lead to all age groups, instructions for flushing the tap prior to
drinking or cooking to reduce lead levels as a result of stagnation in
contact with lead sources, recommendations on the use of filters, and
additional measures consumers can take to prevent lead exposure.
Additionally, stakeholders have expressed concern that some consumers
may lack the financial resources to replace leaded materials. EPA is
reframing the language to provide steps that consumers can take to
reduce the risk of lead exposure and help protect themselves and their
family, rather than implying that they can take responsibility for
controlling lead in their drinking water. EPA is also proposing to
revise the statement to include additional steps consumers can take to
reduce their exposure to lead in drinking water, such as using only
cold water for drinking, cooking, and preparing baby formula. In
addition, EPA is proposing to recommend that consumers refer to the
instructions provided with their filter to ensure it is used properly.
EPA has also heard concerns, in written comments submitted on the
proposed CCR Rule Revisions (Docket ID EPA-HQ-OW-2022-0260), that homes
with lead service lines may need to run the water for a longer period
of time. In response, EPA is proposing to add new language noting that
consumers served by lead or galvanized requiring replacement service
lines may need to flush their pipes for longer periods.
Mandatory Lead Health Effects Language
    Under the current CCR Rule, CWSs are required to include in the CCR
the mandatory lead or copper health effects language listed in Appendix
A to

Subpart O of Part 141 when they fail to take one or more actions
prescribed by Sec. Sec.  141.80(d), 141.81, 141.82, 141.83 or 141.84.
EPA is proposing to require CWSs to include the mandatory lead or
copper health effects language when they fail to take one or more
actions prescribed by Sec. Sec.  141.80 through 141.93. This would
expand the requirement to apply to more situations, such as failing to
meet the public education requirements in Sec.  141.85 or requirements
for sampling in schools and child care facilities under Sec.  141.93,
so that consumers are more informed of the health effects of lead and
copper.
    Under the LCRR, the mandatory lead health effects language required
in the CCR is also required to be included in lead public education and
public notification (see section V.H.). The current mandatory lead
health effects language is as follows:
    Exposure to lead in drinking water can cause serious health effects
in all age groups. Infants and children can have decreases in IQ and
attention span. Lead exposure can lead to new learning and behavior
problems or exacerbate existing learning and behavior problems. The
children of women who are exposed to lead before or during pregnancy
can have increased risk of these adverse health effects. Adults can
have increased risks of heart disease, high blood pressure, kidney or
nervous system problems.
    EPA is proposing to revise the mandatory lead health effects
language that is required in public education, public notification, and
the CCR, as described in section V.H.5. and as follows. Additions are
underlined to illustrate changes from the current text:
[GRAPHIC] [TIFF OMITTED] TP06DE23.083

    See section V.H.5. of this document for more information about the
proposed revised mandatory lead health effects language.
Other Requirements
    Under the LCRR, water systems are not required to include
information about sampling for lead in schools and child care
facilities in the CCR. EPA is proposing to require that water systems
include in the CCR a statement that the water system is required to
sample for lead in schools and licensed child care facilities as
requested by the facility, in accordance with Sec.  141.92 of the
proposed LCRI, to encourage relevant members of the public to contact
their school or child care facility for further information about
potential sampling results. During the LCRR review, EPA heard concerns
about the lack of a reporting requirement to publicly share results
from sampling in schools and child care facilities (86 FR 71574, USEPA,
2021b). EPA does not have the authority under SDWA to require schools
and child care facilities to share the results as part of an NPDWR,
including the proposed LCRI. To address this feedback, the Agency is
proposing to require an informational statement in the CCR that would
help ensure that consumers are aware of the school and child care
sampling requirements and that they can reach out to the school or
child care facility about any potential sampling results. EPA is
requesting comment from the public on this proposed requirement (see
section IX. of this document). See section V.J. of this document for
more information about lead sampling at schools and child care
facilities.
    Under the LCRR, water systems are required to include information
about their service line inventory in the CCR; however, they are not
required to include information about service line replacement. As
stated in section V.B.7. of this document, EPA is proposing for the
LCRI to require water systems to make the service line replacement plan
publicly available. Furthermore, EPA is proposing to require that water
systems with lead, galvanized requiring replacement, or lead status
unknown service lines in their inventory include in the CCR information
on how to obtain a copy of the service line replacement plan or for
systems serving more than 50,000 people, how to view the plan on the
internet. Including information about how to access the plan in the CCR
would further increase transparency about the service line replacement
process, accessibility of the plan, and consumer awareness about
service line replacement in their community.
2. Public Notification Rule (40 CFR Part 141, Subpart Q)
    EPA promulgated a Public Notification Rule in 40 CFR part 141,
subpart Q in 2000 (65 FR 26035, USEPA, 2000b). This Public Notification
Rule implements section 1414(c)(1) and

(2) of SDWA. That rule requires water systems to provide public
notification of any failure of the water system to comply with a
maximum contaminant level, a prescribed treatment technique, or failure
to perform required water quality monitoring, or testing procedures; if
the system has been granted a variance or exemption, if the system has
failed to comply with the requirements of any schedule set under a
variance or exemption; and certain specified situations such as the
occurrence of waterborne disease outbreak or emergency and the
availability of unregulated monitoring data (see Sec.  141.201, Table
1).
    In 2016, Congress amended sections 1414(c)(1) and (2) of SDWA, in
the WIIN Act to require EPA's implementing regulations to ``specify
notification procedures for'' public notice no later than 24 hours
after the water system learns of each exceedance of the action level
for lead prescribed under Sec.  141.80(c) of 40 CFR part 141, ``or a
prescribed level of lead that the Administrator establishes for public
education or notification in a successor regulation promulgated
pursuant to section 1412'' if the exceedance ``has the potential to
have serious adverse effects on human health as a result of short term
exposure'' (42 U.S.C. 300g-3(c)((1)((D) and (c)(2)((C)). In the LCRR
rulemaking, EPA determined that ``such exceedances [of the lead action
level] have the potential to have serious adverse health effects on
human health as a result of short-term exposure'' and therefore
warranted the same treatment as other situations currently categorized
as Tier 1 violations subject to the 24-hour notification requirements
(86 FR 4239-4240, USEPA, 2021a). Under the LCRR, CWSs and NTNCWSs with
a lead action level exceedance must provide public notice to persons
served by the system within 24 hours of learning of the action level
exceedance; that is, within 24 hours of the system receiving and
calculating the 90th percentile value, or after the data is submitted
to the State and the State calculates the 90th percentile. The notice
must be in a form and manner reasonably calculated to reach all persons
served, as described in the Public Notification Rule (Sec.
141.202(c)). A copy of the notice must also be sent to both the State
and the EPA Administrator in accordance with the requirements of Sec.
141.31(d). This notice to the Administrator for a lead action level
exceedance is needed because section 1414(c)(2)(iii) of SDWA was
amended by the WIIN Act to require that such notifications be provided
to the Administrator in addition to the State to allow EPA to identify
whether the Agency must provide notice where required in section
1414(c)(2)(D), which was also added to SDWA by the WIIN Act. It
provides that if a State with primacy enforcement responsibility or the
water system has not issued a notice for an action level exceedance
that has the potential to have serious adverse effects as a result of
short-term exposure, the Administrator is required to issue the notice.
Because EPA does not have any obligation to issue a Tier 1 public
notice for violations of other drinking water standards in States with
primacy, there is no need for EPA to be notified in those other Tier 1
situations.
    In addition to lead action level exceedances, there are violations
that also require public notification for both lead and copper (see
Appendix A to Subpart Q of Part 141 of the CFR). Tier 2 public
notification is required for a treatment technique violation for both
lead and copper no later than 30 days after the system learns of the
violation. This includes violations to Sec.  141.80 through Sec.
141.84 which describe compliance dates of the rule, the action level,
CCT, source water treatment, and service line inventory and replacement
requirements; however, Sec.  141.80(c) which describes exceedances of
the lead action level is excluded from the Tier 2 public notification
requirements since lead action level exceedances require Tier 1 public
notification. Tier 2 public notification is also required for
violations to Sec.  141.85(a) through (c) and (h) which concern the
content of public education materials and inclusion of information for
non-English speaking consumers, delivery of public education after a
lead action level exceedance, supplemental monitoring for lead when
there is a systemwide lead action level exceedance, and outreach
activities for community water systems that fail to meet the LSLR goal.
In addition, Tier 2 public notification is required for violations to
Sec.  141.93 which describes flexibilities for small water systems to
comply with the rule.
    As described in section V.H.3. of this document, EPA is proposing
to require notification of supplemental monitoring for lead under Sec.
141.85(c)(3); EPA is proposing to exclude this from the Tier 2 public
notification requirements as this pertains to notification of
supplemental sampling conducted at individual tap sampling sites,
rather than systemwide. In addition, as discussed in section V.H.2. of
this document, EPA is proposing to revise Sec.  141.85(h) to require
outreach activities for systems that fail to meet the average annual
replacement rate, instead of the goal LSLR rate as required under the
LCRR. Violations to this proposed requirement would require Tier 2
public notification under the proposed LCRI. EPA is also proposing to
require Tier 2 public notification for violations to the proposed
additional public education and filter requirements for water systems
with multiple lead action level exceedances under Sec.  141.85(j). See
section V.H. of this document for more information about the proposed
public education requirements. Tier 3 public notification is required
for monitoring and testing procedure violations for both lead and
copper no later than one year after the system learns of the violation
or begins operating under a variance or exemption. These include
violations to Sec.  141.86 through Sec.  141.90 of the LCRR and
proposed LCRI. EPA is also proposing to require Tier 3 public
notification for violations to Sec.  141.92; as with violations to
other monitoring and testing requirements, EPA believes that the public
should be notified when water systems fail to conduct required sampling
in schools and child care facilities.
    In the LCRI, EPA is not proposing to prescribe a level of lead for
public education or public notification that is different from the lead
action level in Sec.  141.80(c). Nor is EPA proposing to change the
conclusion made during the LCRR rulemaking that a lead action level
exceedance has the potential to have a serious adverse effect on human
health as a result of short-term exposure. Therefore, as required in
section 1414(c)(2)(C) of SDWA, a lead action level exceedance will
continue to trigger the requirement for Tier 1 public notification of a
lead action level exceedance. During the LCRR review (see written
comments and summaries of LCRR engagements, Docket ID EPA-HQ-OW-2021-
0255) and Federalism consultation for the proposed LCRI (USEPA, 2023j),
EPA received feedback on the requirement for 24-hour Tier 1 public
notification of a lead action level exceedance expressing both support
and opposition for this requirement. Many stakeholders expressed
concern about the ability of water systems to distribute public notices
within 24 hours of the system learning of the action level exceedance
(USEPA, 2023j; Docket ID EPA-HQ-OW-2021-0255; Docket ID EPA-HQ-OW-2017-
0300). Many stakeholders questioned whether lead could have serious
adverse health effects from short-term exposure (Docket ID EPA-HQ-OW-
2021-0255). As stated in the final LCRR notice, EPA has concluded that
lead action level exceedances have the potential to have

