEPA, 2023j) and described in section XIII of
this preamble. Copies of the Economic Analysis of the Proposed PFAS
NPDWR and supporting information are available in the Docket (EPA-HQ-
OW-2022-0114).

H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use

    This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. The public and private water systems
affected by this action do not, as a rule, generate power. This action
does not regulate any aspect of energy distribution as the water
systems that are proposed to be regulated by this rule already have
electrical service. Finally, EPA has determined that the incremental
energy used to implement the identified treatment technologies at
drinking water systems in response to the proposed regulatory
requirements is minimal. As such, EPA does not anticipate that this
rule will have a significant adverse effect on the supply,
distribution, or use of energy.

I. National Technology Transfer and Advancement Act of 1995

    The proposed rule could involve voluntary consensus standards in
that it would require monitoring for PFAS and analysis of the samples
obtained from monitoring based on required methods. EPA proposed two
analytical methods for the identification and quantification of PFAS in
drinking water. EPA methods 533 and 537.1 incorporate QC criteria which
allow accurate quantitation of PFAS. Additional information about the
analytical methods is available in section VIII of this preamble. EPA
has made, and will continue to make, these documents generally
available through www.regulations.gov and at the U.S. Environmental
Protection Agency Drinking Water Docket, William Jefferson Clinton West
Building, 1301 Constitution Ave. NW, Room 3334, Washington, DC 20460,
call<PHONE_NUMBER>.
    EPA's monitoring and sampling protocols generally include voluntary
consensus standards developed by agencies such as ASTM International,
Standard Methods and other such bodies wherever EPA deems these
methodologies appropriate for compliance monitoring. EPA welcomes
comments on this aspect of the proposed rulemaking and, specifically,
invites the public to identify potentially-applicable voluntary
consensus standards and to explain why

such standards should be used in this regulation. The Director of the
FR approved the voluntary consensus standards incorporated by reference
in Sec.  141.23 of the proposed regulatory text as of April 11, 2007.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    EPA believes that this action does not have disproportionately high
and adverse human health or environmental effects on minority
populations or low-income populations, as specified in Executive Order
12898 (USEPA, 1994). The proposed rule is anticipated to increase the
level of public health protection for all affected populations without
having any disproportionately high and adverse human health or
environmental effects on any population, including any minority
population. Additionally, EPA has determined that the proposed rule is
anticipated to mitigate the disproportionate impacts of baseline PFAS
exposure. The documentation for this decision, including additional
detail on the methodology, results, and conclusions of EPA's EJ
analysis, is contained in Chapter 8 of USEPA (2023j) and is available
in the public docket for this action.
    Consistent with the Agency's Technical Guidance for Assessing
Environmental Justice in Regulatory Analysis (USEPA, 2016g), EPA
conducted an EJ analysis to assess the demographic distribution of
baseline PFAS drinking water exposure and impacts anticipated to result
from the proposed PFAS NPDWR. EPA conducted two separate analyses: an
EJ exposure analysis using EJScreen, the Agency's Environmental Justice
Screening and Mapping Tool (USEPA, 2019e), and an analysis of EPA's
proposed regulatory option and alternatives using SafeWater MCBC
(detailed in Section XIII of this preamble). EPA's analyses examine EJ
impacts on a subset of PWSs across the country, based on availability
of PFAS occurrence data and information on PWS' service area
boundaries. In EPA's analysis, results for income, race, and ethnicity
groups are generally summarized separately due to how underlying
American Community Survey (ACS) statistics are aggregated at the census
block group level; for more information, please see: https://www.census.gov/data/developers/data-sets/acs-5year.html (United States
Census Bureau, 2022). Additional information on both analyses can be
found in Chapter 8 of USEPA (2023j).
