EPA/600/R-03/142 

December 2003 

Summary Report of the U.S. EPA Technical 

Peer Review Meeting on the Draft Document Entitled: 

Exposure and Human Health Evaluation of Airborne Pollution 

from the World Trade Center Disaster 

U.S. Environmental Protection Agency 

New York, NY 

July 14 – 15, 2003 

National Center for Environmental Assessment 

Office of Research and Development 

U.S. Environmental Protection Agency 

Washington, DC 
NOTICE 

This document has been reviewed in accordance with U.S. Environmental Protection 

Agency (EPA) policy and approved for publication. Mention of trade names or commercial 

products does not constitute endorsement or recommendation for use. 

This report was prepared by Versar, Inc., an EPA contractor (Contract No. 68-C-02-061), 

as a general record of discussion held during the technical peer review meeting on the draft 

document entitled Exposure and Human Health Evaluation of Airborne Pollution from the 

World Trade Center Disaster (July 14 – 15, 2003). As requested by EPA, this report captures 

the main points and highlights of the meeting. It is not a complete record of all details discussed, 

nor does it embellish, interpret, or enlarge upon matters that were incomplete or unclear. 

Statements represent the individual view of each meeting participant; none of the statements 

represent analyses by or positions of EPA. 

Preferred Citation: 

U.S. Environmental Protection Agency (EPA). (2003) Summary Report of the U.S. EPA 

Technical Peer Review Meeting on the Draft Document Entitled: Exposure and Human Health 

Evaluation of Airborne Pollution from the World Trade Center Disaster. National Center for 

Environmental Assessment, Washington, DC; EPA/600/R-03/142. Available from: National 

Technical Information Service, Springfield, VA, and <http://www.epa.gov/ncea>. 

ii 
CONTENTS 

LIST OF ACRONYMS AND ABBREVIATIONS .................................... v

EXECUTIVE SUMMARY .................................................... vii

1. INTRODUCTION .......................................................... 1

1.1 Meeting Purpose .................................................. 1

1.2 Background on Peer Review Process .................................. 1

1.3 Meeting Participants and Agenda ..................................... 5

1.4 Organization of Meeting Summary Report .............................. 6

2. SUMMARY OF OPENING REMARKS/PRESENTATIONS ........................ 7

2.1 Welcome from Meeting Organizer/Facilitator ........................... 7

2.2 Welcome from NCEA Director ....................................... 8

2.3 Chair’s Introduction ................................................ 8

2.4 Background Presentation on World Trade Center Assessment ............... 9

2.5 Peer Reviewer Question and Answer on Background Presentation ........... 9

3. DISCUSSION SESSIONS ................................................... 11

3.1 Purpose and Scope of Assessment .................................... 11

3.2 Exposure Assessment and Risk Characterization Approach ................ 13

3.3 Monitoring Data .................................................. 16

3.4 Particulate Matter ................................................. 18

3.5 Metals .......................................................... 21

3.6 Polychlorinated Biphenyls and Dioxins ............................... 23

3.6.1 PCBs .................................................... 23

3.6.2 Dioxins and Related Compounds ............................... 25

3.7 Asbestos ........................................................ 28

3.8 Volatile Organic Compounds ....................................... 30

3.9 Comment on the First Several Days After September 11 .................. 32

3.10 Occupational and Indoor Exposures .................................. 32

3.10.1 Occupational Exposure Assessment ............................ 32

3.10.2 Indoor Air Exposure Assessment .............................. 34

3.11 Conclusions/Executive Summary .................................... 35

4. OBSERVER COMMENTS .................................................. 36

4.1 First Comment Period ............................................. 36

4.2 Second Comment Period ........................................... 38

4.3 Third Comment Period ............................................ 40

4.4 Fourth Comment Period ............................................ 40

REFERENCES .............................................................. 43

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CONTENTS (continued) 

APPENDIX A PEER REVIEWER BIOGRAPHICAL SKETCHES 

APPENDIX B LIST OF OBSERVERS 

APPENDIX C AGENDA 

APPENDIX D POWERPOINT PRESENTATIONS 

APPENDIX E FLIP CHARTS FROM MEETING 

APPENDIX F WRITTEN COMMENTS FROM REVIEWERS 

APPENDIX G COMMENTS AND WRITTEN MATERIALS FROM OBSERVERS 

iv 
f/cc 

LIST OF ACRONYMS AND ABBREVIATIONS 

AHERA Asbestos Hazardous Emergency Response Act 

AQI Air Quality Index 

ATSDR Agency for Toxic Substances and Disease Registry 

fibers of asbestos per cubic centimeter 

COPC contaminants of potential concern 

DOH New York City Department of Health 

EOHSI Environmental and Occupational Health and Safety Institute 

EPA Environmental Protection Agency 

HVAC heating, ventilation, and air conditioning 

IRIS Integrated Risk Information System 

:g microgram 

:m micrometer 

MIXTOX Toxicologic Interaction Data Base 

MOE margin of exposure 

MRL Minimum Risk Level 

MVA Millette Vanderwood Associates, Inc. 

NAAQS National Ambient Air Quality Standard 

NCEA National Center for Environmental Assessment 

NIEHS National Institute of Environmental Health and Safety 

NIOSH National Institute for Occupational Safety and Health 

NOAEL no-observed-adverse-effects-level 

NYCDOHMH New York City Department of Health and Mental Hygiene 

NYSDEC New York State Department of Environmental Conservation 

NYU New York University 

OSHA Occupational Safety and Health Administration 

PAH polycyclic aromatic hydrocarbon 

PCB polychlorinated biphenyl 

PCM phase contrast microscopy 

v 
PEL Permissible Exposure Limit 

PM, PM2.5, PM10 particulate matter, and PM less than 2.5 :m and less than 10 :m diameter 

PVC polyvinyl chloride 

RfC Reference Concentration 

REL Recommended Exposure Level 

STEL Short Term Exposure Limit 

TDI Tolerable Daily Intake 

TEM transmission electron microscopy 

TEQ toxic equivalent 

TERA Toxicology Excellence for Risk Assessment 

TSP total suspended particle 

UC-Davis University of California-Davis 

VOC volatile organic compound 

WHO World Health Organizations 

WTC World Trade Center 

vi 
EXECUTIVE SUMMARY

The United States Environmental Protection Agency (U.S. EPA) Technical Peer Review 

Meeting on the draft document entitled: Exposure and Human Health Evaluation of Airborne 

Pollution from the World Trade Center Disaster was held July 14 - 15, 2003, in New York, NY. 

This two-day meeting was organized and hosted by Versar, Inc., for the U.S. EPA’s Office of 

Research and Development/National Center for Environmental Assessment (NCEA). The 

purpose of the meeting was to provide a scientific peer review of the draft document Exposure 

and Human Health Evaluation of Airborne Pollution from the World Trade Center Disaster. 

Versar, Inc., assembled a group of seven experts in air monitoring and transport modeling, 

environmental chemistry, public and occupational health, exposure and risk assessment, 

toxicology, risk characterization, and risk communication. In addition, reviewers had 

demonstrated expertise with the contaminants that were evaluated in EPA’s assessment 

(particulate matter [PM], dioxins, polychlorinated biphenyls [PCBs], asbestos, volatile organics, 

and metals). In addition to considerations of expertise and experience, selection was based on 

the reviewers’ availability for the peer review meeting. Additionally, the reviewer selection 

process consisted of screening for conflict of interest. All seven reviewers were asked a series of 

questions concerning potential conflict of interest, and they signed forms certifying that they had 

no conflicts of interest related to EPA’s assessment. About 50 observers attended the meeting, 

providing additional comments and input on issues related to EPA’s document. 

