UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON D.C. 20460
OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
July 18, 2008
EPA-CASAC-08-016
The Honorable Stephen L. Johnson
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
Subject: Clean Air Scientific Advisory Committee (CAS AC) Comments and
Recommendations Concerning the Proposed Rule for the Revision of the
National Ambient Air Quality Standards (NAAQS) for Lead
Dear Administrator Johnson:
The Clean Air Scientific Advisory Committee (CAS AC), augmented by subject-matter-
expert Panelists collectively referred to as the CASAC Lead Review Panel (CASAC Panel)
met via a public teleconference on June 9, 2008. The purpose of this conference call meeting
was to hold discussions and provide comments concerning the Environmental Protection
Agency's (EPA) Proposed Rule for the Revision of the National Ambient Air Quality Standards
(NAAQS) for Lead (40 CFR Parts 50, 5 1, 53 & 58), which the Agency released on May 1, 2008,
and which was published in the Federal Register on May 20, 2008 (73 FR 29184-29291). The
CASAC Panel held a subsequent public teleconference meeting on July 8, 2008 to discuss, and
for the chartered CASAC to approve, the draft letter (dated June 30, 2008) containing our
comments and recommendations. The CASAC Panel roster is enclosed.
While the CASAC is pleased that the Agency has recommended substantially lowering
the allowable air concentration (i.e., the level of the NAAQS) for lead in ambient air which
has not been revised since 1978 the CASAC has several critical concerns vis-a-vis the Notice
of Proposed Rulemaking (NPR), including:
ongoing problems with respect to the implementation of EPA' s revised NAAQS review
process;
the last-minute introduction of a new analytical framework i.e., the "Air-related IQ
Loss Evidence-based Framework" as the basis for setting the primary (human-health
based) Lead NAAQS a framework that was not previously presented for review by the
CASAC or the public and also apparently excludes other analyses that had been produced
to date by the Agency and subject to such external review;
-------
the Agency's consideration of values for certain critical parameters (e.g., the air-to-blood
ratio and the slope of the concentration-response function curve) in this analytical
framework that are contrary to those recommended by the CASAC, and that would
justify a significantly-higher level for the primary Lead NAAQS than the CASAC
recommended at the expense of the values for those selfsame parameters that the
CASAC documented as being most relevant for the low levels of blood lead (Pb) found
in U.S. children today;
the misrepresentation of the CAS AC's statement that "the primary lead standard should
be set so as to protect 99.5 % of the population from exceeding an IQ loss of 1-2 points"
to wrongfully suggest that CASAC declared that an average loss of one to two IQ points
in the population was an acceptable public-health endpoint; and
the Agency' s proposal of a range for the level of the primary standard that includes an
upper bound (i.e., 0.3 |ig/m3) which is higher and therefore less health-protective
than that recommended in the final EPA Staff Paper and by the CASAC in any of its
previous letters to you on this subject.
The following paragraphs describe in detail these and other concerns that the CASAC
identified in the Agency's proposed rule for the revision of Lead NAAQS and, where applicable,
reiterate the scientific basis for the CAS AC's previous recommendations.
Implementation of Agency's Revised NAAQS Review Process
Before commenting on the substance of the NPR, the members of the chartered
(statutory) CASAC wish to note that they are extremely, and increasingly, concerned about the
lack of a reliable, standard "roadmap" for the implementation of the new NAAQS review
process, as starkly illustrated by the content of this NPR. With the introduction of any new
process, of course, it is essential that such a "path forward" be clearly delineated and followed
from the outset. However, CASAC members cannot overstate how dissatisfying it has been to
observe the introduction of the Agency's revised process for reviewing the NAAQS
especially in the middle of the current review of the Lead NAAQS without any discernible,
well-organized plan.
