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> **UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON D.C. 20460**

> **OFFICE OF THE ADMINISTRATOR**
>
> **SCIENCE ADVISORY BOARD**

January 22, 2008

EPA-CASAC-08-007

Honorable Stephen L. Johnson

Administrator

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW

Washington, DC 20460

Subject: Clean Air Scientific Advisory Committee's (CASAC) Review of the
Advance Notice of Proposed Rulemaking (ANPR) for the NAAQS for Lead

Dear Administrator Johnson:

The Clean Air Scientific Advisory Committee (CASAC or Committee),
augmented by subject-matter-expert Panelists --- collectively referred
to as the CASAC Lead Review Panel (Lead Panel) --- met on December
12--13, 2007, in Washington, DC, at the request of EPA's Office of Air
and Radiation to review the Agency's Advance Notice of Proposed
Rulemaking (ANPR) for the National Ambient Air Quality Standards (NAAQS)
for Lead. The Panel also reviewed and provided comments on EPA's Final
Lead Staff Paper and the *Human Exposure & Health Risk Assessment
(Full-Scale) Document* (Final Lead Risk Assessment). The Lead Panel
roster is attached as Appendix A, and Panelists' individual comments are
found in Appendix B.

The CASAC is quite pleased with the content and conclusions of the Final
Lead Risk Assessment and Final Lead Staff Paper. *The Committee
unanimously and fully supports Agency staff's scientific analyses in
recommending the need to substantially lower the level of the pri-mary
(public-health based) Lead NAAQS, to an upper bound of no higher than
0.2 µg/m^3^ with a monthly averaging time. The CASAC is also unanimous
in its recommendation that the second-ary (public-welfare based)
standard for lead needs to be substantially lowered to a level at least
as low as the recommended primary NAAQS for Lead*. However, *the CASAC
finds the ANPR for the Lead NAAQS to be both completely unsuitable and
inadequate as a basis for rulemaking*, in that it does not provide the
underlying scientific justification for the range of options for
stand-ard-setting that the Agency is currently considering.

In the Committee's last two letters to the Administrator on this topic
(EPA-CASAC-07-003, dated March 27, 2007; and EPA-CASAC-07-007, dated
September 27, 2007), the CASAC acknowledged that the Agency wished to
move forward with the implementation of the revised NAAQS review
process, and that this implementation would begin in the middle of EPA's
cur-rent review cycle of the lead standards --- thus resulting in a
"hybrid" process, blending elements of the old and the new NAAQS
processes. Thus far, the Panel has reviewed two drafts of the air
quality criteria document (AQCD) for Lead --- a key component of the
Agency's *former* review process that has been replaced by an Integrated
Science Assessment (ISA) for subsequent criteria pollutant NAAQS reviews
--- and then received a stand-alone risk/exposure assessment docu-ment
in keeping with the *new* process, which has also twice undergone CASAC
review. As the final major step in the NAAQS review process, EPA asked
the Committee to review the ANPR for the Lead NAAQS. As noted in the
December 7, 2006 memorandum from EPA Deputy Ad-ministrator Marcus
Peacock entitled, "Process for Reviewing National Ambient Air Quality
Standards," the Staff Paper would be replaced by a *policy assessment*
to be published as an ANPR. Nevertheless, the CASAC was particularly
pleased to note that, pursuant to a Federal court order, EPA was
required to produce a Final Lead Staff Paper for CASAC and public
re-view in addition to an ANPR for the Lead NAAQS. On November 1, 2007,
the Agency released the Final Lead Staff Paper and the Final Lead Risk
Assessment report. On December 5, 2007, EPA released the ANPR for the
Lead NAAQS, which was published in the *Federal Register* on December
17, 2007 (72 FR 71488).

Overall, the Lead Panel judged that the Agency's Final Lead Risk
Assessment report is responsive to the CASAC's comments in the previous
review and, with the incorporation of the few suggestions listed below,
was considered adequate for use in rulemaking. Likewise, EPA's Final
Lead Staff Paper, with some exceptions also noted in this letter, was
considered to be an excellent document that clearly laid out the
scientific evidence for options for the indicator, level, averaging time
and statistical form of a new air-lead standard. EPA staff are to be
commended for their careful, scholarly approach to the development of
the Final Lead Staff Paper, which the Panel also considered to be
adequate for use in rulemaking.

By sharp contrast, *the CASAC found the Advance Notice of Proposed
Rulemaking* *for the Lead NAAQS* --- the first such document of this
type to be issued under EPA's revised NAAQS review process --- *to be
entirely unsuitable and inadequate for use in rulemaking*. The notable
shortcomings of this ANPR are the timing in this review cycle for the
Lead NAAQS and the absence of substantive information found in the ANPR
document itself. The Agency chose to employ an ANPR as the regulatory
vehicle for soliciting broad-based CASAC and public input on the full
range of available policy options for the lead standards at this late
stage in the process. To the CASAC's understanding, the EPA had not
previously used an ANPR in its NAAQS rule-making activities. Having now
seen the structure and content of an Agency ANPR, the members of the
Committee think that it is a regulatory tool more appropriately-suited
to the *beginning* of the process for reviewing a NAAQS. Even more
fundamental, the information contained in this ANPR fell far short of
what the CASAC expected, per the EPA's own implementation guidance.

Specifically, as noted in the Deputy Administrator's December 2006 memo,
a key ele-ment of the Agency's revised NAAQS review process was for EPA
to develop a *policy assess-ment* in lieu of a staff paper, in order to
properly reflect the views of Agency management, con-sistent with other
EPA rulemakings, and publish this in the *Federal Register* as an ANPR.
This policy assessment was described in the Deputy Administrator's memo
as a document that would "identify conceptual evidence- and risk-based
approaches for reaching policy judgments, discuss what the science and
risk/exposure assessments say about the adequacy of the current
standards, and present any preliminary risk/exposure information
associated with alternative standards." Importantly, this policy
assessment would also "*describe a range of options for standard
setting, in terms of indicators, averaging times, \[statistical\] form,
and ranges of levels for any alterna-tive standards, along with a
description of the alternative underlying interpretations of the
scien-tific evidence and risk/exposure information that might support
such alternative standards and that could be considered by the
Administrator in making NAAQS decisions*" (emphasis added). In addition,
we read in that memo that "such \[a policy\] assessment should help to
'bridge the gap' between the Agency's scientific assessment and the
judgments required of the Administra-tor in determining whether it is
appropriate to retain or revise the standards" --- a description that is
virtually *identical* to what has heretofore been used in reference to
EPA's staff papers for its NAAQS reviews (see, for example, the November
29, 2006 *Federal Register* notice announcing the Agency's release of
the 1^st^ Draft Staff Paper for Lead \[71 FR 69117\]). Therefore, the
Com-mittee had every reason to expect that this policy assessment to be
released and published in the form of an ANPR would contain the breadth
and depth of information and analyses that were previously contained in
the Final Staff Paper for a given criteria air pollutant.

*However, the ANPR for the Lead NAAQS did* not *contain any such "policy
assessment" as described above.* Rather, this ANPR simply laid out *all*
policy options for the CASAC's and the public's consideration while
omitting the underlying scientific rationale for many of them. Indeed,
only EPA's Final Lead Staff Paper provides the scientific justification
for each of the options that Agency staff presented for consideration in
the rulemaking process. The Committee had anticipated that having both
the ANPR and the Lead Staff Paper would provide an opportu-nity to
compare the approach and content of the two documents --- and also, not
insignificantly, to assess the consequences of replacing the Staff Paper
with the ANPR. As it turned out, *without the Lead Staff Paper, the
CASAC would not have had the data and supporting analyses* neces-sary
*to make scientifically-informed recommendations to the EPA
Administrator concerning the adequacy and basis of the Lead NAAQS, as
required by the Clean Air Act (CAA)*.

*The Agency's ANPR for the Lead NAAQS thus represented a remarkable
weakening of the scientific foundation of the NAAQS review process.* Far
from improving the efficiency of the review, the ANPR essentially
*reversed* the process. After describing the scientifically-based advice
and recommendations of the CASAC --- and the similar,
scientifically-grounded choices of Agency staff (which agreed almost
completely with the Committee's findings) --- the ANPR opened up the
discussion of options that had already been considered in open public
advisory meetings and dismissed on scientific grounds by both the CASAC
and EPA staff. For example, the ANPR solicited additional public comment
on whether lead should be de-listed as a criteria pollutant. However,
the Agency had already requested this evaluation in the 1^st^ Draft Lead
Staff Paper ([December 2006]{.mark}), along with an accompanying
assessment as to whether revocation of the Lead NAAQS is an option
appropriate for the EPA Administrator to consider, in light of the
cur-rently-available scientific information. In its March 2007 letter to
the Administrator from its re-view of that document (reiterated in the
Committee's September 2007 letter), *the CASAC unam-biguously concluded
that the option of de-listing lead as a criteria air pollutant was
scientifically indefensible*. As an example of the Committee's
scientific rationale for this recommendation, the CASAC noted that,
although over the past three decades, ambient air exposures and
therefore blood lead (blood Pb or PbB) concentration levels in the U.S.
population have drastically de-clined (primarily due to the elimination
of lead from gasoline), much more is now known about the adverse human
health effects of even low levels of environmental lead exposure, and of
cor-responding PbB concentrations levels \< 10 µg/dl, particularly in
children. Yet in spite of this, EPA's ANPR effectively disregarded the
CASAC's prior discussions and recommendations and reopened this issue.
Numerous other examples of the inadequacy of this ANPR are furnished
below in the Committee's responses to specific sections of the document,
as are more detailed comments on the EPA's Final Lead Staff Paper and
the Final Lead Risk Assessment report.

While this letter will focus specifically on the ANPR for the Lead
NAAQS, the CASAC intends to send a separate letter to the EPA
Administrator in the near future to address our con-cerns and elaborate
on the deficiencies in the Agency's revised NAAQS review process that
the Committee has identified in light of the structure and content of
this ANPR.

**CASAC's Comments on EPA's Final Lead Risk Assessment and Staff Paper**

**General Comments**

The members of the CASAC Lead Review Panel were unanimous in their
praise of EPA's Final Lead Risk Assessment and Final Lead Staff Paper.
The Final Risk Assessment report captures the breadth of issues related
to assessing the potential public health risks asso-ciated with lead
exposures; it competently documents the universe of knowledge and
interpre-tations of the literature on lead toxicity, exposures, blood
lead modeling and approaches for conducting risk assessments for lead.
The Final Lead Staff Paper is also a very well-crafted summary of the
important issues associated with interpreting the results from the Final
Risk Assessment. The Staff Paper captures the scientific issues and
discusses the uncertainties asso-ciated with the various assumptions
made in the risk assessment. The Staff Paper also conducts a thorough
and logical analysis of various options for the NAAQS. The CASAC agrees
with the vast majority of the scientific interpretations made in the
Staff Paper.

Brief synopses of the Final Lead Risk Assessment and the Final Lead
Staff Paper, and a few specific issues that the Panel raised with each
of these documents, are highlighted below.

**Synopsis and Specific Comments on EPA's Final Lead Risk Assessment**

**Synopsis:**

The Agency's *Human Exposure & Health Risk Assessment (Full-Scale)
Document* (Final Lead Risk Assessment report) describes the quantitative
human exposure and health risk assessments conducted to inform EPA's
current review of the Lead NAAQS. This document represented an update
the Agency's *[Lead]{.mark} Human Exposure and Health Risk Assessments
for Selected Case Studies, Draft Report* (2^nd^ Draft Lead Exposure and
Risk Assessments, July 2007) that was reviewed by the Committee in
August 2007, and has been updated in response to the CASAC's advice and
recommendations in its letter to the Administrator on this topic
(EPA-CASAC-07-007, dated September 27, 2007). As noted in the
introduction to this Final Lead Risk Assessment report, "risk results
are provided in this document without substantial interpretation.
Rather, interpretative discussion of these results is provided in the
\[Final Lead\] Staff Paper."

**Specific Comments:**

The Final Lead Risk Assessment document notes uncertainties associated
with the anal-yses. One major uncertainty that is not discussed well is
that associated with quantifying the types of exposures that result in
the higher (\> 5 µg/dL) PbB levels among children in the U.S. The
current approach used in the Final Lead Risk Assessment relies on using
the Integrated Exposure Uptake Biokinetic (IEUBK) model for lead in
children to estimate the mean and median blood lead levels associated
with the various scenarios and then applying a geometric standard
deviation (GSD) to quantify plausible variability associated with the
distribution of PbB levels for a given exposure scenario. The Lead Panel
notes that there is a need for better charac-terization of the
uncertainties associated with the model assumptions related to
children's expo-sures at the upper end of the blood lead distribution
(*i.e.*, the higher percentile) and how those exposures may differ from
those of the mean/ median percentile. See also the individual written
comments of Lead Panel member Mr. Sean Hayes attached in Appendix B of
this letter.

**Synopsis and Specific Comments on EPA's Final Lead Staff Paper**

**Synopsis:**

EPA's Final Lead Staff Paper concluded that the overall body of evidence
on lead health effects clearly calls into question the adequacy of the
current primary Lead NAAQS, and pro-vides strong support for
consideration of a lead standard that would provide greater health
pro-tection for sensitive groups, especially for children. Additionally,
the Staff Paper recommends that EPA *not* remove lead from the list of
six criteria pollutants and also *not* revoke the NAAQS for lead.
Instead, Agency staff recommended that the EPA Administrator consider
*appreciably lowering* the level of the current primary standard for
lead from the current level of 1.5 micro-grams per cubic meter
(µg/m^3^). Specifically, the Final Lead Staff Paper recommends
considera-tion of a range of levels, from levels that are currently seen
in many urban areas across the U.S. (approximately 0.1--0.2 μg/m^3^) to
the lowest levels evaluated in the Exposure and Health Risk Assessment
(0.02--0.05 μg/m^3^). In addition, EPA staff recommends either revising
the averaging time to monthly or retaining the current averaging time of
a calendar quarter.

**Specific Comments:**

Consistent with the CASAC's previously recommendations to the
Administrator in our letter from the Lead Panel's review of EPA's 1^st^
Draft [Lead Staff Paper]{.mark} and the Draft Lead Ex-posure and Risk
Assessments documents (EPA-CASAC-07-003, dated March 27, 2007), and
reiterated in the Committee's September 27, 2007 letter
(EPA-CASAC-07-007) on the 2^nd^ Draft Lead Human Exposure and Health
Risk Assessments Document, *the CASAC unanimously af-firms EPA staff's
recognition of the need to substantially lower the level of the primary
NAAQS for Lead, to an upper bound of no higher than 0.2 µg/m^3^ with a
monthly averaging time.*

With regard to the secondary Lead NAAQS, the Final Lead Staff Paper
concluded that the overall body of evidence of lead effects on the
environment calls into question the adequacy of the current secondary
standard. However, Agency staff also concluded that EPA lacks the
relevant data to provide a clear, quantitative basis for setting a
secondary lead standard that differs from the primary standard in terms
of indicator, averaging time, level or form; thus, the Staff Paper
recommends that the EPA Administrator consider setting the secondary
standard for lead equal to a *strengthened* primary standard to provide
increased protection against adverse environmental effects. The CASAC
had also noted in its previous letters to the Administrator that the
level of the secondary Lead NAAQS should be at least as low as the
lowest-recommend-ed primary lead standard, such that there is no
reversal of the current downward trend in lead concentrations in the
environment.

The Staff Paper also recommended that the EPA Administrator consider
retaining lead in total suspended particulates (TSP-Pb) as the indicator
for lead. The Lead Panel raised issues with the use of TSP or PM~10~
monitors for quantifying concentrations of lead in air. While,
his-torically, the Lead NAAQS has relied on TSP samples for quantifying
ambient lead concentra-tions, the Lead Panel was unanimous in
recommending that EPA should transition to PM~10~ sam-pling for
quantifying ambient lead concentrations. PM~10~ is a much more accurate
and precisely-measured indicator and represents the fraction of lead
that is more relevant for human exposures. In addition, there is a
greater availability of PM~10~ samplers throughout the U.S. More
detailed recommendations on this topic are provided in our comments in
the ANPR monitoring section.

Furthermore, the Final Lead Staff Paper proposes a possible approach of
enumerating the number of children above certain blood lead
concentrations, similar to that used by the Agency in 1978. Such an
approach is inferior to EPA's associated lead risk assessment and would
tend to obscure the health benefits of reducing blood lead levels within
categories. If used, this under-estimation of health risk should be
noted, and the CASAC recommends that a threshold of 2 µg/dL be used as
the cut-point, because of the evidence of adverse effects at higher
levels.

**CASAC's Comments on the Agency's ANPR for the Lead NAAQS**

**Synopsis and General Comments on ANPR for the Lead NAAQS**

**Synopsis:**

The Agency's ANPR for the Lead NAAQS invited public comment on:
scientific evi-dence concerning the health and welfare effects of
current and past air emissions of lead that may be found in ambient air,
indoor dust, and outdoor soil; current lead exposures and health risks
associated with such exposures; and, importantly, *policy options* for
addressing lead air-related exposures and associated risks.
Specifically, the Agency indicated that, with this ANPR, it was
soliciting comment on the *adequacy* of the current lead NAAQS, on
potential *revisions* to the standard, and on questions that have been
raised with regard to *maintaining* a NAAQS for lead --- that is,
whether it is appropriate to *revoke* the lead standard or to *remove*
(*i.e.*, *de-list*) lead from the list of criteria pollutants. In
addition, the ANPR invited comment on issues regarding ambient air
quality monitoring for lead, to include sampling and analysis methods,
network de-sign, sampling schedule, and data handling methods. The
Agency noted that it will consider CASAC recommendations and comments
received from the public on the ANPR in developing EPA's proposed
decision on the adequacy of the current standards and on any revisions
to the Lead NAAQS that may be appropriate; and, furthermore, that the
Agency will propose whether to revise or retain the current lead
standards by no later than May 1, 2008 (with a target date of March
2008), and take final action by September 1, 2008, pursuant to a Federal
court order.

**General Comments:**

*The CASAC notes that the ANPR for the Lead NAAQS adds no new
information --- and certainly no rigorous analyses of the various
options that the Agency is considering --- beyond what has already been
presented in the Final Lead Staff Paper and the Final Lead Risk
Assess-ment.* Furthermore, contrary to the original intent of the review
of EPA's NAAQS-setting pro-cess, as set forth in the Deputy
Administrator's memo of December 15, 2005, the ANPR also failed to
"ensure that the best available science \[will\] guide and inform Agency
decision making" --- nor does the ANPR adhere to the "highest scientific
standards" as stated in the Deputy Ad-ministrator's memo of December 7,
2006 (and essentially reiterated in his April 17, 2007 memo) that "the
Agency's decisions would be informed by the best available science ....
without com-promising the scientific integrity \[*i.e.*, soundness and
transparency\] of the process." Finally, rather than making EPA's NAAQS
review process more efficient, as envisioned by the Deputy
Administrator, the ANPR actually results in a *slowing* of the process
by opening up a discussion of options that were already vetted in public
and found not to be feasible by both CASAC and Agency staff. As noted
above, the ANPR, in effect, puts the NAAQS review process in *reverse*.

**Specific Comments on ANPR Sections on Primary Lead NAAQS**

**Sections III.A (Health Effects Information) & III.B (Human Exposure
and Health Risk Assessments):**

These sections of the ANPR on the Primary Lead NAAQS contain much good
discussion drawn from the Lead Staff Paper, and provide much of the data
needed to understand sources of human lead exposure and the use of IQ
loss in children as the metric for assessing the effects of lead in this
sensitive subpopulation. In the proposed rule for the Lead NAAQS that
will follow --- or, for that matter, in any ANPR for the NAAQS for a
different criteria pollutant --- greater emphasis should be placed on
including tabular and graphical data of the scientific results that
support or underpin the points being discussed. For example, the
"roll-up" scenario helps the reader interpret the incremental risks
associated with sticking with the current NAAQS and any alternative
NAAQS. The incremental risk (*i.e.*, reflected by change in IQ loss)
approach helps the reader assess the impact of the various options that
are under consideration for a Pb NAAQS.

However, there were several problems identified in the discussion of the
primary Lead NAAQS. The ANPR devoted too many pages to describing an
alternative to the Agency's peer-reviewed risk assessment, using instead
the approach of 1978. In 1978, evidence on the effects of lead on
cognitive function was limited to a few studies that showed lower
cognitive function in children with "high" lead levels. Reasonably, EPA
set the NAAQS with a goal of limiting the number of children with "high"
blood lead levels. Necessarily, such an approach recognizes no benefits
to lowering blood lead levels within the "not high" category. As
described by the Agency's Final Lead Staff Paper and affirmed by the
CASAC Lead Review Panel, much more is now known about the dose-response
between blood lead and IQ than in 1978. While there is always
uncertainty in the dose-response relationship, it should be noted that
uncertainty about the slope is not the same as uncertainty that the
slope is not zero. Moreover, it is clear that the ad-verse effects of
lead are demonstrable at blood lead levels even lower than 5 µg/dL, as
docu-mented by the EPA peer-reviewed risk assessment and by empirical
studies.

For example, the ANPR suggests that the slope below 7.5 μg/dL is
unreliable because it is based on data from 103 children from one study
(Lanphear, 2005). This argument is undercut by several other studies
confirming that the relationship of lead exposure is non-linear and
per-sists at blood lead levels considerably lower than 5 μg/dL
(Lanphear, 2000; Wasserman, 2003; Kordas, 2006; Tellez-Rojo, 2006). In
particular, Tellez-Rojo and co-workers reported that the slope of the
association between 24-month blood lead and the 24-month Mental
Development Index (MDI) for 294 children who had peak blood lead levels
below 5 μg/dL was negative (-1.7 points for each 1 μg/dL increase in
blood lead concentration, p=0.01). Collectively, these studies indicate
that there is sufficient evidence to support the use of the
dose-response relationship from the pooled analysis at blood lead levels
\< 5 µg/dL (Lanphear, 2005), as described in the Final Lead Staff Paper
and previously recommended by CASAC.

The Lead Panel was concerned that the ANPR presented analytical choices,
as described below, that may underestimate risks for the adverse effects
of lead and the benefits of reducing the Lead NAAQS. In isolation, each
of these decisions may not be substantial, but the cumula-tive impact
could result in substantially underestimating the adverse effects of
lead and the bene-fits of lowering the NAAQS for lead. Similarly, these
choices would fail to provide an adequate margin of safety, as required
by law. The following examples illustrate the major ways that the ANPR
underestimated the lead effects and the benefits of alternative lead
standards:

-   The Clean Air Act requires special attention to susceptible
    populations. The ANPR notes that there is evidence of increased
    susceptibility in African Americans and persons with certain
    genotypes (*e.g.*, ALAD \[aminolevulinate, delta-, dehydratase\]
    variants), but it is not apparent that these susceptible populations
    were considered in EPA's risk assessment.

-   Members of the Lead Panel reiterate their previous advice to the
    Administrator (EPA-CASAC-07-007, dated September 27, 2007) that the
    Agency use the two-piece linear function for relating IQ alterations
    to current blood lead levels with a slope change or "hinge" point
    closer to 7.5 µg/dL rather than the log-linear with low-exposure
    lineari-zation (LLL) concentration-response function at 1 μg/dL, as
    recommended in the ANPR. The ANPR argued, on the one hand, that
    there were too few children to extrapolate below 7.5 μg/dL. As noted
    above, the Lead Panel disagrees. On the other hand, the ANPR argued
    that it was not reasonable to see such a dramatic decrement in IQ
    scores at the lowest levels of exposure (*e.g.*, \< 1 μg/dL). Use of
    the two-piece linear below 7.5 μg/dL, which is based on empirical
    data, would resolve the concern about steep slope observed with the
    log-linear results and require fewer assumptions or uncertainties.