The peer review meeting consisted of introductory presentations to establish the scope and 

procedures for the review, observer comment periods during both days of the meeting, and 

extended discussion sessions among the reviewers on each major section of the assessment 

document. These comment periods addressed the document’s scope, approach, and use of 

monitoring data, as well as on the chemical-specific assessments. Details on the discussion, 

comments, and recommendations can be found in this report. 

vii 
Reviewers generally had positive responses to EPA’s assessment; however, several major 

recommendations and suggestions were provided for revisions to the report. They include the 

following: 

• The document should focus on ambient “outdoor air” exposures for the general 

population. Although the indoor air and occupational assessments (rescue/recovery 

workers) are important, they are not the focus of the text and could be presented in 

summary form in the appendix to this report. The introduction to this report could 

mention that it focuses on general public exposures to outdoor air, and it could provide 

links to existing or potential reports on the indoor air and occupational exposure 

assessment efforts. EPA was encouraged to complete this outdoor air assessment as 

quickly as possible and work with other organizations to enhance efforts on the indoor 

and occupational issues, possibly by convening an independent group (e.g., the National 

Academy of Sciences) to analyze the indoor air data. 

• It was recommended that the monitoring data section (Section III) of the document be 

expanded to describe in more detail the monitoring program design and available data. 

This section should include information on the purpose, scope, time frame, and 

location/number of samples and other information related to the monitoring that was 

conducted. Providing more information and consolidating the presentation in one section 

of the document would give the reader a more complete picture of the monitoring data 

available for the exposure and health evaluation. The section should also mention those 

chemicals that were not monitored for (or for which data are insufficient for the 

assessment). It is important that EPA’s document clearly present discussion on the utility 

and limitations of the available monitoring data, particularly in terms of their end use for 

evaluating exposures and potential health effects. This section of the report also could 

introduce lessons learned to provide a basis for better response to future events. 

• Reviewers agreed that no conclusions can be made about concentrations and exposures in 

the days immediately following the disaster, prior to the initiation of monitoring. 

viii 
• Discussion of risk-based benchmarks should be expanded in the approach section 

(Section II) to introduce the types of benchmarks that are available, their applicability to 

this assessment, and the human health endpoints of concern for each benchmark. 

Although some reviewers felt that occupational exposure limits should not be used to 

assess general population exposures, others felt that they could be used if appropriately 

adjusted for exposure duration and sensitive individuals. In addition, the report should 

describe the potential health impacts of exceedances, including toxicology and 

epidemiology information for the chemicals of concern. 

• Issues related to chemical mixtures should be introduced, where exposures to multiple 

chemicals having the same toxic endpoints or modes of action might be of concern. 

Reviewers suggested that EPA include relevant information from the chemical mixtures 

guidelines, framework for cumulative risk assessment, historic MIXTOX data base 

interactions, and the Agency for Toxic Substances and Disease Registry (ATSDR) 

interaction profiles (notably those including lead and chromium, and benzene, toluene, 

ethylbenzene, and xylene) and other recent information on mixtures. It was 

recommended that the document acknowledge and discuss the mixtures issue 

qualitatively, because the data are probably not sufficient to do a quantitative analysis. 

• Reviewers had extensive comments on the PM assessment, recommending that EPA 

examine PM10 data and applicable benchmarks. Basing the assessment on PM2.5 values 

might not be health protective because of concerns over respiratory effects from the 

unique PM emitted from the World Trade Center collapse (larger particles, glass fibers, 

and particles that exhibited alkaline characteristics). Suggestions were made to examine 

monitoring data for larger PM and to determine an applicable health-protective 

benchmark. The panel also noted potential inconsistencies in some of the PM2.5 data and 

offered to provide additional input following review of the raw data. 

ix 
• Reviewers found that EPA’s assessments for metals (lead, chromium, and nickel) were 

acceptable and agreed that, with the exception of small exceedances in the first few days, 

metals were not of concern. Although lead was found at elevated concentrations in 

outdoor air, the event contributed little exposure for the general population, especially 

relative to historic lead background exposures. Comments on the chromium and nickel 

assessments were favorable, generally agreeing with EPA’s approach and conclusions 

that these metals are of low concern. 

• The benchmarks for the noncancer PCB assessment should be reexamined. If 

occupational benchmarks are used, they should be adjusted for application to general 

population exposures, which would account for differences in exposure duration and 

sensitive populations as indicated (because depending on the benchmark, there may 

already be some accounting for sensitive subgroups). It was noted that if adjusted 

benchmarks are used, the conclusions might change because more exceedances would be 

expected. The reviewers found EPA’s cancer assessment for PCBs to be acceptable, 

agreeing that cancer risks would be well below levels of concern. 

• The dioxin assessment was generally acceptable, but reviewers did raise concerns about 

(1) dioxin detection limits and presentation of the available data, (2) the approaches used 

for the cancer and noncancer assessments, and (3) exposure factors used for inhalation 

rate and exposure duration for the occupational worker assessment (if retained in the final 

document). Reviewers requested that EPA improve the presentation to make this 

complicated assessment more transparent to the reader. It was also suggested that EPA 

describe in more detail the noncancer health assessment using margin of exposure, 

because it is different from approaches historically used for other chemicals. Revised 

exposure scenarios and exposure factors should be considered for the World Trade 

Center resident and rescue/recovery worker assessments (if retained in the report). 

Finally, reviewers strongly suggested that EPA state that dioxin air concentrations are 

unknown for the first days following 9/11, prior to the initiation of monitoring. The 

document could mention that modeling is currently being done to better estimate releases 

x 
and concentrations during the days immediately following the disaster, but that a 

quantitative assessment of potential health effects could not be conducted at this time. 

• It was noted that the assessment does not address compounds that would be expected to 

be present in elevated concentrations, such as organic combustion byproducts, including 

polycyclic aromatic hydrocarbons (PAHs) and brominated compounds, as evidenced by 

the extremely high dioxin concentrations. It was suggested that EPA discuss PAH data 

availability, perhaps in the expanded monitoring section. 

• Several criticisms were voiced on the asbestos assessment. It was recommended that 

EPA: use the Integrated Risk Information System (IRIS) toxicity values for a healthbased assessment, instead of the Asbestos Hazardous Emergency Response Act 

(AHERA) approach; revisit raw asbestos transmission electron microscopy (TEM) 

monitoring data to convert them from structures per square millimeter (s/mm2

) to 

volumetric units (structures per cubic centimeter [s/cc]); conduct a risk assessment; and 

discuss uncertainties. A more appropriate and health-protective approach would be for 

EPA to revisit the raw TEM analyses data to obtain the concentrations of fibers longer 

than 5 μm and the air volume data from the sampling. These data can be used to convert 

the asbestos data to appropriate volumetric units (s/cc) that can be used in conjunction 

with the IRIS asbestos value to conduct the risk assessment. Several of the reviewers 

commented that they believed that the results of this assessment would likely result in 

slightly more conservative health risk estimates. Reviewers also agreed that there should 

be a qualitative discussion of the uncertainties in the risk assessment, due to the inherent 

uncertainties in the sampling and analysis of asbestos and the conservative assumptions 

used in the risk assessment. 