    EPA's EJ exposure analysis using EJScreen utilized hypothetical
regulatory scenarios, which differ from EPA's proposed option and
regulatory alternatives (for additional detail, please see Chapter 8 of
USEPA (2023j). EPA's EJ exposure analysis demonstrated that across
hypothetical regulatory scenarios evaluated, elevated baseline PFAS
drinking water exposures, and thus greater anticipated reductions in
exposure, are estimated to occur in communities of color and/or low-
income populations. For the exposure analysis, EPA examined individuals
served by PWSs with modeled PFAS exposure above baseline concentration
thresholds or a specific alternative policy threshold. EPA also
summarized population-weighted average concentrations in the baseline
as well as reductions that would accrue to each demographic group from
hypothetical regulatory scenarios. In this analysis, EPA presents the
total affected population as a possible metric of comparison, noting
however that each affected demographic group is reflected also within
the total affected population. For the purpose of evaluating potential
EJ concerns, a commonly used demographic category is ``people of
color,'' which includes those who identify as a race other than White
and/or as Hispanic. It is possible that EPA understates the magnitude
of disproportionate baseline exposure to PFAS for people of color
because the total affected population includes some portion of the
specific populations of concern. For this reason, EPA included
information for non-Hispanic White populations in all tables of Section
8.3 in Chapter 8 of USEPA (2023j). EPA also described differences in
potential disproportionate impact when comparison is drawn from
population groups of concern to the non-Hispanic White population
instead of the total population across all demographic groups. EPA
requests comment on all aspects of the EJ analysis, including its
choice of comparison groups to help identify potential demographic
disparities in anticipated PFAS exposure.
    Additionally, EPA's analysis in SafeWater MCBC evaluated the
demographic distribution of health benefits and incremental household
costs anticipated to result from the proposed PFAS NPDWR. EPA's
proposed option and all regulatory alternatives are anticipated to
provide benefits across all health endpoint categories for all race/
ethnicity groups. Across all health endpoints, communities of color are
anticipated to experience the greatest quantified benefits associated
with EPA's proposed option.
    EPA's analysis in SafeWater MCMC also demonstrated that communities
of color are anticipated to bear elevated incremental household costs
associated with the rule. Although the incremental household cost
differences across race/ethnicity groups are minimal, for communities
already facing underlying EJ concerns, the impact of these incremental
cost increases are likely to impose a higher cost burden. In general,
incremental household costs to all race/ethnicity groups decrease as
system size increases, an expected result due to economies of scale.
Due to the overlap in vulnerabilities demonstrated by slightly elevated
household costs anticipated for particular race/ethnicity groups and
consistently elevated household costs for households served by small
systems, communities of color served by small systems are anticipated
to face compounding burdens. To alleviate potential cost disparities
identified by EPA's analysis, there may be an opportunity for some
communities to utilize funding from national legislation, including BIL
(Public Law 117-58), funds allocated to the Low-Income Household Water
Assistance Program (LIHWAP) by the American Rescue Plan (Public Law
117-2), and funding from other sources, to provide financial assistance
for addressing emerging contaminants. BIL funding has specific
allocations for both disadvantaged and/or small communities and
emerging contaminants, including PFAS.
    Additionally, on March 2, 2022, and April 5, 2022, EPA held public
meetings related to EJ and the development of the proposed NPDWR. The
meetings provided an opportunity for EPA to share information and for
communities to offer input on EJ considerations related to the
development of the proposed rule. During the meeting and in subsequent
written comments EPA received public comment on topics including
establishing an MCL for PFAS, affordability of PFAS abatement options,
limiting industrial discharge of PFAS, and EPA's relationship with
community groups. For more information on the public meetings, please
refer to the Environmental Justice Considerations for the Development
of the Proposed PFAS Drinking Water Regulation Public Meeting Summary
for each of the meeting dates in the public docket at https://www.regulations.gov/docket/EPA-HQ-OW-2022-0114. Additionally, the
written public comments are included within the public docket.

K. Consultations With the Science Advisory Board, National Drinking
Water Advisory Council, and the Secretary of Health and Human Services

    In accordance with sections 1412(d) and 1412(e) of the SDWA, the
Agency consulted with the NDWAC (or the Council); the Secretary of
Health and Human Services; and with the EPA SAB.