serious adverse effects on human health as a result of short-term
exposure (86 FR 4239-40, USEPA, 2021a). SDWA mandates that notice in
such a situation be distributed ``as soon as practicable, but not later
than 24 hours after the public water system learns of the violation or
exceedance''. The feasibility analysis EPA conducts in establishing a
NPDWR is not a prerequisite to implementation of this statutory
mandate. Moreover, EPA notes that water systems have been complying
with the Tier 1 24-hour notice requirement for other situations besides
a lead action level exceedance since the May 6, 2002, compliance date
of the Public Notification Rule, and therefore should also be able to
do so for lead action level exceedances.
    Because EPA is not proposing to prescribe a level of lead for
public education or public notification that is different from the lead
action level in Sec.  141.80(c), EPA is updating the action level for
lead listed in appendix A to subpart Q of part 141 to conform with the
Agency's proposed lead action level of 0.010 mg/L (see section V.E.2.
of this document for more information about the proposed action level).
EPA is retaining the October 16, 2024, compliance date for this
provision. Beginning on that date, systems must comply with the Tier 1
PN requirement for a lead action level of 0.015 mg/L, and beginning on
the final LCRI compliance date, they would comply with the revised lead
action level of 0.010 mg/L (see section VII.A. of this document).
    EPA is also proposing to make conforming changes to the Public
Notification Rule as a result of changes EPA is proposing to make in
the LCRI and the CCR related to the standard health effects language
for lead in appendix B to subpart Q of part 141, to be consistent with
the proposed revised lead health effects language required in public
education and the CCR. See section V.H.5. of this document for more
information about the proposed revised mandatory lead health effects
language.
3. Definitions
    In accordance with EPA's goal identified in the LCRR review notice
to simplify the LCRI, EPA is proposing new definitions to conform with
new proposed requirements under LCRI, as well as updating the
definitions for some existing terms in LCRR to clarify them. EPA's
proposed new and updated definitions for LCRI are as follows:
    Action level. EPA is proposing to revise this definition so that
the lead action level conforms with the proposed new lead action level
of 0.010 mg/L.
    Child care facility. EPA is proposing to make minor clarifications
that specify the definition applies to Subpart I only and that the
licenses for child care facilities must come from a State, local, or
Tribal licensing agency.
    Connector. EPA is proposing to revise this definition in several
ways. EPA is proposing to streamline the definition to only include the
word ``connector'' and not ``goosenecks, pigtails, and connectors''
because throughout the regulatory text, EPA refers to these pipes as
``connectors.'' The definition notes that connectors are also referred
to as ``goosenecks'' and ``pigtails.'' EPA is also clarifying that
connectors typically connect the service line to the main. EPA is also
proposing that the definition for a connector states the short segment
of piping does not exceed two feet.
    During the LCRI engagements, some stakeholders recommended that
lead connectors be added to the LSL definition, noting that separating
the definitions for lead connectors and LSLs could prevent connectors
from being replaced under the service line replacement program, and
that consumers would not receive the same notification that they are
served by a lead connector as if they were served by an LSL. EPA is
proposing to keep the lead connector and LSL definitions separate
because EPA views the connector and service line as distinct
components. Adding connectors to the definition for LSL, such that a
connector would be considered a service line under LCRI, could create
confusion, which is counter to EPA's goal of simplifying the rule.
Instead, EPA is proposing to keep the definitions separate and be clear
about which proposed requirements apply to service lines, and which
apply to connectors. For what EPA is specifically proposing with
respect to connectors, please see section V.D.4. of this document.
    Some stakeholders requested additional guidance on the LCRR
definition of ``gooseneck, pigtail, or connector,'' which included the
phrase ``typically not exceeding two feet'' (USEPA, 2023j). These
stakeholders said that that they are aware of lead connectors that are
10 feet in length or longer and recommended that EPA define a maximum
connector length and remove the word ``typically'' when referring to
their length in the definition (USEPA, 2023j). EPA is proposing to
change the definition of ``gooseneck, pigtail, or connector'' to
exclude any connector that exceeds two feet because EPA is not aware of
anything longer than two-feet that meets the other aspects of the
definition--``short section of piping which can be bent and used for
connections between rigid service piping.'' 40 CFR 141.2 (Emphasis
added.) Moreover, the primary function of piping longer than two feet
is more akin to a service line than ``short'' piping that ``can be bent
and used for connections between rigid service piping.'' In addition,
the contributions of lead into drinking water from something longer
than two feet is expected to be closer to that of an LSL. Additionally,
the materials that make up piping longer than two feet could
potentially be identified for purposes of the inventory through similar
techniques as service lines, such as potholing, given that longer
connectors may extend beyond the street pavement. Therefore, EPA is
proposing to regulate connectors greater than two feet in length the
same way as service lines by narrowing the definition of connector. EPA
is requesting comment on EPA's rationale for these changes and whether
two feet is the appropriate maximum length for a lead connector (see
section IX. of this document).
    Distribution system and site assessment. EPA is proposing to rename
the LCRR's ``find-and-fix'' requirement to better align with the
underlying requirements of the provision. The proposed requirements
apply in a narrow set of circumstances, and they do not require water
systems to either ``find'' the cause of a lead action level exceedance
or ``fix'' all causes found. Since promulgating the LCRR, EPA has
noticed that the phrase ``find-and-fix'' has caused significant
confusion among States, water systems, other stakeholders, and the
public. The new, proposed name, distribution system and site
assessment, more clearly explains what the proposed requirement for
systems entails: assessing potential reasons at the system- and site-
level why a lead sample tested above the lead action level. EPA is also
proposing to update the definition to include the proposed revised lead
action level of 0.010 mg/L.
    Find-and-fix. EPA is proposing to remove the definition of ``find-
and-fix'' given the proposed revised name of the requirement. See the
proposed definition of ``distribution system and site assessment.''
    Full service line replacement. EPA is proposing to remove the
definition of ``full lead service line replacement'' from 141.2 and
instead, specify what constitutes a full service line replacement under
the mandatory replacement program within the regulatory requirements in
141.84(d)(6)(iii). By moving the substantive requirements for service
line replacement out of the definition

section in subpart A of part 141 and including them with the other
substantive requirements of the LCRI in Subpart I of Part 141, the LCRI
would be easier to understand and implement.
    Galvanized requiring replacement. The LCRR includes a definition of
``galvanized service line'' in Sec.  141.2 and the LCRR definition of
lead service line in Sec.  141.2 provides that ``a galvanized service
line is considered a lead service line if it ever was or is currently
downstream of any lead service line or service line of unknown
material'' The definition of LSL also provided that ``if the only lead
piping serving the home is a lead gooseneck, pigtail, or connector, and
it is not a galvanized service line that is considered a lead service
line, the service line is not a lead service line.'' Thus, within the
definition of ``lead service line'' EPA essentially defined a GRR
service line. In contrast, a GRR service line is defined without
reference to connectors in the inventory requirements in Sec.
141.84(a). This discrepancy has caused confusion. Accordingly, EPA is
proposing to add a definition of GRR service lines in Sec.  141.2, and
to reference this same definition within the inventory section. This
would streamline the LSL definition by removing information about GRR
service lines from the LSL definition. During the proposed LCRI
external engagements, EPA heard requests from a range of stakeholders
for more clarity regarding the definition of GRR service lines. EPA
expects the new revised proposed definition would be clearer,
especially in tandem with the proposed definition of connectors that
provides that connectors are not part of the service line to make the
definition for service line clearer as well.
    Gooseneck, pigtail, or connector. EPA is proposing to remove the
definition of ``gooseneck, pigtail, or connector'' and replace it with
a definition for ``connector,'' which is described above.
    Lead service line. EPA is proposing to simplify the definition of a
LSL, moving portions of the text to the regulatory requirements under
Sec.  141.84 and to the proposed definition of ``service line.'' During
the LCRI engagements, EPA heard the definition was confusing and
cumbersome. EPA expects this new definition would be clearer.
    Lead status unknown service line. EPA is proposing to revise the
definition of ``lead status unknown service line'' to specify that the
definition applies ``for the purpose of subpart I of this part only''
and to simplify the definition by stating that it is any line not
demonstrated to be an LSL, GRR service line, or non-lead pursuant to
Sec.  141.84.
    Newly regulated public water system. EPA is proposing to add a
definition of ``newly regulated public water system'' because of the
new proposed revision under Sec.  141.84 which applies to the
requirements of these systems to develop baseline inventories.
    Partial lead service line replacement. EPA is proposing to
eliminate the definition of ``partial lead service line replacement''
and replace it with the proposed definition of ``partial service line
replacement.''
    Partial service line replacement. EPA is proposing to add a
definition of ``partial service line replacement'' which specifies that
the definition applies ``for the purpose of subpart I of this part
only.'' The definition also expands the LCRR definition of ``partial
lead service line replacement'' to include partial replacement of GRR
service lines, in addition to LSLs. The definition also removes the
text describing where partials are permitted and that they don't count
towards the LCRR replacement rates, as the proposed LCRI includes these
provisions in Sec.  141.84.
    Trigger level. EPA is proposing to remove the definition of
``trigger level'' because of the proposed elimination of the trigger
level.
    Service line. EPA is proposing to create a definition for ``service
line'' to clarify proposed requirements under LCRI, especially the
proposed requirement that systems create an inventory ``that identifies
the materials and location of each service line connected to the public
water distribution system.''
    Small water system. EPA is proposing to correct an error from LCRR
to define small water systems as those serving 10,000 persons or fewer.
EPA is specifying that this definition applies to Subpart I, only.
    Tap monitoring period. EPA is proposing to add a definition of
``tap monitoring period'' to specify the period of time during which
each water system must conduct lead or copper tap sampling, which can
range from six months to nine years.
    Tap sample monitoring period. EPA is proposing to remove the
definition of ``tap sampling monitoring period'' and replace it with
the term ``tap monitoring period.'' The revision removes the regulatory
provisions contained within the definition of ``tap sample monitoring
period,'' as the proposed provisions are now included in Sec.  141.86.
    Tap sampling period. EPA is proposing to revise the definition of
``tap sampling period'' to remove the regulatory provisions that were
included in the definition. This revision simplifies the definition, as
the proposed provisions are now included in Sec.  141.86.
    Wide-mouth bottle. In LCRR, EPA added a definition for wide-mouth
bottle that requires bottles to be configured with a mouth that is at
least 55 millimeters (mm) wide and one liter in size. EPA is proposing
to modify the definition of wide-mouth bottle to explicitly state that
55 mm is the outer diameter measurement of the bottle. Since the
promulgation of the LCRR, EPA has received several questions about this
requirement and whether the width is based on the interior or exterior/
cap size of a bottle, as there are few types of bottles that have a 55
mm inner diameter (USEPA, 2023m). EPA anticipates this revised
definition would be clearer and provide systems with more options to
accurately implement the relevant LCRI requirements.
    EPA is also proposing minor revisions to select definitions. EPA is
proposing to a minor revision to the definition of ``elementary
school'' for clarity by changing the word ``purposes'' to ``purpose.''
EPA is proposing to revise the definition of ``galvanized service
line'' to clarify that the definition is intended to apply ``for the
purpose of subpart I of this part'' only. EPA is proposing a
grammatical correction to the definition of ``pitcher filter'' to
remove an unnecessary comma. EPA is proposing a clarification to the
definition of ``secondary school'' to include the grades which
typically encompass secondary schools. EPA is proposing to eliminate
the definition of ``medium-sized water system'' and replace it with an
identical definition under ``medium water system'' for consistency in
how the different system size categories are referred to. EPA is
proposing a grammatical correction to the definition of ``optimal
corrosion control treatment'' to change the word ``insuring'' to
``ensuring.'' EPA is proposing to revise the definition of ``tap
sampling protocol'' to refer to the protocol required by the rule
itself rather than the instructions provided to residents to conduct
sampling, as residents may not conduct sampling. EPA is proposing to
revise the definition of a ``system without corrosion control
treatment'' to specify that the definition applies ``for the purpose of
subpart I of this part.'' EPA is seeking comment on all aspects of the
proposed definitions.

VI. Rule Areas for Which EPA Is Not Proposing Revisions

    EPA is not proposing revisions to the following sections: 40 CFR
141.83 Source water treatment requirements, Sec.  141.88 Monitoring
requirements for lead and copper in source water, and Sec.  141.89
Analytical methods. The provisions in these sections are not affected
by any of the changes EPA is proposing to other sections as part of
this rule.

VII. Rule Implementation and Enforcement

    EPA is proposing requirements that would improve oversight and
enforcement of the NPDWR for lead and copper, including eliminating the
trigger level, enhanced sampling for detecting corrosion control issues
in LSL systems, simplifying small system flexibility, streamlining
public education following elevated lead measurements, and increased
reporting by both systems and States. EPA also provides applicable
guidance and tools on CCT, PE, and other aspects of the rule on the
Agency's website at https://www.epa.gov/dwreginfo/water-system-implementation-resources to support implementation of the LCR and the
LCRR and will continue to use this website to aid implementation of
revisions finalized as a result of this proposed rule.