• Reviewer discussion on the volatile organic compound (VOC) assessment raised several 

issues about the applicability of the VOC monitoring data to assess general population 

exposures because of the locations of the samples, type of samples collected (most data 

points are for grab samples), and issues related to detection limits. All of these issues 

xi 
could impact the conclusions drawn from the assessment. Therefore, EPA should include 

appropriate caveats because of the data limitations. Reviewers also suggested that EPA 

consider using different benchmarks for the VOC assessment, such as ATSDR 

Intermediate Minimum Risk Levels (also considering the toxicity information on which 

they are based) with the 24-hour sample data to evaluate potential risks to the general 

public, and Short Term Exposure Limits, for site recovery workers (if retained in the final 

assessment). Overall, reviewers agreed that VOC concentrations in outdoor air posed 

minimal impacts to the general population, but they were concerned about the limitations 

of the monitoring data. 

• The future studies section (Section VII) should add some suggested efforts, including 

conducting animal toxicity testing with archived dust samples (e.g., 14- and 90-day rat 

inhalation studies and a 2-year rat study to address chronic exposures). Other future 

studies should revisit the nonasbestos fibers, PAHs, and other combustion byproducts, 

incorporating information from other researchers as available (e.g., health studies at New 

York University and PAH analyses from University of North Carolina). 

xii 
1. INTRODUCTION

1.1 Meeting Purpose 

The United States Environmental Protection Agency (U.S. EPA) Technical Peer Review 

Meeting on the Draft Document Entitled: Exposure and Human Health Evaluation of Airborne 

Pollution from the World Trade Center Disaster was held July 14 - 15, 2003, at the Sofitel Hotel 

in New York, NY. This two-day meeting was organized and hosted by Versar, Inc., for the U.S. 

EPA’s Office of Research and Development/National Center for Environmental Assessment 

(NCEA). The purpose of the meeting was to provide a scientific peer review of the draft 

document Exposure and Human Health Evaluation of Airborne Pollution from the World Trade 

Center Disaster. 

1.2 Background on Peer Review Process 

Versar was tasked by NCEA to convene an expert panel and conduct an external scientific peer 

review meeting on EPA’s assessment document. This effort was conducted under EPA Contract 

No. 68-C-02-061, Support for NCEA Peer Review and Risk Assessment Guideline Activities. 

This contract provides for support to NCEA on peer review, exposure and risk assessment 

document preparation, meeting organization, and related activities. Under this contract, Versar 

conducts numerous peer reviews for NCEA of exposure and risk assessment documents. Many 

of these reviews are “letter” reviews where documents are sent to experts who provide individual 

reviews to evaluate the technical merits of an NCEA product. In some cases, peer review 

meetings are held to assemble reviewers to exchange ideas and discuss issues related to a 

document, particularly when the product being reviewed is complex or potentially controversial. 

Additionally, other reviews provide for reviewer interaction through conference calls. The peer 

review of Exposure and Human Health Evaluation of Airborne Pollution from the World Trade 

Center Disaster, conducted under Task Order No. 27, was initiated in April 2003, with the goal 

of conducting a peer review meeting in New York during the summer of 2003. 

1
Versar’s responsibilities included identification and selection of the experts, organization of the 

meeting, and production of the peer review meeting report. These activities were conducted on 

the basis of the specifications in EPA’s Statement of Work and in accordance with the policies 

and procedures established by EPA’s Peer Review Handbook (U.S. EPA, 2000). EPA’s 

Statement of Work called for assembly of a panel of experts with experience in air monitoring, 

environmental chemistry, air transport modeling, public and occupational health, exposure and 

risk assessment, toxicology, risk characterization, and risk communication. In addition, EPA 

specified that reviewers were to have demonstrated expertise with the contaminants that were 

evaluated in EPA’s assessment (particulate matter [PM], dioxins, polychlorinated biphenyls 

[PCBs], asbestos, volatile organics, and metals). 

On the basis of these specifications, Versar identified more than 50 candidate experts and 

selected a final group of seven who had the requisite expertise. A few of the selected reviewers 

had experience specific to monitoring and assessing exposures and human health effects of air 

emissions from the World Trade Center disaster. In addition to considerations of expertise and 

experience, selection was based on the reviewers’ availability for the peer review meeting. 

Furthermore, the reviewer selection process consisted of screening for conflict of interest. All 

seven reviewers were asked a series of questions concerning potential conflict of interest, and 

they signed forms certifying that they had no conflicts of interest related to EPA’s assessment. 

Following Versar’s final selection of the reviewers, EPA provided consent that the group of 

experts met EPA’s requirements. 

 The members of the seven-person panel assembled by Versar for this peer review were: 

Eric J. Chatfield, Ph.D. 

Chatfield Technical Consulting Limited 

2071 Dickson Road 

Mississauga, Ontario L5B 1Y8 

Canada 

Michael L. Dourson, Ph.D., DABT (Chair ) 

Toxicology Excellence for Risk Assessment 

1757 Chase Avenue 

Cincinnati, OH 45223 

2
Alison S. Geyh, Ph.D. 

Johns Hopkins University School of Public Health 

Department of Environmental Health Sciences 

615 N. Wolfe Street Room W6010 

Baltimore, MD 21205 

Gary T. Hunt, M.S., QEP 

TRC Environmental Corporation 

Boot Mills South 

Lowell, MA 01852 

Patrick L. Kinney, Sc.D. 

Columbia University Mailman School of Public Health 

Department of Environmental Health Sciences 

60 Haven Avenue, B-1 

New York, NY 10032 

Margaret M. MacDonell, Ph.D. 

Argonne National Laboratory 

Environmental Assessment Division 

Argonne, IL 60439 

Clifford P. Weisel, Ph.D. 

Environmental and Occupational Health Sciences Institute (EOHSI)/UMDNJ 

Department of Environmental Medicine 

170 Frelinghuysen Road 

Piscataway, NJ 08854 

Following selection of the panel members, Versar’s attention turned to selecting a Chair for the 

group. As called for in EPA’s Statement of Work, the function of the Chair would be to 

facilitate the meeting, ensure that the meeting proceeded in a timely and effective manner, and 

provide all panel members with an ample opportunity to raise issues and contribute to 

discussions during the two-day meeting. The Chair would also assist Versar in developing the 

meeting agenda and peer review report. Versar selected Dr. Michael Dourson to serve as the 

Chair because of his demonstrated abilities in leading scientific meetings. 

Materials were mailed to the reviewers so they could begin their individual evaluations of EPA’s 

assessment. Versar provided reviewers with EPA’s document and instructions for preparing 

brief written premeeting comments and EPA provided a list of general questions to help guide 

3
their reviews. The written premeeting comments were compiled by Versar and distributed to all 

reviewers in the week prior to the meeting so they could be aware of what issues had been raised 

by the other reviewers and prepare for meeting discussions. During this time, Versar began 

working with the Chair to craft a meeting agenda, which was organized according to the major 

sections of the assessment report. The agenda also provided for introductory presentations and 

question-and-answer sessions to help establish the scope and purpose of the document prior to 

moving into more detailed comments on the report. The agenda also set aside four observer 

comment periods during the two days to allow the public to provide input regarding EPA’s 

assessment report. 