1. SAB
    The SAB PFAS Review Panel met virtually via a video meeting
platform on December 16, 2021, and then at three (3) subsequent
meetings on January 4, 6 and 7, 2022 to deliberate on the Agency's
charge questions. Another virtual meeting was held on May 3, 2022, to
discuss their draft report. Oral and written public comments were
considered throughout the advisory process. EPA sought guidance from
the EPA SAB on how best to consider and interpret life stage
information, epidemiological and biomonitoring data, the Agency's
physiologically-based pharmacokinetic (PBPK) analyses, and the totality
of PFAS health information to derive a MCLG for PFOA and PFOS, combined
toxicity framework, and CVD. The documents sent to SAB were EPA's
Proposed Approaches to the Derivation of a Draft Maximum Contaminant
Level Goal for Perfluorooctanoic Acid (PFOA) (CASRN 335-67-1) in
Drinking Water (USEPA, 2021e); EPA's Proposed Approaches to the
Derivation of a Draft Maximum Contaminant Level Goal for
Perfluorooctane Sulfonic Acid (PFOS) (CASRN 1763-23-1) in Drinking
Water (USEPA, 2021f); EPA's Framework for Estimating Noncancer Health
Risks Associated with Mixtures of Per- and Polyfluoroalkyl Substances
(PFAS) (USEPA, 2023d); and EPA's Analysis of Cardiovascular Disease
Risk Reduction as a Result of Reduced PFOA and PFOS Exposure in
Drinking Water. On May 3 and July 20, 2022, EPA received input from
SAB, summarized in the report, Review of EPA's Analyses to Support
EPA's National Primary Drinking Water Rulemaking for PFAS (USEPA,
2022a).
    In response to EPA's request that the SAB review EPA's four draft
documents listed above, the SAB identified subject matter experts to
augment the SAB Chemical Assessment Advisory Committee (CAAC) and
assembled the SAB PFAS Review Panel to conduct the review.
    In general, the SAB recognized the time constraints for completing
the rule-making process and was supportive of EPA's efforts to the
utilize the latest scientific finding to inform their decisions. The
SAB applauded the Agency's efforts to develop new approaches for
assessing the risk of PFAS mixtures and the benefits arising from
reducing exposure to these chemicals as adopted by EPA in the HI
approach in this proposed rule. In general, the SAB agreed with many of
the conclusions presented in the assessments, framework, and analysis.
The SAB also identified many areas that would benefit from further
clarification to enhance their transparency and increase their utility.
The SAB provided numerous recommendations which can be found in the
SAB's final report (USEPA, 2022a) and some highlights are outlined
below.
a. Approaches to the Derivation of Draft MCLGs for PFOA and PFOS
    The primary purpose of the Proposed Approaches to the Derivation of
Draft MCLGs for PFOA and PFOS (USEPA, 2021e; USEPA, 2021f) was to
develop MCLGs based on the best available health effects information
for PFOA and PFOS. Each MCLG draft document includes derivation of an
updated chronic oral RfD, CSF when relevant data were available, and an
RSC for SAB review. The health effects information used to derive these
toxicity values and RSC values built upon the information in the 2016
PFOA and PFOS HESDs (USEPA, 2016e; USEPA, 2016f) and Health Advisories
(USEPA, 2016a; USEPA, 2016b), respectively. EPA has considered all SAB
consensus advice in the development of the proposed values derived in
this health effects assessment and subsequently derived MCLGs for the
NPDWRs for PFOA and PFOS based on the best available science and EPA
guidance and precedent. Please see section IV and V of this preamble
for discussions on the process for derivation of the MCLGs and the
resulting proposed MCLG values for this proposed action.
    The SAB charge questions for the MCLG draft documents addressed the
systematic review study identification and inclusion, non-cancer hazard
identification, cancer hazard identification and slope factor,
toxicokinetic modeling, RfD derivation, and RSC. The complete list of
charge questions was included in EPA's documents prepared for the SAB
(USEPA, 2022a). The SAB provided numerous specific recommendations to
consider alternative approaches, expand the systematic review steps for
the health effects assessment, and to develop additional analyses in
order to improve the rigor and transparency of EPA's documents. The
complete list of SAB consensus advice is described in their final
report (USEPA, 2022a).