A. What are the rule compliance dates?

    Section 1412(b)(10) of SDWA provides that promulgated NPDWRs shall
take effect three years after the NPDWR is promulgated ``unless the
Administrator determines that an earlier date is practicable.'' EPA is
proposing compliance dates for a final LCRI and seeking comment on
whether it would be practicable for water systems to implement any of
the proposed LCRI requirements earlier than three years from the date
of final action on the proposed LCRI (see section IX. of this
document). Additionally, the Agency is proposing to replace LCRR
requirements with the LCRI and is describing in this section which
requirements water systems will be required to follow between the
current October 16, 2024 LCRR compliance date and the LCRI compliance
dates.
    On June 16, 2021, EPA issued a final rule delaying the LCRR
compliance date from January 1, 2024 to October 16, 2024 during which
time water systems must continue to comply with the provisions of the
LCR (40 CFR 141.80 through 141.91, as codified on July 1, 2020) (86 FR
31939, USEPA, 2021e) and work towards compliance with the October 16,
2024 deadline for the service line inventory. While EPA expects to
promulgate the final LCRI prior to October 16, 2024, the Agency also
acknowledged that the announcement of the proposed LCRI ``creates some
uncertainty for water systems and States regarding the deadline and
completion'' of required actions under LCRR, including the LSLR and tap
sampling plans (86 FR 71580, USEPA, 2021b). In the LCRR review notice
published on December 17, 2021, the Agency stated its intention to
propose revisions to the LCRR compliance deadlines ``only for
components of the rule that the Agency will propose to significantly
revise'' (86 FR 71580, USEPA, 2021b). Some stakeholders have requested
that EPA further delay the LCRR compliance date for items the Agency is
proposing to revise in LCRI. For example, some States believe it will
be difficult for them to review all the required plans at the same time
and asked that EPA consider staggering various rule deadlines. Another
stakeholder indicated that EPA should require compliance with the LCRI
requirements beginning no earlier than January 2026. However, other
stakeholders have previously cited concerns that delaying
implementation of LCRR may delay public health protection (86 FR 31943,
USEPA, 2021e; State of Arizona et al., v. EPA, 77 4th 1126 (D.C. Cir.
2023) (dismissing petition for review of EPA's rule to delay the LCRR
compliance date)). For a discussion on how the proposed compliance
dates in this section address public health protection see section
IV.E.
Proposed LCRI Compliance Dates
    For the LCRI, EPA is proposing a compliance date of three years
after promulgation of a final rule and is proposing that systems
continue to comply with the LCR until that date, with the exception of
the LCRR initial LSL inventory, notification of service line material,
associated reporting requirements, and the requirement for Tier 1
public notification for a lead action level exceedance under subpart Q.
This would provide the amount of time necessary for States to work with
water systems to prepare to comply with the final LCRI requirements,
which include revisions to most of the provisions of LCRR. EPA is
proposing a direct transition from the LCR to the LCRI for all rule
provisions with the above exceptions, so that States and water systems
could focus their resources on preparing and updating service line
inventories and conducting Tier 1 public notifications following lead
action level exceedances, in addition to preparing for LCRI
requirements, such as preparing their service line replacement plan.
Water systems would not be required to comply with the other
requirements of the LCRR between October 16, 2024 and the LCRI
compliance date.
    EPA is proposing for water systems to continue to comply with the
LCR until the LCRI compliance dates, with the above exceptions, because
of the significant level of effort required of water systems to plan
for compliance with the LCRI, coupled with the complexity of the LCRR.
Additionally, EPA is proposing significant changes in the LCRI relative
to the LCRR, many of which would render various LCRR requirements
obsolete in a few years. Specifically, EPA is proposing to eliminate
the trigger level and the many associated rule requirements that are
required after a trigger level exceedance, including reporting
requirements to the States that could require significant resources.
Many of the rule requirements in LCRR are so interrelated that changes
in one rule area impacts other areas. For example, the various actions
water systems are required to take are based on a system's 90th
percentile lead level. In LCRR, provisions for CCT are based on system
size; CCT and LSL status; and if the system is above, below, or between
different thresholds (e.g., lead PQL, lead trigger level, lead action
level). In the proposed LCRI, these compliance pathways would be
simplified by the proposed elimination of the lead trigger level, but
also required additional proposed changes to the CCT provisions.
Likewise, the LCR requires first-liter sampling at all sites while the
LCRR requires fifth-liter sampling at LSL sites. The proposed LCRI
would require the highest of the first and fifth liter at LSL sites.
Changing from 90th percentile values based on a sampling approach with
which systems have years of experience (the LCR), to a few years of a
different approach (the LCRR), before changing again to the approach
proposed in the LCRI, would likely cause confusion for systems and the
public, and lead to wasted resources (e.g., developing sampling
instructions, sampling plans, outreach materials).
    Another challenge is that the LCRR small system flexibility
provision in Sec.  141.93 allows systems serving 10,000 people or fewer
to choose between the LSLR provisions or CCT provisions, which
otherwise are specific to systems serving more than 10,000 people.
Without the small system flexibility provision, there would be no
requirements for small systems to

conduct LSLR or CCT. Therefore, any changes to those sections must be
considered together. Compliance with one component of the rule without
compliance with other related components would cause confusion and
could produce inconsistencies across different requirements.
    Additionally, in one of the key features of the rule, EPA is
proposing in the LCRI for all water systems to identify and replace all
LSLs and GRR service lines as quickly as feasible, regardless of lead
levels. In response to the historic funding provided under the
Bipartisan Infrastructure Law, some systems are voluntarily initiating
service line replacement programs. However, despite this progress by
some systems, many other systems have not or are not conducting service
line replacement. Many systems have not been required to replace LSLs
due to an action level exceedance under the LCR and may not have
experience developing replacement programs. EPA has received feedback
from water systems about the potential challenges of implementing
replacement programs including availability of equipment and supplies,
difficulties in securing funding, and hiring crews to complete
replacements. EPA is working with States and water systems to
demonstrate best practices for overcoming or mitigating these
challenges through the Lead Service Line Replacement Accelerator
initiative (USEPA, 2023e) and other technical assistance programs. By
focusing States' and systems' efforts on standing up these service line
replacement programs rather than implementing LCRR provisions that will
be changed or eliminated, the rule will result in systems removing more
LSLs and GRR service lines, which, where present, are the most
significant source of drinking water lead exposure. While the LCRI
would not wholly eliminate the challenges of large scale, nation-wide
service line replacement, EPA anticipates that systems would better use
the three-year period after promulgation of a final LCRI for program
planning, including hiring additional staff, soliciting bids for
contractors, securing grants or other types of funding, and continuing
to improve inventories to ensure that they are better positioned to
conduct mandatory service line replacement. It would also provide time
for the market to correct for potential shortages in resources or
workers. Because of the significant level of effort required of water
systems to plan for compliance with the LCRI, coupled with the
complexity of the LCRR, EPA is proposing to require water systems to
continue to comply with the LCR prior to the LCRI compliance deadline,
with the few exceptions noted above and further discussed below. EPA
also anticipates that requiring systems to simultaneously comply with
LCRR while preparing for LCRI could result in delays in achieving the
public health protections that will result from the proposed LCRI
requirements (see section IV.E.).
LCRR Requirements and Compliance Dates That Will Be Retained
    EPA is retaining the compliance date of October 16, 2024, for
systems to complete their initial service line inventories and to
notify customers about their service line material within 30 days of
completion of the inventory. Water systems and States are aware of and
should be prepared to meet this deadline in light of EPA's August 2022
issuance of Guidance for Developing and Maintaining a Service Line
Inventory guidance and EPA's December 17, 2021 Federal Register
document on the conclusion of EPA's review of the LCRR (86 FR 71574,
71579, USEPA, 2021b).
    Inventories help systems identify the location of LSLs and GRR
service lines. Inventories are critical to support lead reduction
efforts because they will allow customers to know if they are served by
a LSL or GRR service line, as well as evaluate the extent of these lead
sources in their drinking water system as a whole. With the inventory,
water systems will be able to notify all persons served by lead, GRR,
and unknown service lines and provide them with information on steps
they can take to reduce their lead exposure. Additionally, the
inventory is integral to help water systems take actions that will
facilitate compliance with the LCRI: identify sampling locations,
determine the extent of LSLs and GRR service lines within their
systems, and begin planning for service line replacement, including
applying for grants and loans.
    EPA is also retaining the October 16, 2024, compliance date for
Tier 1 PN following a lead action level exceedance. This requirement,
which is a revision of EPA's Public Notification Rule in 40 CFR part
141, subpart Q was established in the same rulemaking as the revisions
to the LCR in 40 CFR part 141, subpart I (i.e., the LCRR), consistent
with SDWA section 1414(c) as amended by the WIIN Act, based on EPA's
determination that a lead action level exceedance has the potential to
have serious human health effects as a result of short-term exposures
(86 FR 4240, USEPA, 2021a). EPA is not proposing any changes to this
requirement in the Public Notification Rule and the Agency does not
anticipate that additional time would be needed for water systems to
comply with this requirement given that systems must already conduct
Tier 1 PN for other contaminants. EPA notes that, between October 16,
2024, and the LCRI compliance date, systems will be required to conduct
this Tier 1 PN following an exceedance of the lead action level of
0.015 mg/L established under the LCR.
Alternative Proposed Compliance Dates
    EPA is seeking comment from the public about its proposed
compliance dates for various rule requirements, including whether it is
practicable for water systems to implement any of the proposed LCRI
requirements sooner than three years from the date LCRI would be
finalized. In particular, EPA is seeking comment on whether it is
practicable for water systems to implement notification and risk
mitigation provisions after full and partial service line replacement
(Sec.  141.84(h)), notification of a service line disturbance (Sec.
141.85(g)), and associated reporting requirements (Sec.  141.90(e)(6)
and (f)(6)) upon the effective date of the LCRI. These provisions were
introduced in the LCRR and have been revised in the LCRI to improve
clarity (see sections V.B.6. and V.H.2. of this document). EPA
introduced risk mitigation requirements to reduce consumer lead
exposure because lead levels can temporarily increase after service
line replacement and some disturbances. Although the Agency is
concerned about systems implementing most provisions of LCRR while
preparing to implement LCRI, EPA also anticipates that systems will
continue to improve inventories, including identifying unknowns, and
may conduct service line replacement either voluntarily or per
regulation prior to the LCRI compliance date. EPA expects that earlier
implementation of these provisions would reduce lead exposure for the
subset of consumers affected by these activities. Therefore, EPA is
seeking information, analyses, and comments on whether systems are
capable of implementing these risk mitigation provisions sooner than
the other LCRI requirements (see section IX. of this document). EPA is
also seeking comment on whether earlier alternative compliance dates
for LCRI requirements are practicable such that water systems
transition directly from LCR to LCRI in less than three years (i.e.,
one or two years) based on the assumption that water systems would
comply with the LCR until the LCRI compliance date (see

section IX. of this document). Exhibit 6 below illustrate these
alternative compliance dates.
[GRAPHIC] [TIFF OMITTED] TP06DE23.018

    EPA is also requesting comment on whether there are other LCRR
provisions for which the October 16, 2024, compliance date should be
retained. Under either of these scenarios, water systems would need to
comply with some mix of the LCR and the LCRR while preparing to comply
with the LCRI requirements three years (or earlier) after promulgation.
EPA expects that piecemeal implementation of the treatment technique
requirements for service line replacement, CCT, and public education
would create a significant implementation challenge for most, if not
all water systems, especially because of the interrelationship between
the treatment techniques, and the role of the action and trigger levels
in requiring systems to take corrective actions and provide additional
public education. As a result, in assessing the impact of this
approach, EPA would need to account for the strong possibility that
there would be widespread non-compliance as a result of that
implementation challenge. EPA seeks comments on these concerns and any
ways EPA could address them if the Agency were to finalize one of these
alternative approaches for compliance with the LCRR and the LCRI (see
section IX. of this document).

B. What are the requirements for primacy?

    SDWA authorizes EPA to regulate PWSs and promulgate NPDWRs that
limit contaminants that may harm public health (SDWA section 1412).
States may also regulate PWSs under SDWA by assuming primacy
enforcement (or primacy) for PWSs in their jurisdictions (SDWA section
1413). PWSs in these Primacy States must then comply with both sets of
State and Federal regulations. Generally, Primacy States monitor
compliance with regulations; however, EPA can also take enforcement
actions against water systems for failure to comply with NPDWRs. EPA
conducts annual reviews of State programs and can also withdraw primacy
(see 40 CFR 142.17).
    This section also describes the regulations, procedures and,
policies that primacy entities must adopt, or have in place, to
implement the LCRI, when it is final. States, Territories, and Tribes
must continue to meet all other conditions of primacy in 40 CFR part
142. Section 1413 of SDWA establishes requirements that primacy
entities (States or Indian Tribes) must meet to maintain primary
enforcement responsibility (primacy) for its PWSs. These include: (1)
adopting drinking water regulations that are no less stringent than
Federal NPDWRs in effect under sections 1412(a) and 1412(b) of SDWA;
(2) adopting and implementing adequate procedures for enforcement; (3)
keeping records and making reports available on activities that EPA
requires by regulation; (4) issuing variances and exemptions (if
allowed by the State) under conditions no less stringent than allowed
by SDWA sections 1415 and 1416; and (5) adopting and being capable of
implementing an adequate plan for the provision of safe drinking water
under emergency situations. 40 CFR part 142 sets out the specific
program implementation requirements for States to obtain primacy for
the Public Water Supply Supervision Program (PWSS), as authorized under
SDWA section 1413.
    Under 40 CFR 142.12(b), all States/territories/Tribes would be
required to submit a revised program to EPA for approval within two
years of promulgation of any final LCRI or request an extension of up
to two years in certain circumstances. To retain primary enforcement
authority for the final LCRI, States must adopt revisions at least as
stringent as the proposed provisions in 40 CFR Subpart I--Control of
Lead and Copper; Sec. Sec.  141.153 and 141.154; Sec. Sec.  141.201 and
202; Appendix A to Subpart O ([Consumer Confidence Report] Regulated
contaminants); Appendix A to Subpart Q (NPDWR Violations and Other
Situations Requiring Public Notice; and Appendix B to Subpart Q
(Standard Health Effects Language for Public Notification).