-   Lead found in "past air" is treated as part of background lead
    rather than as a component of policy-relevant (air) lead in the risk
    assessment. This will tend to underestimate the benefits of lowering
    the NAAQS for lead.

**Section III.C (Considerations in Review of the Standard)**

In its consideration of the Primary Lead NAAQS, the ANPR combines,
presents, and solicits *both* scientific and policy considerations, and
in several areas tends to obscure the transi-tion from science to
policy. As discussed above, the approach taken in the ANPR for the Lead
NAAQS draws heavily from, repeats, or summarizes information by
reference only to the EPA's Final Lead Risk Assessment report and Final
Lead Staff Paper, as well as the letters/reports that the CASAC
previously sent to the Administrator during this current review cycle
for the Lead NAAQS. However, the ANPR fails to convey the scientific
basis of the analyses, findings and conclusions contained therein. In
its review of the available scientific information, the ANPR should have
indicated that: (1) lead would be retained as a criteria air pollutant;
(2) the lowering of the Lead NAAQS substantially below the current value
is fully-justified; and (3) as discussed below in the section on "Lead
Ambient Air Monitoring and Sampling," a new indicator for lead needs to
be developed. The policy implications and the Agency's view of these
conclusions should then have been discussed in a transparent manner and
presented in a strong policy state-ment.

Rather, the ANPR for Lead tends to undermine the scientific process in
EPA's considera-tion of the primary lead standard. The ANPR frequently
notes "limitations and uncertainties" in the available data, analyses,
and assessments. Agency staff, on the other hand, recognized these
difficulties throughout the Lead NAAQS review process and addressed
these unknowns in a sci-entifically-defensible manner. CASAC has
carefully reviewed these analyses, and concurs with the conclusions in
the Agency's Final Lead Staff Paper. However, the ANPR fails to carry
the discussions and cautions forward and suggests that areas of
uncertainty become purely policy issues. While the treatment of
uncertainty in policy decision-making should be consistent with the
development of those uncertainties in the scientific assessments and be
incorporated in an adequate margin of safety, as required by the CAA,
the ANPR contains no discussions sum-marizing either the scientific
treatment of uncertainty, the manner in which reviewers should consider
those uncertainties, or how EPA intends to address these uncertainties
in a margin of safety protective of public health.

Section III.C of the ANPR also conveys *no substantive comparative
assessment* of alter-native primary lead standards --- that is, the
point to which the established and vetted scientific evidence should
lead --- but merely indicates that additional input from anyone would be
wel-come, without specifying whether that input should be additional
data, scientific evaluations, opinions or policy analyses. At best, as
twice-noted above, this is moving the process of devel-oping the NAAQS
for lead *backwards*, *i.e.*, away from an established scientific
foundation, with the ANPR seeming to undermine the clear intent of the
Clean Air Act in what it specifies as the particular role of the CASAC.

In regard to the ANPR solicitation of additional public comment as to
the sufficiency of the data to warrant the de-listing of lead as a
criteria air pollutant, the EPA takes note that all current measurements
are below the present ambient standard of 1.5 µg/m^3^. However, in light
of evidence identified by the Agency in the 1990 review, the current
lead standard is clearly not health-protective. Additionally, this is
clearly no guarantee that future air lead levels will remain low. The
ANPR also solicits comments on whether a broad range of current Federal
and State lead control programs might render the NAAQS unnecessary. The
evidence evaluated, and the position of CASAC, clearly indicate that the
hazardous air pollutants (HAP) standards under Clean Air Act Section 112
are not appropriate, as these generally apply to individual point
sources. Lead is a ubiquitous pollutant, derived from numerous sources,
presenting significant air-related exposures in multiple media; and thus
is better regulated under CAA Section 108 as a "priority" pollutant. As
mentioned above, this issue of de-listing lead was previously considered
by the CASAC on two occasions, and in its summary letters to the
Administrator for the associ-ated reviews the Committee unanimously
indicated that there is absolutely no scientific justifica-tion for an
action to de-list. To the contrary, the CASAC has strongly indicated
that the current standard needs to be *substantially lowered* (and, in
fact, should have been lowered on the basis of existing data many years
ago).

Furthermore, the ANPR for the Lead NAAQS contemplates that the U.S.
Centers for Dis-ease Control and Prevention (CDC) "action" level for
blood lead of 10μg/dL be considered as an acceptable risk level by the
EPA Administrator, either as a mean or as a not-to-exceed level. The
Lead Panel finds any suggestion of using blood lead action levels as a
starting point for a risk assessment to be particularly troubling, in
that it begs the question as to why the Agency would even consider
allowing children to be sufficiently-exposed to ambient lead to permit
PbB levels that require intervention. Surely such an approach --- which
ignores both the CDC and CASAC determinations that there are adverse
health effects at lower blood lead levels --- does *not* allow
protection of public health with an adequate margin of safety as
required by the plain language of Section 109 of the Clean Air Act.
Therefore, the Lead Panel concludes that the ANPR document misapplies
both the nature and purposes of the CDC's advisory statement on measures
to prevent childhood lead poisoning. Specifically, the CDC level of 10
μg/dL PbB is an "action" level, which recommends the initiation of
*secondary* prevention measures, not a "risk" level. The CDC, in its
most recent statements (CDC 2005, 2007), explicitly declares that
adverse health effects of lead occur at PbB concentrations *below*
10μg/dL, but that effective response to sub-10μg/dL blood lead levels
requires *primary* prevention methods --- which can only occur by
significant reductions of ambient air lead levels pursuant to EPA
regulations via the NAAQS. Neither of the CDC's lead-related statements
indicates that, at sub-10 μg/dL levels, adverse health effects are
either non-existent or trivial. Rather, the Center's statements present
action levels for the purpose of prioritizing secondary prevention
methods: screening, identification of exposure, and intervention after
identification. Nowhere in the CDC statements are action levels defined
as a "threshold" of blood Pb levels below which there is no harm.
Indeed, there are several peer-reviewed papers --- with results limited
to children whose blood lead was always lower than 10 µg/dL and, in one
case, always lower than 5 µg/dL --- that report significant
asso-ciations.

Finally, with regard to the indicator, level, averaging time, and
statistical form of a pro-posed NAAQS for lead, the ANPR fails to either
take any position or provide sufficient detail of the position of Agency
Staff or the CASAC that would permit a member of the public to
under-stand or evaluate the scientifically-informed decision process by
which the Administrator will select from a range of options for the lead
standards. The ANPR simply mentions that EPA Staff and the Committee
have fulfilled their responsibilities in the process to date and
solicits further input on each component. There is no indication that
the scientific validity of any evidence presented will be vetted, nor
whether potential conflicts of interest among prospective reviewers will
be ascertained. *Thus, this ANPR fails as a rigorous policy assessment
document that would stand alone as a summary of the current scientific
data, and provides no discussion of the range of alternatives for the
Lead NAAQS as offered by the Final Lead Staff Paper, and therefore does
not provide an adequate basis from which to make sound policy
decisions.*

**Comments on ANPR Sections on Secondary Lead NAAQS**

*The Lead Panel unanimously reaffirms its earlier judgments that, as
with the primary (public-health based) Lead NAAQS, the secondary
(public-welfare based) standard for lead also needs to be substantially
lowered.* As previously noted, it is critical that the secondary Lead
NAAQS be set at a sufficiently-stringent level so as to ensure that
there is no reversal of the cur-rent downward trend in lead
concentrations in the environment. Therefore, at a minimum, the level of
the secondary Lead NAAQS should be at least as low as the level of the
recommended primary lead standard. Moreover, the Agency needs to give
greater priority to the monitoring of environmental lead in the ambient
air, as discussed more extensively in the section of this letter that
immediately follows. As noted in the ANPR, these conclusions are also
fully-supported by EPA staff in the Agency's Final Lead Staff Paper.

**CASAC's Comments on Lead Ambient Air Monitoring and Sampling Issues in
the Agency's ANPR for the Lead NAAQS**

The Lead Panel provides the following comments on the monitoring section
of the ANPR for the Lead NAAQS with respect to: (a) sampling and
analysis method; (b) network design; (c) sampling schedule; and (d)
monitoring for secondary standard.

**Sampling and Analysis Method**. In its previous comments on EPA's AQCD
for Lead, the 1st Draft Lead Staff Paper, and now in this review of the
ANPR for the Lead NAAQS, the Panel unanimously recommends that the
Agency revise the indicator for lead sampling from TSP to PM~10~, as
measured with a low-volume sampler and analyzed with low-cost
multi-elemental analytical methods such as X-Ray Fluorescence (XRF),
Inductively Coupled Plasma--Mass Spectroscopy (ICP-MS), or other
techniques that offer improved detection limits at the lower
concentrations typical of today's ambient air. The detailed rationale
for this recommendation is provided in the CASAC letters to the
Administrator dated March 27, 2007 and September 27, 2007
(EPA-CASAC-07-003, EPA-CASAC-07-007). See also the individual written
comments from Lead Panel members Dr. Barbara Zielinska, Mr. Rich Poirot,
and Dr. Donna Kenski found in Appendix B of this letter.

The Agency should also seize this opportunity to transition from TSP to
PM~10~, since the current review indicates a need for a substantial
lowering of the lead NAAQS. If a standard is lowered by a factor of 10
to 100, it is unimportant if the indicator measures 10% or 15% less than
the indicator selected 30 years ago. The Cavender & Schmidt (2007)
analysis does indicate some variability in the average ratios of
PM~10~-Pb to TSP-Pb. However, it also shows average ratios of \> 0.60 at
all sites, \> 0.75 at 20 of 24 sites, and \> 0.80 at 18 sites. Rather
than needing to arduously establish a large series of site-specific
PM10-Pb to TSP-Pb ratios (which would, in essence, constitute "fitting
good data to bad"), it would be well within EPA's range of
discretion-ary options to accept a slight loss of ultra-coarse lead at
some monitoring sites by selecting an appropriately conservative level
for the revised Pb NAAQS. Conversely, it would be a mistake to hold up
the old TSP metric as the "gold standard" and only allow newer, better
technology if it can reproduce the old, and seriously-flawed, sampler
performance. To further explore and dis-cuss these issues, Agency staff
and the EPA Science Advisory Board Staff Office are currently discussing
a near-term meeting of the CASAC Ambient Air Monitoring and Methods
(AAMM) Subcommittee.

In response to the Agency's concerns that the new PM~10~ indicator must
be tied explicitly to the historic TSP health data, it is the opinion of
the Lead Panel that the above arguments may be one way to justify the
change, especially given that any minor effect of losing coarse
particles is dwarfed by the change in the level of the standard. The
Panel unanimously supported the selection of an indicator that can be
more robustly measured and thus would be more representa-tive of actual
population exposures. (It is also important to note that studies of the
health effects of lead are not based on ambient monitoring at all, but
rather are based on internal biomarkers of dose, such as blood lead and
bone lead.) Finally, a more accurate and precise Pb-PM~10~ indicator
would provide a more stable determination of compliance with the new
lower Lead NAAQS.

**Network Design**: The Lead Panel finds the existing Pb-TSP network
inadequate in its ability to characterize population exposures,
conditions around large sources, and concentrations at typical ambient
concentrations in many parts of the county. The issue of how best to
design a lead monitoring network that would serve the many goals of air
monitoring data collection (while balancing limited resources) is more
complicated than the Panel can do justice to in this meeting. Rather, it
deserves thorough analysis and is a task that could more appropriately
be assigned to the CASAC AAMM Subcommittee. The Lead Panel agrees that
the current PM~10~ and National Air Toxics Trends Sites (NATTS) networks
could be integrated into a new lead monitoring network, while
recognizing that most existing PM~10~ monitors are high-volume samplers
that use quartz filters. These samplers are preferable to high-volume
TSP, but they have less precise cut-points than low-volume samplers, and
the filters are not as clean as Teflon or as amenable to surface beam
analytical techniques. Again, the Panel does not recommend any effort to
develop site-specific or region-specific adjustment factors to make
these measurements more "TSP-like." The one place where Panel members
think continued TSP sampling (or more helpfully, collocated TSP and
PM~10~) would be appropriate is near large sources, where ultra-coarse
particles are most likely to contribute significant mass. Multiple size
fractions can pro-vide a better understanding of exposures, of lead's
movement from a source through the environ-ment, and the influences of
various source types and meteorological conditions on the distribu-tion
and deposition of lead.

**Sampling Schedule:** If the form of the lead standard is changed to a
monthly averaging time, the sampling frequency should be increased to
once every three days (1-in-3) or even more often (another point in
favor of PM~10~, which can be collected with automated sequential
sam-plers). However, in the interests of reducing filter-sampling
efforts, sampling frequency could be adjusted depending on
concentrations; sites with consistently low concentrations could operate
on a one-in-six-day (1-in-6) schedule, and sites that are closer to the
Pb NAAQS could sample more frequently to better characterize the mean.
The Lead Panel discourages the use of longer sampling times (48 or 72
hours) or compositing of samples, since these actions limit the utility
of the data for other purposes.

**Monitoring for the Secondary NAAQS**: The Lead Panel supports the
excellent idea of supplementing the rural/remote PM~2.5~ Pb measurements
from the Interagency Monitoring of Pro-tected Visual Environments
(IMPROVE) network with a smaller "sentinel" network of PM~10~-Pb
samplers. The IMPROVE program already collects PM~10~ samples and these
samples --- from a subset of sites that might be periodically rotated
--- could be at least subject to multi-elemental XRF analysis that would
provide useful information on both fine and coarse lead as well as other
components of coarse particle composition.

In closing, the CASAC acknowledges the distinction between science and
public policy in the NAAQS-setting process. However, it is essential
that policy choices be based both on *sound scientific data and
supporting analyses* and on *independent, expert assessment* thereof.
Additionally, the process for the review of the NAAQS policy options and
the associated infor-mation must be open and transparent --- and should
certainly reflect the results of the analytical efforts of the Agency's
own scientific and technical staff. In the past, this in-depth analysis
has been presented as a policy assessment in the Agency's Final Staff
Paper. *The Committee still needs this rigorous policy assessment of
scientific and technical information, both now and in the future, to be
able to properly advise the EPA Administrator on the NAAQS.*
Accordingly, the CASAC looks forward to working with the Agency to
effectively and appropriately implement a suitable process for NAAQS
review that is scientifically-sound and transparent and will enable the
Committee to properly fulfill its statutory obligations under the Clean
Air Act, with the goal of protecting public health with an adequate
margin of safety and protecting the public welfare.

Sincerely,

*/Signed/*

> Dr. Rogene Henderson, Chair

Clean Air Scientific Advisory Committee

Appendices

**NOTICE**

> This report has been written as part of the activities of the U.S.
> Environmental Protection Agency's (EPA) Clean Air Scientific Advisory
> Committee (CASAC), a Federal advisory committee
> administratively-located under the EPA Science Advisory Board (SAB)
> Staff Office that is chartered to provide extramural scientific
> information and advice to the Administrator and other officials of the
> EPA. The CASAC is structured to provide balanced, expert assessment of
> scientific matters related to issue and problems facing the Agency.
> This report has not been reviewed for approval by the Agency and,
> hence, the contents of this report do not necessarily represent the
> views and policies of the EPA, nor of other agencies in the Executive
> Branch of the Federal government, nor does mention of trade names or
> commercial products constitute a recommendation for use. CASAC reports
> are posted on the SAB Web site at: <http://www.epa.gov/sab>.

**Appendix A -- Roster of the CASAC Lead Review Panel**

**U.S. Environmental Protection Agency**

**Science Advisory Board (SAB) Staff Office**

**Clean Air Scientific Advisory Committee (CASAC)**

**CASAC Lead Review Panel**

**CASAC** Number range CHAPTER**MEMBERS**

**Dr. Rogene Henderson (Chair)**, Scientist Emeritus, Lovelace
Respiratory Research Institute, Albuquerque, NM

**Dr. Ellis Cowling**, University Distinguished Professor At-Large,
Emeritus, Colleges of Natural Resources and Agriculture and Life
Sciences, North Carolina State University, Raleigh, NC

**Dr. James D. Crapo \[M.D.\]**, Professor, Department of Medicine,
National Jewish Medical and Research Center, Denver, CO

Number range CHAPTER**Dr. Douglas Crawford-Brown**, Director, Carolina
Environmental Program; Professor, Environmental Sciences and
Engineering; and Professor, Public Policy, Department of Environmental
Sciences and Engineering, University of North Carolina at Chapel Hill,
Chapel Hill, NC

**Dr. Donna Kenski**, Director of Data Analysis, Lake Michigan Air
Directors Consortium (LADCO), Rosemont, IL

**Dr. Armistead (Ted) Russell**, Georgia Power Distinguished Professor
of Environmental Engineering, Environmental Engineering Group, School of
Civil and Environmental Engineering, Georgia Institute of Technology,
Atlanta, GA

**Dr. Jonathan Samet \[M.D.\]**, Professor and Chairman, Department of
Epidemiology, Bloomberg School of Public Health, Johns Hopkins
University, Baltimore, MD

**PANEL** Number range CHAPTER**MEMBERS**

**Dr. Joshua Cohen**, Research Associate Professor of Medicine, Tufts
University School of Medicine, Institute for Clinical Research and
Health Policy Studies, Center for the Evaluation of Value and Risk,
Tufts New England Medical Center, Boston, MA

**Dr. Deborah Cory-Slechta**, Professor, Department of Environmental
Medicine, University of Rochester School of Medicine and Dentistry,
Rochester, NY

**Dr. Bruce Fowler**, Assistant Director for Science, Division of
Toxicology and Environmental Medicine, Office of the Director, Agency
for Toxic Substances and Disease Registry, U.S. Centers for Disease
Control and Prevention (ATSDR/CDC), Chamblee, GA

**Dr. Andrew Friedland**, Professor and Chair, Environmental Studies
Program, Dartmouth College, Hanover, NH

**Dr. Robert Goyer \[M.D.\]**, Emeritus Professor of Pathology, Faculty
of Medicine, University of Western Ontario (Canada), Chapel Hill, NC

**Mr. Sean Hays**, President, Summit Toxicology, Allenspark, CO

**Dr. Bruce Lanphear \[M.D.\]**, Sloan Professor of Children's
Environmental Health, and the Director of the Cincinnati Children's
Environmental Health Center at Cincinnati Children's Hospital Medical
Center and the University of Cincinnati, Cincinnati, OH

**Dr. Samuel Luoma**, Senior Research Hydrologist, Emeritus, U.S.
Geological Survey (USGS), Menlo Park, CA

**Dr. Frederick J. Miller**, Consultant, Cary, NC

**Dr. Paul Mushak**, Principal, PB Associates, and Visiting Professor,
Albert Einstein College of Medicine (New York, NY), Durham, NC

**Dr. Michael Newman**, Professor of Marine Science, School of Marine
Sciences, Virginia

Institute of Marine Science, College of William & Mary, Gloucester
Point, VA

**Mr. Richard L. Poirot**, Environmental Analyst, Air Pollution Control
Division, Department of Environmental Conservation, Vermont Agency of
Natural Resources, Waterbury, VT

**Dr. Michael Rabinowitz**, Geochemist, Marine Biological Laboratory,
Woods Hole, MA

**Dr. Joel Schwartz**, Professor, Environmental Health, Harvard
University School of Public Health, Boston, MA

**Dr. Frank Speizer \[M.D.\]**, Edward Kass Professor of Medicine,
Channing Laboratory, Harvard Medical School, Boston, MA

**Dr. Ian von Lindern**, Senior Scientist, TerraGraphics Environmental
Engineering, Inc., Moscow, ID

**Dr. Barbara Zielinska**, Research Professor, Division of Atmospheric
Science, Desert Research Institute, Reno, NV

**SCIENCE ADVISORY BOARD STAFF**

**Mr. Fred Butterfield**, CASAC Designated Federal Officer, 1200
Pennsylvania Avenue, N.W., Washington, DC, 20460, Phone: 202-343-9994,
Fax: 202-233-0643 ([butterfield.fred@epa.gov]{.underline})

**Appendix B -- Written Comments from**

**Individual CASAC Lead Review Panel Members**

> This appendix contains the preliminary and/or final written comments
> of the individual members of the Clean Air Scientific Advisory
> Committee (CASAC) Lead Review Panel who submitted such comments
> electronically. The comments are included here to provide both a full
> perspective and a range of individual views expressed by Panel members
> during the review process. These comments do not represent the views
> of the CASAC Lead Review Panel, the CASAC, the EPA Science Advisory
> Board, or the EPA itself. The views of the CASAC Lead Review Panel and
> the CASAC as a whole are contained in the text of the letter to which
> this appendix is attached. Panelists providing written comments are
> listed on the next page, and their individual comments follow.

**[Panelist]{.underline} [Page \#]{.underline}**

Dr. Deborah
Cory-Slechta..............................................................................
B-3

Dr. Ellis
Cowling.........................................................................................
B-4

Dr. James
Crapo...............................................................................\...\...\...\...\...B-12

Dr. Douglas
Crawford-Brown..........................................................................
B-14

Mr. Sean
Hays.....................................................................................\...\...\...
B-17

Dr. Donna Kenski
..............................................................................\...\...\...\...
B-19

Dr. Bruce
Lanphear.................................................................................\...\...
B-22

Number range CHAPTERDr. Paul Mushak
.................................................................................\...\...\....
B-24

Mr. Rich Poirot
..........................................................................................
B-34

Number range CHAPTERDr. Michael Rabinowitz
..............................................................................\...B-42

Number range CHAPTERDr. Armistead (Ted)
Russell........................................................................\.....B-43

Dr. Jonathan M.
Samet.................................................................................
B-44

Dr. Joel Schwartz
........................................................................................B-45

Dr. Frank Speizer
........................................................................................B-49

Number range CHAPTERDr. Ian von Lindern
..............................................................................\...\...\...
B-51

Dr. Barbara Zielinska
...................................................................................
B-62

**Dr. Deborah Cory-Slechta**

These comments in regard specifically to the ANPR concur with those
offered by other Panel members on the content of the document.

1.  First, no specific options are ever proposed that could elicit
    serious systematic deliberations from the community at large, as per
    the stated intent of the change in process that has been evoked.

2.  Nor is it clear how the information that would be obtained from this
    new process would be used and judged. Would information from
    non-experts be given the same weight as those of experts in the
    field? Does preponderance of opinion count? My service as a Panel
    member on the Lead NAAQS Panel is premised on lack of conflict of
    interest. Will information obtained from sources who might have
    financial interest in the outcome be given the same weight as those
    stakeholders who sustain the exposures? The ANPR repeatedly makes
    reference to levels of uncertainty in the effects of blood lead
    levels at \<10 µg/dl, but what level of certainty would be
    sufficient? Since this would be a subjective judgment, how might it
    be related to financial conflicts of interest?

3.  It remains difficult to consider how any loss of IQ could ever be
    acceptable in the context of human health protection and to be
    without public health significance. I remain of the mind set that
    this is a slippery slope and that 20 years from now, these documents
    will be read by people wondering what on earth could these people
    have been thinking?