    In general, the SAB agreed with many of the conclusions presented
in the assessments, framework, and analyses. The SAB recognized the
time constraints for completing the rule-making process and supported
EPA's efforts to use the latest scientific information to inform their
decisions. The SAB applauded the Agency's efforts to develop new
approaches for assessing the risk of PFAS mixtures and the benefits
arising from reducing exposure to PFAS.
    The SAB also identified areas that would benefit from further
clarification, expansion, and transparency. The SAB provided written
comments and responses to EPA's charge questions (USEPA, 2022a) and the
following is a summary of their recommendations and EPA's associated
revisions.
    Regarding the approaches to deriving MCLG draft documents, the SAB
stated that the systematic review methods could be more transparent and
complete. Specifically, study identification and criteria for inclusion
could be improved. EPA made revisions to the systematic review
description and process by updating and expanding the scope of the
literature search; providing greater transparency regarding the study
inclusion criteria; and adding additional systematic review steps and
transparently describing each of these steps in the PFOA and PFOS
systematic review protocols.
    In the charge questions, EPA sought advice on the noncancer health
assessment, and the SAB recommended that EPA separate hazard and dose-
response assessment systematic review steps. In response, EPA made
revisions to the noncancer hazard identification by expanding
systematic review steps beyond study quality evaluation to include
evidence integration to address the need to separate hazard
identification and dose-response assessment and to ensure consistent
hazard decisions; and strengthening rationales for selection of points
of departure for the noncancer health outcomes. Additionally, the SAB
advised EPA to focus on the health endpoints with the strongest
evidence (i.e., liver, immune, serum lipids, development, and cancer).
    EPA consulted with the SAB on the cancer risk assessment. On the
cancer HI and CSF, the SAB agreed that PFOA was a ``likely''
designation but recommended undertaking and describing a more
structured and transparent discussion of the ``weight of evidence'' for
both PFOA and PFOS. EPA revised this assessment by following the
structured approach in the EPA cancer guidelines (USEPA, 2005) to

develop a weight of evidence narrative for cancer, to consider the data
for selecting the cancer classification, evaluating and integrating
mechanistic information, and strengthening the rationales for
decisions.
    For the toxicokinetics model that EPA sought advice on, SAB
requested more details on the toxicokinetic modeling including model
code and parameters and recommended that EPA consider expressing the
RfD in water concentration equivalents to better account for possible
life-stage specific differences in exposure rates and toxicokinetics.
EPA considered the alternate approach suggested by SAB and made
revisions by evaluating alternative toxicokinetic models and further
validating the selected model.
    EPA also sought advice on the draft RfD derivation. The SAB advised
that EPA consider multiple human and animal studies for a variety of
endpoints and populations. The SAB also stated a need for stronger and
more transparent justification of benchmark response selections and
asked EPA to consider adopting a probabilistic framework to calculate
risk-specific doses. SAB also recommended that EPA clearly state that
RfDs apply to both short-term and chronic exposure. EPA made revisions
based on these recommendations by providing additional descriptions and
rationale for the selected modeling approaches and conducting new dose-
response analyses of additional studies and endpoints.
    On the RSC charge question, SAB supported the selection of a 20%
RSC, but asked that EPA provide clarity and rationale to support the
value. To address this recommendation, EPA added clarifying language
related to the RSC determination from EPA guidance (USEPA, 2000c),
including the relevance of drinking water exposures and the
relationship between the RfD and the RSC.
b. Combined Toxicity Framework
    EPA sought advice from an external SAB on the Draft Framework for
Estimating Noncancer Health Risks Associated with Mixtures of PFAS
document (USEPA, 2023d). The main purpose of this document was to
provide a data-driven framework for estimating human health risks
associated with oral exposures to mixtures of PFAS. The charge
questions for the SAB pertaining to the framework draft documents
included whether EPA provided clear support for the assumption of dose
additivity, and application of the HI, RPF, and mixtures benchmark dose
(BMD) approaches for the evaluation of mixtures of PFAS. The full list
of charge questions was included in EPA's documents prepared for the
SAB (USEPA, 2022a). The SAB agreed in general with the assumption of
dose additivity at the level of common health effect, and application
of the HI, RPF and mixture BMD approaches for the evaluation of
mixtures of PFAS. The SAB identified instances in which the
communication of the analyses and approaches in EPA's framework
document could be improved to be clearer.