C. What are the special primacy requirements?

    EPA is proposing to revise the existing special primacy
requirements for the LCRR by modifying some, and establishing new,
special primacy requirements for States as a condition of primacy.
First, EPA is proposing to eliminate the special primacy requirement
related to systems' goal-based service line replacement programs, given
the proposed requirement for mandatory service line replacement in the
LCRI. EPA is also proposing that States must identify any State laws,
including statutes and constitutional provisions, relevant to a water
system's ability to obtain access to conduct a full service line
replacement and notify water systems in writing whether any such laws
exist or not. Systems must provide this notification by the compliance
date and within six months of the enactment of any new or revised State
law that pertains to access.
    Under the LCRR, States must determine if a greater mandatory lead
service line replacement rate is feasible and to notify the system of
its

determination in writing. EPA is proposing to modify this requirement
for States to determine whether a shortened service line deadline is
feasible. The proposed LCRI also includes a new requirement for States
to update their feasibility determination to require a shortened
deadline anytime throughout the system's replacement program, such as
where factors related to feasibility change and make a shortened
deadline feasible. Given the proposed new inventory validation
requirement, EPA is also proposing for States to establish a deadline
to complete inventory validation where shortened deadlines are
feasible, as these systems would be replacing LSLs in less than ten
years.
    EPA is also proposing modifications to special primacy requirements
under the LCRR with respect to the requirement for States to set a
deadline for systems to prepare an updated inventory where they find
discrepancies in their inventory. The LCRR only required States to set
this deadline where water systems identify an LSL that was categorized
as non-lead in the inventory. In the LCRI, EPA is proposing to include
GRRs because these are included in the proposed service line
replacement requirements and may also be improperly identified. In
addition, because EPA is proposing to include lead connectors in the
inventory, and would require systems that have inventories with no lead
connectors and no unknown connectors to update their inventory if a
lead connector is found. Therefore, EPA is proposing to include a
requirement for States to set a deadline for systems to prepare an
updated inventory in these cases.
    EPA is also proposing for States to describe how the State will
determine if an alternative lead sampling program is as ``stringent as
the Federal requirements'' including how the State will use the
definitions of elementary schools, secondary schools, and child care
facilities as defined in Sec.  141.2 to issue waivers. EPA is proposing
that States must describe how the State will review the lists of
schools and child care facilities submitted by CWSs to ensure the list
includes schools and child care facilities that meet the definitions of
elementary school, secondary school, and child care facility in Sec.
141.2, and that States must certify that this list of schools and child
care facilities is complete. EPA received questions about the LCRR
requirement for States to define schools and child care facilities. EPA
is aware that which facilities meet the definition of child care
facility under Sec.  141.2 may differ among States (e.g., which
facilities are licensed by the State). However, it is not the Agency's
intention for States to develop new definitions for schools and child
care facilities for purposes of complying with the new rule. In LCRI,
EPA is proposing to clarify the ``child care facility'' (see section
V.L.3. of this document). EPA is proposing to modify the LCRR
requirement that States verify that systems have complied with follow-
up requirements following a single site sampled above the action level.
Under the LCRR, this requirement was part of find-and-fix. In the
proposed LCRI, this requirement is relabeled as distribution system and
site assessment (see section F.2. of this document).

VIII. Economic Analysis

    This section summarizes the Economic Analysis (EA) supporting
document (USEPA, 2023b) for the proposed LCRI, which is written in
compliance with SDWA section 1412(b)(3)(C). Section 1412(b)(3)(C)(ii)
of SDWA states that, when proposing an NPDWR that includes a treatment
technique, the Administrator ``shall publish and seek comment on an
analysis of the health risk reduction benefits and costs likely to be
experienced as the result of compliance with the treatment technique
and the alternative treatment techniques that are being considered,
taking into account, as appropriate, the factors described [under
section 1412(b)(3)(C)(i)].'' This analysis is commonly called the
Health Risk Reduction Cost Analysis (HRRCA). SDWA section
1412(b)(3)(C)(i) lists the analytical elements of the required HRRCA as
follows: (1) quantifiable and non-quantifiable health risk reduction
benefits; (2) quantifiable and non-quantifiable health risk reduction
benefits from reductions in co-occurring contaminants; (3) quantifiable
and non-quantifiable costs that are likely to occur solely as a result
of compliance; (4) incremental costs and benefits of rule options; (5)
effects of the contaminant on the general population and sensitive
subpopulations including infants, children, pregnant women, the
elderly, and individuals with a history of serious illness; (6) any
increased health risks that may occur as a result of compliance,
including risks associated with co-occurring contaminants; and (7)
other relevant factors such as uncertainties in the analysis and
factors with respect to the degree and nature of the risk.
    Based on this HRRCA analysis and pursuant to SDWA section
1412(b)(4)(C), the Administrator has determined that the estimated
quantified and nonquantifiable benefits of the proposed regulation
justify the quantified and nonquantifiable costs.
    In this analysis, EPA assumes that the LCRI NPDWR will be
promulgated in 2024. The Agency estimated the year or years in which
all costs and benefit accrue over a 35-year period of analysis. The 35-
year window was selected to capture costs associated with rule
implementation as well as water systems conducting service line
replacement and installing and operating corrosion control treatment.
Note that EPA accounts for the Illinois, New Jersey, Michigan, and
Rhode Island State-required service line replacement programs in the
regulatory analysis baseline, so that the estimated proposed LCRI cost
will not double count the service line replacement costs already
required by States.
    EPA annualized the estimated future streams of costs and benefits
that accrue from compliance activities occurring over this same period
of analysis symmetrically. EPA does not capture the effects of
compliance with the proposed LCRI after the end of the period of
analysis, although it does account for benefits that continue to accrue
in the future from compliance activities that occur during the 35-year
window. Costs and benefits are presented as annualized values in 2022
dollars. EPA determined the present value of these costs and benefits
using social discount rates of three and seven percent as prescribed by
the Office of Management and Budget (OMB) Circular A-4 (OMB, 2003).
    Estimated benefits, in terms of health risk reduction from the
proposed LCRI, result from the activities performed by water systems,
which are expected to reduce risk to the public from exposure to lead
and copper in drinking water at the tap. EPA quantifies and monetizes
some of this health risk reduction from lead exposure by estimating the
decrease in lead exposures accruing to both children and adults from
the installation and re-optimization of CCT, service line replacement,
the implementation of point-of-use filter devices, and the provision of
pitcher filters in systems with multiple action level exceedances and
by quantifying and monetizing the resulting increases in intelligence
quotient (IQ) in children zero to seven years old, and reductions in
incidents of low birth weight, attention-deficit/hyperactivity disorder
(ADHD) in children, and adult cardiovascular disease premature
mortality.

A. Affected Entities and Major Data Sources Used To Characterize the
Sample Universe

    The entities potentially affected by the proposed LCRI are PWSs,
that are classified as either CWSs or NTNCWSs, and Primacy Agencies
(States). In the economic modeling performed, EPA uses the Safe
Drinking Water Information System Fed Data Warehouse (SDWIS/Fed) to
derive the number of CWSs and NTNCWSs, 49,529 and 17,418, respectively.
The Agency also assumed, for modeling purposes, 56 Primacy Agencies.\9\
---------------------------------------------------------------------------

    \9\ The 56 Primacy Agencies include 49 States (excluding
Wyoming), Puerto Rico, Guam, United States Virgin Islands, American
Samoa, North Mariana Islands, and Navajo Nation. For cost modeling
purposes, EPA also included the District of Columbia (DC) as a
Primacy Agency when assigning burden and costs of the rule although
some of these costs are incurred by the actual Primacy Agency, EPA
Region 3.
---------------------------------------------------------------------------

    EPA used a variety of data sources to develop the drinking water
industry characterization for the regulatory analysis. Exhibit 7
(Exhibit 3-1 in Chapter 3 of the proposed LCRI Economic Analysis
(USEPA, 2023b)) lists the major data sources, describes the data used
from each source, and explains how it was used in the estimation of the
regulatory analysis baseline, which corresponds to the LCRR.\10\
Additional detailed descriptions of these data sources and how they
were used in the characterization of baseline industry conditions can
be found in Chapter 3 of the proposed LCRI Economic Analysis (USEPA,
2023b).
---------------------------------------------------------------------------

    \10\ Note that EPA provides an alternative regulatory analysis
which assumes a pre-2021 LCR baseline during the 35-year period of
analysis starting in 2024, in Appendix C of the EA (USEPA, 2023b).
Because PWSs and Primacy Agencies will likely not have implemented
the parts of the LCRR associated with compliance dates post October
16, 2024, the Agency is providing this alternative baseline analysis
that describes LCRI incremental costs and benefits relative to a
non-LCRR state of the industry.
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BILLING CODE 6560-50-P

[GRAPHIC] [TIFF OMITTED] TP06DE23.019

BILLING CODE 6560-50-C

B. Overview of the Cost-Benefit Model

    EPA updated its SafeWater LCR model that was used to analyze the
costs and benefits of the LCRR. For a detailed description of the
model, see Chapter 5 of the Economic Analysis for the Final Lead and
Copper Rule Revisions (USEPA, 2020c). EPA originally

developed SafeWater LCR because of the need to model costs and benefits
where significant variability existed in both regulated entity
characteristics (i.e., baseline) and regulatory compliance scenarios, a
fact that remains true of the analysis for the proposed LCRI. PWSs will
face different compliance scenarios depending on the size and type of
water system, the presence of lead, GRR, and unknown service lines,
water quality, and existing corrosion controls. In addition, PWSs will
also face different unit costs based on water system baseline
characteristics including size, type, and number of entry points (e.g.,
labor rates, and CCT capital and operation and maintenance unit costs).
    One of the strengths of the SafeWater LCR model is that it
incorporates a large degree of variability across water system baseline
characteristics that influence compliance and costs. For example, under
the proposed LCRI, PWSs will face different compliance scenarios and
costs depending on their size, primary source water type, number of
entry points to the distribution system, number of lead service lines
(LSLs) and galvanized requiring replacement service lines (GRRs) in
their distribution system, and existing corrosion controls in place.
The SafeWater LCR model also includes variability in compliance
characteristics like different labor rates and number of tap and water
quality parameter (WQP) samples required by system size.
    One limitation of the cost-benefit analysis is that EPA does not
have all of the PWS-specific data needed to fully reflect baseline and
compliance variability across PWSs, therefore, the SafeWater LCR model
applies a ``model PWS'' approach. From a set of system baseline
characteristic data including system type, system size, and primary
water source, EPA defined 72 PWS categories, or strata, in the
SafeWater LCR model. The 72 PWS categories consist of each combination
of PWS type (2), PWS population size category (9), PWS primary source
water (2), and PWS ownership (2).
    The SafeWater LCR model creates model PWSs representing systems in
each category by combining the PWS-specific data available in SDWIS/Fed
with data on baseline and compliance characteristics available at the
PWS category level. When categorical data are point estimates, every
model PWS in a category is assigned the same value. When EPA has
probabilistic data representing system variability, SafeWater LCR model
assigns each model PWS a value sampled from the distribution. Examples
of the distributional data inputs that characterize variability in the
SafeWater LCR model include the burden for PWS and State staff to
conduct tasks like sampling and compliance documentation and review.
These distributions are assumed to be independent which is a limitation
of the model.
    While the model system approach allows for a good characterization
of variability across PWSs, it is less exact than if EPA had full
information on each PWS. For additional detail on the development of
model-PWSs in the SafeWater LCR model, see Appendix B, section B.2.1 of
the Economic Analysis (USEPA, 2020c). Because of this model PWS
approach, SafeWater LCR does not output any results at the PWS level,
but rather, outputs cost (and benefit) estimates at the PWS category,
or strata. For additional information on the data sources used in the
estimation of costs see Chapter 3 and Chapter 4, sections 4.2.2, 4.3,
4.4, and 4.5 of the Economic Analysis (USEPA, 2020c).
    Chapter 3 of the proposed LCRI Economic Analysis (USEPA, 2023b)
describes in greater detail the baseline data elements, their
derivation, and the inherent sources of uncertainty in the developed
data elements. Chapter 4, sections 4.3 and 4.4 of the proposed LCRI
Economic Analysis discuss how each data element is used in the
estimation of costs and provides examples and references to how these
data were developed. Chapter 5 of the proposed LCRI Economic Analysis
(USEPA, 2023b) provides detail on the water lead concentrations under
baseline conditions (e.g., presence of an LSL and CCT) and the
functions used to quantify benefit categories, their derivation, and
the inherent sources of uncertainty associated with the use of those
functions. All significant uncertainties of this economic analysis are
described in the following sections of the proposed LCRI EA (USEPA,
2023c). Section 3.4 and Exhibit 3-81 outline uncertainties associated
with the analytical baseline and water system compliance
characteristics. SafeWater LCR model and cost uncertainty is discussed
in section 4.2.2 and Exhibit 4-3. Also, for a discussion of the
uncertainties in the benefits analysis, see section 5.7 and Exhibit 5-
43.
    SafeWater LCR follows each model PWS, which represents a cohort of
systems with the same characteristics, in the sample through each year
of the period of analysis and determines how the PWS will comply with
each requirement of the proposed rule, estimating the yearly compliance
cost and tracking the impact of the compliance actions on drinking
water lead concentrations and the resultant effects on health outcomes.
It also tracks how other events, such as changing a water source or
treatment, effect the water system's compliance requirements for the
next year. The estimated costs and benefits for each model PWS are
weighted so they represent the number of actual PWSs known to have
similar characteristics (e.g., population served, entry points to the
distribution system, etc.), and then summary statistics are calculated,
including total quantified costs of the proposed regulatory
requirement, total quantified benefits of the proposed regulatory
requirement, the variability in PWS-level costs (e.g., 5th and 95th
percentile system costs), and the variability in household-level
costs.\11\
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    \11\ The exception to the use of model PWSs and the assignment
of system characteristic data in the SafeWater LCR model are the 24
very large water systems serving more than one million people.
Because of the small number of water systems in this size category,
the uniqueness of their system characteristics, and the potential
large impact of these systems on estimated national costs and
benefits, EPA attempted to collect information on very large water
systems' CCT practices and chemical doses, pH measurements and pH
adjustment practices, number of LSLs, service populations, and
average annual flow rates for each entry point to the distribution
system. When facility-specific data were available, EPA used it to
estimate compliance costs and benefits for the very large water
systems. If data were not available, EPA assigned baseline
characteristics using the same process as previously described. See
Chapter 4, section 4.2.3 of the proposed LCRI EA for a summary of
the data EPA collected on these very large systems (USEPA, 2023b).
---------------------------------------------------------------------------