4.  In addition, the lack of any full economic analysis of the costs
    associated with lead exposure and its consequences as a component of
    these documents is a highly significant omission. Such an analysis,
    which should include the costs of all the health consequences, both
    for children and adults, and the long-term effects of early academic
    failure for children and its ability to result in sustained academic
    failure should be weighed in the deliberations. The focus strictly
    on IQ point loss is misleading at best and thus does not allow a
    full consideration of all of the consequences of any policy
    decision.

5.  The document conveys a bias in its request for information. For
    example, in its solicitation of information on the primary standard,
    it requests comment on delisting, revocation and adequacy of the
    current standard, but does not specifically, in the same sentences,
    request comments on the inadequacy of the current standard, as
    consistent with CASAC recommendations and the OAQPS Staff paper.

6.  It seem apparent that the intent of the change in process imposed
    during the Lead NAAQS review has been to downgrade input and
    recommendations provided by CASAC and thereby diminish public health
    protection. It certainly leaves this panel member wondering why they
    are spending time providing any advice to the Administrator.
    Likewise, the current process serves to undermine the careful and
    considered deliberations of its own EPA staff.

**Dr. Ellis Cowling**

Ellis Cowling

North Carolina State University

January 3, 2008

**[Individual Comments Prepared in Connection with the December 12 and
13, 2007 CASAC Review of the Advanced Notice of Proposed Rule Making
(ANPR) and the]{.underline}**

**[November 2007 Staff Paper for Pb NAAQS]{.underline}**

Before dealing with my specific assignment with regard to the Secondary
(public-welfare based) NAAQS Standards for Pb, permit me to offer the
following general comments on: the **importance of EPA's role in
helping** **eliminate childhood lead poisoning** **in the United States
by 2010,** and the **structure and content of the** **ANPR for the Pb
NAAQS** in the context of the new processes and procedures for NAAQS
reviews.

**EPA's role in "eliminating childhood lead poisoning" in the United
States**

As indicated in my individual comments on January 27, 2007 and again on
July 23, 2007 regarding the USEPA's implementation of the *Lead
Renovation, Repair, and Painting Rule*, it was an inspiration to learn
that many different agencies of our federal Government had established a
very noble goal for multi-agency cooperation and collaboration in:

"eliminating childhood lead poisoning \[in the United States\] by the
year 2010!"

At the same time, it was very disappointing to learn how little the
USEPA had done during the several years after this interagency goal was
established during the early 1990s to do its part together with other
federal agencies to help fulfill this very noble national goal.

As the members of our CASAC Lead Panel look forward to the time it will
take for EPA to implement its *Lead Renovation and Repair Rule*, we
could not help but wonder why it was not until February 2007 that CASAC
was asked to review two separate documents -- the *[Draft Assessment
Plan in Support of the Lead Renovation and Repair Rule]{.underline}* and
*[An Approach for Estimating Children's Health Risk (IQ) Changes
Associated with Dust Lead Generated by Renovation, Repair, and Painting
Activities]{.underline}* -- when the goal of our government is
"eliminating childhood lead poisoning by 2010" -- then 3 years away and
now only 2 years away!

We commend the present administration of the USEPA for undertaking their
presently renewed interest and actions with regard to lead pollution and
poisoning and hope that the Agency will in fact now do its important and
appropriate part -- together with other federal agencies -- and thus
help our country make further progress toward our self-declared national
goal of "eliminating childhood lead poisoning -- \[hopefully\] by 2010,"
but if not by then "as soon thereafter as possible. **Better late than
never!**

The references listed below describe important parts of the reasons why
the currently proposed actions and reports regarding lead poisoning of
children in the United States are so long overdue.

References:

1\) Childhood lead poisoning prevention. Too little, too late. B P
Lanphear. J Amer Med Assn. 2005 May, 293(18):2274-2276.

2\) "Cater to the children": The role of the lead industry in a public
health tragedy, 1900-1955. G Markowitz and D Rosner. Am J Public Health.
2000 January; 90(1):36--46.

**General Comments on the Advanced Notice of Proposed Rulemaking for Pb
NAAQS**

As our CASAC Lead Panel gathered in Washington DC on December 12 and 13,
2007 to meet and discuss our individual review comments on the Advanced
Notice of Proposed Rulemaking for the Pb NAAQS, once again we could not
help but wonder if the form and substance of the ANPR was in fact
intended to facilitate continuing delay and lack of timely action in
fulfilling the noble goal of "eliminating childhood lead poisoning \[in
the United States\]."

In this context, permit me to offer the following general comments on
the **ANPR for the Pb NAAQS** and its relationship to two other sources
of insight about the Pb NAAQS:

> **1) The detailed and firmly stated conclusions and recommendations
> with regard to both the Primary (public-health based) NAAQS for Lead
> and the Secondary (public-welfare based) NAAQS for Lead developed by
> the staff in EPA's Office of Air Quality Planning and Standards
> (OAQPS) in their *2007 EPA Staff Paper for the Pb NAAQS*, and**
>
> **2) The similarly detailed conclusions and recommendations prepared
> over the past two years by the CASAC Lead Panel and summarized in our
> two most recent letters to the Administrator of EPA (EPA-CASAC-07-003
> dated March 27, 2007 and EPA-CASAC-07-007 dated September 27, 2007)
> following careful Peer Reviews of earlier assessment documents on
> these same Primary and Secondary NAAQS for Lead.**

I agree with the general comments made during our CASAC meeting on
December 12 and 13 by essential all of my expert colleagues on our CASAC
Lead Panel. We all are greatly puzzled and disturbed about:

> 1\) The intent and purposes of these three separate sources of insight
> about the adequacy (or inadequacy) of the present identical Primary
> and Secondary NAAQS for lead, and possible changes in the indicator,
> level, statistic form, and averaging time of alternative NAAQS
> standards,

2)  Presentation in the ANPR of the carefully reasoned and very
    congruent science-based conclusions and recommendations of both
    OAQPS and CASAC -- as though both of these organizations were merely
    two additional "interested parties" in offering advice and counsel
    with regard to final decisions about the NAAQS for Pb and their
    important role in "eliminating childhood lead poisoning" and
    protecting ecosystems from further poisoning by both current
    atmospheric deposition and redistribution of historically deposited
    lead in the United States.

3)  What is expected to be gained from our CASAC Lead Panel Review of
    the ANPR on December 12 and 13 -- beyond what has already been
    communicated through CASAC's recent letters to the Administrator of
    EPA following careful Peer Reviews of earlier assessment documents
    on these same Primary and Secondary NAAQS for Lead.

4)  How the additional comments received from the CASAC Lead Panel after
    our meeting on December 12 and 13, the already finalized conclusions
    and recommendations in the OAQPS Staff Paper for Pb NAAQS, and the
    comments being solicited through the ANPR from other federal, state,
    and local government agencies, public interest groups, industry and
    trade associations, and individual citizen will be weighed,
    evaluated, and assessed during the final rule making process.

Joel Schwartz summarized our CASAC Lead Panel's collective puzzlements
very well when he wrote:

> "I agree with the comments of Paul Mushak that this document
> summarizes the risk assessment that OAQPS did, ... but then ignores
> the recommendations of OAQPS, ...and blithely asks for comments on a
> range of standards from zero to infinity. This is really not
> acceptable. The Clean Air Act requires the administrator to set
> standards for a pollutant that "may reasonably be anticipated to
> endanger public health," using criteria that "accurately reflect the
> latest scientific knowledge useful in indicating the kind and extent
> of all identifiable effects on public health and welfare which may be
> expected from the presence of a pollutant in ambient air...".
>
> "The range of possibilities proposed for comments ignores the comments
> of CASAC on what those effects are, at what levels, ignores the Staff
> Paper summary of those effects at different levels, and ignores the
> risk assessment."

**Comments on Replacement of the OAQPS Staff paper with a Policy
Assessment and Rulemaking document in the form of an Advanced Notice of
Proposed Rule Making**

In my opinion, the ANPR for lead is not consistent with the high
scientific principles outlined in Deputy Administrator Marcus Peacock's
original memo of December 7, 2006 (and repeated again in his follow-up
memo of April 17, 2007) where he outlined his high hopes and principled
aspirations for the new NAAQS review processes as follows:

> **"I believe these changes will help improve the efficiency of the
> NAAQS review process while ensuring that the Agency's decisions are
> informed by the best available science and broad participation among
> experts in the scientific community. These improvements will help the
> Agency meet the goal of reviewing each NAAQS on a 5-year cycle as
> required by the Clean Air Act without compromising the scientific
> integrity of the process. It is imperative that the NAAQS process
> continue to adhere to the highest scientific standards to ensure
> adequate protection of public health and welfare."**

As outlined below, the ANPR for Pb is not consistent with the Deputy
Administrator's hopes and written assertions about:

"... ensuring that the Agency's decisions are informed by the best
available science,"

"... broad participation among experts in the scientific community,"

"... without compromising the scientific integrity of the process," and

"It is imperative that the NAAQS process continue to adhere to the
highest scientific standards to ensure adequate protection of public
health and welfare."

The information contained in the ANPR for Pb is presented in two
distinctly different ways:

1)  Carefully reasoned analyses of scientific evidence and insights
    developed since the last review to indicate if the current
    public-health based and current public-welfare based NAAQS for lead
    are adequate, or if alternative levels, indicators, statistical
    forms, and averaging times are needed to protect public health with
    an adequate margin of safety and to protect public welfare.

> (These parts of the ANPR are consistent with the publicly available
> and well documented consensus findings and recommendations contained
> in the November 2007 OAQPS Staff Paper and in both the March 27, 2007
> and September 27, 2007 CASAC letters to the Administrator of EPA.)

2)  Much less carefully reasoned descriptions of uncertainties,
    alternative views, and/or possible alternative courses of action
    that might be considered by the Administrator of EPA in making his
    final court-ordered decisions about the current NAAQS for lead in
    September 2008.

> (These parts of the ANPR are not consistent with the publicly
> available consensus findings and recommendations contained in the
> November 2007 OAQPS Staff Paper and in the March 27, 2007 and
> September 27, 2007 CASAC letters to the Administrator of EPA and thus
> are not consistent with the high principles of scientific integrity
> outlined in the Deputy Administrator's memorandums of December 7, 2007
> and April 17, 2007.)

**Comments about My Specific Assignment**

As requested by our CASAC Chair, Dr. Rogene Henderson, my specific
comments about the ANPR are focused primarily on the six ***Areas in
Which EPA Solicits Comments*** with regard to the Secondary
(public-welfare based) NAAQS Standard for Pb.

As we all are aware, EPA promulgated the present identical Primary
(public-health based) and Secondary (public-welfare based) National
Ambient Air Quality Standards for Lead on October 5, 1978. These
standards were established at a level of 1.5 micrograms per cubic meter
of air, measured as Pb in total suspended particulate matter (Pb-TSP),
not to be exceeded by the arithmetic mean concentration averaged over a
calendar quarter.

The six ***Areas of EPA Solicitation*** deal with the following issues
related to the Secondary NAAQS standard for Pb. My comments are
presented in ordinary type (or in ***bold face* i*talic type*** in the
case of important quotations from published documents) after each of
these important Areas of Solicitation is presented in ordinary
**non-italic bold type**.

1)  **The questions of delisting and revocation.**

> These two questions have been very thoroughly considered and discussed
> by both CASAC in its March 2007 letter to Administrator Johnson and
> also by OAQPS staff in their November 2007 Staff Paper. In fact, the
> March 2007 CASAC letter contains a very detailed
>
> and carefully reasoned separate section titled "**Scientific Basis for
> Continuing or De-listing the Lead NAAQS."** This letter contains the
> following firmly stated overall conclusions regarding the questions of
> delisting and revocation:
>
> **"*The unanimous judgment of the CASAC Lead Panel is that lead should
> not be de-listed as a criteria air pollutant, as defined by the Clean
> Air Act, for which primary (public-health based) and secondary
> (public-welfare based) NAAQS are established, and that both the
> primary and secondary NAAQS air standards should be lowered
> substantially."***
>
> "***It is also recommended that future monitoring of lead exposure be
> conducted with low volume PM~10~ samplers rather than with total
> suspended particulate (TSP) samplers, and that the averaging time be
> decreased from seasonal to monthly."***
>
> ***"If lead were de-listed as a criteria air pollutant, would it be
> appropriately regulated under the Agency's Hazardous Air Pollutants
> (HAP) program? The answer is "No." The HAP program regulates according
> to use of maximum achievable control technology (MACT) and is
> appropriate for point sources. However, the most widespread source of
> airborne lead throughout the nation is the historically-deposited lead
> along roadways. Thus, this source of airborne lead could not be
> regulated under the HAP program."***
>
> ***"The large environmental burden of historically-deposited lead is
> currently decreasing. Accordingly, the goal should be to set the
> secondary Lead NAAQS such that there is no reversal of the current
> downward trend in lead concentrations in the environment. The limited
> funds available for monitoring environmental lead should be focused on
> this critical task."***
>
> Exactly these same questions of delisting and revocation also were
> very critically examined in the OAQPS November 2007 Staff Paper. The
> final carefully reasoned conclusions of EPA staff are also stated very
> clearly:
>
> ***"For reasons discussed above, staff concurs with CASAC with regard
> to consideration of Pb in the environment today and the adequacy of
> the current standard. Accordingly, we suggest that there is a need for
> the Administrator to consider a revision of the current standard to
> provide increased protection against reasonably anticipated adverse
> environmental effects."***
>
> ***"In conclusion, staff concludes that in the absence of information
> on which to base independent recommendations for the secondary
> standard consistent with a reduction in the level of the primary
> standard (Section 5.5.4) would provide increased protection against
> adverse environmental effects. Accordingly staff recommends that the
> Administrator consider a revised secondary standard set identical to
> the indicator, averaging time, form, and level of a revised primary
> standard."***

2)  **Whether the evidence suggests that adverse effects are occurring,
    particularly near point sources, under the current standard.**

> Here too both CASAC and OAQPS staff have thoroughly considered the
> question of whether adverse effects are occurring, particularly near
> point sources. Both organizations agree that although there are few if
> any catastrophic damages to aquatic or terrestrial ecosystems that can
> be unequivocally be attributed specifically to Pb pollution, as
> opposed to Pb acting in concert with other stress factors, the general
> conclusion from the available scientific evidence is that adverse
> effects are occurring, especially near point sources and that the
> current identical primary and secondary NAAQS for Pb need to be
> strengthen.

3)  **The role of deposition of Pb from current sources and the
    availability of this Pb to ecological receptors.**

> Most air emissions from current Pb sources are dispersed into the
> environment in the form of particulate matter that is transported over
> both short and long distances. Thus Pb particles are deposited onto
> the leaves, shoots, and stems of agricultural crops, forest and shade
> trees, and natural vegetation at low and high elevations throughout
> the United States as well as directly deposited onto soils and surface
> waters in natural and man-made lakes, streams, ponds, reservoirs, and
> estuaries throughout our country. From these initial deposition sites,
> Pb is generally absorbed, adsorbed, or chemically bound to organic
> matter from which it is only very slowly transported deeper into soil
> layers and eventually incorporated into sediments. Thus air emissions
> from current sources are readily available to a wide variety of
> ecological receptors that include all the living plants, domesticated
> and wild animals, and both beneficial and harmful insects and
> microorganisms as well as the physical components of both aquatic and
> terrestrial ecosystems.
>
> Both CASAC and OAQPS staff have summarized current scientific
> understanding of the role of atmospheric deposition of Pb from current
> sources and the availability of this Pb to ecological receptors and
> how this knowledge should be considered in relationship to the
> adequacy of the current secondary standard for Pb and needs for
> consideration of alternative indicator, averaging time, form, and
> level of a revised secondary standard.

4)  **The adequacy of the current standard and the rationale upon which
    such views are based.**

> Please note once again the firmly stated summary conclusions of both
> CASAC and OAQPS staff (see the discussion under Item 1 above) with
> regard to the adequacy of the current secondary NAAQS standard for Pb
> and the recommendation from both organizations that both the primary
> and secondary NAAQS air standards for Pb should be decreased
> substantially. The principal rationale for recommending that the
> secondary standard be set at least as low as the proposed primary
> standard is that:
>
> "***The large environmental burden of historically-deposited lead is
> currently decreasing. Accordingly, the goal should be to set the
> secondary Lead NAAQS such that there is no reversal of the current
> downward trend in lead concentrations in the environment."***

5)  **The option of a reduction in the secondary standard consistent
    with any reduction of the primary standard that would provide
    increased protection against adverse environmental effects.**

> As stated in the discussion under item 4 above, the principal
> rationale for recommending that the secondary standard be set at least
> as low and the proposed primary standard is that:
>
> "***The large environmental burden of historically-deposited lead is
> currently decreasing. Accordingly, the goal should be to set the
> secondary Lead NAAQS such that there is no reversal of the current
> downward trend in lead concentrations in the environment."***

6)  **Additional information pertaining to and comment on the
    considerations described above, as well as on other views with
    regard to the elements of a secondary standard for Pb, and the
    rationale upon which such views are based.**

> The ANPR, CASAC's March 27 and September 27, 2007 letters to
> Administrator Johnson, and the November 2007 OAQPS Staff paper on the
> NAAQS standards for Pb are essentially congruent in that all three
> documents summarize compelling scientific evidence that current
> atmospheric lead concentrations and deposition --- combined with a
> large reservoir of historically-deposited lead in soils, sediments and
> surface waters --- continue to cause adverse environmental effects in
> aquatic and/or terrestrial ecosystems, especially in the vicinity of
> large emission sources. These effects persist in some cases at
> locations where current airborne lead concentrations are below the
> levels of the current identical primary and secondary lead standards.
>
> **Thus, from an environmental perspective, there are convincing
> scientific reasons to both retain lead as a regulated criteria air
> pollutant and to lower the level of the current secondary standard.**
>
> Since concentrations of historically deposited lead in soils
> throughout the U.S. (averaging 0.5 to 4 g/m^2^ of land area) are
> changing only slowly --- with a half-life exceeding a century ---
> these concentrated deposits of lead are expected to remain accessible
> for exchange with the atmosphere and the rest of the biosphere into
> the foreseeable future. Fires, changes in land use, or climatic events
> such as regional dust storms could mobilize significant quantities of
> lead that would be harmful both to human health and ecosystems
> downwind. This potential for harm is not adequately recognized in the
> 1^st^ Draft Lead Staff Paper and the Draft Lead Exposure and Risk
> Assessments technical support document, but is a concern that warrants
> careful continued monitoring in the future.
>
> In addition, I recently reexamined the magnitude of the reservoir of
> "historically deposited lead" and found that \-- 0.5 to 4 grams per
> square meter of land area translates into 4.4-35.7 pounds of lead that
> is available for potential redistribution from every acre of land area
> in this country! This simple recalculation adds significance to the
> CASAC assertion in the March 2007 CASAC letter to Administrator
> Johnson that:
>
> ***"Fires, changes in land use, or climatic events such as regional
> dust storms could mobilize significant quantities of lead that would
> be harmful both to human health and ecosystems downwind."***
>
> Among these several potential causes of atmospheric redistribution of
> lead, wild fires in forest and grassland areas -- which are occurring
> with increasing frequency and intensity in recent decades in many
> parts of the US -- are potentially very important for both human
> health and ecosystem health and stability.

The EPA is also encouraged to identify the necessary funds to support
needed continuing research on the ecological effects of airborne lead
pollution and to consider developing alternative secondary standards
such as critical loads for lead, which may be different from primary
standards in indicator, averaging time, level or form.

Finally, although the ANPR, CASAC's March and September 2007 letters to
Administrator Johnson, and the November 2007 OAQPS Staff Paper for Pb do
not provide a clear quantitative basis for identifying a specific lower
level at which a more protective secondary Pb NAAQS should be set, there
are no reasons to expect that humans are uniquely sensitive to lead
pollution among the millions of plant, animal, insect, and
microorganisms with which we share our life on this planet.
***Therefore, at a minimum, the level of the secondary Pb NAAQS should
be at least as low as the lowest-recommended primary Pb standard.***

**Dr. James Crapo**

Review Comments: EPA's Advance Notice of Proposed Rulemaking for the
NAAQS for Lead

James D. Crapo, M.D.

Professor

National Jewish Medical and Research Center

Denver, CO 80206

The ANPR for the NAAQS for Lead as released by the EPA December 17, 2007
is a severe disappointment and raises substantial questions regarding
the viability of the revised NAAQS Review Process and the intent of the
Agency to used this process to appropriately meet the requirements of
the Clean Air Act. The ANPR for lead failed to meet the Agency's
obligation to consider the "best available science" and provide an
advance notice of, and rationale for, a justifiable range of standards
that the agency is considering for rule making.

The ANPR for Lead contained only a restatement of the Agency's Final
Lead Risk Assessment report and the Agency's Staff Paper along with the
statement that the Agency would consider all options for its eventual
rule making for this air criteria pollutant, including delisting lead.
This does not constitute an advance notice of the agency's assessment of
the science in this field and its thinking regarding how the NAAQS for
lead should be revised to conform to the requirements of the Clean Air
Act. One is left to assume that the Agency plans to make a closed door
decision on a final rule after the scientific and public review is
completed, thereby ignoring their responsibility to conduct this process
in a more open fashion and provide an advance notice of the agency's
assessment of the scientific and public policy issues that will frame
the final decision.

I would applaud the quality of the Agency's work on the Final Lead Risk
Assessment document and the Agency's Staff Paper on Lead. Both were well
done and correctly reflected the marked evolution of the science in the
field of lead toxicity. These documents correctly identified the
substantial adverse risk of even low levels of lead on neurocognitive
function in children and the obvious need for a marked tightening of the
current lead standards. The documents also identified the central role
that air lead plays in the movement of lead between environmental
reservoirs and the need to maintain a strict air quality standard for
lead as a central mechanism to control exposures of sensitive
populations (i.e., children). While the ANPR lists findings and
conclusions found in the Agency's Staff Paper, it does not provide any
insight into the Agency's assessment of these findings and conclusions.

The current review of the Lead NAAQS is the first time that the revised
NAAQS is being implemented. It is essential that this process be done
correctly in order to establish credibility for the Agency and for the
process it will use to meet its legal obligations under the Clean Air
Act. I would recommend that the Agency accept the failure of the current
Lead ANPR to meet even minimum expectations and to redo this document.
The revised document should consider the critical scientific and policy
issues and provide a range of standards that the Agency is actively
considering for the eventual rule. This range of standards should be
defended in the ANPR by showing that it can be supported by high quality
science and that it considers health risks to sensitive populations as
required by EPA's legislative mandate.

**Dr. Douglas Crawford-Brown**

**Comments on the Lead Human Exposure and Health Risk Assessments for
Selected Case Studies (ANPR), Volume I.**

Doug Crawford-Brown, December, 2007

This review focuses largely on Section III B of the ANPR document and
the associated Volume I and appendices.

**General Remarks**

I am generally supportive of the approach taken by the authors in this
assessment. The methodologies used are sophisticated and complex,
capturing the major issues associated with what is perhaps the most
difficult set of exposure pathways to model of any of the NAAQS due to
the wide range of sources of lead in the environment. Because of this
complexity, I support the idea of examining some selected case studies
rather than attempting to produce a distribution of risks in the entire
U.S. population, and I support the particular cases the authors have
selected. The cases cover a reasonable range of exposure scenarios and
include a significant number of people in the U.S.