Plans for the peer review proceeded with identification of a meeting site in New York City for 

July 14 - 15, 2003, based on the availability of the peer reviewers. Logistics information for the 

meeting was prepared and provided to EPA for inclusion in the Federal Register notice 

announcing the meeting. The Federal Register notice, published on June 18, 2003, informed the 

public of the meeting, listed logistics information (dates, times, and location), instructed the 

public on how to obtain a copy of EPA’s assessment, and described procedures to preregister for 

the meeting. Versar developed observer preregistration procedures to facilitate members of the 

public in attending the meeting and making statements during the observer comment periods. A 

Web site was developed by Versar (http://www.versar.com/epa/wtcpeerreview.htm) to facilitate 

observer registration. Interested members of the public preregistered with Versar via telephone, 

fax, email, or using the web site. Approximately 50 people preregistered and approximately 10 

people signed up to make statements during the observer comment periods. Prior to the meeting, 

observers were provided with the agenda and logistics fact sheet on the location of the peer 

review meeting. 

Versar conducted observer registration and opened the peer review meeting with a statement of 

purpose and ground rules for conducting the review. Versar staff assisted in organizing observer 

comment sessions and collecting materials submitted by reviewers. The Chair had the lead 

responsibility for conducting the meeting and the observer comments periods. Versar 

documented the proceedings via note taking and tape recording, which were used in preparing 

4
this peer review summary report. This report captures the main points and highlights of the 

meeting. It is not a complete record of all detailed discussion, nor does it embellish, interpret, or 

enlarge upon matters that were incomplete or unclear. The report summarizes the major 

recommendations and suggestions provided by the reviewers, documents reviewer discussion, 

and describes other aspects of the peer review meeting, including introductory presentations, 

question and answer sessions, and observer comment periods. 

1.3 Meeting Participants and Agenda 

Attendees at the peer review meeting included the seven peer reviewers (biographical sketches 

for the peer reviewers are presented in Appendix A) and about 50 observers (list of observers is 

presented in Appendix B). The agenda for the peer review meeting (Appendix C) was developed 

by Versar and the Chair to include introductory presentations to provide background and 

establish the scope for the peer review, discussion sessions among the reviewers on each major 

section of the assessment document, and observer comment periods during both days of the 

meeting. In general, the agenda for reviewer discussion followed the organization of the 

assessment document. Specifically, the meeting began with a welcome, introductions, and a 

presentation highlighting the assessment and major conclusions, which were followed by 

extended discussion among the reviewers on the scope, approach, and use of monitoring data in 

the assessment. The second day of the meeting continued with reviewer discussion on the 

assessment, addressing the major chapters of the report, which present the assessments for each 

chemical/contaminant of concern. Over the course of the two-day meeting, four observer 

comment periods were scheduled to allow the public to provide input on the document. 

1.4 Organization of Meeting Summary Report 

This report summarizes the meeting discussions, focusing on the recommendations and 

suggestions provided by the peer reviewers. 

5
• The executive summary provides a summary of the peer review meeting, 

including a brief list of the major recommendations and suggestions from the peer 

reviewers. 

• Section 2 of this report summarizes the opening presentations and discussion. 

• Section 3 presents summaries of the major discussion, comments, and 

recommendations provided by the reviewers on the assessment document. 

• Section 4 summarizes the observer comments and statements. 

• Section 5 contains references cited in this meeting report. 

• The appendices to this report present written and visual materials from the 

meeting, including biographical sketches for the reviewers, list of observers, the 

agenda, presentation materials, flip charts produced during the meeting 

summarizing major recommendations, and the reviewers’ written comments 

(prepared before the meeting and, in some cases, revised after the meeting). In 

addition, statements and handouts provided by the observers at and following the 

peer review meeting are presented. 

6
2. SUMMARY OF OPENING REMARKS/PRESENTATIONS

Opening remarks and presentations were provided by several of the people responsible for 

organizing and hosting the peer review meeting, including staff from Versar, Inc., and EPA’s 

National Center for Environmental Assessment (NCEA), as well as the meeting Chair. 

Presentation materials used in these talks are included in Appendix D. 

2.1 Welcome from Meeting Organizer/Facilitator 

Mr. David Bottimore, Project Manager from Versar, Inc., opened the meeting by welcoming the 

peer reviewers and observers. He provided an overview of the meeting agenda, including a 

statement of the goals and intended outcome of the peer review. The objective of the meeting 

was to obtain technical input on EPA’s document related to the assessment approaches used, 

data analysis, and interpretation of the results. Included in these opening remarks were ground 

rules and procedures for conducting the meeting. One issue that was emphasized was that 

consensus would not be sought; rather, the goal was to seek the individual comments and 

suggestions from the peer reviewers. He also clarified the roles of observers, including EPA 

staff, and highlighted the time periods set aside to obtain observer comments. These opening 

remarks concluded with an overview of the agenda and introductions of the seven peer 

reviewers. During the introductions, reviewers provided summaries of their pertinent experience 

and disclosed information related to conflict of interest. Following these introductions, Mr. 

Bottimore introduced the meeting Chair, Dr. Michael Dourson, Director of Toxicology 

Excellence for Risk Assessment (TERA). Dr. Dourson continued the conflict of interest 

discussion among the reviewers. None of the panel members had additional questions or 

concerns about conflict of interest for the reviewers. 

7
2.2 Welcome from NCEA Director 

Dr. Peter Preuss, Office Director of NCEA, welcomed the panel and observers to the peer review 

meeting. He voiced his enthusiasm for the peer review panel that was assembled to provide 

feedback on EPA’s assessment because of their credentials and experience with the topic areas 

and chemicals addressed in the document. EPA increasingly relies on peer review to ensure that 

its documents use the best science. EPA was not involved with selection of the reviewers; that 

was Versar’s role, so the process was as independent as possible. He also welcomed the 

observers and stated that he looked forward to hearing their thoughts on the document. During 

his introduction he noted that written public comments had been received earlier on the 

assessment, and he invited observers to provide additional comments and suggestions. The 

ultimate goal is for EPA to receive recommendations and suggestions from the peer reviewers 

and observers on how best to improve the scientific content of the assessment, which will be 

incorporated by EPA into the final report. 

2.3 Chair’s Introduction 

Dr. Dourson was the Chair for the peer review meeting and served as facilitator. He began his 

introduction by describing the peer review process and setting the ground rules. He reiterated 

the goal of the meeting and emphasized that technical input was sought from each participant, 

noting that there would be no attempt to achieve consensus. Rather, the discussion should bring 

out the diverse perspectives of individual experts in the group. He also described the procedure 

for the observer comment periods and encouraged observers to provide technical information 

that might be of assistance to the panel and to EPA in revising the assessment; observers were 

further requested to answer clarifying questions from either panel members or authors at the time 

of their presentation. He also permitted reviewers to approach either authors or observers with 

technical questions during breaks, but not the reverse. Reviewers were asked to report 

significant information from such conversations back to the entire group during the discussion 

sessions. Authors were permitted to respond to reviewers’ questions and were also permitted to 

8
ask clarifying questions of panel members, but not to participate in the discussion. He concluded 

his opening remarks by reviewing the agenda for the meeting. 