    This treatment technique rulemaking, and therefore the SafeWater
LCR model, is complex, incorporating multiple compliance triggers
(e.g., action level exceedance, single sample exceedance, multiple
action level exceedances) that require multiple and varying compliance
actions (e.g., CCT installation or re-optimization, distribution system
and site assessment, public education, temporary filter distribution)
requiring a large number of inputs for the estimation of total
compliance costs and benefits. Many of these inputs, which are specific
to the assessment of the costs and benefits of the proposed LCRI, are
uncertain.
    EPA determined it does not have enough information to perform a
probabilistic uncertainty analysis as part of the SafeWater LCR model
analysis for this rule. Instead, to capture uncertainty, EPA estimated
compliance costs and benefits using the SafeWater LCR model under low
and high bracketing scenarios. For costs, the bracketing scenarios are
defined by the following three cost drivers: the number of PWSs that
will exceed the action

level under the revised tap sampling requirements; the cost of service
line replacement; and the cost of CCT. The low and high scenarios for
benefits are driven by the number of PWSs that will exceed the action
level under the revised tap sampling requirements (the same variable
which is used to define the low and high cost scenarios) and the
concentration-response functions that characterize how reductions in
blood lead levels (caused by changes in lead exposure) translate into
estimates of avoided IQ reductions, cases of ADHD, and cardiovascular
disease premature mortality. These low and high scenarios are defined
by the assignment of low and high values for the set of cost and
benefit drivers listed above. Detailed descriptions of these variables
and the derivation of their values under the low and high scenarios can
be found in Chapter 4 and Chapter 5 of the proposed LCRI Economic
Analysis (USEPA, 2023b). Due to the data limitations mentioned above,
with the exception of the uncertain variables which define the
difference between the low and high scenarios, the remaining baseline
water system and compliance characteristics are treated as certain and
remain constant across the scenarios. While this limits the full
description of the uncertainty in the monetized cost and benefit
estimates, it does allow EPA to clearly define the uncertainty
characterized in the cost-benefit range provided by the low and high
scenarios and maintains consistency between the estimation of costs and
benefits for the LCRR and proposed LCRI (e.g., number of systems with
LSLs and percent of connections that are LSLs).
    When evaluating the economic impacts on PWSs and households, EPA
uses the estimated PWS cost of capital to discount future costs, as
this best represents the actual costs of compliance that water systems
would incur over time. EPA used data from the 2006 Community Water
System Survey (CWSS) to estimate the PWS cost of capital. EPA
calculated the overall weighted average cost of capital (across all
funding sources and loan periods) for each size/ownership category,
weighted by the percentage of funding from each source. The cost of
capital for each CWS size category and ownership type is shown in
Appendix B of the proposed LCRI Economic Analysis (USEPA, 2023b). Since
similar cost of capital information is not available for NTNCWSs, EPA
used the CWS cost of capital when calculating the annualized cost per
NTNCWS. Total capital investment may be greater than costs water
systems bear when complying with future regulatory requirements because
financing support for lead reduction efforts is available from State
and local governments, EPA programs, and other Federal agencies. The
availability of funds from government sources, while potentially
reducing the cost to individual PWSs, does not reduce the social cost
of capital to society.
    EPA projects that rule implementation activities will begin
immediately after rule promulgation. These activities will include one-
time PWS and State costs for staff to read the LCRI, become familiar
with its provisions, and develop training materials and train employees
on the new rule requirements. States will also incur burden hours
associated with adopting the rule into State requirements, updating
their LCR program policies and practices, and modifying data management
systems. PWSs will incur costs to comply with the service line
materials inventory requirements, service line materials notification
requirement, and requirement for public notification following an
action level of 0.015 mg/L (LCRR action level) in years one through
three of the 35-year period of analysis. EPA expects that water systems
will begin complying with all other LCRI rule requirements three years
after promulgation, or in year four of the analysis.
    Some requirements of the proposed LCRI must be implemented by water
systems regardless of their water quality and tap sampling results
(e.g., service line material inventory updates, service line
replacement, and CWS school and child care facilities sampling
programs). However, most of the major cost drivers are a function of a
water system's 90th percentile lead tap sample value. Because a water
system's lead 90th percentile value is important to determining
regulatory requirements and costs and benefits under the proposed LCRI,
the SafeWater LCR model tracks each model PWS's 90th percentile value
over each annual time step in the model. The 90th percentile value, and
if it exceeds the action level, dictates actions including, but not
limited to, tap sampling and water quality parameter monitoring
schedules, the installation or re-optimization of CCT, the installation
of point-of-use devices or pitcher filters at water systems selecting
this treatment option as part of the small water system flexibilities
under the proposed LCRI, and public education requirements.\12\ Under
the proposed LCRI the SafeWater LCR model assumes a PWS's 90th
percentile tap sample values will drop at or below the action level
once they: (1) install or reoptimize CCT; \13\ (2) install point-of-use
devices or (3) remove all service lines with lead content. When the PWS
no longer has a 90th percentile tap sample value above the action
level, it incurs lower sampling and public education costs.
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    \12\ Distribution system and site assessment adjustments to CCT
are required for a single lead tap sample exceedances of the action
level of 0.010 mg/L. The provision of temporary pitcher filters is
triggered by multiple action level exceedance violations. Both these
compliance requirements are also positively associated with system
level 90th percentile tap sample values.
    \13\ The SafeWater LCR model implements a required systemwide
distribution system and site assessment activity as a change in pH
which is equivalent to pH adjustments associated with CCT
installation or preoptimization in the model.
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    The SafeWater LCR model allows for future increases in 90th
percentile lead values as a result of changes in source water and
treatment. The likelihood of these events occurring has been derived
from SDWIS/Fed data (see Chapter 3, section 3.3.9 of the proposed LCRI
Economic Analysis (USEPA, 2023b)). When a change in source or treatment
occurs in a modeled year, a new 90th percentile value is assigned to
the water system. This value may be higher or lower than the current
value, thus potentially triggering new corrective actions. In the
model, if a water system already has ``optimized'' CCT in place, it is
assumed that no additional action is needed and that the current
treatment is adequate, therefore the 90th percentile will not change.

C. Cost Analysis

    This section summarizes the cost elements and estimates the total
cost of compliance for the baseline (LCRR), the proposed LCRI, and the
incremental cost of the proposed LCRI, under both the low and high cost
scenarios, discounted at three and seven percent. EPA presents the
estimated PWS proposed rule implementation costs; the calculated
distributions of incremental annualized costs for CWS households by
primary water source and size category; and the estimated costs to
States for implementation and administration of the rule.\14\ This
section also quantifies the potential increase in phosphates that would
result from the increased use of corrosion inhibitors under the rule,
the resulting cost for treating to remove the additional phosphates at
downstream wastewater treatment plants that may be

constrained by nutrient discharge limits, and discusses the ecological
impacts that may result from increased phosphorus loads to surface
waters.
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    \14\ Note that reporting costs are represented in the cost
totals provided in the estimates below, but a separate summary of
the reporting costs, as required by the Paperwork Reduction Act, can
be found in section X.C. of this document.
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1. Drinking Water System Costs
    EPA provides estimates of the proposed LCRI regulatory requirement
costs that accrue to PWSs for the following cost components: rule
implementation and administration, sampling, service line inventory and
replacement, CCT, point-of-use program (if a small system selects this
compliance option), and public education and outreach. For the purpose
of developing the PWS costs for each of these rule components EPA
further subdivided these groupings into sub-components and activities,
to be completed by systems implementing the requirements of the
proposed LCRI. For most activities, water systems will incur labor unit
costs (e.g., PWS staff participate in training). Systems will also
incur unit capital and operation and maintenance costs for a number of
activities (e.g., installation of CCT). Exhibit 8 (Exhibit 4-6 in the
proposed LCRI Economic Analysis (USEPA, 2023b)) provides an overview of
the rule components, subcomponents, and activities for which EPA
estimates water system unit costs for the proposed LCRI. Detailed
information on the derivation of unit costs associated with each
activity can be found in the proposed LCRI Economic Analysis sections
identified in Exhibit 8.
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    EPA uses the derived unit costs associated with each regulatory
activity from Exhibit 8 as inputs to the SafeWater LCR model which
estimates low and high scenario PWS total costs for the baseline (LCRR)
and the proposed LCRI.\15\ Baseline total costs are then subtracted
from the LCRI total costs to determine the incremental costs of the new
regulatory requirements under the proposed LCRI for both the low and
high cost scenarios. These incremental costs are presented as
annualized values, discounted at both three and seven percent in
Exhibit 9 and Exhibit 10, respectively. The estimated total PWS
incremental annualized costs of the proposed LCRI range from $2.1 to
$2.93 billion at a three percent discount rate, and $2.5 to $3.58
billion at a seven percent discount rate in 2022 dollars. The exhibits
also detail the proportion of the annualized costs attributable to each
rule component. For estimated total and incremental costs by
subcomponent see Chapter 4, section 4.3 of the proposed LCRI Economic
Analysis (USEPA, 2023b).
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    \15\ For additional information on how the SafeWater LCR model
uses unit cost date to estimate PWS costs see Chapter 4, section 4.3
of the proposed LCRI rule EA (USEPA, 2023b).