    On EPA's charge question for dose additivity, the SAB agreed with
the use of the dose additivity default assumption when evaluating PFAS
mixtures that have similar effects and concluded that this assumption
was health protective. SAB recommended a more thoroughly and clearly
presented list of the uncertainties associated with this approach along
with information supporting this approach. EPA made revisions that
added clarity to the text by expanding upon the uncertainties and
including additional support for using dose additivity.
    The SAB panel agreed with the use of the HI as a screening method
and decision-making tool. SAB advised that EPA should consider using a
menu-based framework to support selection of fit-for-purpose
approaches, rather than a tiered approach as described in the draft
mixtures document. Based on this feedback, EPA has since reorganized
the approach to provide a data-driven ``menu of options'' to remove the
tiered logic flow and is adding text to clarify the flexibility in
implementation.
    EPA sought SAB's opinion on the RPF approach for estimating health
risks associated with PFAS mixtures and the SAB panel considered the
RPF approach to be a reasonable methodology for assessing mixtures. On
the mixture BMD, the SAB agreed that the mixture BMD approach was a
reasonable methodology for estimating a mixture-based POD. For both the
RPF and mixture BMD approach, SAB recommended that EPA's approach would
be strengthened by the use of PODs from animal studies that are based
on HEDs rather than administered doses. SAB also requested
clarification as to the similarities and differences among the RPF and
mixture BMD approaches. SAB also asked EPA to provide additional
information on how the proposed mixtures BMD approach would be applied
in practice. To address these concerns, EPA made revisions to provide
better context and delineation about the applicability of the data
across these approaches.
c. CVD Analysis
    EPA consulted with the SAB on the Agency's methodology to determine
the avoided cases of CVD events (e.g., heart attack, stroke, death from
coronary heart disease) associated with reductions in exposure to PFOA
and PFOS in drinking water to support a benefits analysis.
Specifically, EPA sought SAB comment on the extent to which the
approach to estimating reductions in CVD risk is scientifically
supported and clearly described. EPA posed specific charge questions on
the exposure-response information used in the analysis, the risk model
and approach used to estimate the avoided cases of CVD events, and
EPA's discussion of limitations and uncertainties of the analysis.
Overall, the SAB supported EPA's approach to estimating reductions in
CVD risk associated with reductions in exposure to PFOA and PFOS in
drinking water. The SAB provided feedback on several areas of the
analysis; main points of their feedback and EPA's responses are
discussed below.
    The SAB noted a discrepancy between the draft CVD document's focus
on CVD risk, and the draft MCLG documents' conclusions that the
evidence of CVD was not sufficient to form the basis of a RfD. Based on
SAB feedback on the draft MCLG document's assessment of CVD related
risks, EPA has developed an RfD for total cholesterol (For more
information see USEPA, 2023b; USEPA, 2023c). The derivation of an RfD
for this endpoint addresses the SAB's concerns about inconsistency
between the two documents. The SAB also recommended that EPA ensure
that recommendations for the draft MCLG documents relating to evidence
identification and synthesis are applied to the CVD endpoint. All
studies in EPA's CVD benefits analysis were evaluated for risk of bias,
selective reporting, and sensitivity as applied in EPA's Public Comment
Draft--Toxicity Assessment and Proposed MCLGs for PFOA and PFOS in
Drinking Water (USEPA, 2023b; USEPA, 2023c).
    The SAB recommended that EPA provide more discussion as to the
rationale for selecting CVD for risk reduction analysis and that the
approach follows the pathway that links cholesterol to cardiovascular
events rather than looking at the reported effects of PFAS directly on
CVD. The SAB also recommended that EPA consider risk reduction analyses
for other endpoints. In Section 6.5 of the Economic Analysis, EPA
discusses the rationale for quantifying CVD and analytical assumptions.
Sections 6.4 and

6.6 discusses the Agency's quantified risk reduction analyses for other
adverse health effects, including infant birthweight effects and RCC,
respectively. In Section 6.2.2 EPA assesses the qualitative benefits of
other adverse health effects of PFAS.