2.4 Background Presentation on World Trade Center Assessment 

Mr. Matthew Lorber of NCEA provided a presentation summarizing the scope, approach, and 

findings of EPA’s assessment. He began his presentation with background information on the 

development of the assessment, which was initiated at the request of EPA Region 2. The 

assessment focuses on outdoor measurements of exposure to the general population and 

evaluation of the potential human health effects. The contaminants evaluated include particulate 

matter (PM), metals, polychlorinated biphenyls (PCBs), asbestos, dioxin, and volatile organic 

compounds (VOCs), which were monitored by EPA and other organizations following the World 

Trade Center collapse. His presentation summarized the principal findings from EPA’s 

assessment, including specific conclusions for each chemical/contaminant of concern. Included 

in this discussion were the available monitoring data and approach for evaluating potential health 

effects. This approach relied on the use of health-based screening benchmarks and traditional 

risk assessment procedures, according to available data for each chemical. Although some 

chemicals were found at elevated concentrations in the time period following September 11, 

most returned to background concentrations in the following months. He concluded his 

presentation by noting lessons learned with respect to monitoring and assessing exposures and 

health effects. He also reviewed some general charge questions for the peer review panel to 

consider during its deliberations. 

2.5 Peer Reviewer Question and Answer on Background Presentation 

The peer reviewers asked clarifying questions, which introduced many of the topics that would 

be discussed in further detail over the course of the two-day meeting. Some of these questions 

were raised prior to the meeting by reviewers in their individual comments (Appendix F). Most 

of these initial comments pertained to the scope, approach, and overall purpose of the 

assessment. Specifically, reviewers raised questions about the target audience for the document, 

9
selection of the contaminants of concern, and breadth of issues that are addressed in the report. 

Several reviewers inquired about EPA’s purpose for the document relative to the various issues 

that the report addresses. Consideration was given to the idea that the document might benefit if 

it were to focus on the outdoor ambient air exposures to the general public, leaving other issues 

to be assessed in separate documents. Reviewers questioned the assessment’s focus on 

inhalation exposures, noting that there are concerns about dermal contact, ingestion, or 

secondary inhalation exposures from indoor dust. The Chair concluded this questions session by 

reminding reviewers that these issues would the topics for more in-depth discussion during the 

rest of the meeting. 

10
3. DISCUSSION SESSIONS

This section presents reviewer discussion on EPA’s assessment, organized according to the 

major sections of the document. Subsections include brief summaries of major 

recommendations and suggestions, followed by more detailed presentation of the discussion. 

3.1 Purpose and Scope of Assessment 

The reviewers began their discussion by addressing the overall purpose and scope of the 

assessment and report. Most reviewers suggested that the purpose and scope of the EPA study 

be clarified to explicitly state that this report emphasizes ambient (outdoor) air quality and 

inhalation exposures to the general population. It does not focus on occupational (e.g., rescue 

and recovery worker) risks or secondary indoor air exposures. It was recommended that the 

language be clarified so the reader would get the proper impression of the report’s purpose and 

scope. Several reviewers noted that secondary exposure to indoor dust should be examined, but 

that might be the focus of another (or subsequent) report. Another reviewer pointed out that the 

report does a good job of identifying other issues and studies that might be of interest to readers 

but agreed that this report should be kept more focused on ambient (outdoor) concentrations to 

which the general population might have been exposed and the potential health effects. 

One reviewer noted that the document does an adequate job of summarizing ambient 

concentrations of contaminants following the World Trade Center event and of indicating when 

levels had returned to background. It was pointed out that the document does have a short 

section on indoor and occupational exposures, but they are secondary to the ambient air 

assessment for the general population. Although a few reviewers felt that the indoor air section 

should be significantly expanded to provide the data and assessments that these topics warrant, 

other reviewers recognized that this report cannot be comprehensive. Another reviewer offered 

the opinion that indoor air issues are totally different because of the nature of the particles and 

should be addressed separately. As a result of this discussion, most reviewers felt that the 

document would be better served by keeping the focus on ambient exposures. The indoor air and 

11
occupational exposures are important, but they should be addressed in a separate assessment, and 

with other organizations who have been involved in these issues. EPA was encouraged to 

complete this outdoor air assessment as quickly as possible while expanding associated efforts 

on the indoor and occupational issues and perhaps convening an independent group to analyze 

the indoor air data (e.g., the National Academy of Sciences). If there are plans to do such a 

separate assessment, then the current section in this report can be kept brief or even removed so 

that it does not confuse the reader or distract from the main purpose of this assessment. 

Following this discussion, it was suggested that the title of the report be changed to reflect the 

focus on ambient (outdoor) air monitoring, general population exposures, and the potential 

health effects (both short- and long-term endpoints). Another suggestion was that the executive 

summary be revised and expanded, such that it could be used as a stand-alone document, because 

many readers will not take the time to read the entire report. 

Reviewer discussion raised the importance of completing and releasing this document as soon as 

possible, while referencing the other issues and on-going studies that are being performed. One 

idea proposed was that the document could be a “living text,” updated with new information as it 

becomes available. The final report could be considered an interim report, which links this 

report to studies being conducted by other groups (e.g., EPA Regions, Occupational Safety and 

Health Administration [OSHA], National Institute for Occupational Safety and Health [NIOSH], 

Agency for Toxic Substances and Disease Registry [ATSDR], National Institute of 

Environmental Health Sciences [NIEHS], etc.) that will be published at later dates. The final 

report would include mention of the occupational studies, indoor air assessments, evaluations of 

other exposure routes, epidemiological assessments, and modeling efforts (used to “back 

calculate” concentrations and exposures immediately following the September 11 disaster, 

before monitoring was initiated) that are ongoing. Most reviewers agreed with these suggestions 

and encouraged EPA to continue associated efforts and issue other reports at later dates. Two 

reviewers agreed to provide lists of on-going health and epidemiological studies. 

A suggestion was made that the document be restructured so as to explicitly lay out the subject 

matter in a more linear fashion, particularly with respect to the monitoring data. One reviewer 

12
suggested that the document expand and reorganize the presentation of information on the 

monitoring that had been conducted. The document would be clearer if the monitoring section 

(Section III) included background on the purpose of different data collection efforts, including 

information on how decisions were made, why they were made, and the purpose for which the 

data were to be used. There is a lack of clarity on the process and how the monitoring efforts 

evolved over time. Readers would better understand the data and the challenges in trying to 

assess the data for exposure and risk assessment purposes if this discussion were to be reworked 

in this manner. The report should outline the process and highlight what can be learned (and 

what cannot be learned) from the data collected, recognizing that data are very limited. 

It was also emphasized that ambient air data are not available for the first few days immediately 

following the disaster, with the exact delay until sampling varying by the contaminants 

monitored. Therefore, conclusions cannot be drawn about the potential impacts from exposures 

during that time period. Including this information would also help to explain the lessons 

learned with regard to the data collection process and planning to be more responsive in the 

future. 

3.2 Exposure Assessment and Risk Characterization Approach 

Reviewer discussion on the exposure and risk characterization approach focused on (1) 

identifying and selecting of public health protective benchmark values, (2) defining the 

populations addressed in the exposure assessment, and (3) describing the potential short- and 

long-term health effects that could result from concentrations that exceeded applicable 

benchmarks. 

One reviewer encouraged EPA to describe the process used to select the screening benchmark 

values, such as a ranking system or hierarchy, to choose among available values. It was 

recognized that not all contaminants have benchmark values available, but when more than one 

is available, the reader should understand the basis for EPA’s selection. This reviewer suggested 

noting which benchmark value was being used, and whether that was the preferred value or not 

13
and explain why. Several reviewers agreed and suggested that the process be clearly delineated 

and the context for decisions be made clear. It was felt that the report should provide a basis for 

the benchmarks used; indicate whether acute, subchronic or chronic values were available; and 

explain how they are tied to the target population being assessed. The issue was particularly 

evident for the use of occupational screening values to evaluate potential impacts to the general 

population. Although some reviewers felt that occupational exposure limits should not be used 

to assess general population exposures, others felt that they could be used if adjusted for 

exposure duration and sensitive individuals. The report should describe when such values were 

used and how they were derived. 