As a significant example of the root cause of the CASAC's frustration, we noted in our
January 23, 2008 letter on this subject (EPA-CASAC-08-008) that, in the memorandum from
EPA Deputy Administrator Marcus Peacock dated December 7, 2006, the Agency stated the new
process would include a true policy assessment that reflects the views of EPA management to
be published in the Federal Register as an advance notice of proposed rulemaking (ANPR)
that would "describe a range of options for standard setting, in terms of indicators, averaging
times, [statistical] form, and ranges of levels for any alternative standards," along with the
underlying scientific justification and supporting data and analyses for each of these." The
Deputy Administrator's memo goes on to state that such a policy assessment would "help ...
'bridge the gap' between the Agency's scientific assessment and the judgments required of the
Administrator in determining whether it is appropriate to retain or revise the standards."
Therefore, the CASAC was surprised to read in the NPR that, "in analyses subsequent to the
Staff Paper and ANPR, the Agency has primarily considered the evidence in the context of an
-------
alternative evidence-based framework" (73 FR 29238, italics not in original) that is, the
aforementioned "air-related IQ loss framework." While it is entirely reasonable to expect that
the policy assessment contemplated by the Deputy Administrator's December 2006 memo would
include such an "evidence-based" analytical framework, the CASAC notes with dismay that this
alternative framework is not found in the Lead Staff Paper, the Lead Risk Assessment or the
ANPRfor the LeadNAAQS.
Therefore, the CASAC is led to conclude that the ostensible scientific basis for standard-
setting that had been previously presented for rigorous review by the CASAC and the public was
substituted at the last minute for an "alternative" analytical framework that EPA plainly notes
was their primary consideration as the basis for the proposed rule for the Lead NAAQS. At a
minimum, the manner in which this process is being implemented suggests that the Agency is
"winging it" in an ad hoc, rather than a systematic, manner. This is not what the public expects
of their EPA.
Finally, the CASAC notes with disappointment that, to date, there has been no response
from the Agency to our January 23, 2008 letter. In that letter, the CASAC complimented certain
features of the new NAAQS process (e.g., the "kick-off science workshop and the integrated
science assessment. However, the CASAC also requested a modification of other aspects of the
revised process (such as the absence of a meaningful policy assessment discussed above) that
appear to be ever-shifting and that tend to conceal the Agency's underlying scientific analyses
from its own, statutorily-mandated scientific advisory body.
Introduction of New Air-Related IQ Loss Evidence-based Framework
By the Agency's own acknowledgment, as noted above, the analyses that led to the
proposed range for the standard, especially the upper bound of 0.3 |ig/m3 (and possibly extending
as high as 0.5 |ig/m3), are based primarily on consideration of the evidence found "in the context
of an alternative evidence-based framework" resulting from analyses conducted subsequent to
the release of the Final Lead Staff Paper (November 1, 2007) and the ANPR for the Lead
NAAQS (December 17, 2007) that is, the evidence in a single new meta-analysis, entitled the
"Air-related IQ Loss Evidence-based Framework." The following comments are focused
primarily on this new analytical framework:
1. Timing: In the professional judgment of the CASAC, the issuance of the NPR is far too late
a point in the regulatory process to introduce a set of new and apparently determinative risk
calculations. The CASAC notes that the Agency's stated intent is that this evidence-based
framework "builds on a recommendation by the CASAC Pb Panel" (73 FR 29237). The
CASAC infers that this recommendation stems from the information contained in Appendix
D of the CAS AC's letter of March 27, 2007 (EPA-CASAC-07-003) concerning its review of
the 1st Draft Lead Staff Paper (December 2006) and the Draft Lead Exposure and Risk
Assessments (December 2006). The CASAC included Appendix D in its letter in order to
provide the Agency with several population-based risk assessment analyses for the primary
Lead NAAQS. However, the CASAC questions why EPA's analyses reflected in this "Air-
related IQ Loss Evidence-based Framework" were not explicitly presented to the CASAC
much sooner, either as part of the Agency's 2nd Draft Lead Human Exposure and Health Risk
Assessments (July 2007), the Final Lead Risk Assessment (November 2007), or the Final
-------
Lead Staff Paper (November 2007) or, at the very least, aired for open review by the
CASAC and the public in the ANPR (December 2007). Instead, at this very late stage in the
rulemaking process, we are presented with a set of heretofore unseen quantitative analyses
an unfortunate scenario that, by definition, precludes an in-depth, thoughtful deliberation by
the CASAC. Our objections to these analyses are noted in detail below. Moreover, there is
considerable concern that this might be an example of EPA's "standard operating
procedures" under the new NAAQS review process.