I remain unclear as to how the results in the tables at the end of
Section III B -- the results concerning the NUMBER of people with a BLL
or an IQ loss -- are to be used by the Agency in making a final decision
on the NAAQS. I suppose the conclusion that can be drawn is that the
numbers of people affected are by no means insignificant (tending to be
in the hundreds of thousands), and that these numbers would be even
larger if the Agency were to perform the same kind of assessment over
the entire United States rather than just for the case studies. And
these numbers are presented in the context of other tables that report
the median and 95^th^ percentiles of the BLL and IQ loss, which provides
a range of considerations the Administrator might take into account in
making a final decision. I simply was struck by the lack of any clearly
stated decision criteria to be employed in interpreting the tables at
the end of Section 3 III, but can understand if those criteria are being
left to the discretion of the Administrator. As the tables stand, they
demonstrate that any decision will be made in the face of results that
show that the existing NAAQS is associated with significant IQ loss to a
significant number of people in urban areas and near smelters located in
diverse regions of the United States. It would improve the ANPR to show
not just numbers of people affected in the case studies, but the
fraction affected.

However, there is a problem I see in interpreting the results of the
tables at the end of this section. While the risks appear significant,
the large majority of those risks must be due to sources that are not
impacted by the NAAQS, or at least are not completely modeled in the
assessment. The tables show what I believe to be very small reductions
in the 95^th^ percentile IQ loss (or even median IQ loss) as the NAAQS
is progressively lowered all the way down to 0.02. There are two
possible interpretations of this result. The first is that a more
stringent NAAQS will have little impact on improving public health
because the large majority of the risk is coming from sources unaffected
by a NAAQS (an indication of the success the Agency has had with past
regulatory action). The other interpretation is that this finding is an
artifact of the current inability to fully model the effect of lowered
air concentrations on exposures through soil, indoor dust, etc. The
claim could be made that the differences in the results as the NAAQS are
lowered are significantly understated in the tables (i.e., that the
benefits of regulation are understated). Both interpretations have merit
here. The problem is that the latter one, the one that would support a
more stringent NAAQS for lead, can't be determined one way or the other
from the current assessment. I will say that the authors have done a
good job of pointing to this issue in the document, so it hasn't simply
been ignored. And I have no suggestions as to how the problem can be
removed; it seems to me inherent in the current limitations on the state
of the science in modeling non-air exposures resulting from past
releases.

On the issue of the various exposure-response functions, I can't support
the use of the stratified analysis with two separate slopes. I
understand the reasoning that there might be two mechanisms at play at
two different concentrations, but I just can't find any biological
justification for a discontinuous curve. And as the curves currently
stand, one is left with the odd situation (not called out in the text)
that there is an intermediate range of exposures surrounding the
cut-point where it looks as if a small increase in exposure leads to a
decrease in IQ loss. This is an artifact of having the two separate
slopes with no attempt to provide a single model over the entire range
of exposures. The issue is hidden in Figure 5-2 of Volume I by the fact
that the authors have chosen to force the two parts of the curve to meet
(in both the 7.5 and 10 µg/dL curves). But I am not sure that this is
how the modeling was done. Unless I am misreading that Volume, the C-R
function used in the modeling was actually a piece-wise model with an
IF-THEN-ELSE structure (IF BLL\<7.5, THEN slope = X, ELSE slope = y). So
there seems to me to be a disconnection between the computational form
of the model and the picture shown in Figure 5-2. But absent having the
code in front of me, I can't be sure this is the case. If it is, I
suggest de-emphasizing this approach. I also suggest that Tables 3 and 4
contain a footnote letting the reader know which models constitute the
Low and High C-R function estimate.

On a related note, I am supportive of the claims on pages 57 and 58 that
the models that have undergone the extensive development and statistical
diagnoses should have top priority in the assessment. At several points
in the ANPR, the authors then mention that the log-linear model form
should enjoy greater "confidence". I can't, however, see any place in
the assessment where the idea of "confidence" plays a role formally. And
this mention of increased confidence doesn't appear again in the tables.
So, I am not convinced that this claim will have any impact on
conclusions drawn by the reader or the Administrator. The authors might
consider some way to give this judgment of confidence more of a role in
interpreting the tables of results.

This assessment of IQ loss, and the claim that there is no threshold,
places the assessment more in line with probabilistic risk assessments
such as for cancer rather than in the older non-cancer, threshold,
assessments. In the case of regulating for reduction of cancer risk,
there is a need to specify an unacceptable level of risk, giving rise to
the "fuzzy bright line" concept that generally plays itself out as a
range of target values between 1E-6 and 1E-4. I kept wondering
throughout the ANPR what the analogue is for IQ loss. The tables present
estimates of the number of people with an IQ loss above 1 and an IQ loss
above 7, but I can't find a coherent explanation as to why these are the
relevant values defining anything like a "fuzzy bright line". I am not
saying they are the wrong values, I just don't understand the
implications of these values for anything like quality of life. In the
case of cancer risk, the Agency did a reasonable job of looking at
lifetime excess incidence of disease that is accepted in different
occupations, and used this as basis for establishing target levels of
risk to be deemed unacceptable. Something akin to that is needed here,
or at least will be needed when a numerical value for a NAAQS is
established and presented for public comment.

The authors have chosen, in my mind, the appropriate exposure measure
from the list of possibilities (concurrent, etc.). I doubt the results
would change significantly if the others were used, but it might improve
the document by at least including the results of sample calculations in
which the same case study is assessed through these 4 different measures
(or at least the two that Lanphear et al found most predictive). This
would help the reader see that the results are not extremely sensitive
to this choice.

I remain supportive of the proportional roll-up and roll-down approach
used in the assessment, although it will introduce errors due to the
fact that the impact of a revised NAAQS on non-air pathways is not being
modeled directly. But given this caveat, the roll-up and roll-down
procedures are the best available at the moment.

I also remain supportive of the post-processing approach to
incorporating inter-subject variability into the assessment. The choice
of a lognormal distribution is appropriate, as it agrees reasonably well
with existing data on variability of the biological parameters going
into the relationship between exposure and BLL. There remains some minor
concern that they are assuming that the "central tendency" values they
calculate are equal to the medians of a lognormal distribution, without
any evidence that they are in fact medians rather than means or just
some kind of "representative typical" value (as is often the case in
such regulatory assessments, typified by NATA). But that is a minor
quibble and in any event it is made routinely both in risk assessment in
general and in EPA assessments in particular.

On the issue of uncertainty, the authors have chosen not to employ a
formal statistical approach, and have instead provided results under a
range of different C-R models. I support this idea in principle, because
it would not be feasible at present to place such a complex
computational system into a full, nested, uncertainty-variability
framework. However, I think the uncertainties in characterizing
exposure, and in the exposure-to-BLL conversion, are at least as large
as those associated with the C-R functions. As a result, the document
should make it clear that the uncertainties described are a lower bound
estimate on uncertainties (and then make it clear that this uncertainty
can cut both ways).

On Page 73 of the ANPR, the authors note that the uncertainties and
limitations in the Secondary Lead Smelter case study are large. The
closing sentences in this bullet appear to suggest that this analysis
should not be used. Is that what the authors intend to convey?

Finally, I note that the authors have, for the most part, responded to
all of my concerns with the first draft assessment, and most of the
concerns raised in the CASAC review overall. There remain areas where
the science needs to be improved, especially with respect to non-air
exposure pathways that reflect "past" exposures, but the authors have
done what I believe is the best assessment possible given these current
limitations and complexities. I was especially pleased to see the
complete dropping of calculations at the 99.5^th^ percentile.

**Mr. Sean Hays**

Individual Review Comments

By: Sean M. Hays

Date: December 19, 2007

**[Comments on Final Lead Risk Assessment and EPA Staff
Paper]{.underline}**

I commend the EPA for providing the incremental changes in blood lead
levels associated with the various NAAQS scenarios. As I have commented
before, the incremental changes in blood lead levels are far more
certain and informative than the predicted absolute blood lead levels.
In my opinion, these incremental changes in blood lead (and thus IQ
decrements) between current levels and the various NAAQS options should
be relied upon for setting the NAAQS.

Providing the "roll-up" scenario is very helpful and informative for
NAAQS decision making. It is important to see what could happen if the
NAAQS is set at a level that allows for levels of air lead to increase
above those occurring today.

The final risk assessment notes many uncertainties associated with the
analyses. One major uncertainty that is not discussed well is related to
uncertainties associated with quantifying the types of exposures that
result in the higher (\> 3 - 5 µg/dL) PbB levels among children in the
United States. The current approach used in the Final Lead Risk
Assessment relies on using the Integrated Exposure Uptake Biokinetic
(IEUBK) model for lead in children to estimate the mean/median blood
lead levels associated with the various scenarios and then applying a
geometric standard deviation (GSD) to quantify plausible variability
associated with the distribution of PbB levels for a given exposure
scenario.

The Final Lead Risk Assessment notes on page 4-17 that "pathway
apportionment of blood Pb levels for higher population percentiles is
specified to be the same as that estimated using the central tendency
estimate of blood Pb in an exposure zone." In other words, if air lead
is thought to contribute ten percent (10%) of total lead exposures for
the central tendency of the U.S. population, this estimate is also used
for the higher population percentiles of PbB. Since the goal of any lead
risk assessment will be to reduce the blood lead for the higher
percentiles, knowledge of the exposure sources for these higher
percentile PbB levels and the potential to impact these exposures via
the Lead NAAQS is critically important. The current Final Lead Risk
Assessment does not provide any assessment or assurances that the
alternative NAAQS will impact the PbB levels among the upper percentiles
beyond those predicted for the mean/median percentiles. I still have
uncertainties about whether lowering the NAAQS below current exposure
levels will meaningfully impact the levels of lead in children who
already have blood lead levels above 5 µg/dL (the population of children
most at risk of developing neurological effects). Since it appears there
are no data to fill this gap, this issue should be identified and
highlighted as a data gap and research need.

The other major uncertainty that exists is the shape of the
dose-response curve for children with blood lead levels below
approximately 5 µg/dL. The EPA has provided a range of slopes (both
linear and non-linear) to help bound the variability or uncertainty in
the dose-response relationship relating children's concurrent blood lead
levels with IQ decrements. I agree with the use of the various models as
it is unclear which model provides the best fit (since EPA was unable to
independently validate the model fits to the data from the Pooled
International Analysis).

**[Comments on ANPR]{.underline}**

Not having expertise in the policy aspect of setting the NAAQS, I find
it difficult to comment on the ANPR as a tool for setting the ANPR.
However, I find the ANPR to read somewhat of a two-handed report. One
the one hand it carefully summarizes the EPA final risk assessment and
staff paper, and then on the other hand it offers other alternatives and
discussions of science that were already passed off as not being
supported or supportable by the science as deemed by the risk
assessment, staff paper, and opinions of the CASAC. In addition, when
discussing the various options, the ANPR fully characterizes the
uncertainties noted by EPA and CASAC for the various issues with the
risk assessment, but does not fully characterize the uncertainties with
the new options being offered in the ANPR which were eliminated from
consideration by EPA and CASAC. It is unclear how expanding the universe
of options and interpretations at this late in the process helps to
advance the policy options for setting the NAAQS.

Other specific comments include:

-   On page 118 of the ANPR, it is stated that CASAC recommended 1.0 --
    1.4 µg/dL or lower to be considered as an estimate of the non-air
    component of blood Pb. I do not agree with this estimate nor do I
    understand the basis for such an estimate. This estimate may be fine
    for the median child, however it may grossly underestimate the
    non-air contribution among children with much higher blood lead
    levels. This distinction needs to be made clear.

-   On page 65 of the ANPR, it is stated that "inclusion of indoor lead
    Pb as a component of "other" indoor air (and consequently as a
    component of "past air" exposure) represents a source of potential
    high bias in our prediction of total exposure and risk associated
    with past air because conceptually, exposure to indoor paint Pb is
    considered part of background exposure." I agree this biases the
    "past air" contribution to total Pb exposure. Pb from paint should
    not be attributed to "past air".

-   On page 67 it is stated that a "probabilistic exposure model" was
    used to generate distributions of blood lead concentrations for the
    various scenarios. The Agency should be careful not to characterize
    what they did as a probabilistic effort. Use of a GSD on top of
    estimates of the mean does not constitute a probabilistic effort.

**Dr. Donna Kenski**

Comments on the NAAQS for Pb ANPR

Donna Kenski

December 11, 2007

As a new member of CASAC, I came to this panel very late in the process
of reviewing the Pb standard. My *a priori* view was that we'd made
wonderful progress in controlling lead and that maybe it was time to
retire the standard, since EPA's direction to the states has been to
retire the monitors. The Staff Paper quickly set me straight. The new
health effects data reviewed in that document make an absolutely
convincing case that the standard must significantly lowered from the
current level in order to protect at-risk populations. The ANPR,
however, failed to convey the tone of the staff paper and also failed to
present any concrete options or preferences on EPA's part for the
direction of the rulemaking with respect to anticipated level or
averaging time. It seems to have summarized most of the science and data
analysis of the staff paper but failed to include the logical
conclusions that were, for the most part, presented there. Instead, it
asks CASAC again for its opinions on issues we have already weighed in
on. Consequently, my responses to the specific solicitations for comment
below reiterate some of the advice that panel members have discussed and
documented in their deliberations and letters to the Administrator
(e.g., Henderson, Sept. 2007).

**Monitoring considerations**:

**On the issue of variability of collection efficiency of the
high-volume TSP sampler**: The ANPR and the staff paper fail to make a
compelling case for continuing to use the high-volume TSP sampler as the
FRM. In light of the clearly established need to lower the level of the
standard and make more frequent measurements at additional sites, EPA
should take this opportunity to make low-volume PM10 sampling on Teflon
filters the new FRM. It offers significant improvements in precision,
allows for sequential sampling, allows for analyses of multiple species,
and makes it possible to integrate Pb measurements made in existing
networks that are already making PM10 metal measurements like NATTS and
IMPROVE (not all of these PM10 measurements are currently low volume).

The Staff Paper and the Cavender/Schmidt memo made it clear that PM10
and TSP lead are generally highly correlated. The instances where they
were not well correlated is most likely due to the inefficient and
variable collection of large particles by the TSP sampler. Some of these
poorer relationships were based on a small number of data points, many
at concentrations close to the detection limit for the TSP FRM. The
range of proposed levels (0.02 to 0.5 µg/m^3^) is sufficiently broad
that the selection of PM10 vs. TSP FRM has a minor impact in comparison.
The average Pb-PM10/Pb-TSP ratio was 0.8, with all sites examined being
above 0.6. So a level of 0.03 for PM10 would be as protective as a level
of 0.05 for TSP at most sites. The sensible approach would be to choose
a more conservative (lower) level of the standard and use a method to
monitor that, while collecting slightly less Pb mass, offers significant
monitoring advantages and makes it possible to collect the additional
high-quality data necessary to make stronger assessments of Pb impacts
on public health. The very large particles that will be missed by the
PM10 are the same ones collected with the least reliability by the TSP
method.

**Retain TSP or require around large sources?** As stated above, I think
retaining TSP is unnecessary because a PM10 indicator could be
sufficiently protective, based on the data presented in the Staff Paper
and Cavender memo, and offers numerous advantages. That said, I like the
idea of continuing to collect TSP (although a low-volume method would be
preferable) in a few places, including around large sources, because
there is much value in collocated measurements of the various size
fractions. Multiple size fractions can give us a better understanding of
exposures, of lead's movement from a source through the environment, and
the influences of various source types and meteorological conditions on
the distribution and deposition of lead. More important than what kind
of monitoring is a requirement for any monitoring---PM10 or TSP---around
large sources (but see comments on network below).

**Appropriateness of using Pb-PM10 data as a surrogate for Pb-TSP:** As
noted above, I think low volume PM10 would be the appropriate indicator,
not TSP. Making PM10 a surrogate for TSP is merely trying to make a more
precise and well-defined measurement match a less precise and poorly
defined measurement, which is the wrong approach.

**Appropriate range of concentrations for an FEM demonstration:**
Clearly FEM demonstrations should be made across a range of
concentrations that represent real-world conditions. Presuming a switch
from TSP to PM10, a range of 0.01 µg/m^3^ to 0.2 µg/m^3^ should cover
current ambient Pb-PM10 concentrations.

**Adequacy of current lab analysis methods for use at alternative NAAQS
levels considered in Staff Paper:** A lower level of the standard,
preferably one with an accompanying PM10 indicator, should be supported
with a change in lab analysis method, or a requirement for a minimum
detection limit that permits concentrations at typical ambient levels to
be accurately quantified. At current ambient Pb-TSP or Pb-PM10 levels, a
detection limit of 0.01 µg/m^3^ is too high. As noted in Sec. 2.3.2.5 of
the Staff Paper, 57 of 129 non-source-oriented monitors reported more
than 50% of their raw data below the MDL. In order to support future
reviews of the NAAQS and assess exposures to Pb, the monitoring network
must do a better job characterizing these low concentrations. A method
like ICP/MS has a detection limit that is sufficiently low and permits
the quantitation of multiple metal species on the filter, another
consideration that should be weighed in determining the appropriate
choice of indicator and FRM.

**Adequacy of current Pb-TSP network and need for additional sites to
determine compliance with current or revised Pb NAAQS**: Serious
deficiencies in the monitoring network must be addressed. The fact that
only 2 of the 27 largest Pb point sources have a monitor within 1 mile
is appalling. Two of the sources on the list of 27 reside in a state
with no Pb monitors at all. How can this be??? By allowing the nation's
lead monitoring network to be dismantled, EPA has made a grave error in
judgment. The new standard could address this in part by requiring
monitoring around point sources (can this be made a condition of
operating permits?) EPA could conduct the necessary analyses to
determine what facility size or emission rate would require monitoring
and how far from the fenceline is acceptable. Expanded monitoring for
population exposure and to support future health risk assessments is
also necessary. EPA's goals for monitoring are much broader than merely
NAAQS determination. As stated in the recent PM Draft Integrated Review
Plan, "monitoring networks provide data that serve a wide variety of
purposes as part of an iterative process in managing air quality. These
include: (1) determining compliance with the NAAQS; (2) characterizing
air quality status; (3) supporting air quality analyses used to conduct
assessments of exposure, health risks, and welfare effects; (4)
developing and evaluating emissions control strategies; and (5)
measuring overall progress for the air pollution control program." All
of these are necessary goals that need to be accommodated so that we
don't go through another NAAQS review with wholly inadequate data.

But expanded monitoring has to be funded, and hopefully not at the
expense of other monitoring programs. Yet another reason for moving to
PM10, which would allow the NATTS monitors to take up some of the
burden. In pondering the question of where to monitor for lead under a
new NAAQS, I find that the issue of network design is more complicated
than can be addressed adequately here. It deserves a much more thorough
analysis and careful deliberation that could appropriately be assigned
to the CASAC Ambient Air Monitoring and Methods Subcommittee, as Rich
Poirot has suggested. Hasty decisions are likely to be regretted.

**Options for improving the coverage of the Pb network**: As noted
above, there are many, many options, and the design of an adequate
network that would provide sufficient information to support NAAQS
determinations and also support exposure and risk assessments for the
next review needs more attention than I can address here. To do this
properly requires careful analysis. Of the options laid out in the ANPR,
none are wholly satisfactory. Some combination of source monitors,
population monitors, and rural monitors is needed, and taking advantage
of the existing PM10 network would be great, although most are not
low-volume samplers.

**Appropriateness of sampling options and suggestions for others:** The
concept of a sampling frequency that increases as concentrations
approach the NAAQS is clever. It reduces the sampling burden (and
expense) where concentrations are low, and assures that as
concentrations approach levels of concern, we collect enough data to
assess concentrations accurately. I like this option best. Multi-day
samples (48-hr, 72-hr) and composited samples are satisfactory for
assessing attainment but less so for supporting other potential uses of
the data.

**Conventions for interpreting NAAQS:** The proposed conventions are
fine.

**Value and appropriateness of use of IMPROVE Pb-PM2.5 data for
assessing trends:** Yes, it is a great idea to analyze some of the
IMPROVE PM10 filters for Pb (and other metals at the same time).
Adopting a PM10 indicator makes this a no-brainer.

**Reference:** Henderson, R. (Sept. 27, 2007) Letter from Dr. Rogene
Henderson, Chair, Clean Air Scientific Advisory Committee, to
Administrator Stephen L. Johnson. Re: CASAC Review of the 2^nd^ Draft
Lead Human Exposure and Health Risk Assessments.

**Dr. Bruce Lanphear**

Comments on ANPR

Clean Air Scientific Advisory Committee December 12^th^-13^th^, 2007

The general tone of ANPR is one of complete disregard for the CASAC
Panel recommendations and a failure to provide any margin of safety. The
fact that "EPA is seeking comment and supporting information about
whether it would be appropriate to determine that Pb emissions no longer
contribute to air pollution that may reasonably be anticipated to
endanger public health or the extent to which reductions in the ambient
air Pb standard would benefit public health" at this late stage (page
114), makes me wonder why the CASAC Panel has been meeting for the past
two years and providing advise to US EPA Administrator Johnson.

The ANPR also raises other fundamental issues about low-level lead
toxicity that have largely been resolved. For example, the fact that the
ANPR is soliciting comments on the appropriateness of using a mean or
individual target blood lead value 10 μg/dL as the foundation for
deriving a level for the primary lead standard (see page 148) is
troubling and misguided for a federal agency that purports to protect
the publics' health using most recent and relevant scientific evidence.
The CDC clearly recognizes that the 10 μg/dL is an action level that is
triggered for an individual child at the same time they clearly
recognize that there is no evidence of a threshold for the adverse
effects of lead on children's intellectual ability.

The ANPR consistently recommends alternatives that underestimate the
effect of lead or the benefit of reducing air lead standards, thus
failing to provide any margin of safety.

-   Consistent with the 1978 NAAQS, the CASAC Lead Review Panel
    considers that the primary lead standard should be set so as to
    protect 99.5% of the population from exceeding substantive IQ loss
    (\~1-2 IQ points). Due to uncertainties in estimating the 99.5% of
    the populations, the 95^th^ percentile is reported as the estimate
    of the high end of the distribution (page 122). While it may not be
    possible to estimate the 99.5%, relying on the 95^th^ percentile to
    make decisions about the lead standard will inevitably fail to
    protect 99.5% of the population.

-   The ANPR ignored emerging but consistent research indicating that
    sub-populations of children with various polymorphisms (e.g., DRD4
    7-repeat) are more susceptible to lead toxicity than children
    without the DRD4 7-repeat (Froehlich, 2007).

-   Using a ratio of 1:5 rather than 1:10 for air lead

-   Use of the log-linear with linear extrapolation at 1 μg/dL rather
    than the two-piece linear estimate recommended by CASAC Panel. The
    ANPR argued, on the one hand, that there were two few children to
    extrapolate below 7.5 μg/dL. On the other hand, they argued that it
    wasn't reasonable to see such a dramatic decrement in IQ scores at
    the lowest levels of exposure e.g., \< 1 μg/dL. A more logical
    choice would have been to use the two-piece linear below 7.5 μg/dL
    because the linear extrapolation was based on actual data. Moreover,
    as described below, there are other studies with over 200 children
    having blood lead levels \< 5 μg/dL that confirm the non-linear
    relationship (Tellez-Rojo 2006).

