January 30, 2009 

MEMORANDUM

SUBJECT: CASAC Review of Integrated Science Assessment for Particulate Matter: First 

External Review Draft 

FROM: John Vandenberg, Ph.D 

Director 

 National Center for Environmental Assessment – 

Research Triangle Park Division (B243-01) 

TO: Holly Stallworth, Ph.D 

Designated Federal Officer 

Clean Air Scientific Advisory Committee 

EPA Science Advisory Board Staff Office (1400F) 

 The draft Integrated Science Assessment for Particulate Matter: First External Review 

Draft (ISA) prepared by the Environmental Protection Agency’s (EPA) National Center for 

Environmental Assessment – Research Triangle Park Division (NCEA –RTP) as part of EPA’s 

ongoing review of the national ambient air quality standards (NAAQS) for particulate matter 

(PM) was released on December 22, 2008. The draft ISA will be reviewed by the Clean Air 

Scientific Advisory Committee (CASAC) PM NAAQS Review Panel (the CASAC PM Panel) at 

a public meeting to be held in Chapel Hill, NC on April 1–2, 2009. I am requesting that you 

forward the draft ISA to the CASAC PM Panel to prepare for that review. 

 The purpose of the draft ISA is to identify, evaluate, and summarize scientific 

information on the health and welfare effects associated with PM. The ISA is intended to 

“accurately reflect the latest scientific knowledge useful in indicating the kind and extent of 

identifiable effects on public health which may be expected from the presence of [a] pollutant in 

ambient air” (Clean Air Act, Section 108; 42 U.S.C. 7408). This first external review draft ISA 

integrates the scientific evidence for review of the primary (health-based) and secondary 

(welfare-based) NAAQS for PM and provides draft findings, conclusions and judgments on the 

strength, coherence and plausibility of the evidence. The draft ISA is supported by five Annexes 

that provide more comprehensive and detailed information on the relevant evidence available 

from the disciplines of atmospheric sciences and human exposure (Annex A), dosimetry (Annex 

B), clinical studies (Annex C), toxicology (Annex D), and epidemiology (Annex E). These 

Annexes are provided with the ISA for the Panel’s information. The CASAC PM Panel is being 

asked to review the draft ISA. NCEA-RTP will also address comments received on supporting 

material in the Annexes, to the extent that Panel members wish to review and provide comments 

on the Annexes. 
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 Following the review of the draft ISA, NCEA-RTP staff will produce a second draft ISA, 

which will be released for CASAC and public review in the summer of 2009. Subsequent steps 

in the NAAQS review process include risk and exposure assessments, and a draft plan for these 

assessments will be sent to the CASAC in the next month. 

Charge to the CASAC PM Panel 

 We ask the Panel to focus on the following questions in their review: 

1. The framework for causal determination and judging the overall weight of evidence is 

presented in Chapter 1. Is this framework appropriately applied for this PM ISA? How 

might the application of the framework be improved for PM effects? 

2. Chapter 2 presents the integrative summary and conclusions from the health effects 

evidence at the beginning of the ISA with the evidence characterized in detail in 

subsequent chapters. (Environmental and public welfare effects evidence is evaluated and 

summarized in Chapter 9.) Is this a useful and effective summary presentation? How 

does the Panel view the inclusion in Chapter 2 of only health categories with causal 

determinations of (a) likely to be a causal relationship or (b) a causal relationship? 

3. To what extent are the atmospheric chemistry and air quality characterizations clearly 

communicated, appropriately characterized, and relevant to the review of the PM 

NAAQS? Does the information on atmospheric sciences and exposure provide useful 

context and insights for the evaluation of human health effects of PM in the ISA? 

a. Is accurate and appropriate information provided regarding PM source 

characteristics, techniques for measuring PM and its components, policy-relevant 

background PM, and spatial and temporal patterns of PM concentration? Are the 

analyses and figures presented in Chapter 3 effective in depicting ambient PM 

characteristics? 

b. Is the evidence relating human exposure to ambient PM and errors associated with 

PM exposure assessment presented clearly, succinctly, and accurately? Are there 

PM exposure issues that should be expanded, shortened, added or removed? 

c. To what extent does the Panel find Annex A appropriate, adequate and effective 

in supporting the ISA? 