2. Exclusivity: All other previous analyses, risk/exposure assessments, staff, CASAC and
public recommendations appear to have been set aside, with this single new meta-analysis
used as the exclusive basis for the proposed NAAQS level. The range of proposed standards
appears to be predominantly driven by alternative and, in the C AS AC's judgment,
unwarranted assumptions of the appropriate concentration-response (C-R) functions to
relate IQ score point reductions to blood Pb concentrations, combined with a policy judgment
that a mean population loss of up to two IQ points is the desired health outcome of a revised
Lead NAAQS. Significantly, the CASAC notes that, aside from this new "air-related IQ loss
evidence-based framework, " no other analyses are presented that support a level as high as
0.3 (or 0.5) fig/m3.
3. Air Pb-to-blood Pb ratios: The analytical results are constrained to an assumed range of
air-to-blood ratios of 1:3 to 1:7, which is described as being consistent "with the results and
observations drawn from the exposure assessment, including related uncertainties" (73 FR
29197). But this is only true if one: (1) discards the many estimated ratios that fall above this
range; (2) ignores the clear indications that the air Pb to blood Pb ratio increases as both air
Pb and blood Pb decrease; and (3) assumes that the related "uncertainties" are directionally-
biased and somehow justify the use of lower ratios that are more representative of the much
higher air Pb and blood Pb levels found in the U.S. in the 1970s and 80s. By contrast, EPA's
Final Lead Staff Paper noted that, while "there is uncertainty and variability in the absolute
value of an air-to-blood relationship, the current evidence indicates a notably greater ratio...
e.g., on the order of 1:3 to 1:10" (p. 5-17) that is, not 1:3 to 1:7.
Even from EPA's 1986 Air Quality Criteria Document (AQCD) for Lead, the
analysis cited asBrunekreef etal. (J. Air Pollut. ControlAssoc. 1983; 33: 872-876) indicated
an air-to-blood ratio of 1:8.5. The Schwartz and Pitcher analyses (Schwartz, J., Pitcher, H.,
J. Official Stat. 1989; 5(4): 421-431) suggest a ratio of 1:9 or 1:10. Additionally, results
from Hayes et al. (Pediatrics 1994; 93:195-200) suggested a range from about 1:6 (at high
air Pb levels near 1 |ig/m3) to 1:16 (at ambient air Pb of about 0.25 |ig/m3 which are within
the range currently being considered for the Lead NAAQS). In EPA's Final Lead Risk
Assessment, estimated ratios ranged from 1:2 to 1:9 across the range of alternative standards
considered for the urban case study and from 1:10 to 1:19 across the range of alternative
standards considered for the primary smelter. The NPR discredits these risk assessment
calculations by noting (without attribution of authorship) that "some have suggested,
however, that the regression modeling ... could produce air-to-blood Pb ratios that are biased
high" (73 FR 29197), although it later notes (73 FR 29215) that the ratios used in the risk
assessment "reflect a subset of air-related pathways related to inhalation and ingestion of
indoor dust [and that] inclusion of the remaining pathways would be expected to yield higher
ratios." The lower end of the proposed range (1:3) reflects the much higher air and blood
levels encountered decades ago, while the upper end of the range (1:7) fails to account for the
-------
higher ratios expected at lower current and future air and blood Pb levels, especially when
multiple air-related lead exposure pathways are considered.