Page 58: The ANPR was concerned that the relatively few children who had
peak blood lead levels less than 7.5 μg/dL (n=103). Still, other studies
corroborated the results of the pooled analysis (see, for example,
Tellez-Rojo 2006). Moreover, a host of other studies confirm that the
relationship at lower blood lead levels is non-linear (Lanphear, 2000;
Canfield, 2003; Wasserman, 2003; Schnaas, 2006; Kordas, 2006). Thus, we
have considerable confidence that lead exposure is associated with
adverse effects at the lowest measurable levels of lead in blood; the
only question is the size of the effect.

While the effect for each of these decisions in isolation would not
result in a large difference in the estimated IQ reduction or the
predicted benefit of alternatives NAAQS for Pb, it is troubling that the
cumulative effect of the decisions described in the ANPR fail to provide
a margin of safety.

On page 79, there is discussion about significant uncertainty at lower
blood lead levels (e.g., below 5 μg/dL) for concurrent blood lead
levels. The uncertainty is not whether there are effects below 5 μg/dL
or that there is an inverse association of lead with IQ, but the size of
the effect. Although it is reasonable to be concerned that the
low-linear model may not be ideal at the lowest levels of exposure, the
two-piece linear estimate \< 7.5 μg/dL serves as a reasonable estimate
that provides a built-in margin of safety that is otherwise ignored in
the ANPR.

It is important to consider differing opinions, but it is questionable
to treat the opinions of a commentator that has a clear conflict of
interest (e.g., the National Association for Battery Recycling) as
equivalent to the recommendations of the CASAC Panel. In several places
in the ANPR, it notes that there are differing opinions and that the
dramatic reductions in air lead raise questions about whether it is
still appropriate to maintain a NAAQS for lead or retain lead as a
criteria pollutant. If these differing (and conflicted) views are
treated as equal with the CASAC Panel, it undermines the Federal
Advisory Committee Act that restricts members who have conflicts of
interests from serving on the CASAC Panel (see, for example, p. 111, 129
and 131).

I was struck by the US EPA's recognition that there are important
limitations in the design of, and data and methods employed in, the
exposure and risk analyses in a passive voice. To be completely candid
with the public, it might have read, "EPA recognizes that it has failed
to generate studies and monitoring data to ensure that the public is
protected against lead toxicity."

Page 146: I was struck by the comment that there is "increasing
uncertainty with regard to the magnitude and type of effects at levels
below 5 μg/dL". This makes it sound like, despite considerable evidence
about adverse effects below 5 μg/dL, we know less and less about the
effects below 5 μg/dL. Or, if we only did less research there would be
less uncertainly about the magnitude and type of effect at blood lead
levels bellow 5 μg/dL. The evidence is quite clear that there is no
apparent threshold; that is certain. It is also quite clear that the
effects appear to be greater for a given increment in exposure at the
lower levels of exposure.

**Number range CHAPTERDr. Paul Mushak**

**PRE-MEETING COMMENTS: THE USEPA PB NAAQS ADVANCE NOTICE OF PROPOSED
RULEMAKING (ANPR)**

CASAC Pb NAAQS Panel Member: Paul Mushak, Ph.D.

December 8, 2007

My comments, per the request to the Panel from Chairperson Dr.
Henderson, deal with the ANPR exclusively. Per Dr. Henderson's lead
discussant assignments, I focus comments on Section III, The Primary
Standard, and particularly on Section III.C of the ANPR, *Considerations
in Review of the Standard.*

**I. GENERAL AND SECTIONAL COMMENTS**

A review of the ANPR and an accompanying "Fact Sheet" allows a number of
conclusions, notwithstanding the review being limited by the time
constraints posed by late release of the ANPR relative to the CASAC
12/12-13/07 meeting in Washington.

The ANPR represents an impressive effort on the part of multiple groups.
I do have a number of comments about the document's potential for
causing confusion, however. First, the ANPR is not the notice of
proposed rulemaking but many in the public may not get the distinction
from proposed rulemaking. It is, rather, a multi-part invitation to the
regulatory dance for ambient air Pb standard review. The invitation, I
fear, is organized in a way that will appear quite confusing to
stakeholders, the general public, the media, and those in the scientific
community not directly involved in the Pb NAAQS review over the past
several years.

The ANPR proposes no specific air Pb NAAQS or range of NAAQS for
Administrator selection. The section on the Primary Standard
considerations, including policy options, Sec. III.C, says a
considerable amount about where the overall process is, i.e., OAQPS
exposure/risk assessments and CASAC Panel recommendations, but says
nothing explicit that prioritizes the thinking of the Agency about what
NAAQS selection options are really in the running. It only says where
things might go in a proposed rulemaking of a NAAQS.

Specifically, while ANPR made good use of the OAQPS Exposure/Risk
Assessments and Staff Paper analysis, this document did not pay
appropriate attention to the Staff Paper's sets of conclusions and
recommendations. The ANPR document simply indicated it was taking note
of the OAQPS conclusions and recommendations. It did so by burying the
reference to it in the document. Reviewers or other readers can
rightfully ask "How many EPAs are there?" One has produced a full Staff
Paper with recommendations for NAAQS selection, while the other has
seemingly relegated the OAQPS full Staff Paper to the status of some
sort of submission from an interested party.

The ANPR requests comment on a document which structurally resembles no
regulatory creation ever seen before and a structure that likely will
not appear as such again. The document's contents embody the transition
from the conventional review process with its production of Staff Papers
and CASAC Panel peer reviews to ANPRs which cut out the Staff Paper and
attenuate the traditional role of CASAC Panels for criteria pollutants
mandated by statute. Consequently, this Pb ANPR invites comments at a
seeming preliminary level on something which has already matured to a
Staff Paper and almost two years of CASAC Pb NAAQS Panel review
submissions to the Administrator.

I assume it was the call of EPA's policy office to continue with a Pb
NAAQS ANPR alongside a full Staff Paper mandated by court order rather
than opting for the ordered Staff Paper and leaving the maiden voyage of
the ANPR approach to some other criteria pollutant that has no court
challenge and no deadline date certain. Having issued both a Staff Paper
and an ANPR, the Agency has two products which basically use the same
information. The Agency is stitching an extra toe (ANPR) to an intact
and fully functional foot (OAQPS Staff Paper and multiple CASAC Panel
reviews).

The health, scientific and broader public, not to mention the various
stakeholders, will find it difficult to reconcile a preliminary ANPR
that only invites comment on Agency work and findings so far with a
final Staff Paper that says here are our NAAQS conclusions,
recommendations, and options for air lead based on (1) OAQPS' extensive
scientific and policy considerations and (2) the serial recommendations
from extensive peer review by the principal reviewers, the CASAC Pb
NAAQS Panel.

A critical concern is how an ANPR, however well done, would play out in
the overall NAAQS decision-making process when it comes time to propose
a Pb NAAQS or a range of NAAQS.

> --- In the present case, we have an ANPR whose extensive and
> reasonably well-prepared sections are such because they directly
> benefited from the work done by others via the Staff Paper and the
> CASAC Panel reviews.
>
> --- To what extent does that continue in the lead standard case after
> solicited comments via ANPR are received and assimilated?

--- How much relative weight will be given to the Staff Paper's and
CASAC Panel's recommendations versus recommendations of non-Agency or
non-CASAC Panel parties? The ANPR does note that those submitting
comments will presumably have to provide a credible basis for their
comments. Is it not appropriate for EPA to spell out clear criteria for
scientific support needed for outside parties in offering their comments
so they can be ranked with the scientific database being used in the
Agency efforts so far?

> --- In future criteria pollutant regulatory rule making, will the
> associated ANPRs be as comprehensive and transparent as this one for
> Pb?

**II. SPECIFIC COMMENTS ON THE ANPR DOCUMENT**

The invitations for comment in the ANPR do so with an odd, repetitive
semantic style of "Some might conclude\..." "Some might not
conclude\...," etc. This is a rather unusual style in my experience with
these matters, whatever the novelty of the ANPR approach in transition
from the classical methodologies for criteria pollutants. The style
presents no ranking or weighting to be accorded input on the basis of
expertise, freedom from bias or official roles in the NAAQS review
process. It may be true that "Some may say A, while some may say B," but
B may be totally incorrect owing to lack of expertise, absence of
arms-length exercise of judgments, existence of an agenda, or all three.

Nowhere in Sec. III.C do I find a coherent tabular compilation, with
associated contexts, rationales and evidence, that lays out even a broad
range of those Pb NAAQS offered in the final Staff Paper and the two
CASAC Panel's Letters to the Administrator. Such one-stop reading would
help clarify things immensely. These options on the basis of policy or
whatever should not be scattered and buried in the dense text. The
reviewer or any other interested reader will not harvest a clue, from
the present language, about what EPA will eventually consider seriously
*even within an extreme range of options.* They may de-list; then again,
they may not. They may keep the obsolete current standard; then again,
they may not. They may adopt a fully protective stance with regard to IQ
loss; then again, they may not. And so forth down the line.

As noted already, a significant part of the ANPR draws heavily from,
repeats, or summarizes information in the OAQPS Risk Assessments, the
OAQPS Staff Paper and the several CASAC Panel Administrator Letters and
attachments therein. These documents and the dependency on them in the
ANPR would serve, collectively, to anticipate a strong argument
presented in the policy part of Section III.C for (1) retaining Pb as a
criteria pollutant and (2) lowering the Pb NAAQS substantially below the
current value.

This has not occurred in Sec. III.C. There is a serious disconnect
between the new evidence and its assessments and the relative treatment
in Sec. III.C of the various options for the NAAQS. Sec. III.C conveys
no real comparative assessment of alternative NAAQS values in terms of
where the established and vetted scientific evidence should take the
ANPR's thinking. For example, Sec. III.C leaves open the option of
delisting and, barring delisting, keeping the present air lead standard
at 1.5 g/m^3^ averaged quarterly.

Within the ANPR are several items on which I provide more detailed
comment below.

**A. Potential U.S. Child Health Consequences of Retaining the Current
Air Pb Standard**

Retention of the current air Pb NAAQS as one of EPA's eventual proposed
options for action in this preliminary ANPR obliges EPA to consider the
consequences to child health. The data are available to do so.

The CASAC Pb NAAQS Panel has already presented its conclusions in its
Administrator Letters about the issues of delisting Pb as a criteria
pollutant and the arguments for promulgating a NAAQS much lower than the
current one. I will quantify some of the concerns here.

I am particularly concerned about the ANPR not ruling out an eventual
NPR setting forth a rationale for keeping the current air Pb standard of
1.5 g/m^3^. EPA has attempted to model through "proportional roll-up"
methods the simulated consequences of air lead at the current NAAQS with
respect to fractional distributions of impacts. I agree with OAQPS' Risk
Assessment effort that there is considerable uncertainty associated with
this. I do not agree that it is highly unlikely that general, ambient
urban air Pb values will ever re-attain levels near or at the current
standard since achievement of such high levels would derive from point
sources.

A better approach is a revisiting of the historical record. In this, I
follow up and elaborate on Dr. Joel Schwartz's earlier meeting comments
about the nature and extent of toxic lead exposures in U.S. children in
earlier years. The Pb exposure record of past decades shows retaining
the current standard would be potentially catastrophic to the
environmental and developmental health of young U.S. children and the
health of other national risk groups.

> --- Setting standards for toxics such as lead in air cannot be based
> on what a particular national, regional, or stratified expression of
> that substance's level in the environment happens to be at some
> isolated time, nor on simulations of hypothetical returns to some
> previously high value. The process hinges on the full regulatory and
> public health record for that substance. All Federal agencies
> entrusted with regulating toxic substances via diverse statutes have
> adhered to this prescriptive dictum. Besides EPA, these include the
> FDA, HUD, and the USDA.
>
> --- Specifically, current air Pb levels in the U.S. cannot be taken as
> a permanent environmental feature of U.S. air quality. They are simply
> a reflection of the present processes for lead's entry or reentry into
> the ambient atmosphere. As such, they are subject to abrupt changes in
> U.S. technological and/or industrial activity using lead. I do not
> agree with the ANPR's assumption that return to past air Pb levels
> would be highly unlikely. We should be mindful that discussions of
> lead control in the 1920s, such as they were, did not anticipate the
> enormous adverse child health consequences of the introduction of
> leaded gasoline in the U.S.
>
> --- Re-promulgation of the current primary air Pb standard or
> promulgation of an even weaker one would simply mean there is no
> *de-facto* regulatory barrier to the introduction or re-introduction
> of lead sources and ambient atmospheric emissions that would expose
> millions of American children to lead at toxic levels, as happened in
> the 1970s.
>
> --- Alternative regulation of air Pb as a hazardous air pollutant
> under Sec. 112 of the CAA would not be as effective for control as a
> criteria pollutant process. The CASAC Panel put forth reasons for this
> and made this explicitly clear in past communications to EPA.

--- In the late 1970s, the nationwide U.S. air Pb values (as maximum
quarterly averages) for the years 1978 and 1979 were around or even
below the current air Pb standard, 1.5 g/m^3^. The national values were
1.67 and 1.36 g/m^3^ respectively (see, e.g., USEPA, 1994).

> --- In the period 1976-1980, corresponding to the above air Pb values,
> the NHANES II survey (Annest and Mahaffey/USDHHS, 1984, Table 4; US
> EPA, 1986 Criteria Document, Ch. 11, Table 11-2, Mahaffey et al.,
> 1982) showed that:
>
> --- The arithmetic and geometric means of blood lead (Pb-B) for U.S.
> children 6 mos. to 5 years of age were 16.0 and 14.9 g/dl in the
> 1976-1980 time respectively. The great majority, 87.8%, of children in
> this age band at that time had Pb-Bs of 10 g/dl or higher. The tally
> of U.S. children in this age band was 17 million (rounding), meaning
> 15 million children had Pb-Bs at or above this value. A significant
> fraction of these children, 20.5%, had Pb-Bs at or above 20 g/dl, or
> a total of 3,500,000 children (rounding).
>
> --- The arithmetic and geometric means for black children 6 mos.-5
> years of age were 20.9 and 19.6 g/dl, respectively, while this age
> block of white children showed 14.9 and 14.0 g/dl, respectively.
> Virtually all U.S. black children (97.5%) had Pb-Bs at or above 10
> g/dl, while the corresponding percentage figure for white children
> was 85.5%. The tally of black children in this age band was 2,600,000
> (rounding), meaning over 2,500,000 black children had Pb-Bs at or
> above this value.
>
> --- For a total of 13,600,000 white children (rounding), 11,600,000 of
> these had Pb-B at 10 g/dl or higher. A majority of black children,
> 51.1%, had Pb-Bs 20 g/dl or higher. With a total base of 2,600,000,
> 1,340,000 black children had a Pb-B of 20 units or higher. White
> children had lower prevalence, 18.1%, of Pb-B 20 g/dl or higher, but
> the much greater population base meant higher tallies at 20 g/dl and
> higher, i.e., 2,460,000 (rounding) white children.
>
> --- The major source of the above-described greatly elevated Pb-B
> values was direct and indirect air Pb exposures, the latter as dusts
> and fallout onto soils. We know this from the quantitative features of
> time trend correlational analyses of ambient air Pb and declines in
> Pb-B.

[Illustrative Refs for 1970s Pb Exposures:]{.underline}

Annest JL, Mahaffey K. 1984. Blood lead levels for persons ages 6
months-74 years: United States, 1976-1980. Hyattsville MD: National
Center for Health Statistics, U.S. Department of Health and Human
Services. Series 11, No. 233.

> Mahaffey KR, Annest JL, Roberts J, Murphy RS. 1982. National estimates
> of blood lead levels: United States, 1976-1980: association with
> selected demographic and socioeconomic factors. N. Engl. J. Med. 307:
> 573-579.
>
> U.S. EPA. 1986. Air Quality Criteria for Lead, 4 Vols. EPA
> 600/8-83/028bF. Research Triangle Park, NC: Environmental Protection
> Agency, Ch. 11, Vol. III.
>
> U.S. EPA. 1994. National Air Quality and Emissions Trend Report, 1994.
> Report No. EPA 454/R-95-014. OAQPS, RTP, NC. Appendix Table A-9.

**B. Gaps in Regulatory Policy Options in ANPR Sec. III.C.**

The ANPR accepts that there is no documented "safe" level for lead
exposures indexed as Pb-B in children. It accepts, as do virtually all
other expert consensus public documents on the topic, the huge database
for human populations showing lead is a non-threshold toxicant in
children. Characterization of lead as a non-threshold toxicant has
obvious regulatory policy implications for its control.

> --- The ANPR does not go the next obvious step and discuss the
> question of whether lead needs to be regulated the way EPA regulates
> other non-threshold toxicants, for example, the toxicants classified
> as likely or established human carcinogens. I am not saying that lead
> bears toxicological and mechanistic analogy with human carcinogens,
> only analogy with this class of toxicants in terms of the clear need
> for harmonization of regulatory rationales and methodologies for all
> non-threshold toxicants.
>
> --- EPA may in fact take the view that lead is theoretically a
> threshold toxicant but that threshold has not yet been revealed.
> However, the issue remains: if lead is a threshold toxicant it has an
> extremely small window in which to exhibit this characteristic. The
> window is now so small that the potential range for a claimed
> threshold becomes a dose-response distinction without a toxicological
> difference from non-threshold toxicants.
>
> --- Regulation of lead in air or elsewhere as a non-threshold toxicant
> retains in a more stringent way the suite of policy questions of what
> non-threshold toxic endpoint and its numerical value are to be
> determinative for control and at what risk management level, i.e.,
> what frequency of toxic occurrence within a risk group is to be
> acceptable.
>
> --- The upshot of the above that the nature of lead as a non-threshold
> toxicant clearly requires that any selected air Pb NAAQS be as low as
> possible.

**C. Use of CDC Statements in the ANPR**

The various CDC Statements on childhood lead poisoning appear to occupy
a central position in the general thinking in the ANPR, but EPA's grasp
of these Statements appears to be tenuous at best. It is necessary to
put CDC Statements in context in terms of their scope and purposes for
use by regulatory agencies for lead control and to avoid misuse.

CDC Statements, contrary to implied or expressed interpretations and
roles given them in the ANPR, were and remain highly flexible
prescriptive instruments for addressing the problem of childhood lead
poisoning in the U.S. and elsewhere. Every incarnation and iteration of
the CDC Statements has made two characterizations of the Statements
explicit. First, there was and is every expectation that the nature and
advisory utility of the Statements would change as the science changed.
For example, the CDC April, 1978 Statement, which was used in the
derivation of the 1978 and current NAAQS primary standard of 1.5 g/dl,
stated that (p. 1, Introduction):

> "The CDC recognizes that there will doubtless be further development
> in this field which may alter or redefine our current understanding."

The 1985 Statement (p. 1, Introduction) noted:

> "The revised recommendations in this 1985 Statement reflect current
> knowledge concerning screening, diagnosis, treatment, follow up, and
> environmental intervention for children with elevated blood lead
> levels."

The second aspect of all Statements, including the 2007 version, was the
use of the Statements to eventually effect primary lead poisoning
prevention for children in the U.S. and elsewhere. Furthermore, this
ultimate goal of primary prevention was presented in print to the public
health and clinical communities for more than 30 years. We clearly see
this in the evolution of the prescriptive language of successive
Statements which simply translates as 'it is much easier to prevent than
to treat.'

The 1978 Statement (p. 1, Introduction) notes:

> "The ultimate preventive goal is identification and removal of lead in
> the environment before it enters the child. Until this occurs,
> screening, diagnosis, treatment, and environmental management will
> continue to be necessary public health activities."

The 1985 Statement (p. 1, Introduction) notes:

> "Clearly, the goal is to remove lead from the environment of children
> before it enters their bodies. Until this goal is reached, screening,
> diagnosis, treatment, and environmental management will continue to be
> necessary public health activities."

The 1991 Statement (pp. 1-4, Introduction) notes:

> "Primary prevention efforts (that is, elimination of lead hazards
> before children are poisoned) must receive more emphasis as the blood
> lead levels of concern are lowered \[p.1\]."
>
> "Primary Prevention. Efforts need to be increasingly focused on
> preventing lead poisoning before it occurs. This will require
> communitywide environmental interventions, as well as educational and
> nutritional campaigns. \[p.3\] "
>
> "The focus of prevention efforts, therefore, must expand from merely
> identifying and treating individual children to include primary
> prevention\....\[p.4\]"

The 2005 Statement (p. ix, Preface) notes:

> "The data demonstrating that no "safe" threshold for blood lead levels
> (BLLs) in young children has been identified highlights the importance
> of preventing childhood exposures to lead. It confirms the need for a
> systematic and society wide effort to control or eliminate lead
> hazards in children's environments before they are exposed. This
> emphasis on primary prevention, although not entirely new, is
> highlighted here and is clearly the foremost action supported by the
> data presented in *A Review of Evidence of Adverse Health Effects
> Associated with Blood Lead Levels \< 10 g/dL in Children.* "

The CDC 2007 Statement (MMWR 56: 11/2/07, p. 1), in advising how
clinicians are to deal with Pb-B values \< 10 g/dl, essentially
iterates parts of the 2005 Statement from which it drew considerable
information.

CDC presented the CDC Statements of 1975, 1978 and 1985 as tabulated Pb
toxicity risk advisories for *secondary prevention of childhood lead
poisoning.* That is, the focus was to be on identification of the
frequency and nature of lead exposures in U.S. children where the
mechanisms are *post-hoc* in nature: children are identified as to toxic
lead exposures after they have sustained such toxic lead exposures.

However, developmental neurotoxic effects in children appear to be
persistent and may be irreversible to some significant extent. Once such
effects are expressed, whether recognized or not, they are not easily
reversed (Rogan et al., 2001; Rosen and Mushak, 2001).

[Refs:]{.underline}

> Rogan WJ, Dietrich KN, Ware JH et al. 2001. The effect of chelation
> therapy with succimer on neuropsychological development in children
> exposed to lead. N. Engl. J. Med. 344: 1421-1426.
>
> Rosen JF, Mushak P. 2001. \[Editorial\]. Primary prevention of
> childhood lead poisoning\--the only solution. N. Engl. J. Med. 344:
> 1470-1471.

The October 1991 CDC Statement presented prescriptive language that was
transitional in nature, combining elements of both secondary and
*primary prevention mechanisms*. Primary prevention deals with
prevention of the toxic lead exposures in the first place.

The August, 2005 and November, 2007 Statements clearly state that
adverse health effects in children occur below 10 g/dl. These
Statements acknowledged the huge growth in the database for low-level
lead poisoning in the global literature from 1991 to the present. The
2005 and 2007 Statements render the 14 to 16 years-old 1991 Statement
irrelevant to doing quantitative health risk assessments for lead in
children now.

The latter two Statements preserved the value of 10 g/dl as the action
level for earliest intervention in terms of a prioritization rationale.
Nowhere in the 2005 and 2007 Statements does CDC say that effects in
children below 10 g/dl are trivial, merely that BLLs in this range
require primary prevention through the various agencies entrusted with
such primary prevention, to include EPA.

More specifically, the CDC material shows EPA needs to recognize one
obvious fact about the need for primary prevention methods spelled out
in the 2005 and 2007 Statements. Primary prevention methods to address
the toxic effects of lead at Pb-Bs \<10 g/dl require the actions of
regulatory agencies such as EPA, not advisory agencies such as CDC.
Ambient air Pb through direct and indirect pathways poses adverse health
risk to children and EPA is in the business of regulating air lead so as
to prevent such adverse health risks through the primary prevention
modality of continued ambient air Pb reduction.