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2. Annualized per Household Costs
    The SafeWater LCR cost model calculates the annualized cost per
household, by first calculating the cost per gallon of water produced
by the CWS. This cost per gallon represents the cost incurred by the
system to comply with the requirements of the LCRI. This is a total
implementation cost for the system which includes the rule
implementation and administration, including, but not limited to,
sampling, service line inventory and replacement, CCT, point-of-use
program (if a small system selects this compliance option), and public
education and outreach component costs. Because of uncertainty in three
important LCRI cost input variables, discussed in section VIII.B. of
this document, the Agency developed low and high cost scenarios. These
scenarios produce a range in the estimated cost per gallon and two
estimates for annualized per household costs.
    The SafeWater LCR model multiplies this low and high scenario costs
per gallon by the average annual household consumption (in gallons) to
determine the cost per household per year associated with increased
costs borne by the CWS. Exhibits 11 and 12 show the distributions of
incremental annualized costs for CWS households by primary water source
and size category. Note that the percentiles represent the distribution
of average household costs across CWSs in a category, not the
distribution of costs across all households in a CWS category.\16\
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    \16\ Note that although EPA assumed in the cost analysis that
systems would pay for customer-side service line replacement. It is
possible that in some systems individual homeowners may bear a much
greater annual household burden which includes the customer-side
service line replacement. EPA estimates the cost of removing the
customer-owned side of a service line range from $1,920 to $5,400,
with a central tendency of $3,273. The percentage of customers in
each water system paying the higher customer-side service line
replacement costs depends on the number of LSLs and GRR service
lines in the water system, the rate of replacement, and the details
of the water systems service line replacement program.
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3. State Costs
    For each of the PWS cost components and subcomponents, previously
described in section VIII.C.1., States (i.e., Primacy Agencies) have
associated costs. Exhibit 13 (Exhibit 4-142 in the proposed LCRI
Economic Analysis (USEPA, 2023b)) provides a list of the State
activities, organized by LCRI cost component and subcomponent groups,
for which EPA developed unit costs. Detailed information on the
derivation of the unit costs associated with each State activity can be
found in the proposed LCRI Economic Analysis sections identified in
Exhibit 13.
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    In the SafeWater LCR model, the majority of the costs associated
with States are determined on a per water system basis. State
activities and costs are largely driven by the rule required actions
that are triggered for the individual water systems. The exception to
this rule is the implementation and administrative costs which are
tallied on a per State basis. The per water system State costs and per
State costs are summed to obtain aggregate costs for this category. For
additional information on how the SafeWater LCR model uses unit cost
data to estimate State costs see Chapter 4, section 4.4 of the proposed
LCRI economic Analysis (USEPA, 2023b).
    The SafeWater LCR cost model estimates that States will incur
monetized incremental estimated annualized costs, under the low cost
scenario, totaling $16.1 million at a three percent discount rate and
$12.6 million at a seven percent discount rate. For the high cost
scenario total estimated monetized incremental cost is $15.3 million at
a three percent discount rate and $11.3 million at a seven percent
discount rate.
4. Costs Impacts Associated With Additional Phosphate Usage
    Adding orthophosphate CCT creates a protective inner coating on
pipes that can inhibit lead leaching. However, once phosphate is added
to the PWS, some of this incremental loading remains in the water
stream as it flows into wastewater treatment plants (WWTPs) downstream.
This generates treatment costs for certain WWTPs. In addition, at those
locations where treatment does not occur, water with elevated
phosphorus concentrations may discharge to water bodies and induce
certain ecological impacts. Due to many water systems operating both
the wastewater and drinking water systems, EPA is evaluating the costs
of additional phosphate usage for informational purposes. These costs
are not ``likely to occur solely as a result of compliance'' with the
proposed LCRI, and therefore are not costs considered as part of the
HRRCA under SDWA, section 1412(b)(3)(C)(i)(III).
    To estimate the potential fate of the orthophosphate added at PWSs,
EPA developed a conceptual mass balance model. EPA applied this
conceptual model to estimate the increase in loading at WWTPs, given an
initial loading from corrosion control at water treatment plants. WWTPs
could incur costs because of upstream orthophosphate additions if they
have permit discharge limits for phosphorus parameters. The percentage
of WWTPs with phosphorus limits has increased over time. From 2007 to
2016, in annual percentage rate terms, the growth rate in the
percentage of WWTPs with phosphorus limits is 3.3 percent (see Chapter
4, section 4.5.1 of the proposed LCRI Economic Analysis, USEPA, 2023b).
    EPA applied the growth rate observed from 2007 to 2016 to estimate
the anticipated percentage of WWTPs with phosphorus limits in future
years. This growth rate results in an estimated 41 percent of WWTPs
with phosphorus discharge limits after 35 years. Applied as the
percentage of WWTPs that need to take treatment actions, this estimate
is likely conservative.
    The specific actions a WWTP might need to take to maintain
compliance with a National Pollution Discharge Elimination System
(NPDES) phosphorus permit limit will depend on the type of treatment
present at the WWTP and the corresponding phosphorus removal provided.
Based on a review of NPDES data, it is likely that most of the WWTPs
that already have phosphorus limits have some type of treatment to
achieve the limit.
    Some treatment processes can accommodate incremental increases in
influent loading and still maintain their current removal efficiency.
Such processes might not need significant adjustment to maintain their
existing phosphorus removal efficiency, given an incremental increase.
Other treatment processes may need modifications to their design or
operation to maintain their removal efficiency in the face of an
influent loading increase.
    EPA derived a unit cost of $5.44 per pound for removing incremental
phosphorus (see Chapter 4, section 4.5.1 of the proposed LCRI Economic
Analysis for additional information). This unit cost includes the cost
of additional chemical consumption and the operating cost of additional
sludge processing and disposal. The costs a WWTP could incur depend on
the magnitude of the loading increase relative to the specific WWTP's
effluent permit limit. WWTPs, whose current discharge concentrations
are closer to

their limit, are more likely to have to act. WWTPs whose current
treated water concentrations are well below their limit are less likely
to incur costs but might, under certain conditions, incur costs (for
example, when phosphorus removal achieved by technology in place at a
WWTP is sensitive to incremental phosphorus loading increases and must
be modified to continue to meet the limit). Furthermore, future
phosphorus limits could be more stringent than existing limits.
    Therefore, EPA conservatively assumed that any WWTP with a
discharge limit for phosphorus parameters could incur costs.
Accordingly, in calculating costs, EPA used the anticipated percentage
of WWTPs with phosphorus discharge limits as the likelihood that
incremental orthophosphate loading from a drinking water system would
reach a WWTP with a limit. EPA combined this likelihood and the unit
cost (previously estimated) with incremental phosphorus loadings to
calculate incremental costs to WWTPs for each year of the period of
analysis. The incremental annualized cost that WWTPs would incur to
remove additional phosphorous associated with the LCRI, under the low
cost scenario, ranges from $4.2 million to $4.3 million at a three and
seven percent discount rate, respectively. The high cost scenario
produced an incremental estimated impact of $5.8 million using a three
percent discount rate, and $5.9 million at a seven percent discount
rate.
    EPA estimates that WWTP treatment reduces phosphorus loads reaching
water bodies by 59 percent, but they are not eliminated. The rule's
national-level total incremental phosphorus loads reaching water bodies
are projected to grow over the period of analysis from the low/high
scenario range of 343,000 to 491,000 pounds fifteen years after
promulgation to the low/high scenario range of 511,000 to 693,000
pounds at year 35. See Chapter 4, section 4.5.2 of the proposed LCRI
Economic Analysis (USEPA, 2023b) for information on how loading
estimates are calculated. The ecological impacts of these increased
phosphorous loadings are highly localized: total incremental phosphorus
loadings will depend on the amount and timing of the releases,
characteristics of the receiving water body, effluent discharge rate,
existing total phosphorus levels, and weather and climate conditions.
Detailed spatially explicit information on effluents and on receiving
water bodies does not exist in a form suitable for this analysis.
Rather, to evaluate the potential ecological impacts of the rule, EPA
evaluated the significance of the national-level phosphorus loadings
compared to other phosphorous sources in the terrestrial ecosystem.
    To put these phosphorus loadings in context, estimates from the
U.S. Geological Survey (USGS) Spatially Referenced Regression On
Watershed Attributes (SPARROW) model suggest that anthropogenic sources
deposit roughly 750 million pounds of total phosphorus per year (USEPA,
2019b). The total phosphorus loadings from the LCRI high cost scenario
would contribute about 0.5 percent (3.9 million/750 million) of total
phosphorus entering receiving waterbodies in a given year, and the
incremental amount of total phosphorus associated with the proposed
LCRI relative to the LCRR grows only 0.1 percent (693,000/750 million).
At the national level, EPA expects total phosphorus entering
waterbodies as a result of the proposed LCRI update to be small,
relative to the total phosphorus load deposited annually from all other
sources. National average load impacts may obscure localized ecological
impacts in some circumstances, but the existing data do not allow an
assessment as to whether this incremental load will induce ecological
impacts in particular areas. It is possible, however, that localized
impacts may occur in certain water bodies without restrictions on
phosphate influents, or in locations with existing elevated phosphate
levels.
    An increase in phosphorus loadings can lead to economic impacts and
undesirable aesthetic impacts. Excess nutrient pollution can cause
eutrophication--excessive plant and algae growth--in lakes, reservoirs,
streams, and estuaries throughout the United States. Eutrophication, by
inducing primary production, leads to seasonal decomposition of
additional biomass, consuming oxygen and creating a state of hypoxia,
or low oxygen, within the water body. In extreme cases, the low to no
oxygen states can create dead zones, or areas in the water where
aquatic life cannot survive. Studies indicate that eutrophication can
decrease aquatic diversity for this reason (e.g., Dodds et al., 2009).
Eutrophication may also stimulate the growth of harmful algal blooms
(HABs), or over-abundant algae or cyanobacteria populations. Algal
blooms can seriously harm the aquatic ecosystem by blocking sunlight
and creating diurnal swings in oxygen levels because of overnight
respiration. Such conditions can starve and deplete aquatic species. In
addition, rapid photosynthesis may consume dissolved inorganic carbon
and elevate pH (Chislock et al., 2013). Certain types of phosphorous-
fueled cyanobacterial blooms, may produce toxins to both humans and
aquatic life. These toxins include microcystins (liver toxins) and
neurotoxins. This issue is particularly prevalent in lakes or other
slow-flowing water bodies. HAB events have directly or indirectly
contributed to fish kill events by causing the absorption or ingestion
of toxins, or by creating conditions of limited sunlight and oxygen
(Glibert et al., 2005).
Total Monetized Costs
    The estimated annualized low and high scenario costs, discounted at
three percent and seven percent, that PWSs, households,\17\ and States
will incur in complying with the baseline LCRR, the proposed LCRI, and
incrementally are summarized in Exhibits 14 and 15. The estimated total
monetized incremental annualized cost of the proposed LCRI range from
$2.06 to $2.92 billion at a three percent discount rate, and $2.51 to
$3.56 billion at a seven percent discount rate in 2022 dollars. The
exhibits also detail the proportion of the annualized costs
attributable to each rule component.
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    \17\ Note that as part of the baseline (LCRR) analysis of
service line replacement costs EPA assumed that customer-side
service line replacements under the goal-based service line
replacement program would be paid by the household. For the
estimation of proposed LCRI service line replacement costs EPA
assumed that all replacement cost would be borne by the PWS. These
differing costing assumptions result in the positive household costs
(not accruing to PWSs) reported under the baseline (LCRR) cost
estimates while no household service line replacement costs are
reported under the proposed LCRI. These assumptions also result in
decreased incremental costs for the LCRI under household service
line replacement costs, but the cost of replacing the customer-side
of service lines is now included, by assumption, in the LCRI
incremental costs for PWS service line replacement.
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D. Benefits Analysis

    The proposed LCRI is expected to result in significant health
benefits, since both lead and copper are associated with adverse health
effects. Lead is a highly toxic pollutant that can damage neurological,
cardiovascular,