The NPR states (73 FR 29197), "For the general urban case study, air-to-blood ratios
ranged from 1:2 to 1:9.... [and] this pattern of model-derived ratios generally support the
range of ratios obtained from the literature and also supports the observation that lower
ambient air Pb levels are associated with [a] higher air-to-blood ratio." As several CASAC
Panel members noted in their individual written comments attached to the CASAC's March
27, 2007 letter (EPA-CASAC-07-003), the best documented evidence for the blood-to-air
ratio under current conditions is based on actual epidemiology data showing that declines in
U.S. national blood Pb levels from the National Health and Nutrition Examination Survey
(NHANES) surveys tracked declines in EPA- and state-monitored air Pb levels over the same
time period and the air-to-blood ratio was 1:10. Given that there is agreement that the lower
the current air Pb levels the higher the air-to-blood ratio, the CASAC recommends that the
Agency use an air-to-blood ratio closer to 1:9 or 1:10 as being most reflective of current
conditions.
4. C-R Functions: The critical concentration-response functions used in this meta-analysis
represent the estimated slope of the relationship between IQ point decrements and blood Pb
concentration. As summarized in Table 1 of the NPR (73 FR 29203), the analysis identifies
two groups of C-R functions one with steeper slopes (ranging from -1.71 to -2.94 IQ
points per |ig/dl blood Pb) and one with shallower slopes (ranging from -0.4 to -1.79 IQ
points per |ig/dl blood Pb). The median value of the shallow-sloped group (-0.90) is
subsequently used (as the "2nd group of C-R functions") in the summary Table 7 "Estimates
of Air-Related Population Mean IQ Loss for Children Exposed at the Level of the Standard"
(73 FR 29239). Like the lowest air-to-blood Pb ratio (1:3), the shallow-slope C-R function
(-0.9) is based on analyses of populations exposed to much higher air Pb concentrations and
exhibiting much higher blood Pb levels than is appropriate for current U.S. populations and
the levels under consideration for a revised Lead NAAQS.
For example, the median blood Pb level for children one to five (1-5) years of age
from the NHANES survey dropped from 3.5 |ig/dl in 1988-91 to 1.9 |ig/dl in 2003-04 (at
which time the 90th percentile blood Pb level was 3.5 |ig/dl. However, all eight of the
"shallow slope" C-R functions presented in Table 1 had geometric mean blood Pb levels
(indicated as "BLL" in Table 1) greater than 3.3 |ig/dl, and the four studies with slopes below
the median value of-0.9 IQ points/|ig/dl BLL had geometric mean blood levels ranging
between 4.3 and 9.7 |ig/dl. Within the shallow-slope group, the only studies with geometric
mean BLLs less than 4 |ig/dl (which were the only studies in that group based entirely on
U.S. population groups) had slopes of-1.6 and -1.8 respectively. It is only the combination
of the lowest C-R slopes and lowest air Pb to blood Pb ratios both representative of much
higher exposure conditions of 30 years ago that provides any basis for considering a
standard as high as 0.3 jjg/m .
In questioning the validity of the higher slope C-R functions (typically based on
lower blood Pb level population subsets of larger population studies), the NPR (73 FR
29209) first notes that "these analyses are quite suitable for the purpose of investigating
whether the slope at lower concentration levels is greater compared to higher concentration
levels" but then cautions that the "use of such coefficients as the primary C-R function in
-------
a risk analysis such as this may be inappropriate." The NPR further notes that, while a subset
of children with maximal blood Pb levels below 7.5 |ig/dl "may better represent current
blood Pb levels, not fitting a single model using all available data may lead to bias" (73 FR
29209). Therefore, the NPR admits that the slope of the C-R functions steepens at lower
concentration and also concedes that this is more reflective of the current blood Pb levels.