4. The dosimetry of PM is discussed in Chapter 4. The primary focus is on factors that 

might lead to differences in deposition and clearance between individuals, species, and as 

a function of the physicochemical properties of particles. Is the review of basic 

dosimetric principles presented in sufficient detail? Are the new particle translocation 

data adequately and accurately described? Recognizing an overall goal of producing a 

clear and concise chapter, are there topics that should added or receive additional 

discussion? Similarly, are there topics that should be shortened or removed? To what 
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extent does the Panel find Annex B appropriate, adequate and effective in supporting the 

ISA? 

5. Chapter 5 is intended to support the evaluation of health effects evidence for both shortterm and long-term exposures to PM. Some potential modes of action may underlie a 

number of health outcomes and may contribute to health effects of both short- and longterm exposures. Thus, the potential modes of action are described briefly in Chapter 5, 

and some specific study findings are discussed in more detail in the relevant sections of 

Chapters 6 or 7. What are views of the Panel on this approach and on the 

characterization of potential modes of action for PM-related effects in Chapter 5? 

6. To what extent are the discussion and integration of evidence on the health effects of PM 

from the animal toxicological, human clinical, and epidemiologic studies, technically 

sound, appropriately balanced, and clearly communicated? Does the integration of health 

evidence focus on the most policy-relevant studies or health findings? 

a. Are the tables and figures presented in Chapters 6 and 7 appropriate, adequate and 

effective in advancing the interpretation of these health studies? To what extent 

does the Panel find Annexes C, D and E appropriate, adequate and effective in 

supporting the ISA? 

b. In Chapters 6 and 7, toxicological studies were included in the PM ISA text if 

they were conducted at PM concentrations <2 mg/m3

. The toxicological focus in 

these chapters was on inhalation studies, with intratracheal instillation studies and 

in vitro studies included only if they contributed significantly to the understanding 

of health effects from exposure to PM. The toxicological studies excluded from 

the text are presented in Annex D. What are the Panel members’ thoughts on this 

approach and the selection criteria? 

7. What are the views of the Panel on the conclusions drawn in the draft ISA regarding the 

strength, consistency, coherence and plausibility of the evidence for health effects of PM? 

In evaluating the evidence to draw preliminary judgments on causality, EPA carefully 

considered evidence from the various scientific disciplines for the PM indicators and 

general health or environmental effect categories. Examples of a few specific health 

categories are listed below that were particularly difficult in reaching a causal 

determination. We would appreciate CASAC comments on all of the causal 

determinations presented in this first draft ISA. 

• Short-term exposure to PM2.5 and cardiovascular and respiratory morbidity. 

• Short-term exposure to PM2.5 and mortality. 

• Short-term exposure to PM10-2.5 and respiratory and cardiovascular morbidity, and 

mortality. 

• Long-term exposure to PM2.5 and mortality. 
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8. What are the views of the Panel on the definitions of susceptibility and vulnerability in 

Chapter 8? Are the characteristics included within the broad susceptibility and 

vulnerability categories appropriate and consistent with the definitions used? 

9. How useful and complete is the scientific evidence presented and summarized in Chapter 

9 regarding the effects of atmospheric PM on the environment, including (a) effects on 

visibility, (b) effects on individual organisms, (c) direct and indirect effects on 

ecosystems, (d) effects on materials, and (e) effects on climate? To what extent do the 

discussions and integration of evidence correctly represent and clearly communicate the 

state of the science? 

10. This first external review draft PM ISA is of substantial length and reflects the copious 

amount of research recently conducted on PM. EPA has attempted to succinctly present 

and integrate the policy-relevant scientific evidence for the review of the PM NAAQS. 

Does the Panel have opinions on how the document can be shortened without eliminating 

important and necessary content? 

 We look forward to discussing these issues with the CASAC PM Panel at our upcoming 

meeting. Should you have any questions regarding the draft PM ISA, please feel free to contact 

Dr. Mary Ross (919-541-5170, ross.mary@epa.gov) or Dr. Lindsay Wichers Stanek (919-541-

7792, stanek.lindsay@epa.gov). 

cc: Vanessa Vu, SAB, OA 

 Peter Preuss, ORD/NCEA 

 Debra Walsh, ORD/NCEA 

 Mary Ross, ORD/NCEA 

 Lindsay Wichers Stanek, ORD/NCEA 

 Karen Martin, OAR/OAQPS 

 Lydia Wegman, OAR/OAQPS