Although a few reviewers advocated derivation of new benchmarks when no applicable values 

are available for a chemical, others cautioned against generating new values that have not been 

peer reviewed. EPA could consider deriving new values or using benchmarks derived by EPA 

Region 2 for its study (WTC, 2003), but the preference is to use existing values. Reference 

concentrations (RfCs) are particularly applicable for assessing chronic effects for short-term 

exposures. Reviewers reiterated that it is important that the processes for identification, 

selection, and adjustment of screening benchmarks be transparent to the reader. 

Discussion continued on the interpretation of potential health implications from benchmark 

exceedances (first paragraph on page 16), particularly on the level of conservatism of such a 

screening assessment. One reviewer suggested that the document provide more information to 

the reader on the meaning of such comparisons with respect to the magnitude of the exceedance, 

time frame (acute or chronic exposures), and also the endpoint (health effect) that would be of 

concern. Discussion should address the potential implications of exceedances for acute and 

chronic exposures and include an indication of the number of samples that exceed the 

benchmark. Such qualitative information (e.g., whether there is only one high data point and all 

others are well below the level of concern) would help to assess the magnitude of concern. One 

suggestion was to add a table showing the benchmark values, their source/how they were 

adjusted, and the health endpoints of concern. Similar discussion and guidance should be 

provided to the reader on the utility of comparisons to monitoring data collected previously or 

14
from other areas that are intended to represent background. One reviewer cautioned that it is not 

necessarily true to say that if concentrations were below benchmarks that there are no health 

effects. Issues related to chemical mixtures could be discussed in this section, where exposures 

to multiple chemicals having the same endpoints might be of concern. Reviewers suggested that 

EPA look at their chemical mixtures guidelines, cumulative risk issues, and MIXTOX 

database on interactions, additivity, and antagonism among chemicals. It was 

recommended that EPA acknowledge and discuss the mixtures issue qualitatively but 

recognize that the data are probably not sufficient to do a quantitative analysis. 

Reviewers also reiterated the need to clarify in the exposure and health assessment approach 

section (Section II) that the exposed population being evaluated is the general public and not the 

rescue/recovery workers inside the restricted zone and that secondary indoor exposures are not 

assessed. A suggestion was made to improve the clarity of the map depicting the restricted 

zones in Figure 1 and tie in the receptor/exposure scenario information presented later on page 

78. Again, such a presentation at this point in the document would help the reader to gain a 

clearer picture of the specific populations being assessed with these datasets and to whom it 

applied (and to whom it does not). A question was brought up as to how the area was restricted 

and whether the general population could have gotten back into the restricted areas, such that 

they might have been exposed to elevated concentrations. There is a need to clearly state in the 

report what receptors are assessed (and not assessed, such as rescue workers) in this document so 

that this is clear to the reader. 

During the discussion of the exposure and risk characterization approach, one of the reviewers 

pointed out that, for the asbestos assessment, the Asbestos Hazardous Emergency Response Act 

(AHERA) method should be removed and health-based values from Integrated Risk Information 

System (IRIS) be used. The AHERA level of concern value (70 s/mm2

) is not a health-based 

benchmark (it is a technology-based value), and it should not be used. The only drawback is that 

the IRIS value does not include short fibers, so the assessment would have to leave those out. 

Regardless, this reviewer suggested that using transmission electron microscopy (TEM) data and 

the IRIS approach would result in a more health-protective assessment. Another reviewer added 

15
that the TEM method is inherently conservative, because it will likely identify more fibers than 

is generally possible using phase contrast microscopy (PCM). Several reviewers agreed that this 

approach would be preferred because of the additional protectiveness. 

3.3 Monitoring Data 

Suggestions were provided for reorganizing and expanding the monitoring discussion (Section 

III) of the document to better introduce the scope of the monitoring effort and the data available 

for the exposure and risk assessment. By expanding the section and providing additional 

information, this section could provide a better basis for the subsequent exposure and health 

effects evaluation in Section IV. Information should be included on the purpose of each 

sampling station, analytes monitored, start and end dates of sampling, frequency of sampling, 

and sampling periods with missing data. These descriptions should include qualitative 

information as well as details on analytical methods and quality assurance efforts. This 

reorganization would expand the section by approximately 10 pages by moving forward 

information from the evaluation discussion in Section IV. It should also include the table of 

monitoring locations and pollutants measured presented in Appendix B of EPA’s assessment 

report. This table could be rearranged by contaminant to be more intuitive, which would help to 

set the stage for the subsequent use of the data to assess exposure and risks to specific 

populations. As a result of this proposal for reworking this section, a reviewer suggested that 

perhaps the section be re-named something like “Environmental Monitoring Program Design.” 

The reviewers agreed that by expanding this section to better describe the monitoring conducted, 

questions could be answered as to why certain chemicals or data were not included in the 

assessment. One reviewer noted that the document should point out whether some data were not 

included because they were not collected under similar conditions and using comparable 

protocols. Expanding this section with additional discussion would provide better context for 

including or excluding data in the assessment, such as data collected from locations that might 

not represent general population exposures, (e.g., grab samples taken close to Ground Zero in the 

restricted zone). Reviewers agreed that the changes suggested would improve this section by 

16
providing a clearer presentation of the data used in evaluating exposures and risks. Providing 

more information and consolidating the presentation in one section of the document would give 

the reader a more complete picture of the monitoring data available for the exposure and health 

evaluation. The section should also mention those chemicals that were not monitored for (or for 

which data are insufficient for the assessment). 

It is important that EPA’s document clearly present discussion on the utility and limitations of 

the available monitoring data, particularly in terms of their end use for evaluating exposures and 

potential health effects. Reviewers reiterated that the section should be expanded and 

reorganized to present the rationale for the monitoring sites, identifying the purpose of each 

site/sample, and adding timelines and descriptions of how many and where data/samples were 

collected. One reviewer suggested that additional figures be added to the report, such as 

timelines and graphics showing in more detail the location of monitoring sites (denoted by 

alphabetized lettering in maps) for each contaminant, explaining how they were chosen and why. 

It was also suggested that a discussion of meteorological conditions be included in this section, 

to better explain the behavior and movement of the plume over the time periods corresponding to 

elevated concentrations at particular locations. The reader needs to understand whether elevated 

concentrations at monitoring sites could be attributed to increased emissions or whether they 

were due to meteorological conditions. Such information would help to provide more context 

for the spatial and temporal trends in concentrations and evaluation of the data from broader 

geographic scales. 

3.4 Particulate Matter 

Commentary from the reviewers on the PM assessment was extensive, questioning the 

applicability of the PM2.5 monitoring data and PM2.5 National Ambient Air Quality Standards 

(NAAQS) benchmark for evaluating the potential health effects of the PM. Several reviewers 

challenged the use of the PM2.5 values because of concern for the health effects of larger particles 

17
(including glass fibers) that exhibited alkaline characteristics. Suggestions were made to 

examine monitoring data for larger PM and to determine an applicable health-protective 

benchmark. Additional comments on this section called for examination of dusts for combustion 

byproducts such as polycyclic aromatic hydrocarbons (PAHs), which would be expected to be 

present in elevated concentrations. 