However, the NPR then concludes that limiting the C-R analysis to this range of blood Pb
levels would introduce "bias." This vague statement is not only completely unscientific
(since any assertion of "bias" should be accompanied by a demonstration of why that is the
case and include appropriate references), it is also at best a specious argument, since we are
indeed concerned with current blood Pb levels in the setting of a health-protective NAAQS,
not with blood Pb levels of the past.
Furthermore, the CAS AC rejects the suggestion that the existence of "a larger set of
studies" (73 FR 29238) indicating C-R functions with shallower slopes is scientifically-
relevant for choosing the most appropriate C-R functions for risk analyses. Rather, the
selection of C-R function should be based on determining which studies indicate slopes that
best reflect the current, lower blood Pb levels for children in the U.S. which, in this
instance, are those studies from which steeper slopes are drawn.
In turn, the CASAC notes that three additional studies have recently been published
that confirm the steep slope at the lowest blood lead concentrations (Surkan et a/.,
NeuroToxicology 2007; 28:1170-1177; Solon et a/., JPediatr 2008; 152:237-43; and Jusko
et a/., Environ Health Perspect 2008; 116:243-248, the last of which is a follow-up of the
cohort first described in Canfield etal, New EnglJMed2003; 348:1517-26).
5. Target IQ Decrements: The air-related IQ loss framework proposes a target mean IQ
decrement of roughly one to two (1-2) points in the population as a level of damage that the
proposed standard is intended to protect against. This target level has been erroneously
attributed as being the CAS AC's recommendation. The use of this target level is
inappropriate for several reasons. First, in the CASAC's letter dated March 27, 2007 (EPA-
CASAC-07-003) from its review of the Agency's 1st Draft Lead Staff Paper and Draft Lead
Exposure and Risk Assessments, the CASAC wrote that "the CASAC Lead Review Panel
considers that a population loss of 1-2 IQ points is highly significant from a public health
perspective. Therefore, the primary lead standard should be set so as to protect 99.5% of the
population from exceeding thatlQ loss" (italics in original).
The CASAC wishes to emphasize that this comment refers to 1-2 IQ points as being a
"highly significant" loss to be prevented not as a desired national damage level goal that a
standard should be set to assure. The CASAC also notes that the recommendation is that IQ
decrements as large as this should be prevented in all but a small percentile of the population
and certainly not accepted as a reasonable change in mean IQ scores across the entire
population. Indeed, if a loss of one IQ point (rather than losses of up to 3.9 points) in mean
IQ levels were considered a significant loss to be prevented, this analysis would point to a
range of proposed standards between 0.05 and 0.2 jjg/m , with the lower end of that range
being more consistent with the higher C-R slopes and higher air-to-blood ratios
representative of current U.S. ambient air and blood lead concentrations. However, by
combining the lowest air-to-blood Pb ratios (1:3), the shallowest C-R slope (-0.9) and a
higher-than-acceptable IQ decrement endpoint (>1 IQ point), the NPR subsequently, even
-------
shockingly, goes on to suggest (73 FR 29244) that a standard as high as 0.5 jug/m3 would
somehow be adequate to protect public health while failing to point-out that, at the higher
air-to-blood ratios and steeper C-R slopes more representative of current U.S. exposures,
this contemplated level of the standard would allow mean losses of five (5) 1Q points or
more.