**D. Adequacy of CDC Statements in Meeting Section 109, CAA
Requirements**

The ANPR seems to dance around the issues of adequate health protection
and adequate margins of safety expressed in Section 109 of the CAA with
legalisms rather than convincing health science. It needs to address 109
with the latter.

Secondly, there is no explicit or causal quantitative linkage between
values presented in CDC Statements and the requirements of Sec. 109 in
the Clean Air Act. The "action" levels of those earlier CDC Statements
employing secondary prevention methods are not values that provide
adequate protection of human health with adequate margins of safety.
They were meant to be and remain as triggers for prioritizing secondary
lead poisoning prevention strategies: screening, diagnosis, treatment,
and environmental management.

The CDC risk categories, with their successive reductions in earliest
levels of concern for Pb-Bs, do not scientifically satisfy nor are they
synonymous with these Sec. 109 requirements.

[Refs for CDC Use of Statements and Reference Values]{.underline}

U.S. DHEW/CDC. 1975. Increased Lead Absorption and Lead Poisoning in
Young Children: A Statement by the Centers for Disease Control. Atlanta,
GA: U.S. Department of Health, Education and Welfare.

U.S. DHEW/CDC. 1978. Preventing Lead Poisoning in Young Children: A
Statement by the Centers for Disease Control. Atlanta, GA: U.S.
Department of Health, Education and Welfare. April.

U.S. DHHS/CDC. 1985. Preventing Lead Poisoning in Young Children. A
Statement by the Centers for Disease Control. Atlanta, GA: U.S.
Department of Health and Human Services. January.

U.S. DHHS/CDC. 1991. Preventing Lead Poisoning in Young Children. A
Statement by the Centers for Disease Control. Atlanta, GA: U.S.
Department of Health and Human Services. October.

U.S. DHHS/CDC. 1997. Preventing Lead Poisoning in Young Children. A
Statement by the Centers for Disease Control. Atlanta, GA: Department of
Health and Human Services. November.

U.S. DHHS/CDC. 2005. Preventing Lead Poisoning in Young Children. A
Statement by the Centers for Disease Control and Prevention. Atlanta,
GA: Department of Health and Human Services. August.

U.S. DHHS/CDC. 2007. Interpreting and Managing Blood Lead Levels \<10
g/dL in Children and Reducing Childhood Exposures to Lead.
Recommendations of CDC's Advisory Committee on Childhood Lead Poisoning
Prevention. MMWR 56: 1-14; 16.

**Mr. Rich Poirot**

**Post-Meeting Comments on (monitoring section of) 12/07 Pb ANPR,** R.
Poirot, VT DEC

I was disappointed by the overall form and content of the Pb ANPR --
both as a guide to policy decision-making for revising the current
(1978) Pb standards, and more generally as a harbinger of how the new
NAAQS review process may be conducted in the future. Nearly as much
space is devoted to summarizing and justifying the logic and rationale
for the 1978 standards and 1990 decision not to revise them, as is
provided to summarize and synthesize the new scientific information that
is relevant to the current NAAQS review. In discussing the current
review, the ANPR presents -- and specifically seeks comment on - such a
broad range of policy options for all aspects of a revised (or
de-listed) Pb NAAQS, that its difficult to see how it informs the public
on the Agency's intentions for rule-making, or solicits useful new
information to inform that rule-making. The resulting general 'public
opinion survey' also provides an inherently difficult target for
scientific review, and raises questions about the future role (if any)
of CASAC review at this point in the NAAQS process.

Carefully considered, thoroughly documented EPA staff recommendations
and associated CASAC comments are often presented as a sort of "extreme"
low bound to an open-ended range of policy options, for which
alternative viewpoints of "some" or "others" are presented in the ANPR
without documentation, justification or attribution of authorship. We
learn that "questions have been raised" regarding the option of
delisting Pb as a criteria pollutant, but not by whom or for what
purpose. After explaining why the CDC action level of 10 µg/dL BPb is
used to identify individual at-risk children for follow-up remedial
action, and should clearly not be "misinterpreted as a definitive
toxicological threshold", the ANPR then proceeds, bizarrely, to request
comments on the use of this screening level as a (misinterpreted)
"foundation for deriving the level for the primary Pb standard", because
"some" might consider this appropriate. The ANPR also features a very
heavy emphasis on 'limitations and uncertainties' in all sections (the
words "limitations", "uncertainty" or "uncertainties" appear a total of
136 times in the ANPR), but provides few if any quantitative assessments
of these uncertainties for context.

By contrast, the final Pb Staff paper was clearly written, intelligently
reasoned, thoroughly documented, and should provide a useful basis for
Agency decision-making. It was difficult to imagine reviewing the
current ANPR, without benefit of this focused Staff Paper. Nor can I
imagine how future ANPRs - without benefit of preceding Staff Papers -
can effectively present the recommendations of technical staff and
CASAC, along with the contrasting anonymous opinions of some and others.
If open-ended ANPRs of this nature are contemplated for future NAAQS
reviews, they should be issued at the beginning, rather than at the end,
of the review process, and the Staff Paper should be retained as a
critical step in the NAAQS review process.

**Pb Indicator and Considerations for Ambient Monitoring**

In previous comments on the Pb CD and 1^st^ draft Staff Paper, the CASAC
Pb Panel had encouraged the Agency to consider revising the indicator
for Pb sampling from TSP to low volume PM~10~ (with provisions for low
cost multi-elemental analytical methods like XRF and ICP-MS). Reasons
for this recommendation (from Henderson, 2007) included:

> "Most other TSP sampling was discontinued after PM~10~ standards were
> promulgated in 1987. TSP samplers capture particles with an imprecise
> and variable upper particle cut size in the range of approximately 30
> to 50 microns on fiberglass filters which are not well-suited for
> analysis by inexpensive, multi-elemental surface beam techniques like
> particle-induced X-ray emission (PIXE) or X-ray fluorescence (XRF).
> Consequently TSP sampling by imprecise samplers is primarily conducted
> only for lead analysis and these filters are rarely analyzed for other
> species. If Lead NAAQS monitoring was based on (low-volume) PM10
> sampling on Teflon filters, the resulting data would be correlated
> with TSP lead, as suggested by limited data in the 1st Draft Lead
> Staff Paper, but would have substantially improved sampling precision.
> The Lead Panel recognizes that either monitoring system would be
> subject to variability based on location, particularly near sources.
> Other advantages of low-volume PM~10~ sampling include:
>
> 1\. Focus on those biologically-relevant particles that, when inhaled,
> are deposited in the thoracic region;
>
> 2\. Larger spatial-scale representativeness for population exposures
> to monitored particles which remain airborne longer;
>
> 3\. Could utilize more widespread PM~10~ and "air toxics" metals
> sampling networks, leading to collection of more data at lower costs;
>
> 4\. Potential for inexpensive multi-elemental analysis by XRF or PIXE
> would provide useful supplemental metals information for health
> effects studies and source apportionment;
>
> 5\. Potential for automated sequential PM~10~ samplers (not available
> for TSP) would be especially useful if sampling frequency is increased
> from once every six days; and
>
> 6\. Weighing filters would provide useful information on PM~10~ mass;
> and, if collocated with PM~2.5~ Federal Reference Methods (FRM), could
> provide needed information on PM~10--2.5~ mass and speciation."

The Pb Panel had acknowledged that PM~10~ sampling could exclude some
ultra-coarse particle (\>10 um) Pb that had previously been captured by
TSP samplers (and that may or may not become ingested), but that given
the needs to substantially reduce the level of the standard and to
increase the sampling frequency for a shorter-term monthly standard, the
low volume PM~10~ Pb measurements, with greater accuracy and precision,
lower detection limits, and potential for automated sample collection
with lower cost and more useful multi-elemental analysis, would be a
preferable method for future monitoring. The Pb panel also suggested
that, if necessary, an "adjustment factor" might be applied to reduce
the level of a PM~10~ standard to account for ultra-coarse Pb not
captured by the PM~10~ samplers, as it was expected that PM~10~ Pb would
represent a large fraction of, and be highly correlated with TSP Pb.

One minor criticism of the Final Staff Paper is that prior CASAC
suggestions on approaches the Agency might consider in changing the Pb
indicator from TSP to PM~10~ are presented in the Staff Paper as
"requirements" rather than "recommendations". For example, at the bottom
of p 5-25 and top of p. 5/26, it's stated that "CASAC recognized...that
a scaling of the NAAQS level [would be needed]{.underline} to
accommodate the loss of very large coarse-mode Pb particles, and that
concurrent Pb-PM10 and Pb-TSP sampling [would be needed]{.underline} to
inform development of scaling factors..." (emphasis added). I think the
previous CASAC intent was to suggest that such approaches could help
inform a judgment about an appropriate revised indicator, rather to
suggest that a detailed quantitative analysis would be a necessary
prerequisite.

In the 12/07 ANPR and associated support documents, the Agency presented
an evaluation of the limited available collocated TSP and PM~10~ Pb data
(Cavander and Schmidt, 11/26/07) from which it is concluded that no
single PM~10~:TSP ratio could be developed that would accurately predict
TSP Pb for all US locations, although it did appear likely that such
ratios might be developed for individual sites based on future
site-specific measurements. An additional evaluation of precision and
bias of existing TSP Pb data (Camilier and Rice, 2007) demonstrated that
the average precision of TSP Pb measurements (averaging 12%
^[+]{.underline}^ 19%) and sampling bias were not substantially poorer
than for some other NAAQS FRMs (although it should be noted that this
analysis excluded 21% of measurements which were below MDL of 0.01
µg/m^3^, and also showed much poorer relative precision at the lower
concentrations more typical of actual current population exposures.

Based on these analyses, the Agency continues to advocate retention of
the TSP Pb indicator, although it does request comments on various
related issues and options, including:

-   whether the variability of the TSP sampler warrants discontinuation
    of its usage as the Pb indicator,

-   the appropriateness of using Pb-PM~10~ data as a surrogate for
    Pb-TSP,

-   a perceived need to tighten the Pb FEM demonstration requirements
    (which currently call for testing over a \[1970s - type\] range of
    Pb concentrations of 0.5 to 4 µg/m^3^) to better reflect the much
    lower current concentrations,

-   the need to add source-oriented Pb monitoring near many of the
    largest Pb emitters which are not currently monitored,

-   the desirability of various network options including
    population-based sampling, source-oriented sampling, a combination
    of these approaches, and/or utilization of the current PM~10~
    network if an acceptable regional or site-specific correlation of
    TSP-Pb and PM~10~-Pb can be established.

Regarding sample frequency, the Agency suggests and seeks comments on a
wide range of options including:

-   1-in-6 day, 1-in-3-day, 1-in-1 day sampling, perhaps with increased
    sample frequency for sites with higher concentrations,

-   increased sample duration -- from 24-hour to 48 or 72-hour or
    longer,

-   allowing for sample compositing (analyzing sequential samples
    together), and

-   allowing for multiple samplers at one site.

Regarding Pb monitoring in rural areas to compare with secondary NAAQS -
which is presumed to be equal to the primary NAAQS (what a surprise!),
comments are requested on the appropriateness of using rural/remote
PM~2.5~ Pb measurements from the IMPROVE network -- possibly
supplemented with a smaller "sentinel" network of TSP-Pb or PM~10~-Pb
samplers, to track spatial and temporal patterns of Pb concentration and
deposition in non-urban areas.

I continue to strongly encourage the Agency to **transition away from
TSP sampling with the clear goal of using low-volume PM~10~ Pb sampling
in the near future**. The Agency has recently specified low volume
PM~10~ sampling as a component of the new FRM for coarse particles
(PM~10-2.5~), and so there will be an expansion of population-oriented
sites using this method and collecting (elementally clean) Teflon
filters amenable to low cost multi-elemental analysis methods for Pb and
other species indicative of emission sources and other health risks. At
the same time, the Agency and the States are also expanding their
sampling efforts for "toxic air contaminants", including Pb and other
metals. The consensus method for NAATS metals sampling is low volume
PM~10~ with associated ICP-MS analysis. In addition to the large savings
in costs and human resources that would be realized if Pb NAAQS sampling
were harmonized with these established and expanding programs, there are
other good reasons why a transition to PM~10~-Pb NAAQS sampling would be
timely.

The current Pb standard was established in 1978, and based on sampling
using 1950's technology. Pb is somewhat unique among the criteria
pollutants in that it has more or less "skipped" a mid-term review
cycle. Twenty years ago, there was clear evidence in the 1986-90 review
to support both lowering the level of the 1978 NAAQS (from 1.5 to 0.5 to
1 µg/m^3^) and also shortening the averaging time from quarterly to
monthly (adding further stringency). But as the Agency chose an
alternative, aggressive multi-media Pb emission reduction strategy,
ambient air concentrations declined in most areas to well below the
level of the antiquated NAAQS. Subsequently, Pb sampling was
discontinued at many sites, since it is labor intensive, provides no
useful information on sources or other pollutants, and revealed
concentrations "safely" below the NAAQS. The current review provides
compelling evidence of a need for a further substantial lowering of the
standard, which in turn poses an especial challenge for monitoring,
since the current network lacks sufficient size and orientation to focus
on either populations or current sources. The continued use of 1950's
sampling technology poses additional obstacles, as TSP samplers are not
suited for automated sequential sampling, and the labor-intensive filter
collections are not suitable to analyses for other pollutants. The TSP
samplers collect a variable and unspecified mix of respirable air
pollutants and coarse mode dust, and by inclusion of unknown fractions
of ultra-coarse Pb containing particles, promote an FRM which -- by
definition -- can't represent population exposures over areas extending
much beyond monitoring locations at any sites where TSP-Pb differs
significantly from PM~10~-Pb. Measurements that are heavily influenced
by ultra-coarse particles (where TSP-Pb differs from PM~10~-Pb) have
micro-scale spatial representativeness, and would be extremely sensitive
to the exact height of the sampler inlet above the ground. It should
also be noted that 2-meter separation requirements for TSP Hi-Vols,
combined with the absence of sequential TSP samplers (requiring multiple
samplers for monthly means) may render TSP-Pb sampling impossible at
many existing monitoring sites.

This would be an opportune time to make or initiate a transition from
TSP to PM~10~, since the current review indicates a need for such a
substantial lowering of the NAAQS - to the range suggested in the Staff
Paper of between 0.1-0.2 µg/m^3^ to as low as 0.02 to 0.05 µg/m^3^. If a
standard is lowered by a factor of 10 to 100, it is unimportant if the
indicator measures 10% or 15% less than the indicator selected 30 years
ago. The Cavander & Schmidt (2007) analysis does indicate some
variability in the average ratios of PM~10~-Pb to TSP-Pb. However, it
also shows average ratios of \> 0.60 at all sites, \> 0.75 at 20 of 24
sites, \> 0.80 at 18 sites. Some of the extreme high or low individual
sample ratios (ranging from 0.04 to 11.9 at 1 site) or poor correlations
are not reflective of true PM~10~ to TSP Pb ratios, but likely the
result of poor quality monitoring practices or inaccuracies in the TSP
measurements - which are generally \> those for hi-vol PM~10~ and \>\>
those for low volume PM~10~ (not available for this analysis). Rather
than needing to arduously establish a large series of site-specific
PM~10~-Pb to TSP-Pb ratios (fitting good data to bad), I think it would
be well within the Agency's range of discretionary options to consider a
slight loss of ultra-coarse Pb at some sites in selecting an
appropriately conservative level for the revised NAAQS. Conversely, I
think it would be a mistake to hold up the old TSP metric as the "gold
standard" and only allow newer, better technology if it can reproduce
the old, seriously flawed sampler performance.

As observed in the ANPR, TSP samplers have a variable and poorly
characterized upper particle cut size -- of "between 25 and 50 um
depending on wind speed and direction". In Figure 1 below, I've plotted
the Hi-Vol TSP collection efficiency data reported by Wedding et al.
(1977) cited in the ANPR. These wind tunnel measurements were taken with
a single Hi-Vol at a wind speed of 4.6 meters, but with the slanted shed
roof of the sampler at different orientations with respect to the wind
direction. The lower blue curve represents sampling with the ridge of
the shed roof aligned parallel to the WD, while the red curve represents
sampling with the ridge of the shed roof aligned perpendicular to the
WD. Note both how poorly defined (not sharp) the collection efficiency
is for larger particles and how greatly it varies with wind direction.
At sites which have a high fraction of ultra-coarse Pb, the TSP Hi-Vol
is a lousy way to measure it.

Those relatively few sites that actually have large contributions of
ultra-coarse Pb also clearly have large, nearby coarse mode (industrial
process or fugitive dust) emissions, but how much coarse Pb is measured
(and any measure of the sampling precision) is strongly dependent on
wind speed and sampler orientation. The Agency would be better off
prescribing and enforcing specific control technologies for those large
dust sources, than requiring (& greatly expanding) an extensive national
monitoring network to accommodate the occasional extreme cases.
Conversely, if ultra-coarse Pb is a widespread problem of concern, the
Agency should develop appropriate methods to accurately characterize
those dust particles. "Whatever it is that the TSP sampler happened to
collect today" is not a sufficiently clear definition.

![](media/image2.wmf){width="5.004861111111111in" height="5.125in"}

It should also be noted that Pb in ultra-coarse particles is not
deposited in the lower respiratory tract, and inefficiently deposited
(especially during nasal breathing) in the upper respiratory tract --
from which only a fraction is ultimately ingested. Ultra-coarse
particles are also inefficiently exchanged between outdoor and indoor
air and so contribute less effectively to Pb loadings on indoor surfaces
than does fine particle air lead. The Staff Paper argues (p. 5-25) that
"nonrespirable Pb in the environment may, at some point, become
respirable through weathering or mechanical action." But by this
"logic", we should also use TSP samplers to determine compliance with
PM~10~ and PM~2.5~ standards. The variability of TSP sampler cut size,
the higher MDL associated with TSP-Pb sampling, and the relatively poor
precision at lower Pb concentrations all contribute to variability in
the TSP-Pb indicator. So a PM~10~-Pb indicator would have the added
advantage of providing a more [stable]{.underline} metric for compliance
determination, as well as a more [representative]{.underline} metric of
population exposures to support future health studies and risk
assessments.

It is recognized that the Agency may lack the time to develop a new Pb
FRM for the current NAAQS review cycle. But at the same time, it would
be an unfortunate waste of scarce resources to require a large expansion
of the TSP-Pb sampling network. One option might be for the Agency to
simply designate low volume PM~10~-Pb as an FEM -- having first taken
into consideration the slight, occasional loss of ultra-coarse Pb in
setting the (slightly conservative) level of the standard. Another
possible variation on this might be to require TSP-Pb sampling only at
sites which exceed standards with the new PM~10~-Pb FEM. Another option
might be to designate two separate Pb NAAQS, one based on the current
TSP-Pb FRM indicator and one based on a new PM~10~-Pb FRM indicator --
allowing either method to be used for attainment compliance
determination, but perhaps requiring both methods at sites which exceed
either standard. Alternatively, the Agency might specify TSP sampling at
source-oriented locations and PM~10~ at population-oriented sites. The
latter could be used for compliance determination, while the former
might be used to trigger additional monitoring or control requirements
if "action levels" are exceeded. Possibly the Agency should seek advice
from the CASAC AAMM Subcommittee to develop recommendations for
appropriate Pb FRM, FEMs and network design strategies. That
Subcommittee had previously reviewed EPA's National Ambient Air
Monitoring Strategy -- at a time when the currently implied large
expansion of a Pb sampling network was not envisioned. Unless new funds
are provided, any new sampling needs to be paid for by reductions in
existing programs.

Regarding the Agency's request for comments on the suitability of using
the current PM~10~ network for Pb sampling if adequate regional or
source-specific PM~10~-Pb/TSP-Pb correlations could be established -- I
would prefer this to a large expansion of the TSP-Pb network, regardless
of whether acceptable correlations are developed. However, a large
fraction of current PM~10~ sites use hi vol PM~10~ samplers, equipped
with quartz filters. The particle cut size for these hi vol PM~10~s is
much more clearly defined than for TSP, but is not as sharp as for low
vol PM~10~, nor are the quartz filters as clean as Teflon or as amenable
to surface beam analytical techniques.

Regarding the request for comments on changes to the Pb FEM
certification requirements, I agree that there should be accuracy and
precision performance specifications tested within a range of Pb levels
more representative of today's ambient concentrations than the 0.5 to 4
µg/m^3^ range in the current FEM specs. But I think FEM certification
need not (& should not) require statistical equivalency to the flawed
TSP method (or perhaps might allow equivalency to be determined under
test conditions which do not include high levels of ultra-coarse Pb.

Regarding sample frequency, the move to a monthly averaging time
provides another reason to switch to PM~10~ samplers, as they are
available in automatic sequential sampling configuration. Sample
compositing or sample collection over prolonged multi-day periods is
useful only for "bright line" compliance determination (for a pollutant,
in this case, for which there is no bright line for effects). But the
aggregation produces information of limited value for source attribution
or effects studies. I would also like to encourage, however, that every
effort is made to avoid a need for high frequency, filter-based
sampling. I would imagine a large portion of the difference between
monthly and quarterly averages could be described as a "statistical
issue." That is there's an average or median ratio of monthly max to
quarterly max, and data from most sites will fall within a fairly narrow
range of that ratio over time. Only a relatively few sites near
extremely episodic emission sources will have month/y/quarterly ratios
that consistently fall well above the average. When concepts like the
"2^nd^ highest monthly max" and/or "the 3 year average" are introduced
to provide some stability in the compliance metric, the difference
between monthly and quarterly is reduced to more of a scaling factor. I
would think some metric reflective of the "episodicity" of the daily
sample values (perhaps the standard deviation or ratio of the 98^th^ to
50^th^ percentile) could be used to supplement a quarterly mean in a way
that sites with much higher monthly values could be targeted for
increased sample frequency, while a majority of sites might get by with
1-in-3 sampling, or even 1-in-6 day sampling at sites that consistently
fall below standards.

Regarding the request for comments on Pb monitoring in rural areas to
compare with secondary NAAQS (and which would also help define regional
background, transport and trends), I think its an excellent idea to
supplement the rural/remote PM~2.5~ Pb measurements from the IMPROVE
network with a smaller "sentinel" network of PM~10~-Pb samplers (no
TSP-Pb please), The IMPROVE program already collects PM~10~ samples and
these samples -- from a subset of sites that might be periodically
rotated -- could be at least subject to multi-elemental XRF analysis
which would provide useful information on fine and coarse Pb as well as
other components of coarse particle composition.

**References**

Camalier, L. and J. Rice (2007) Estimates of Precision and Bias for Lead
in Total Suspended Particulate (TSP), Memo to Lead NAAQS Review Docket
(OAR-2006-0735), 11/29/07.

Cavander, K. A. and S. M. Schmidt (2007) Review of Collocated Lead in
Total Suspended Particulate Matter Less than Ten Micrometers, Memo to
Lead NAAQS Review Docket (OAR-2006-0735), 11/26/07.

Henderson, R. (2007) Letter from Dr. Rogene Henderson, Chair, Clean Air
Scientific Advisory Committee, to Steven L. Johnson. Re: Clean Air
Scientific Advisory Committee's (CASAC) Review of the 1^st^ Draft Lead
Staff Paper and Draft Lead Exposure and Risk Assessments, 3/27/07

Wedding, J. B., A. R. McFarland and J. E. Cermak (1977) Large Particle
Collection Characteristics of Ambient Aerosol Samplers, *Environ. Sci.
Technol.* 11: No. 4, pp 387-390.