One reviewer stated that this section overall was well written and was comprehensive but 

brought up two specific points during this initial discussion. The first point was that there is text 

that discusses estimating exposures from the results of tests conducted to resuspend particulates 

from settled dust. Although this is valuable information, it should be noted that it is difficult to 

recreate fine aerosol from resuspended dust, and resulting data will be biased toward particulate 

sizes that are larger than the original airborne PM. This needs to be stated as a caveat in the 

report. 

 The second point was that the PM assessment should be expanded to include coarse particles 

(>2.5 :m). There are some PM10 monitoring data, but they are not extensive, and there needs to 

be an explanation of what the potential health implications might be from all PM. There are 

respiratory health effects being identified, but the PM2.5 numbers do not indicate a problem. This 

reviewer stated that this discrepancy could be attributed to the characteristics of the particulates 

released from the collapse of the World Trade Center buildings. Specifically, there was an 

unusually large proportion of larger particles composed of glass fibers and having high alkalinity 

that may pose acute and chronic respiratory effects. It was suggested that PM10 monitoring data 

be examined to determine whether they could be incorporated into the assessment. Several 

reviewers agreed with this suggestion, noting that some PM10 data are available. Another 

reviewer agreed with the statement about the high concentrations of the larger particle sizes 

found in the dust but noted that much of it is even larger than PM10 (ranging from 10 to 53 :m) 

from settled dust sampling by Lioy et al. (2002). 

PM

Several reviewers discussed the use of a more appropriate health protective benchmark than the 

2.5 NAAQS standard or the Air Quality Index value. Reviewers noted that the PM10 NAAQS 

18
standard is higher than the PM2.5 benchmark, but because the concentrations of the larger 

particulates are believed to be significantly higher, the assessment might find more exceedances. 

Furthermore, because the respiratory irritation was caused by these particles, there is even more 

of a concern than what would be expected for “typical” PM, which might call for an even more 

protective benchmark than the PM2.5 or PM10 values. Looking at total suspended particle (TSP) 

standards or occupational benchmarks might be worthwhile to determine an applicable screening 

value for this unique PM. Several reviewers noted that the particulate characteristics changed 

over time (after initial collapse, after resting, later from fires, etc.), so this assessment gets very 

complicated. 

Several reviewers considered the utility of conducting toxicity tests on the dust (e.g., 14- or 90­

day rat inhalation studies), which could be used to derive a site-specific benchmark, but such an 

effort would be costly and time consuming. The reviewers concluded this PM discussion by 

suggesting that EPA consider these comments and revisit the issue to determine whether a more 

health-protective screening benchmark (in addition to PM2.5 and PM10 values) could be 

determined that could be used in conjunction with the available PM monitoring data, providing 

increased attention on the potential health effects of the larger particles. 

Another reviewer voiced concern that the dust would be expected to contain elevated 

concentrations of organic combustion byproducts such as PAHs and brominated compounds, as 

evidenced by the extremely high dioxin concentrations. The reviewers questioned EPA as to 

whether there are data available on PAHs that could be used in a manner similar to the write-ups 

of other contaminants. It was stated that there are no concurrent PAH data but that it would be a 

separate data set. There were limited PAH data available during the preparation of this report, 

but since then, more have become available. EPA noted that there was no real ambient 

measurement of PAHs; there were only two sample days in November 2001 and then regular 

sampling from January 2002 through May 2002. 

It was suggested by reviewers that a qualitative discussion of the new PAH data be included in 

the report. A reviewer suggested that EPA should discuss the availability of PAH data in the 

19
methods section so that the audience is aware of what data were collected and were available for 

use in the assessment. Another suggestion was made by one reviewer that the dust be 

reexamined to determine the composition and concentration of PAHs and related organic 

combustion byproducts. Many organic compounds persist in the environment and PAHs would 

still be in the dust samples collected. It was recommended that the dust samples be analyzed for 

other organic combustion byproducts that could substantially increase estimated risks. 

Alternatively, if toxicity testing were to be conducted on the dusts, it might more accurately 

reflect the cumulative effects from contaminants that had not been characterized and for which 

no benchmarks are available. The reviewers felt that such tests might be worthwhile in the 

future but that other approaches could be used in the short term for this document. 

In subsequent discussion, reviewers raised miscellaneous comments related to the PM section. 

One reviewer suggested that the 1976 New York University (NYU) Medical Center monitoring 

data (included in Table 2 on page 43) be moved to a different table, separate from the 2000 

values, and be more clearly described as providing historical context on background levels. 

Another reviewer, reflecting back to previous discussion, suggested that pie charts be added to 

the presentation, showing information on particle size distribution and composition of PM. 

Other comments reflected on the difficulty in characterizing exposures, especially in the first few 

days following the disaster, before monitoring was initiated. Additionally, there were some 

regional episodes in the following weeks when concentrations were elevated in areas away from 

Ground Zero, which could have been due to transport of the plume. One such episode occurred 

in early October, but the data were suspect. To help assess the PM issue in more detail, one 

reviewer offered to examine in more detail the PM data from three perimeter monitoring sites 

(particularly an October 2, 2001 data point that appeared to be suspect). Another reviewer 

volunteered to do some research to see whether any health-based benchmark values exist for 

glass fibers. This reviewer reported later that NIOSH has an occupational exposure limit of 3 

fibers/cm2

 for glass fiber. 

Discussion concluded with the Chair asking the reviewers whether they agreed with the 

conclusions presented in EPA’s report. It was agreed by the reviewers that EPA’s conclusion 

20
bullets, presented on page 2 of the assessment, would hold true for PM2.5. However, reviewers 

were concerned about larger particulates and the need to evaluate PM10 monitoring data against a 

site-specific PM10 benchmark that would account for the unique composition of the particles 

released from the World Trade Center collapse and fires. Reviewers generally agreed that the 

greatest risks were from exposures in the time period immediately following the collapse and 

that PM levels to which the general public would be exposed decreased after a few weeks. They 

agreed that it was tough to apply such broad conclusions to a particular contaminant and 

suggested that if contaminant-specific conclusions are presented in this manner, that more 

precision should be applied to the statement of the time frame before levels returned to 

background. 

3.5 Metals 

The reviewers discussed the assessments for those metals that were reported to be contaminants 

of concern: lead, chromium, and nickel. In general, reviewers found that EPA’s assessments for 

metals were acceptable and agreed that, with the exception of small exceedances in the first few 

days, metals were generally not of concern. 

The first metal addressed by the panel was lead. One reviewer suggested looking at the source 

of lead and indicated that the discussion on lead was good but there was a need for more fate and 

transport information. A question was raised as to the bioavailability of the airborne lead in 

comparison to the types of sources to which the NAAQS standard would typically be applied. 

The bioavailability would depend on the form present which would be a result of the type of 

source. If the bioavailability were lower, then the dose resulting from a similar concentration 

would be lower (making the assessment more conservative). Two reviewers discussed this issue 

and suggested that EPA look further into the relative bioavailability of lead in the ambient air 

samples collected. In discussing this issue in more detail, the question was raised as to whether 

the lead concentrations observed were a product of particulates or combustion. Several 

reviewers hypothesized that lead was likely combustion generated, because it was found 

predominantly in the 2.5 :m fraction, and concentrations decreased fairly quickly. Reviewers 

21
generally agreed that, with the exception of small exceedances in the first few days, outdoor air 

exposures to lead was not of concern. Another reviewer agreed with this statement and pointed 

out that the event contributed little exposure relative to background exposures, especially relative 

to historic lead concentrations. 