    Although the SAB generally agreed with the meta-analysis, life
table and risk estimation methods, the SAB recommended that EPA provide
additional clarity as to the application of these approaches and
conduct additional sensitivity analyses. In response to these comments,
EPA expanded documentation and conducted additional sensitivity
analyses to evaluate the impact of inclusion or exclusion of certain
studies in the meta-analyses of exposure-response estimates. Further,
EPA expanded documentation and conducted additional sensitivity
analyses to assess the effects of using a key single study approach
versus the meta-analysis approach to inform the exposure-response
estimates. EPA identified two suitable key studies for use in the
single study approach. EPA found that the single study approach
resulted in increased benefits, and this trend was driven by the larger
estimates of PFAS-total cholesterol slope factors and inverse
associations in the HDLC effect for one or both contaminants in the key
single studies. EPA elected to retain the meta-analysis approach in the
benefits analysis because the Agency identified several studies on
adults in the general population with large numbers of participants and
low risk of bias, and in this case the meta-analytical approach offers
an increased statistical power over the single study approach. While
the single study approach is common for RfD derivations, the meta-
analysis pooled estimate provides a slope factor that represents the
average response across a larger number of studies, which is useful in
evaluating benefits resulting from changes in CVD risk on a national
scale.
    The SAB also recommended that EPA evaluate how inclusion of HDLC
effects would influence the results and provide further justification
for the inclusion or exclusion of HDLC and blood pressure effects. EPA
found that, as expected, inclusion of HDLC effects decreases annualized
CVD benefits and inclusion of blood pressure effects slightly increases
annualized CVD benefits. Because HDLC was shown to have a stronger
effect than blood pressure on annualized CVD benefits, inclusion of
blood pressure and HDLC effects together decreases annualized CVD
benefits. For more information see sensitivity analyses evaluating
these effects in Appendix K of the EA. Inclusion of HDLC effects into
the national analysis would reduce national benefits estimates but
would not change EPA's bottom-line conclusion that the quantifiable and
nonquantifiable benefits of the rule justify the quantifiable and
nonquantifiable costs. After further examination of the evidence for
HDLC and blood pressure effects, EPA elected to include blood pressure
effects because the findings from a single high confidence study and
several medium confidence studies conducted among the general
population provided consistent evidence of an association between PFOS
exposure and blood pressure. EPA did not include HDLC effects in the
national benefits analysis because available evidence of associations
between PFOS exposures and HDLC levels is inconsistent and there is no
evidence of an association between PFOA exposures and HDLC levels.
    Finally, the SAB noted that while the ASCVD model is a reasonable
choice for estimating the probability of first time CVD events, it is
not without limitations. The panel recommended that EPA include more
discussion of the accuracy of its predictions, particularly for sub-
populations. EPA expanded its evaluation of the ASCVD model's
limitations, including a comparison of the ASCVD model predictions with
race/ethnicity and sex-specific CVD incidence from CDC's public health
surveys (See Section <IP_ADDRESS> and Appendix G of the Economic Analysis
for details). Results show that the ASCVD model coefficients for the
non-Hispanic Black model are more consistent with data on CVD
prevalence and mortality for Hispanic and non-Hispanic other race
subpopulations than the ASCVD model coefficients for the non-Hispanic
White model.
2. NDWAC
    The Agency consulted with NDWAC during the Council's April 19,
2022, virtual meeting. A summary of the NDWAC recommendations is
available in the National Drinking Water Advisory Council, Fall 2022
Meeting Summary Report (NDWAC, 2022 https://www.federalregister.gov/documents/2022/03/29/2022-06576/meeting-of-the-national-drinking-water-advisory-council) and the docket for this proposed rule. EPA carefully
considered NDWAC recommendations during the development of a proposed
drinking water rule for PFAS, including PFOA and PFOS.
3. HHS
    On September 28, 2022, EPA consulted with the Department of Health
and Human Services (HHS). EPA provided information to HHS officials on
the draft proposed NPDWR and considered HHS input as part of the
interagency review.

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