**Number range CHAPTERDr. Michael Rabinowitz**

Number range CHAPTERReview by Michael Rabinowitz of

"Lead: Human Exposure and Health Risk Assessments for Selected Case
Studies" and

"Review of the National Ambient Air Quality Standards for Lead: OAQPS
Staff Paper"

(October 2007)"

> November, 2007

[General Comments:]{.underline}

These two documents are the fruits of years of labor of groups of
well-funded and co-coordinated workers. In its current form I think it
provides a sufficient basis for the Administrator to set an appropriate
air standard, taking into account a vast amount of older and newer
information. At this stage, I can think of nothing to add to or take out
of the text, aside from some small items below.

I would like to again stress that to achieve a lead-safe environment not
only must lead in air (and water) be regulated, but the burdens of lead
paint, still in homes, and lead accumulated in outdoor areas, whether
from old exhaust, paint, or industrial sources, all need to be
addressed.

Although I raise some fairly minor points below, and I am without the
benefits of hearing from my panel colleagues, I see no reason not to
approve these documents in their present form.

[Minor Remarks]{.underline}

Might this document have a useful "Executive Summary"? pages 3-21 to
3-23 and 5-41-46 might serve as a good start.

Page 2-8 line 3 Yes, indeed. You could actually point to a Feb 1972
publication of EPA's fuel additive regulations which resulted in the
reduction of lead in gasoline which were to start in January 1977.
{California lead the way}

Page 2-23 Figure 2-7 In my draft the middle (average lines) were not
visible.

Page 3-18 Section 4.4.2 I understand that this section is suppose to
show how lead can make other health problems worse. But it was not clear
to me how lead makes diabetes worse. This section needs to be clarified
and expanded or eliminated. Also, the 3 groups of adults (hypertensives,
diabetics, and kidney patients) may not be separate. Diabetes,
hypertension, and kidney disease often co-occur in the same individual.
I suggest just focusing on hypertension, where the case is clearest.

**Number range CHAPTERDr. Armistead (Ted) Russell**

Comments of Dr. Armistead (Ted) Russell

Georgia Power Professor of Civil and Environmental Engineering

Georgia Institute of Technology, Atlanta, GA

on

**EPA's Advance Notice of Proposed Rulemaking (ANPR) on the NAAQS for
Lead**

December 6, 2007

The lead staff paper is very responsive to our deliberations, and I was
quite pleased with what is there. The ANPR, on the other hand, raises
some concerns looking to a future where the ANPR replaces the Staff
Paper. The ANPR says rather little new, but regurgitates the findings of
the Staff Paper and CASAC comments. I trust, and hope we get
reassurance, that the future ANPRs will really be more like the current
Staff Paper, not the current ANPR.

We also received a memo from Cavender and Schmidt on the comparison of
PM10 and TSP lead at collocated monitors. I would like to thank them for
providing this information. I must admit, the data raises some questions
about the TSP monitoring, and makes me wonder what is happening at some
of the TSP monitors (I have a bias towards using PM10 in that I think
the inlet is better characterized, PM10 monitors are more ubiquitous,
having the additional metals will provide more information in the long
run, and they provide a better characterization of area-wide lead
exposures). I actually think that this analysis further argues towards
using PM10 monitoring as it makes me a bit more leery of the TSP
monitoring. I disagree with the idea of adding a delta (e.g., one
standard deviation) to make a change to PM10 conservatively protective.
I generally don't like such arbitrary changes. Going to a tighter
standard and going to PM10 at the same time will be both more protective
and better in the long run from a monitoring perspective. While I might
prefer monthly averaging, the difference between this and quarterly
averaging is relatively minor, so I might just suggest we show a
preference towards monthly, but not be overly emphatic about such.

In regards to the level of the standard, I view that the staff paper has
captured the range of where I might fall, and given that I will not be
present for the final discussions I hesitate to be overly specific at
this time as those discussions might fine tune my suggestions.

In regards to the secondary standard, and what is said both the ANPR and
Staff Paper, I might suggest that we enshrine the various comments made
by Rich \[Poirot\], \[Dr.\] Ellis \[Cowling\] and others about the lack
of data how ever many years ago, and that little has been done to
alleviate that inadequacy. It is quite apparent that their words will be
just as applicable five years from now. I trust that our furry, scaled,
leafed and single-celled friends will reap benefits from tightening of
the primary standard in the mean time.

**Dr. Jonathan M. Samet**

Review Comments: EPA's Advance Notice of Proposed Rulemaking (ANPR)

Jonathan M. Samet, MD, MS

Professor and Chair

Department of Epidemiology

Johns Hopkins Bloomberg School of Public Health

[General Comments:]{.underline}

Having reviewed the staff paper and the ANPR for lead, I was left
concerned by a process that had left the ANPR as an isolated document,
lacking any links to either the Criteria document or the Staff Paper.
Additionally, the peer review that had been provided by CASAC, as well
as comments by the public to date, were not acknowledged to a sufficient
extent. I recognize that this ANPR represents the first that the Agency
has developed and that it is linked still to the prior process involving
a Criteria Document and Staff Paper, now set aside in terms of the new
ISA model. Nonetheless, this ANPR cannot stand as the model for
developing a National Ambient Air Quality Standard (NAAQS).

The ANPR reads as though there was not sufficient certainty with regard
to the health effects of lead and the need for a standard that would be
protective of public health. Rather, it appears to take a seemingly
"neutral" stance, appropriate only if the evidence were in equipoise,
hardly the case. The role of CASAC is diminished as a commenter, as is
the Agency's own staff which has synthesized the evidence through the
Criteria Document and the Staff Paper. This ANPR is an unacceptable
result of a process that should be evidence-based, but has clearly gone
off course and lost its links to a substantial body of evidence.

[Specific Comments:]{.underline}

1.  Handling of uncertainty: On reading the document, I was troubled by
    the manner in which uncertainty was handled and emphasized. The
    obvious truism, that uncertainty is greater at the lower end of the
    dose-response relationship, received excessive emphasis, without
    adequate interpretation. The document failed to adequately call
    attention to how the points on the dose-response curve at which
    effects have been observed with certainty has become increasingly
    lower, and guideline values have followed.

2.  With regard to the handling of susceptibility, the ANPR addressed
    some of the groups that may be at risk. Meriting greater emphasis
    are those persons, primarily inner-city children, who are at risk
    for higher levels of exposure in general. There is potential that
    additional exposure from airborne lead will move them into a range
    of much greater risk.

**Dr. Joel Schwartz**

**Review of ANPRM for Lead**

General Comments:

I am concerned that there are continuing choices made, each for
understandable reasons, all of which have the effect of biasing downward
the estimated health effects of lowering the standards, and which in
net, constitute a large downward bias. For example:

1\. The effects of decreased renal function are difficult to quantify,
but they are not zero. Why not either a crude attempt to bound them, or
a fuller discussion when reporting the estimated benefits.

2\. The effect of air lead on food lead is ignored, despite evidence
that it is an important source. The old CD had some estimates, based on
a period of higher air lead. The expected value of uncertainty is not
zero. Why not a sensitivity analysis assuming 40% of food lead is from
air deposition?

3\. Past air is treated as part of background, not part of air. Again, a
downward bias. And there are measures to control this source. I
understand there are technical limitations, but again, a sensitivity
analysis, which, for example, attributes 15% of indoor dust to "past
air", and makes some assumptions about turnover rates, would avoid the
impression that there is a desire to understate effects.

4\. There may not be time to quantify the blood pressure benefits, but
it should be noted that when that has been done in the past, e.g. the
RIA for lead in gasoline and the RIA for the water lead rule, the
magnitude of the benefits was of the same order as the magnitude of the
cognitive benefits in children. Thus this decision alone likely cuts the
estimated health benefits in half. This needs to be discussed, with
reference to the previous RIAs.

5\. A back of the envelope estimate of the effects of lead exposure on
criminal behavior, using estimates of the economic costs of crime,
suggest that again a potentially large benefit is being ignored.

I agree with the comments of Paul Mushak that this document summarizes
the risk assessment that OAQPS did, summarizes the risk assessment, but
then ignores the recommendations of OAQPS, buries them, and blithely
asks for comments on a range of standards from zero to infinity. This is
really not acceptable. The Clean Air Act requires the administrator to
set standards for a pollutant that "may reasonably be anticipated to
endanger public health", using criteria that "accurately reflect the
latest scientific knowledge useful in indicating the kind and extent of
all identifiable effects on public health and welfare which may be
expected from the presence of a pollutant in ambient air..". The range
of possibilities proposed for comments ignores the comments of CASAC on
what those effects are at what levels, ignores the Staff Paper summary
of those effects at different standard levels, and ignores the risk
assessment. It seems, in fact, to ignore science. Are we now doing
faith-based risk assessment?

While the Clean Air Act requires special attention to susceptible
populations, and the ANPRM notes that there is evidence of increased
susceptibility in Blacks and persons with certain ALAD variants, there
is no place in the ANPRM where this is specifically addressed in the
risk assessment or proposal for comments.

The ANPRM notes that CASAC reviewed the science and said that it was
clear that air pollution by lead still had public health impacts, slides
by the Staff Paper and Risk Assessment documents which quantitate
adverse effects on children's IQ, and asks for comments on whether it
would be appropriate to determine that air lead no longer has any public
health impact. "We take not of the views of CASAC summarized above... We
recognize, however that there may be differing views on interpreting or
weighing the available information. "If CASAC is just another interested
party to submit comments, what are we doing at this meeting? This is
precisely the issue that has already been addressed by the statutory
reviewer of science for EPA air standards, addressed by OAQPS in its
Risk Assessment and Staff Paper documents, and again reviewed by CASAC.
Either CASAC is the committee that reviews the "differing views" or it
is not. If this change in status has happened for CASAC, then I believe
that we need to inform the Congressional Committee's that authorized
CASAC in the clean air act that this has occurred, so that they can
determine whether this was their legislative intent.

HAPs are focused on major stationary sources, and are inadequate to
control emissions from a variety of smaller sources which become
relevant when we stop focusing on smelters.

Specific Comments

P19. States that 5 is the level at which there are significant effects
reported, arguing that levels below that may not need protection. But
this is a distortion of the literature. Restricting analyses only to
Blood Lead levels below 7, Lanphear has reported a significant
association, which makes it highly unlikely that levels below 5 have no
effect. Indeed, the bulk of the literature indicates that the slope of
the blood lead-IQ dose response curve increases as we get to lower blood
lead levels, rather than decreasing to zero.

If NHANES 2003-04 and has reported the median, then the 95^th^
percentile must "exist", contrary to the note on this page. Given a set
of data, it must have a 95^th^ percentile, and the data clearly exist if
the median has been published. CDC may not have published it, but that
does not prevent EPA from asking them for the number.

P26. footnote 13. Duh! Of course uptake of lead in **solution** is
greater than uptake of lead from food, some of which may be non-soluble.

However, this page seems to ignore the role that air lead plays in lead
in food. Content of lead in red wine in France dropped considerably when
lead was banned as a gasoline additive, because of lower deposition on
the skins of the grapes. Lead content of white wine, where the skins are
quickly removed, had always been lower. Hence the dichotomy between
dietary lead and air lead being proposed is flawed.

P33. Should note that there have been several publications since the
close of the CD which continue to report significant associations of
lead \< 10 µg/dL and IQ, and continue to report steeper slopes at lower
levels (e.g. Tellez-Rojo 2006, Lanphear 2007). It should also note that
if a threshold existed, one would expect slopes to decrease as we
limited the sample to subjects with lower and lower blood lead.

P47 should note a recent publication (Jain et al 2007, EHP) which
provides further support for the association of lead exposure with
ischemic heart disease, not just blood pressure.

P 57. Again, an assumption is made about the shape of the dose response
that, based on the data, appears unlikely. If there were a threshold
below which the dose-response became zero, then in repeated analyses
that excluded blood lead concentrations above certain levels, one would
expect the slope to decrease. This is not observed, rather the opposite
is observed---a steeper slope at low levels. It is one thing to assume
that as we go to levels outside of the realm of the Lanphear study the
slope stops increasing. It is another to assume direction of change in
slope suddenly reverses, and the slope plummets to zero. I agree that
when we have no data, we need to make an assumption---but this one seems
mathematically implausible. Further, there is other circumstantial
evidence that suggests it is not likely. Analyses of bone lead
concentrations from inhabitants of the Southwest desert in the US from
circa 1100 show much lower bone lead concentrations than in modern
Americans. These bone lead concentrations are consistent with blood lead
concentrations well below 0.1 µg/dL. Hence the range of blood lead we
are talking about for this extrapolation is still about an order of
magnitude higher than background concentrations.

p.59 The argument is made that the slope below 7.5 from Lanphear is
unreliable because a)it comes predominantly from one study; and b) it
includes only 103 children. This argument is undercut by the subsequent
publication of Tellez-Rojo (Pediatrics, 2006) of an analysis of a cohort
of 294 children, whose blood lead concentrations never exceeded 10
µg/dL. This study reported a significant association in 294 children in
two birth cohorts (not in the Lanphear pooled analysis) in Mexico City
whose blood lead concentration never exceeded 10 µg/dL. The slope of the
association between 24 month blood lead and 24 month MDI, when
restricted to blood lead concentrations never exceeding 5 µg/dL was -1.7
points/µg/dL, and highly significant (p=0.01). When 90 children whose
blood lead concentrations had exceeded 10 µg/dL but otherwise met all
inclusion criteria were analyzed, a smaller slope was found at the
higher dose. Hence, a significant association is found in another large
cohort of children who never exceeded 10 µg/dL, it is significant when
restricted to children who never exceeded 5 µg/dL, and this study also
confirms the nonlinear shape of the dose-response reported by Lanphear.
This study should be cited in the ANPRM, and its support for the
Lanphear study should result in a modification of the argument on p59
that support for the Lanphear analysis is "dissipated", which
incidentally elicits an image of a bedraggled Bruce, slumped over a bar.
I attach a PDF of the study for convenience.

P 59. The discussion of dose response makes much of the fact that the
loglinear function has undergone more extensive sensitivity analysis
than any other, and uses this to justify the log-linear function *with
linearization at the low dose*. However, this argument seems logically
inconsistent. First it argues that the most convincing evidence is for a
*nonlinea*r relation with the slope of the dose-response curve
constantly increasing as one goes to lower blood lead levels. Then it
argues that the slope must be *linear* below the bottom of the blood
lead levels observed in the study. But if all the evidence says we have
a nonlinear relation, what is the justification for suddenly linearizing
it? What that is saying is "everytime we test for a linear association,
the evidence is against us, so let's insist on it where there is not
enough evidence to show we are once again wrong". Anything is possible,
but is this really the most likely?

**Addendum to Comments on EPA's ANPR for the Lead NAAQS**

**Dr. Joel Schwartz**

December 14, 2007

The ANPRM has many pages devoted to elucidating an alternative to the
peer reviewed risk assessment, using instead the approach of 1978. In
1978, the evidence on the effects of lead on cognitive function was
limited to a few studies showing lower cognitive function in children
with "high" lead levels. Reasonably, EPA sent the ambient standard with
a goal of limiting the number of children with "high" blood lead levels.
Necessarily, such an approach recognizes no benefits to lowering blood
lead levels within the "not high" category, or within the "high"
category.

We know much more about the dose-response between lead and IQ now than
we knew in 1978. The CASAC has reviewed the CD and the Staff Paper and
expressed itself on that issue. While there is always uncertainty in the
dose-response relationship, it is clear that it is continuous, not a
step function, and that it persists to concentrations well below 5
µg/dL. Therefore, the proposed approach is a step backward and
inconsistent with the science. Merely substituting a level of 5µg/dL or
2 µg/dL for the earlier level does not remedy this defect, and ignores
the substantial health benefits from lowering ambient concentrations
that has been documented by the peer reviewed risk assessment, most of
which does not involve children moving from one category to another.

**Dr. Frank Speizer**

Pre-meeting Comments on ANPR for Lead dated December 5, 2007

Submitted by Frank E. Speizer, MD

12/11 /07

General Comment: Although the idea of replacing the Staff paper with
this ANPR was only approximately accomplished as we transition from the
"old style" to this new approach because of the court ordered Staff
paper, and because of what we have here I for one have to congratulate
the court for its fore-wisdom for insisting on a Staff paper. The format
of this ANPR is extremely disappointing. In sum it simply restates what
has come before in the form of a staff paper, and whether CASAC agreed
or did not agree with what was previously produced, and what CASAC has
recommended and then goes on to solicit further comment, presumably from
CASAC again and the public. If we did not have a Staff paper it is not
clear that the ANPR would have sufficient scientific input to make any
statement that resulted in a position that could be criticized one way
or another. I would have expected the ANPR to come to some conclusion
rather than restating the case, and by presenting the argument as it has
simply leaves open to the Administrator the option for doing anything he
wants, without scientific justification. Separate from this process we
will need to revisit what the role of CASAC will be in the future as
well as what will bind the Administrator in using scientific data with a
margin of safety to make a NAAQS. I as others on the committee have
already suggested recommend that we send not only a response to this
ANPR but a separate letter, addressed not only to the Administrator, but
also SAB and potentially the Congressional oversight committees of our
concerns with the execution of the changes in the standard setting
process and the degree to which the process appears **not to be
working.**

Paraphrase of areas in which EPA is soliciting comments

Primary Standard, Section III, C---Adequacy of the Current Standard.

1\. Question of delisting. Pp 114, 131. The whole question of delisting
was previously considered by CASAC and unanimously on two occasions
(documented in the appendices to the staff paper in which we responded
to the Administrator) **rejected.** To raise it again can only be to
solicit potentially biased responses from individuals and groups with
potential and real conflict of interest. Furthermore CASAC considered
whether the other Federal agencies were sufficient to provide adequate
protection. We rejected that and unless compelling argument can be
brought forward in some open forum I would recommend we reject it again.
This all raises a potential issue for future NAAQS procedures, when the
ANPR is supposed to replace the Staff paper. It is not clear that since
the public had the opportunity already to have input into the process
that lead to the CASAC summaries without repeating what has already been
said by CASAC isn't the Administrator essentially stepping backwards and
redoing what has already been done either with or without a Staff paper?
Is the Administrator aware of other data that has not already been
considered? If so shouldn't that be part of the ANPR? What will be the
procedure for vetting the additional information that comes into the
administrator's office? Will it meet the Federal Guideline of a Federal
Advisory Committee if it is not vetted though CASAC? These are serious
procedural issues that the current offered approach of the ANPR by
specifically soliciting additional input at this stage of the process
creates.

2\. Understanding the decline ratio for air-to-blood ratio. Pp120. I
believe the data reported in 1986 and the summary suggested in the CASAC
panel letter clearly indicted what the ratio implied. EPA seems to be
asking for new or additional data to help them understand further what
we have written. Again, I think we need to refer them back to our
previous comments.

Elements of the Standard

1.  Indicator. Pp135, 136. The exercise performed by Cavender and
    Schmidt dated as Memo 11/26/07, suggest that there is generally a
    high correlation between TSP and PM10; it is the case that there are
    significant discrepancies. At this point in time I think this means
    that we have to continue to go with the concept of all particles
    contribute to the risk. More research is obviously needed to sort
    this out. Further side by side studies that take into account
    potential confounders and risk modifiers may increase our knowledge
    as to factors influencing the deltas seen between TSP and PM10;
    however, in that research it will also be important to look as
    course and fine fractions as well. For now I would recommend staying
    with the TSP system but could be persuaded otherwise.

2.  Averaging time and Form pp143. CASAC has previously indicated a
    preference for a monthly average because of the evidence that blood
    Pb concentrations related to shorter time scales and therefore this
    would be more protective than the current quarterly scale. This was
    the recommendation that was rejected by the Administrator in the
    previous round of lead standard setting. In making the
    recommendation again, CASAC indicated that a second highest monthly
    would be acceptable. We now have some predictive data as indicated
    in Appendix table 5.A. The table is quite informative in predicting
    what might be seen and there clearly are regional differences in
    terms of potential for non-attainment of new standards below 0.5.
    Selecting from that table it would appear for the total country were
    TSP Pb are measured that an acceptable level of attainment for
    levels of exposure below 0.50 might be in the range of 75-85%. To
    obtain such levels one must move to somewhere around 0.20 with any
    of the averaging times of max quarterly, max monthly or 2^nd^ max
    monthly.

3.  Level pp148. The entire argument suggesting because CDC uses 10µg/dl
    as a monitoring level is simply wrong. The CDC level is an action
    level not a risk level. The data presented and fully discussed in
    both the CD and the Staff paper clearly demonstrates important
    health effects at or below the 5µg/dl and to even raise this issue
    and ask for comments is to mislead the public.

**Number range CHAPTERDr. Ian von Lindern**

**COMMENTS: THE USEPA LEAD NAAQS ADVANCE NOTICE OF PROPOSED RULEMAKING
(ANPR)**

CASAC Panel Member: Ian von Lindern, P.E.,Ph.D.

December 24, 2007

**General Comments**

The Staff Paper and the ANPR both include synthesis analyses of the
NAAQS process to this point. As a result, it is important that the flow
of information, the assumptions and underlying strategies of the
analyses, and the interpretations forwarded to the Administrator and the
public be objective, transparent and consistent. In that regard, there
are candid discussions missing from these documents. There is concern
that the message carried forward to the Administrator does not inform
policy makers, or the public, of the consequences of the Agency's
failure to adequately regulate lead in air over the last fifteen years.

The regulatory exercise that the EPA and CASAC are currently engaged in
evaluates the costs and benefits of the various alternative scenarios in
addressing contemporary lead exposures. This is clearly a difficult and
challenging task, largely due to lack of data regarding sources,
transport mechanisms, and exposures throughout the nation. This lack of
pertinent data can be traced to EPA's decision to not update the NAAQS
in 1991, followed by suspension of monitoring and collection of
characterization data.

In hindsight, EPA would have been well-advised to have lowered the NAAQS
to a protective level consistent with observed ambient concentrations.
In that case the monitoring programs would, likely, have not been
abandoned. Failure to recognize this shortcoming could result in
repeating that mistake in 2008 and eliminating the NAAQS, or adopting a
NAAQS that simply certifies current conditions.

The base of information for the 2008 decision-making process was
developed in the AQCD. Those data and findings were forwarded to the
Risk Assessment document, where analyses were performed to evaluate the
potential risk to human health and welfare across the nation. Those
results and findings were then interpreted and evaluated and Staff
conclusions and recommendations were captured in the OAQPS Staff Paper.
CASAC has followed, evaluated and provided input throughout this process
and staff has been attentive to and responsive to CASAC's comments and
suggestions. Staff did an excellent job under the circumstances
presented, and the Staff Paper recommendations are reasonable and
appropriate. Staff has also done a good job of summarizing and
presenting CASAC's views, conclusions and recommendations. Based on the
outcome of these documents, the recommendations made by CASAC in past
letters to the Administrator should stand as presented and that the
Staff Paper is adequate for use in assessing the NAAQS.

However, those same conclusions do not extend to the ANPR. This document
seems to be a meatless version of the Staff Paper, with no real
conclusions or recommendations. No standard is proposed, no position is
taken on whether the standard should be retained, there is vague mention
of, perhaps, deleting the standard, noting that lead compounds are
included in HAPs, and no tentative Agency position is provided. It seems
to be a solicitation for input on whether the Agency should agree or
disagree with its own Staff and Scientific Advisors. The Agency should
either agree or disagree with its staff and advisors, tell the public
why, espouse a proposed course of action, and then solicit comment on
that position.