Level of the Primary Lead Standard
As noted above, the proposed upper-bound level of 0.3 |ig/m3 for the revised Lead
NAAQS lies above the upper bound of levels recommended by both EPA Staff and by the
CAS AC Panel. The NPR indicates (73 FR 29190) that three general sets of recommendations
were taken into account in developing this proposal: "(1) staff assessments .. .upon which staff
recommendations for revisions to the primary Pb standard are based, (2) CASAC advice and
recommendations.. .and (3) public comments..."; and further states that "among the many public
comments the Agency has received in this review regarding the level of the standard, the
overwhelming majority recommended appreciable reductions in the level, e.g., setting it at 0.2
|ig/m3 or less..." (73 FR 29241). (For the CASAC's previous advice to the Agency concerning
this CAS AC-recommended level of the Lead NAAQS, see our letters dated March 27, 2007
[EPA-CASAC-07-003, p. 6 & Appendix D]; September 27, 2007 [EPA-CASAC-07-007, p. 2];
and January 22, 2008 [EPA-CASAC-08-007, pp. 2, 5].) Accordingly, since the overwhelming
majority of public comments, the recommendations in the EPA Staff Paper and underlying risk
and exposure analyses, and the CASAC Panel's unanimous recommendations advocated a
maximum level of 0.2 |ig/m3 or less, it is not clear either where this proposal for a higher (that is,
less stringent) level of 0.3 |ig/m3 level for the primary Lead NAAQS originated (i.e., on what
scientific basis) or why it is necessary at this late stage in the rulemaking process to seek
additional public comment on levels for the Lead NAAQS ranging as high as 0.5 |ig/m3.
Lead NAAQS Indicator
In several rounds of previous comments, the CASAC Panel recommended that a revised
(and substantially-lowered) Lead NAAQS should be accompanied by a transition of the sampling
indicator from total suspended particulates (TSP) to a low-volume ambient air monitor for lead
in paniculate matter (PM) less than 10 micrometers in diameter (PMio) in ambient air. In the
CASAC's advice dated January 22, 2008 (EPA-CASAC-08-007), the CASAC noted that the
CASAC Panel "unanimously supported the selection of an [PMio] indicator that can be more
robustly measured and thus would be more representative of actual population exposures,"
adding that "a more accurate and precise Pb-PMi0 indicator would provide a more stable
determination of compliance with the new lower Lead NAAQS." With regard to concerns over a
potential loss of ultra-coarse lead particles by PMio samplers, the CASAC Panel further noted
that "it would be well within EPA's range of discretionary options to accept a slight loss of ultra-
coarse lead at some monitoring sites by selecting an appropriately conservative level for the
revised Lead NAAQS." In a subsequent teleconference consultation by the CASAC Ambient
Air Monitoring and Methods (AAMM) Subcommittee held on March 25, 2008, a majority of the
subcommittee members also supported a transition from TSP to low-volume PMio sampling for
lead (see EPA-CASAC-08-010 dated April 14, 2008).
-------
The CASAC needs to call attention to the fact that these recommendations were based, in
part, on an assumption that the level of the primary Lead NAAQS would be "substantially"
lowered to the EPA Staff-recommended range (with an TSP indicator) of between 0.1 to 0.2
|ig/m3 as an upper bound and 0.02 to 0.05 |ig/m3 as a lower bound (with the added consideration
that the selection be made somewhat "conservatively" within this range to accommodate the
potential loss of ultra-coarse lead with a PMi0 Pb indicator). For example, at most population-
orientated monitoring sites, levels of PMio Pb are essentially the same as TSP Pb, but at source-
oriented monitoring sites with high coarse mode particulate lead emissions, TSP Pb was roughly
twice as high as PMio Pb. This factor-of-two difference is small compared to the factor of 10 to
100 of the recommended lowering in the level of the standard, and could be readily
accommodated by considering a slightly more conservative upper bound of 0.1 |ig/m3 rather than
0.2 |ig/m3.
However, since with the publication of this proposed rule for the revision of the Lead
NAAQS the Agency now appears to disagree with previous staff recommendations as well as
those of the CASAC and the "overwhelming majority" of the public and is considering an
upper bound of 0.3 |ig/m3 and possibly as high as 0.5 |ig/m3, a transition from TSP to PMio at
these much less protective upper levels of the proposed range could represent a critical
weakening of the health protection afforded at the level of the standard that the CASAC
proposed. Significantly, a particulate (PM10) Lead standard at 0.5 pg/m3 could potentially allow
TSP Pb levels as high as 1 jug/m3 at sites near large sources with coarse-mode particulate lead
emissions. Therefore, if the level of the standard is set toward the upper end of the range the
Agency is now considering, the CASAC is unanimous in its recommendation that the current
TSP indicator should not be changed. As previously recommended, a transition to a PMio
indicator would be preferable, but only at a level conservatively below an upper bound of 0.2
|ig/m3 or lower.