immunological, developmental, and other major body systems. There is no
known safe level of exposure to lead (USEPA, 2013). EPA is particularly
concerned about ongoing exposure experienced by children because lead
can affect brain development, which impacts lifelong level of function.
Additionally, children through their physiology and water ingestion
requirements may be at higher risk. Research shows that, on average,
formula-fed infants and young children consume more drinking water per
day on a body weight basis than adolescents. Using the USDA Continuing
Survey of Food Intakes by Individuals (CSFII) data, Kahn and Stralka
(2009) demonstrated this trend, is most pronounced in children under
one year of age who drink more than double older children and adults
per kg of body weight. Additionally, children absorb two to four times
more lead than adults through the gastrointestinal tract (Mushak, 1991;
WHO, 2011; and Ziegler et al., 1978). EPA's health risk reduction and
benefits assessment of the LCRI revisions concentrates on
quantification and monetization of the estimated impact of reductions
in lead exposure on IQ values and cases of ADHD in children, lower
birth weights in children of women of childbearing age, and cases of
cardiovascular disease premature mortality in adults. As explained in
appendix D of the proposed LCRI Economic Analysis (USEPA, 2023b), there
are additional non-quantified lead health impacts to both children and
adults that will be realized as a result of this rulemaking. Therefore,
the quantified benefits of this rule are likely underestimated.
    Although copper is an essential element for health, excess intake
of copper has been associated with several adverse health effects. Most
commonly, excess exposure to copper results in gastrointestinal
symptoms such as nausea, vomiting, and diarrhea (National Research
Council, 2000). In susceptible populations, such as children with
genetic disorders or predispositions to accumulate copper, chronic
exposure to excess copper can result in liver toxicity. Because
household level data on the change in copper concentrations that result
from changes in CCT are not available, this analysis does not quantify
any potential benefits from reduced copper exposure that may result
from the rule. See Appendix E in the proposed LCRI Economic Analysis
for additional copper health impact information.
1. Modeled Drinking Water Lead Concentrations
    In updating EPA's drinking water lead concentrations for the
proposed LCRI, the Agency built upon the data and models used in the
analysis of the final LCRR. Detailed information on the residential
lead concentration data and modeling from the final LCRR can be found
in Chapter 6 of the final LCRR Economic Analysis (USEPA, 2020c). In the
2021 LCRR analysis, EPA collected and used data on lead concentrations
and information regarding LSL and CCT status, location, and date of
sample collection, representing 14 water systems across the United
States and Canada. EPA updated this data for the LCRI analysis by
initially identifying eight additional sampling datasets.\18\ After
close assessment, it was determined that seven of the datasets had data
availability and study design issues and could not be included.\19\
Only the 324 samples collected from the City of Clarksburg, WV in fall
to winter of 2021 could be added to the lead concentration dataset,
resulting in a total of 18,363 samples collected from 1,657 homes in 16
cities representing 15 city water systems. EPA grouped the samples into
LSL status categories (``LSL,'' ``Partial LSL,'' ``No LSL''). The
samples were also grouped by CCT treatment, assigning status as having
``None,'' ``Partial,'' or ``Representative.'' ``Partial'' includes
those water systems with some pH adjustment and lower doses of a
phosphate corrosion inhibitor, but this treatment is not optimized.
``Representative'' are those water systems in the dataset that have
higher doses of phosphate inhibitors, which in the model are considered
optimized. For additional detail see Chapter 5, section 5.2.1 of the
proposed LCRI Economic Analysis (USEPA, 2023b).
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    \18\ EPA identified 8 data sets from Clarksburg WV, Cleveland
OH, Chicago IL, Kalamazoo MI, Parchment MI, Flint MI, Galesburg IL
and Sebring OH with drinking water lead sampled collected from 2016
to 2021.
    \19\ For additional detail on the assessment of the lead
concentration data see Chapter 5, section 5.2.1 of the proposed LCRI
(USEPA, 2023b).
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    EPA fit several regression models, following the same methodology
from the LCRR final benefits analysis (see Economic Analysis Chapter 6,
section 6.2.2 of the final LCRR Economic Analysis (USEPA, 2020c)), of
tap water lead concentration as predicted by LSL presence (``LSL'' or
``No LSL''), LSL extent (``Partial LSL''), CCT status, and ``profile
liter.'' Profile liter is the cumulative volume a sample represented
within a consecutive sampling series at a single location and time.
Models to describe the profile liter accounted for the variation among
sampling events, sampling sites, and city. The water lead
concentrations exhibited a right-skewed distribution; therefore, the
variable was log-transformed to provide a better modeled fit of the
data. EPA selected one of the regression models based on its fit and
parsimony and used it to produce simulated lead concentrations for use
in the benefits analysis (Exhibit 5-8, in Chapter 5 of the proposed
LCRI EA). The selected model suggests that besides water system,
residence, and sampling event, the largest effects on lead
concentration in tap water come from the presence of LSLs and the
number of liters drawn since the last stagnation period. Although CCT
can reduce lead concentrations from LSLs and other sources of lead,
such as residential plumbing fixtures, the presence or absence of CCT
produces smaller effects on water lead concentration than the presence
or absence of LSLs. Because locations with LSLs are more likely to have
high lead concentrations than those without, CCT reduces water lead
concentrations more in homes served by LSLs than in those not served by
LSLs. See the Economic Analysis document for the proposed LCRI, Chapter
5, section 5.2.2, Exhibit 5-9 (USEPA, 2023b) for additional detail and
estimated regression coefficients. The regression results indicate that
although CCT can significantly reduce water lead concentrations the
removal of LSLs in systems with representative CCT will still reduce
water lead concentrations. The regression model results for the LCRI
analysis are consistent with those conducted for the LCRR, which is not
unexpected given the fact that the Agency added approximately two
percent of new data to the drinking water lead concentration dataset.
    To statistically control for some sources of variability in the
input data, EPA, following the LCRR analysis, did not use summary
statistics from the original data directly in estimating the effects of
LSL and CCT status. Instead, EPA produced simulated mean lead
concentrations for 500,000 samples, based on the selected regression
model. The simulations were performed on the log-scale to conform to
the fitted model (which used a log-transformed water lead concentration
variable) and converted to the original scale to produce geometric
means and geometric standard deviations. Geometric means are more
representative of the central tendency of a right-skewed distribution
than are arithmetic means and prevent

overestimation of the impact of water lead levels on estimated blood
lead levels and resulting benefits values. The simulated sample
concentrations represent new estimates for the updated lead
concentration dataset. These simulations rely on estimates of
variability and uncertainty from the regression model described above
and given information on LSL and CCT status. For more detail regarding
this regression, see Chapter 5, section 5.2.2 of the proposed LCRI
Economic Analysis (USEPA, 2023b). Individual estimates are best thought
of as the central tendency for a lead tap sample concentration, given
regression model parameters and estimated variance. The simulated
samples represent, on average, the lead concentrations taken after a
short flushing period of roughly 30 seconds for all combinations of LSL
and CCT status. This represents a point near the average peak lead
concentration for homes with full or partial LSLs, and a point slightly
below the peak lead concentration for homes with no LSLs, regardless of
CCT status.
    EPA estimates that improving CCT will produce significant
reductions in lead tap water concentration overall. However, in the
case of ``no LSL'', the final model produced predictions of drinking
water concentrations that overlapped almost completely for all CCT
conditions.\20\ In the available profile data there were no
statistically significant differences in measured water lead
concentrations between the different CCT scenarios when LSLs were not
present, likely because apart from LSLs the remaining sources of lead
in residential plumbing (old solder and brass) are small, compared to
the LSL, and contribute far less lead to a multi-liter sequential
sampling profile. Therefore, EPA used the pooled estimate of predicted
drinking water concentrations for all residences with no LSL regardless
of CCT condition for the main analysis in Chapter 5 of the proposed
LCRI Economic Analysis (USEPA, 2023b).\21\
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    \20\ EPA does not believe that there are lead water mains in the
country. Water mains are typically six to 16 inches in diameter
whereas service lines have a smaller diameter. The common water main
materials include ductile iron, PVC, asbestos cement, HDPE, and
concrete steel (Folkman, 2018). Lead service lines are two inches or
less in diameter (LSLR Collaborative, n.d.g.).
    \21\ Note that EPA in the economic analysis does not make
restrictive assumptions in pairing specific CCT and LSL statuses. It
is not improbable to have systems with CCT in place when no LSLs are
present. The pre-2021 LCR requires all systems serving 50,000 or
more people to install CCT. Systems may also install CCT for other
reasons apart from the LCR. Also, a number of systems have had 90th
percentile tap sample values above the AL requiring CCT even when
LSLs are not present due to initial corrosivity of the water and
secondary sources of lead like old brass and solder. Systems that
have LSLs but no CCT are possible because the existing water
chemistry in a system may be non-corrosive and therefore lead 90th
percentile lead tap sample values may be lower than the AL. EPA
combine data from two source to estimate the percent of CCT systems
with LSLs, SDWIS and DWINSA data. See sections 3.3.3 and 3.3.4 for
the Economic Analysis of the proposed LCRI (USEPA, 2023b) for
additional detail.
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    Because small CWSs that serve 3,300 or fewer persons have
flexibility in the compliance option they select in response to a lead
action level exceedance, some CWSs are modeled as installing point-of-
use devices at all residences. See section V.G. of this document for
additional information on the compliance alternatives available to
small CWSs. For individuals in these systems, EPA assumed in the
analysis, that consumers in households with point-of-use devices are
exposed to the same lead concentration as residents with ``No LSL'' and
``Representative'' CCT in place. The proposed LCRI also requires the
water systems to make available to all customers pitcher filters or
point-of-use devices certified to reduce lead in cases where multiple
ALEs have occurred. See section V.I. of this document for additional
information on the regulatory requirements associated with multiple
action level exceedances. EPA assumed that households receiving pitcher
filters or point-of-use devices would be exposed to the same lead
concentration as residents with ``No LSL'' and ``Representative'' CCT
in place. Uncertainties in the water modeling are discussed in section
5.2.5 and in Exhibit 5-43 of the proposed LCRI EA (USEPA, 2023c).

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    In the estimation of the benefits of the proposed LCRI, each
modeled person within a water system is assigned to one of the
estimated drinking water lead concentrations in Exhibit 16, depending
on CCT, point-of-use, pitcher filter, and LSL/GRR service line status.
Note that EPA assumes GRR service lines are equivalent to LSLs in terms
of modeled water lead concentrations. EPA estimated benefits under both
the low and high scenarios used in the proposed LCRI analysis to
characterize uncertainty in the estimates. With regard to benefit, the
low and high scenarios differ by the number of PWSs that will exceed
the action level under the revised tap sampling requirements and the
concentration-response functions that characterize how reductions in
blood lead levels (caused by changes in lead exposure) translate into
avoided IQ reductions, reductions in lower birth weight, cases of ADHD,
and cardiovascular disease premature mortality (see Chapter 4, section
4.2 and Chapter 5, section 5.1 of the proposed LCRI Economic Analysis
(USEPA, 2023b). EPA predicted the status of each system under the low
and high scenarios at baseline (prior to rule implementation) and in
each year of rule implementation for both the LCRR and proposed LCRI.
Depending on the timing of required actions that can change CCT, point-
of-use, pitcher filter, and LSL/GRR service line status under both the
LCRR and proposed LCRI low and high scenario model runs, changes in
lead concentration and resultant blood lead are predicted every year
for the total population served by the systems for the 35-year period
of analysis. In the primary benefits analysis for the proposed rule,
improvements to CCT and the use of installed point-of-use devices are
only predicted for individuals in households with LSLs prior to
implementation of the LCRR and proposed LCRI requirements (consistent
with discussion above about the limits of the data for predicting the
impact of CCT when LSLs/GRR service lines are not present). In the
model, LSL/GRR service line removals are predicted by water system, by
year, for both the LCRR and LCRI and multiplied by the average number
of persons per household (across demographic categories) to determine
the number of people shifting from one LSL/GRR service line status to
another. To predict the changes in exposure that result from an
improvement in CCT, EPA predicts the entire LSL/GRR service line
population of a water system will move to the new CCT status at the
same time. EPA also assumes that the entire water system moves to the
drinking water lead concentration assigned to point-of-use devices when
this option is implemented, which implies that everyone in households
in a distribution system with LSLs/GRR service lines is properly using
the point-of-use devices. As part of the multiple action level
exceedances requirements under the proposed LCRI, EPA assumes that only
20 percent of a water system's population with LSL, GRR service line,
and service lines of unknown material will request and receive pitcher
filters or point-of-use devices and hence will move to the assigned
drinking water lead concentration for pitcher filter or point-of-use
device use, which implies that everyone who receives a pitcher filter
or point-of-use device is using it properly. See Chapter 5, section 5.3
of the proposed LCRI Economic Analysis (USEPA, 2023b) for more detailed
information on the number of people switching lead concentration
categories under the low and high scenarios.
2. Blood Lead Modeling
    EPA has determined that health impact functions exist in the
literature so that the Agency can quantify the improvements from the
decreases in water lead concentrations that result from implementation
of the proposed LCRI. The four health endpoints EPA quantifies are
increased IQ values and reduced cases of ADHD in children, reductions
in lower birth weights in children of women of childbearing age, and
reduced cases of cardiovascular