This is critically important with the lead NAAQS because the agency
failed in 1990 to act on Staff and CASAC recommendations and that
decision, unfortunately, had unintended adverse effects for the Nation's
health, and for the NAAQS process. The current analyses could be
interpreted to indicate the numerous children have suffered cognitive
decrements and the Agency has little idea of the extent of deleterious
exposures in most of the country.

Perhaps the most important function of the ANPR is to convey the status
of air lead regulation to the public and underscore the policy the
Agency is using to protect the health and welfare. This document fails
to convey the poor state of knowledge regarding lead in air, the
Agency's role in allowing the knowledge base to deteriorate, the
uncertainties resulting from that lack of knowledge, the likelihood that
there is insufficient information available to consider deleting the
NAAQS, and that large margins of safety may be appropriate to assure
protectiveness in the development of the revision.

The Agency has failed in the last fifteen years in one of its primary
missions to characterize the extent and severity of this priority
pollutant's exposures in the U.S. The deleterious effects of lead have
always been underestimated and now, from a health perspective, there may
be significant damage ongoing to susceptible populations. Consequently,
the Agency must now reassess the significance of lead exposures without
adequate data and greater uncertainty. Twenty years ago lead was among
the best characterized priority pollutants in terms of exposure and
response relationships. As a result, the current NAAQS was adopted with
an atypically low margin of safety incorporated in the standard. Such a
low margin cannot be justified by the state of knowledge today.

This lack of data was first noted in the initial AQCD reviews by CASAC.
Almost no useful emissions or ambient air data were available in the
peer-reviewed literature in 2005. CASAC urged EPA to use the Agency's
own resources and the trade and professional literature to augment the
knowledge base. The Staff did find some useful information and included
this in the AQCD. However, there certainly was not sufficient data to
conduct a "national" risk assessment and Staff opted to develop pilot
risk assessments for three source-type situations. At the risk
assessment stage, CASAC was again critical of this approach, urging that
a "national" perspective risk evaluation be conducted. Staff made an
admirable effort to accommodate this request in the urban analyses
presented in the final Risk Assessment.

Despite the success of this effort, this risk assessment should be
recognized as largely a modeling exercise utilizing numerous
assumptions, often based on decades old data and empirical relationships
derived from environmental regimes that no longer exist in the U.S. This
approach was necessary and had to be undertaken because the data do not
exist to address this problem more appropriately. With regard to these
shortcomings, the discussions do not sufficiently convey the lack of
information and unknowns associated with the knowledge base of lead in
the air, as documented in the AQCD.

Nevertheless, these analyses show that there is substantial indication
of significant deleterious health effects (IQ decrements greater than 1
point) ongoing in, presumably, many areas of the country. These were
effects that were suspected in 1990 and it was recommended that a margin
of safety be incorporated into an NAAQS strategy to protect against this
possibility. That was not implemented. The default margin of safety
inherent in the 1978 Primary NAAQS, was clearly inadequate. This leads
to a potential interpretation-- that, despite phenomenal lead exposure
declines in other media, some children were likely harmed in the
interim, and little data were collected to support conducting a
"national" risk assessment when the Agency was forced in Court to
reconsider the NAAQS.

The status today as summarized, but not explicitly made clear, in these
documents is:

The 1978 Standard is clearly non-protective. A one to two order of
magnitude reduction should be considered requisite to an effective
health protective strategy.

The emissions and ambient air database is insufficient to characterize
the extent of potentially deleterious exposures across the U.S. Large
urban areas are largely uncharacterized with respect to both area and
point sources. There was not even sufficient data to characterize a
single secondary source in the country for this risk assessment.
Hypothetical data and combinations of data from different sites and time
periods had to be synthesized for the secondary source risk analyses.

The primary source analysis relies on an area that has been de-populated
and remediated, but continues to show substantial risk. The maximum (or
worst case) situation developed in the primary smelter application seems
to be about 50% of the current NAAQS. This result seems to derive from a
combination of the ratio between the quarterly and annual average, *and*
the current geographic disposition of population relative to the smelter
in Missouri. The ultimate result is that potentially worst case
exposures and estimated IQ decrement are possibly underestimated by a
factor of, perhaps, 1.5 to 2 times. Were the 1.5 km sub-area repopulated
to previous decade densities, a substantial portion of the childhood
population would exhibit unacceptable risk levels, in the current NAAQS
and current conditions scenarios.

As a result, exposures are likely underestimated, due to lack of
monitoring and coverage which the Risk Assessment and Staff Paper admit
for the urban cases, but seem less articulated in the ANPR.
Nevertheless, the pilot studies as presented indicate both urban and
point source communities are at risk of substantial harm.

A critical issue that has been seemingly ignored throughout this process
is the potential non-representative nature of the database that is being
used as it might apply for *future* applications. All emissions and most
of the ambient data are from the 2002-2005 era at best. This was an era
of relatively low lead production and use in the U.S. The emissions
picture and particularly, the spatial characterizations and peak-to-mean
ratios, used in the roll-up and roll-down calculations were based on an
industry in a minimal production and use mode.

There are suggestive data that indicating the possibility that this
trend may reverse and that potential increases in point source emissions
be considered. Base metal prices have exploded since 2005, first in
copper and zinc and, in the last year, by silver and lead. Recent metals
exchange prices are appended below. Production has increased, mining and
milling operations are being rehabilitated, and substantial legislative
lobbying for considerations in several forums supporting revival of the
industry in the U.S. are underway; much of it for national security
reasons. Significant damage to some of the nation's infrastructure is
occurring due to base-metal shortages and copper thievery. The energy
crisis in petroleum is leading to even more demand for these metals.

The country's mining and metal-refining and fabrication industries need
to know what the rules will be, what level of controls will be required,
and where EPA believes there are ongoing and significant ambient air
lead risk. The current standard and state of knowledge are both
inadequate to this task.

Reliance on HAPs seems questionable at this time. The documents only
note that HAPs is applicable. No presentation is provided regarding the
effectiveness of a technology based standard being protective in the
case of this ubiquitous contaminant. The EPA has not evaluated, and for
the most part does not know, the extent of deleterious exposures, where
current sources are located, how these impact local airsheds, the
sources that need to be controlled, nor the level of control required.
Had EPA revised the NAAQS to those levels considered to be of concern in
the 1990's and monitored accordingly, analyses of potential HAPs
applicability could be undertaken. Unfortunately that database is
probably lagging the imposition of a new standard and appropriate
monitoring by 3 to 5 years.

Few if any of these issues are discussed in the ANPR.

![](media/image3.png){width="4.688888888888889in"
height="2.813888888888889in"}

> Silver (source London Metals Exchange 12/4/07)

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  ![](media/image4.png){width="4.478472222222222in"
  height="2.717361111111111in"}

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Copper \$US/tonne (source London Metals Exchange 12/4/07)

![](media/image5.png){width="4.478472222222222in"
height="2.717361111111111in"}

Zinc \$US/tonne (source London Metals Exchange 12/4/07)

![](media/image6.png){width="4.478472222222222in"
height="2.717361111111111in"}

Lead \$US/tonne (source London Metals Exchange 12/4/07)

**Post-meeting responses to Pb ANPR -- Areas in which EPA solicits
comment**

The EPA invites general, specific, and/or technical comments on all
issues discussed in

this ANPR, including issues related to the Agency's review of the
primary and secondary Pb NAAQS (sections III and IV below) and
associated monitoring considerations (section V below). EPA also invites
comments on all information, findings, and recommendations presented in
this notice (section VI below). \[pp. 23-24, section II.D.\]

**Specifically, EPA solicits comments on ...**

**Primary Standard -- Approach for Current Review** {III.C.2 - p. 112}

... on the appropriate weight to be placed on the results from these
*{quantitative exposure/risk}*assessments in evaluating the adequacy of
the current primary standard and in considering alternative standards.

***These risk assessments are appropriate and should be given
substantial weighting as these are the best that can be accomplished
under the circumstances. Despite the success of this effort, this risk
assessment should be recognized as largely a modeling exercise utilizing
numerous assumptions, often based on decades old data and empirical
relationships derived from environmental regimes that no longer exist in
the U.S. This approach was necessary and had to be undertaken because
the data do not exist to address this problem more appropriately. With
regard to these shortcomings, the discussions do not sufficiently convey
the lack of information and unknowns associated with the knowledge base
of lead in the air, as documented in the AQCD.***

... on a number of aspects of the design of the assessments and
interpretation of the assessment results, including in particular:

\(1\) the appropriateness of rolling up ambient Pb concentrations to
simulate just meeting

the current standard for areas in which current concentrations are well
below the level of

the current standard;

***The emissions picture and particularly, the spatial characterizations
and peak-to-mean ratios, used in the roll-up and roll-down calculations
were based on an industry in a minimal production-mode. There is
suggestive evidence that production of base metals and use of lead in
consumer products may increase in the foreseeable future. As EPA has
indicated that it may entertain retaining the current standard, take no
action as occurred in 1991, or develop a new standard between the
current levels and the current NAAQS, analyzing the potential impacts
under the current standard seems requisite.***

***Moreover, should the Agency delete the NAAQS, and develop a
HAPs/technology-based approach and rely on other media controls to
reduce risk, emissions and ambient concentrations; this would likely
increase exposures in areas where new or expanding industries locate. As
such, consideration of the impacts of increased ambient concentrations
should be included in the decision-making process.***

\(2\) the use of a proportional method to roll-up and roll-down Pb
concentrations to simulate just meeting the current and alternative
standards;

***The methodology should be consistent with the above, but acknowledge
the inherent uncertainties, and should bias the analyses toward
protectiveness with an appropriate margin of safety. It should also be
explicitly noted that the risk assessments are based on current source,
receptor and population configurations. These do not emulate worst-case
scenarios that would be used in compliance evaluations for NAAQS
pollutants. Should new sources be developed, the roll-up analyses
presented in the risk assessments likely under-estimate exposures for
the determining allowable emission rates under a NAAQS scenario.
Additionally there is no discussion in any of the documents relating to
how potential impacts would be addressed in a HAPs-multi-media
strategy.***

\(3\) the categorization and apportionment of policy-relevant exposure
pathways and

policy-relevant background, particularly with regard to exposures
related to historically

deposited Pb from leaded gasoline and from Pb paint; and

***Lead is, and will continue to be, a multimedia multi-source
ubiquitous contaminant. Multiple effects must be considered in any
attainment strategy. Staff has done as good an analysis as can be
provided, given the scarcity of data. Should the Agency find that these
sources in whole produce unacceptable risk levels, then a coordinated
strategy to reduce exposures should be developed. Control of both recent
and past lead will be requisite. Presumably, the effort required for the
latter will diminish over-time, as the older sources are removed or
stabilized. Control of current sources will be an ongoing obligation.***

\(4\) the weight to be given to risk estimates derived using various
concentration-response

functions.

***The model form recommended by CASAC should be given the most weight
as it provides a margin of safety appropriate to the state of knowledge.
The results from the other functions should help frame the margin of
safety incorporated into the development of the control strategy. Please
see the CASAC's conclusions.***

... on the approach of considering exposures and risks resulting from
the ingestion of historically emitted Pb that may now be present in
indoor dust and outdoor soil (e.g., that associated with past use of Pb
in gasoline or Pb paint) impacted by ambient air Pb as being
policy-relevant for the purpose of setting a NAAQS.

***Consideration of these exposures is requisite to establishing a
protective health strategy. Remediation of past sources may be an
effective element in an eventual compliance strategy. As a result,
failure to consider these sources or relying on a technology-based
standard only addressing current sources would not be efficient or
effective.***

**Primary Standard**--**Adequacy of the Current Standard** {III.C.3 -
pp. 114, 120, 131, 132}... and supporting information on the issue of
whether it would be appropriate for EPA to determine that emissions of
Pb no longer contribute to air pollution that may reasonably be
anticipated to endanger public health.

***Because the Agency has little knowledge of the extent of exposures
currently in the U.S., EPA could only make this determination if it
required that all lead emissions be reduced to zero.***

... and supporting information on the extent to which reductions in the
ambient air Pb standard would benefit public health.

***The risk assessment developed indicates that current lead levels in
particular areas likely contribute to an IQ decrement in children living
in these areas. The extent of continuing exposures in urban areas and
the possibility that lead emissions may increase in the future indicate
that this effect may manifest in other communities. Lowering or
preventing these exposures and consequent neuro-cognitive effects would
be beneficial. The difficult question is how beneficial in relation to
other risks and expenditures. Please see the CASAC's conclusions.***

... on data or studies that may help inform our understanding of this
important parameter *{the air-to-blood relationship}*.

***Several studies have addressed this factor and Staff has done a good
job of identifying and comparing these results. It seems clear that the
ratios reported all have site-specific and study-specific considerations
related to a host of factors common to the ubiquitous lead exposures.
The approach used in 1978, clearly underestimated this ratio for air
quality regimes that followed and has been inappropriate for decades,
CASAC has advised using 1.5 and addressing the uncertainty through
applying an appropriate margin of safety.***

... on whether the broad range of current multimedia Federal and State
Pb control programs, summarized above in section II.C, are sufficient to
provide appropriate public health protection in lieu of a Pb NAAQS.

***Several non-air programs implemented by various entities have
resulted in major reductions in lead exposures from non-air sources, and
decreases in re-entrained or fugitive source emissions. As a result the
baseline lead level (from non-air sources) has declined dramatically, as
noted. CASAC estimated this reduction as decreasing typical mean blood
lead levels from 12 µg/dl to 1-1.4 µg/dl. Exposures and blood lead
levels in some areas, however, remain higher as residual lead continues
to circulate in the environment. Significantly less reduction, however,
has been due to lead in air since the 1990s. Most of the reductions in
lead emissions were achieved by curtailment of industry associated with
the economics of mineral industry and consumer goods that utilize lead.
No analyses have been presented in any of the documents regarding the
possibility of increased lead output and emissions.***

... on delisting, revocation, and the adequacy of the current standard
and the rationale upon which such views are based.

***There is overwhelming evidence of the adverse effects of lead at
blood low-levels noted for young children in the U.S. today. Lead is an
ubiquitous contaminant present in several media involved in air-related
transport and transformation processes. There is an overwhelming absence
of emissions and ambient exposure data available to assess how many U.S.
children at at-risk today. The EPA should not consider deleting the
NAAQS simply because the Agency has neglected to monitor.***

**Primary Standard -- Elements of the Standard-- Indicator**
{III.C.4.a - pp. 135, 136}

... on previous Agency conclusions that the health evidence indicates
that Pb in all particle size fractions, not just respirable Pb,
contributes to Pb in blood and to associated health effects.

***The Agency should continue to assess and monitor all size fractions
through direct or surrogate methods.***

... and information that would help inform such analyses *{of Pb
particle size relationships}* and the Agency's views on the indicator
for the primary Pb NAAQS.

***Please see the CASAC's conclusions.***

**Primary Standard - Elements of the Standard-- Averaging Time and
Form**

{III.C.4.b - pp. 143}

... on a range of options, including the recommendations in the Staff
Paper that include changing the averaging time to monthly, with a form
of maximum or second maximum, as well as retaining the quarterly
averaging time.

***Please see the CASAC's conclusions.***

... on the options of changing the form to apply to a three-year period
as well as retaining a single-year period.

***Please see the CASAC's conclusions.***

... on these ranges of averaging times and forms as well as views and
related rationales that might support alternative options.

***Please see the CASAC's conclusions.***

**Primary Standard - Elements of the Standard --Level**

{III.C.4.c-pp. 143, 148, 149, 150, 160, 161}

... on a wide range of possible options ... range from lowering the
standard, to the levels recommended by CASAC and the OAQPS Staff paper
or lower, as well as on other alternative levels, up to and including
the current level, and the rationale upon which such views are based.

***Lead should be retained as a criteria air pollutant; (2) the lowering
of the Lead NAAQS substantially below the current value is
fully-justified; and (3) a new indicator for lead should be developed.
Please see the CASAC conclusions.***

... on the appropriateness of using a mean or individual target blood Pb
value of 10 μg/dL as the foundation for deriving a level for the primary
Pb standard.

***Totally inappropriate, please see the CASAC's conclusions.***

... on mean target blood Pb levels as well as other factors that would
be important in applying the 1978 framework *{using the current
evidence}*.

***The new standard should recognize the benefits of lowering blood lead
levels across the entire population, as well as preventing threshold
concentrations for the most-exposed individuals.*** ***Please see the
CASAC's conclusions.***

... on the definition and appropriate values for this parameter *{the
nonair (background)*

*contribution to total blood Pb}*

***The NAAQS compliance strategy should consider all sources of lead,
coordinate with other federal, State and local programs effecting
reductions in other media and include past-air impacts and exposure
reduction strategies directly in the NAQQS.***

... and supporting information regarding the air-to-blood ratio and
differences in the available estimates.

***Please see the CASAC's conclusions.***

... on all of these factors *{important to application of 1978
framework}*

... on the 1978 standard setting framework and on alternate approaches
and the factors that are relevant to those approaches.

***Please see the CASAC's conclusions.***

... on levels of IQ loss considered to be significant from a public
health perspective.

***Please see the CASAC's conclusions.***

... on the magnitude of IQ loss associated with exposures to ambient Pb
by the pathways

categorized as "recent air" in the risk assessment described in this
notice that are considered to be significant from a public health
perspective.

***Please see the CASAC's conclusions.***

... on the approach of adopting a public health policy goal of limiting
policy-relevant air

exposure such that the incremental blood Pb level (and the associated
resulting IQ loss) are below a specified level (e.g., to a magnitude of
0.5 or 1 μg/dL, or other alternative values).

***Please see the CASAC's conclusions.***

**Dr. Barbara Zielinska**

**THE US EPA LEAD NAAQS ADVANCE NOTICE OF PROPOSED RULEMAKING (ANPR)**

**Comments on Section V:** **Considerations for Ambient Monitoring**.

Barbara Zielinska

My general comment regarding the Pb ANPR is that if this document is
designated to replace the Staff Paper in the future, I would expect it
to be more conclusive and not only limited to a restatement of the
Agency's Staff Paper findings and CASAC recommendations. Specifically,
one would expect some sort of justifiable recommendations as to the
indicator, level, statistical form, and averaging time of the standard
and not only an invitation for all interested parties to submit their
recommendations. After all, this document was formulated after several
years of gathering and synthesizing new scientific information on this
subject and at this stage the Agency should be able to formulate some
conclusions regarding the range of the Pb standard. Saying that all
policy options are still on the table, from delisting Pb as a NAAQS,
keeping the present level of 1.5 µg/m^3^ or going down to 0.02 µg/m^3^,
is like starting the whole process all over again.

My specific comments are limited to Section V, Considerations for
Ambient Monitoring, as requested by Dr. Rogene Henderson. For this
Section, the Agency invites comments regarding (a) sampling and analysis
method; (b) network design; (c) sampling schedule; (d) data handling;
and (e) monitoring for secondary standard.

Regarding (a), the CASAC Pb Panel had strongly encouraged the Agency in
its previous letter to the Administrator (Henderson, 3/27/07) to
consider revising the indicator for Pb sampling from TSP to low volume
PM~10.~ The current ANPR and associated support documents (memos by
Cavender and Schmidt 11/26/07, and Camalier and Rice, 11/29/07),
reviewed the collocated Pb-TSP and Pb-PM~10~ data and evaluated the
precision and bias of the Pb-TSP monitors. Although the high-volume TSP
methods have an average precision of 11.7 % with a standard deviation of
18.6 %, it is evident from Figure 1 of Camalier and Rice memos, that at
the relevant ambient concentrations below 1 µg/m^3^ this precision is
much worse (and this is after exclusion of 21% of measurements which
were below MDL of 0.01 µg/m3). The memo comparing Pb-TSP and Pb- PM~10~
data also shows that the relation between these two measurement methods
is much worse at lower concentrations (below 0.03 µg/m^3^). Both, the
average sampling bias (based on the flow audits) and the bias for lab
analyses were low (in the range of 1%), so they do not contribute
significantly to the overall precision of Pb-TSP monitors. These pieces
of information taken together indicate some problems with TSP monitors.
The variability of TSP sampler cut size, the higher minimum detection
limit (MDL) associated with TSP-Pb sampling, and the relatively poor
precision at lower Pb concentrations all contribute to variability in
the TSP-Pb indicator. In my opinion, PM~10~ samplers are preferred over
the much less reliable, old technology, TSP samplers. PM~10~ samplers'
inlet is much better characterized, they are used in many sampling
locations and they are utilized for many other measurements, including a
suite of elements, in addition to Pb. The TSP monitors are used for lead
only and they have been discontinued in many sampling locations. I do
not recommend retaining hi-volume Pb-TSP monitors, neither investing in
the development of low-volume, sequential Pb-TSP samplers.

The memo "Summary of method detection limits" by Rice, indicates that
the current FRM analytical method (based on atomic absorption) has the
highest MDL. Since this MDL was estimated for high-volume TSP samplers,
if the low-volume samplers are to be used in the future, the analytical
MDL would be even higher (per m^3^). For these reasons, I would rather
recommend more sensitive and widely used analytical methods, such as XRF
or ICPMS. Clearly, ICPMS has a superior sensitivity of 0.00001 µg/m^3^
(for high volume samples). However, XRF (which is less expensive) may be
sufficient for the lowest alternative NAAQS -- based on my experience,
the MDL for the equivalent high-volume sample would be 0.005 µg/m^3^

Regarding (b), I favor the option number 4: to utilize the current
PM~10~ network. I'm not particularly concerned about finding an
acceptable regional or site-specific correlation of Pb-TSP and Pb-
PM~10~, since I do believe that Pb-TSP are much less accurate than Pb-
PM~10~ and I don't think that the Pb-TSP method can serve as a "golden
standard", especially if the Pb NAAQS will be tightened considerably.
Since PM~10~ monitors may not be currently located near the large Pb
emission sources, the additional monitors may be utilized at these
specific sites. Also, since Pb levels and particle size ranges are
expected to be higher near major Pb emission sources, Pb-TSP monitors
can be used, in addition to Pb-PM~10~ to establish the equivalency
factor for these specific sites. There are only a few such major Pb
emission sources in the U.S. anyway.

Regarding (c), sampling schedule, if the monthly averaging period is
selected, the sampling frequency should be increased from 1-in-6 to at
least 1-in-3 sampling schedule. This would yield sufficient amount of
samples per averaging period with 75% completeness. However, I'm not
feeling very strongly about monthly averaging period. I think quarterly
averaging period could be acceptable as well, especially at sites that
consistently fall below the standard.

Regarding (d), data handling, I assume that that the third bullet should
specify that 50% of the expected number of samples is needed for a month
to be considered complete, if daily sampling schedule is adopted.
Otherwise, for 1-in-3 sampling schedule, 75% should be required.

Regarding (e), monitoring for the secondary NAAQS, I think that the
Pb-PM~2.5~ data from the IMPROVE network should be utilized to track
changes in ambient Pb concentrations in rural and remote areas. Since it
is very likely that in these remote locations nearly all (if not all) Pb
is present in the PM size range below 10 µm, PM~10~ monitors can be used
to develop the relationship between Pb- PM~10~ and Pb- PM~2.5~.
Likewise, the data from the National Water Quality Assessment (NAWQA)
and Geochemical Landscape project should be used to track the
concentrations of Pb in water bodies and soil, respectively.