Lead NAAQS Averaging Time and Form
The NPR proposes consideration of a monthly averaging time with a "second highest
month in three years" form, but also seeks comment on retaining the current "calendar" quarter
"not to be exceeded" form. The CASAC wishes to emphasize that there is no logic for averaging
only by "calendar" quarter, as there is nothing unique about effects that may occur exclusively
during the four calendar seasons. A "rolling" three-month (or 90-day) average would be more
logical than a "calendar" quarter. The CASAC's previous recommendations both in the
current review cycle and during the prior review of the Lead NAAQS conducted in the 1980s
advocated reducing the averaging time of the Lead NAAQS from "calendar" quarter to monthly,
with the rationale that adverse effects could result from exposures over as few as 30 days'
duration. A monthly or "rolling" 30-day averaging time with a "not to be exceeded" form would
be more protective against adverse short-term effects than a form (such as a "second-highest
month in three years") that periodically allows a month of exposures to much higher
concentrations.
Zero Level for the Lead NAAQS
The NPR has raised the question of the feasibility of a Lead NAAQS of "zero." While it
would not be practical to set an enforceable primary Lead NAAQS of zero, it is both entirely
-------
appropriate and indeed very important that we as a Nation have the goal of reducing exposure of
our children to lead to as close to zero as feasible. The reasons for this are numerous, and
include: (1) lead is an apparent non-threshold neurotoxicant that reduces cognitive abilities in
children (that is, by directly affecting children's IQ loss) so that the smaller the amount of Pb in
air and from other sources of lead, the smaller the blood Pb and associated IQ loss; (2) such
neurotoxic effects of lead as IQ loss appear to be persistent and may be irreversible; and (3) the
environmental reality for childhood lead exposures is that these exposures often occur
concurrently with exposures to mixtures of other neurotoxicants, with these multiple exposures
producing an additive neurotoxicity over that for lead alone. Nonetheless, consistent with the
CASAC's previous advice in this current review cycle for the Lead NAAQS, the CASAC
continues to believe that the level of the primary Lead standard unanimously recommended by
the CASAC i.e., an upper bound for the primary Lead NAAQS of no higher than 0.2 jug/m3
is necessary to provide an adequate margin of safety for the protection of human health,
including susceptible subpopulations such as children, as explicitly required by the Clean Air Act
for primary NAAQS.
The CASAC stands ready to assist you by advising the Agency concerning the scientific
basis on which to base your scientific policy judgments, as EPA Administrator, in setting the
NAAQS. It is our sincere desire and goal to work more closely and effectively with the Agency
in the future. As always, the members of the CASAC wish EPA well in our vital and, as
previously stated, our mutual efforts to protect both human health and the environment.
Sincerely,
/Signed/
Dr. Rogene F. Henderson, Chair
Clean Air Scientific Advisory Committee
Enclosure
-------
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), an
independent 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 CAS AC
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 EPA Web site at:
10
-------
U.S. Environmental Protection Agency
Clean Air Scientific Advisory Committee (CASAC)
CASAC Lead Review Panel
CASAC MEMBERS
Dr. Rogene F. 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
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 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
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
1
-------
Dr. Samuel Luoma,* Senior Research Hydrologist, Emeritus, U.S. Geological Survey (USGS), Menlo
Park, CA
Dr. Frederick J. Miller, Consultant, Gary, 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, Charming 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)
*Dr. Luoma did not participate in the June 9, 2008 or the July 8, 2008 public teleconferences or the CASAC's
advisory activity to provide comments on the NPR.
------- |