disease premature mortality in adults. As a prerequisite to estimating
the impact to these health endpoints, EPA must first use the drinking
water lead concentration data it developed to determine the potential
impact to blood lead levels from the regulatory requirements of both
the LCRR (baseline) and the proposed LCRI for both children aged zero
to seven years, using the coupled Stochastic Human Exposure and Dose
Simulation Multimedia (SHEDS-multimedia) model and the Integrated
Exposure and Uptake Biokinetic model (SHEDS-Pb, formerly known as
SHEDS-IEUBK), and eight years olds through adulthood with the All Ages
Lead Model (AALM).
3. Estimating Blood Lead Levels in Children (0-7 Year Olds)
    Consistent with the LCRR benefits analysis, EPA estimated the
distribution of blood lead levels in children, age zero to seven, using
EPA's SHEDS-Multimedia model coupled with its IEUBK model. For further
information on SHEDS-Pb model development and evaluation, refer to
Zartarian et al. (2017). As a first step in estimating the blood lead
levels, EPA utilized the SHEDS-Multimedia model, which can estimate
distributions of lead exposure, using a two-stage Monte Carlo sampling
process, given input lead concentrations in various media and human
behavior data from EPA's Consolidated Human Activity Database (CHAD)
and the Centers for Disease Control and Prevention's (CDC) National
Health and Nutrition Examination Survey (NHANES). SHEDS-Multimedia, in
this case, uses individual time-activity diaries from CDC's NHANES and
EPA's CHAD for children aged zero to seven to simulate longitudinal
activity diaries. Information from these diaries is then combined with
relevant lead input distributions (e.g., outdoor air lead
concentrations) to estimate exposure. Drinking water tap concentrations
for each of the modeled LSL/GRR service line and CCT scenarios, above,
were used as the drinking water inputs to SHEDS-Multimedia. For more
detail on the other lead exposure pathways that are held constant as
background in the model, see Chapter 5, section 5.4, of the proposed
LCRI Economic Analysis (USEPA, 2023b).
    In the SHEDS-Pb coupled methodology, the SHEDS model takes the
place of the exposure and variability components of the IEUBK model by
generating a probability distribution of lead intakes across media.
These intakes are multiplied by route-specific (e.g., inhalation,
ingestion) absorption fractions to obtain a distribution of lead
uptakes (see Exhibit 5-21 in Chapter 5, section 5.4 of the proposed
LCRI EA, USEPA, 2023b). This step is consistent with the uptake
estimation that would normally occur within the IEUBK model. The media-
specific uptakes can be summed across exposure routes to give total
lead uptake per day. Next, EPA used age-based relationships derived
from IEUBK, through the use of a polynomial regression analysis, to
relate these total lead uptakes to blood lead levels. Exhibit 17
presents modeled SHEDS-Pb blood lead levels in children by year of life
and LSL or GRR service line, CCT status, pitcher filter and point-of-
use device. The blood lead levels in this exhibit represent what
children's blood lead level would be if they lived under the
corresponding LSL or GRR service line, point-of-use, pitcher filter and
CCT status combination for their entire lives. Note that when ``No
LSL'' is the beginning or post-rule state, 0.81 [micro]g/L (the
simulated geometric mean) is the assumed concentration across all
levels of CCT status (none, partial, representative). As previously
noted, the extent to which changes in CCT status make meaningful
differences in lead concentrations for those without LSLs or GRR
service lines cannot be determined from the data available to EPA.
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4. Estimating Older Child and Adult Blood Lead Levels
    In order to estimate the changes in blood lead levels in
individuals from eight years old through adulthood (referred to here as
adults) associated with the proposed LCRI, EPA selected the AALM. The
AALM tool is primarily intended for ``quantitatively relating lead (Pb)
exposures from environmental media that occur over the life time to Pb
levels and concentrations in blood, other body tissues, and excreta''
(USEPA, c). The tool consists of a lead exposure model and a lead
biokinetics model. User inputs for selected environmental media (soil,
dust, water, air and food) are used in the exposure model to predict
lead intake per day for a simulated individual accounting for sex and
age differences. Lead absorption by inhalation or ingestion are
simulated in the biokinetics model to calculate the daily total rate of
lead transfer to the central compartment. The AALM tool produces an
estimate of lead concentration in various tissues and excreta,
including estimates of blood lead levels over a lifetime.
    The water concentrations calculated for each combination of LSL and
CCT status from EPA's regression modelling, Exhibit 16 above, was used
to estimate the distribution of blood lead levels in males and females
aged eight to 79 years using EPA's AALM. Each distinct LSL/GRR and CCT
scenario was modeled and represented by water lead concentrations, and
each scenario was run for females and males as the AALM requires that
each sex be modeled separately. Model inputs include: water intake
rates per age group, which are the same across sexes and were obtained
from EPA's 2011 Exposure Factors Handbook (Table 3-1); lead intake from
food for each age group, which varies by sex and was calculated using
values from the AALM TSD, Appendix C; lead concentrations in soil and
dust, which are consistent for all age groups and calculated as a
weighted average based on data from the U.S. Department of Housing and
Urban Development's (HUD) American Healthy Homes Survey (AHHS) II Lead
Findings report (USHUD, 2021); soil and dust intake rates by age group
up to age 21 were estimated by Ozkaynak et al. (2022), which used EPA's
SHEDS Soil and Dust model; and an air lead concentration of

0.01 [micro]g/m\3\ was used for all age groups and sexes based on
national air monitoring results reporting in Cavender (2013).
    The AALM modeling output provides the yearly estimated blood lead
level ([micro]g/dL) by age from eight to 79 years for each combination
of sex, LSL/GRR service line, CCT, point-of-use and pitcher filter
combination. For additional detailed information on the AALM inputs and
modeling results see Chapter 5, section 5.4 of the proposed LCRI
Economic Analysis (USEPA, 2023b). A summary of the AALM results by sex
are presented in Exhibit 18.
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BILLING CODE 6560-50-C

5. Quantifying and Monetizing Health Endpoints
    EPA quantified and monetized the change in four health endpoints in
the economic analysis of the proposed LCRI. The endpoints are
reductions: in IQ values and cases of ADHD in children, lower birth
weights in children of women of childbearing age, and cases of
cardiovascular disease premature mortality in adults. The subsections
below outline the methods EPA used in analysis of each of these
endpoints.
6. Estimating IQ Benefits
    EPA uses the SHEDS-Pb estimated set of potential geometric mean
blood lead levels for children zero to seven years of age, presented in
Exhibit 17, as inputs in the modeling of IQ benefits for the proposed
LCRI. The benefits analysis uses lifetime average blood lead values to
determine estimates of avoided IQ loss that correspond to reductions in
water lead concentrations resulting from changes in LSL/GRR, point-of-
use, pitcher filter, and CCT status at some point in a representative
child's life (between ages zero and seven), and those made prior to the
child's birth for those born seven years after the LCRR (baseline) or
LCRI are implemented. Therefore, the SafeWater LCR model, in each year
of the analysis, calculates IQ benefits based on the cohort, or percent
of the modeled population, that turns seven years of age in the year
being analyzed. The SafeWater LCR model, for both the LCRR (baseline)
and proposed LCRI, tracks PWS implementation over the period of
analysis. This data allows the model to determine the number of
children that fall within each of the 11 possible LSL/GRR service line,
CCT, point-of-use, pitcher filter lead exposure scenarios for each of
the seven years prior to the year being modeled. The model then
calculates a set of average lifetime blood lead levels for the possible
LSL/GRR service line, CCT, point-of-use, pitcher filter exposure
scenarios (the set of scenarios includes not only the change in LSL/GRR
service line, CCT, point-of-use and pitcher filter status but also the
years, zero to seven, in which the status changes occur) and applies
these values to the appropriate percentage of the seven year old cohort
(the percent of seven year olds that are estimated to experience the
scenarios represented by the average lifetime blood lead levels (BLLs))
for that analysis year under both the LCRR (baseline) and LCRI
requirements. The change in average lifetime BLLs for the seven year
old cohort is then used to determine the incremental benefit of avoided
IQ losses for both the LCRR and proposed LCRI.
    In order to relate the child's estimated average lifetime BLL to an
estimate of avoided IQ loss, EPA selected concentration-response
functions based on lifetime blood lead from two studies. For the high
estimate function, the Agency used a study by Lanphear et al. (2019),
and for the low estimate EPA selected the independent analysis by Crump
et al. (2013), which is based on the same data used in Lanphear et al.
(2019). Since the regulatory requirements are expected to reduce
chronic exposures to lead, EPA selected lifetime blood lead as the most
appropriate measure with which to evaluate benefits. No threshold has
been identified for the neurological effects of lead (Budtz-
J[oslash]rgensen et al., 2013; Crump et al., 2013; Schwartz et al.,
1991; USEPA, 2013). Therefore, EPA assumes that there is no threshold
for this endpoint and quantified avoided IQ loss associated with all
blood lead levels.
    The estimated value of an IQ point decrement is derived from
USEPA's (2019d) reanalysis of Salkever (1995), which estimates that a
one-point increase in IQ results in a 1.871 percent increase in
lifetime earnings for males and a 3.409 percent increase in lifetime
earnings for females. Lifetime earnings are estimated using the average
of 10 American Community Survey (ACS) single-year samples (2008 to
2017) and projected cohort life tables from the Social Security
Administration. Projected increases in lifetime earnings are then
adjusted for the direct costs of additional years of education and
forgone earnings while in school. USEPA's (2019d) reanalysis of
Salkever (1995) estimates a change of 0.0812 years of schooling per
change in IQ point resulting from a reduction in lead exposure for
males and a change of 0.0917 years of schooling for females.
    To estimate the uncertainty underlying the model parameters of the
Salkever (1995) reanalysis, USEPA (2019d) used a bootstrap approach to
estimate a distribution of model parameters over 10,000 replicates
(using random sampling with replacement). For each replicate, the net
monetized value of a one-point increase in IQ is subsequently estimated
as the gross value of an IQ point based on a lifetime of earnings, less
the value of additional education costs and foregone earnings while in
school. EPA uses an IQ point value discounted to age seven. Based on
EPA's reanalysis of Salkever (1995), the mean value of an IQ point in
2022 dollars, discounted to age seven, is $6,887 using a seven percent
discount rate and $27,336 using a three percent discount rate.\22\ See
Appendix F, of the proposed LCRI Economic Analysis (USEPA, 2023b) for a
sensitivity analysis of the value of avoided IQ loss benefits based on
Lin et al. (2018).
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    \22\ It should be noted that these values are slightly different
than those used in other recent rulemaking (e.g., the Lead Dust
Standard). This is simply due to the differences in the age of the
child when the benefits are accrued in the analysis. Benefits for
the LCRI are accrued at age seven and therefore the value of an IQ
point is discounted back to age 7 in the LCRI analysis. This results
in a slightly higher estimate than the values used for the Lead Dust
Standard, which are discounted to age zero and age three,
respectively. It should also be noted, and is described in Chapter
5, Section 5.4.5 of the proposed LCRI Economic Analysis (USEPA,
2023b), that the benefits in the LCRI are further discounted back to
year one of the analysis and annualized within the EPA LCRI cost-
benefit model.
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    EPA used the estimated changes in lifetime (age zero to seven)
average blood lead levels that result from changes in LSL/GRR, CCT,
point-of-use use, and/or pitcher filter status as inputs to the
concentration response functions estimated by Lanphear et al. (2019)
and Crump et al. (2013). The resultant annual avoided IQ decrements per
change in LSL, CCT, point-of-use, and/or pitcher filter status change
are then summed and multiplied by the EPA reanalyzed Salkever (1995)
value per IQ point, which represents a weighted average for males and
females (three or seven percent depending on the discount rate being
used to annualize the stream of benefits across the period of
analysis). This annual stream of benefits was annualized at three and
seven percent, and further discounted to year one of the period of
analysis. Note that this analysis quantifies the benefits from water
quality changes that occur during the 35-year period of analysis but
accounts for the fact that monetized IQ benefits continue to accrue
beyond the 35-year period because they are not experienced by modeled
children until they reach adulthood. See Exhibit 19 (discounted at
three percent) and Exhibit 20 (discounted at seven percent), in section
VIII.D.10., for the estimated benefit from avoided IQ losses from lead
and GRR service line replacement, CCT installation and re-optimization,
point-of-use program operation, and pitcher filter distribution as a
result of the LCRR, the proposed LCRI, and the incremental difference
between the two sets of regulatory requirements under both the low and
high scenarios. For detailed information on the quantification and
monetization of the IQ benefits associated with the proposed LCRI see
Chapter 5, section 5.5 of the proposed LCRI Economic Analysis (USEPA,
2023b).

7. Estimated ADHD Benefits
    This is the first regulation in which EPA has estimated benefits of
avoided cases of ADHD associated with reductions in lead exposure; as
discussed below the approach for quantifying such benefits will
continue to evolve as our understanding of the potential relationship
improves. The causes of ADHD are not fully understood, but research
suggests a number of potential causes, including genetics, exposure to
environmental toxins, prenatal cigarette smoking or alcohol intake, and
brain changes, such as areas of the brain that control attention being
less active in children with ADHD (Tripp et al., 2009; Pliszka et al.,
2007). The EPA lead ISA states that in children, ``attention was
associated with biomarkers of Pb exposure representing several
different lifestages and time periods. Prospective studies did not
examine a detailed Pb biomarker history, and results do not identify an
individual critical lifestage, time period, or duration of Pb exposure
associated with attention decrements in children. Associations in
prospective studies for attention decrements with tooth Pb level, early
childhood average and lifetime average blood Pb levels point to an
effect of cumulative Pb exposure.'' Therefore, additional research is
needed to understand the critical exposure window (thus exposure
metric), the mode of action of lead in the development of ADHD and/or
related symptoms, and potential interplay with genetic factors and
exposures to other substances. Symptoms of ADHD alone, while important
for the child and their families, can be difficult to link to
monetizable outcomes considered in benefits analysis such as reduced