The next metals discussed were chromium and nickel. Several suggestions were made that are 

applicable to all the metals, such as presenting graphs with the tables that summarize the metals 

concentration data (such as Table 2). Such a visual presentation would help the reader to see 

that metals levels were generally not above background concentrations. Similarly, it was 

suggested that the graphs of chromium and nickel concentration data in Figure 18 include 

notations on where the benchmarks and background levels would be, much like what was done 

in the PM graphs. One reviewer suggested that EPA review data from the Speciation Trend site 

(operated by the New York State Department of Environmental Conservation, on Canal Street) 

to show background levels of metals from 2000 to the present. It was also suggested that trace 

metal data be included in the report even if they were below detection levels. 

Comments on the chromium and nickel assessments were favorable, with reviewers generally 

agreeing with the approach and conclusions that these metals are of low concern. Questions 

were raised briefly on whether the benchmarks selected for chromium and nickel were the best 

available, and whether EPA has newer reference concentrations (RfCs) for these compounds that 

could be used instead of the OSHA Permissible Exposure Limit (PEL) and ATSDR Minimum 

Risk Level (MRL) values. It was later clarified that there is an RfC for hexavalent chromium, 

but that the one for nickel was only in draft form. 

Several reviewers stated that the data do not seem to indicate elevations of chromium and nickel 

above background levels and therefore felt that EPA’s conclusions were correct, though they did 

question what the source of nickel might be. Another reviewer pointed out that nickel is a fuelrelated element that is commonly present whenever there is a fuel combustion source. One 

reviewer stated that the plots for chromium and nickel for the 2.5 :m fraction do not follow the 

other plots and suggested that the monitored concentrations might not be attributable to the 

22
World Trade Center. Another reviewer pointed out that the third paragraph on page 33, which 

talks about all metals and elements, states that chromium, arsenic, antimony, potassium, and zinc 

all had ambient air concentration peaks in late November. The reviewer stated that these 

elevated concentrations might be associated with the World Trade Center but could also be due 

to other sources. Another reviewer stated that the graphs on page 55 show that concentrations of 

metals and halides track with the World Trade Center collapse and seem to be indicative of 

combustion sources. The reviewer felt that the report should also mention that there were 

significant sources of chlorine and bromine in the World Trade Center prior to the collapse (e.g., 

PVC wire coating and perhaps bromine flame-retardant material on the furniture). It was 

suggested that the report present data for other trace metals, even if the levels are low or below 

detection limits. 

3.6 Polychlorinated Biphenyls (PCBs) and Dioxins 

3.6.1 PCBs 

Reviewer comments on the PCB assessment generally focused on the benchmarks used for the 

noncancer assessment and the suggestion that the occupational benchmarks used should be 

adjusted for application to general population exposures. The results for the assessment could 

change as there might be exceedances if adjusted benchmarks are used. The reviewers found 

EPA’s cancer assessment for PCBs to be acceptable, agreeing that cancer risks would be well 

below levels of concern. Additional comments were made on the presentation of the PCB data 

and the need for more discussion of organic combustion byproducts such as PAHs and 

brominated compounds. 

One reviewer observed that there are not a lot of benchmarks available for PCBs; there are no 

subchronic or acute MRLs and no subchronic or acute RfCs. The reviewer suggested 

considering deriving a new benchmark based on available no-observed-adverse-effect-levels 

(NOAELs). There is already good information on the bottom of page 68 that could be used in 

setting a safe margin of exposure (MOE) or dose. Alternatively, the assessment of noncancer 

effects could be based on the NIOSH Recommended Exposure Level (REL) and OSHA PEL 

23
occupational benchmarks, but those values should be adjusted for exposure duration and 

susceptible populations if they are to be health protective for the general population. This 

reviewer estimated that comparison of ambient air concentrations with either of these adjusted 

benchmarks might result in some exceedances. 

Another reviewer noted that the rationale and description for adjusting occupational benchmarks, 

to make them more appropriate for assessing general population exposures, should be introduced 

earlier in the document, in Section II, the exposure and health assessment approach. Another 

reviewer noted that some of the PCB samples were taken close to “the pile,” which might 

provide concentration data that are more representative of rescue/recovery worker exposures; in 

this case, occupational benchmarks could be used, but with an adjustment for exposure duration 

(because recovery workers were present for much more than the typical 8 hrs/day and 5 days/wk 

used in deriving occupational benchmarks). 

Other comments on the PCB section included identification of a missing value in Table 3 (PCB 

monitoring data from September 2001 to April 2002) for the November 2, 2001 sample at 

Barclay and West Broadway. Another comment provided on the location of PCB monitoring 

stations in Figure 21 questioned the sampling site numbering and whether it matches the official 

designations for the World Trade Center buildings (i.e., WTC Building #5). One reviewer noted 

that the report identifies the likely fact that PCBs were in the building and that levels found were 

in some cases higher than those in ambient air. This reviewer felt that the levels and extent of 

PCB contamination were well characterized in the report. It was reiterated that various types of 

organic compounds that were found to be present in the buildings can participate in the creation 

of a variety of combustion byproducts, such as brominated compounds, which have not been 

characterized and could contribute to elevated risks. Several reviewers agreed that this larger 

issue should be discussed in the expanded monitoring section to clearly state what data are 

available and which compounds that might be a concern have not been characterized. One of the 

reviewers emphasized the importance of introducing such issues early in the document, in the 

monitoring section, to reduce the complexity of the exposure and risk evaluation discussion. 

24
Reviewer discussion on PCBs concluded by reiterating that EPA’s cancer risk assessment 

appears to be accurate, finding risks to be well below levels of concern. The noncancer effects 

assessment should be revised by revisiting the benchmarks used, which might change the 

conclusions. 

3.6.2 Dioxins and Related Compounds 

Reviewer comments on the dioxin assessment addressed (1) issues related to the monitoring 

data, particularly with respect to detection limits and presentation of the available data, (2) the 

approaches used for the cancer and noncancer assessments, and (3) exposure factors used for 

inhalation rate and exposure duration, particularly for the occupational worker assessment. In 

general, the reviewers found this section to be well done and requested that EPA improve the 

presentation to make this complicated assessment more accessible to the reader. 

Initial discussion on the dioxin section focused on monitoring methods and detection limit 

issues, which resulted from two types of sampling that were used. Several reviewers questioned 

the applicability of some of the monitoring data that had high detection limits, but they 

ultimately agreed that EPA used the available data in an appropriate manner. Although 

reviewers did have concerns about the data, they recognized that dioxin levels were extremely 

high during the first few months, so detection limit issues were not of major concern until later, 

as levels decreased. Reviewers suggested that the discussion be clarified, both in the Section III 

monitoring methods section as well as in this section (particularly Table 4, which summarizes 

dioxin toxicity equivalent [TEQ] concentrations at three monitoring locations). This should 

provide a better characterization of the limitations of the data and the impact of the high 

detection limits for select samples at WTC Building #5 and Church and Dey during the first few 

months. In addition, the Park Row data should also include detection limit information. 

Reviewers also asked that EPA reorganize Table 4 to make the dates comparable across the three 

dioxin sampling locations. Reviewers also commented that EPA should provide its rationale for 

using half the detection limit, which is commonly used, instead of other possible approaches for 

dealing with nondetects. These comments also pointed out certain data points (e.g. 10/11 at 

25
WTC Building #5), where most of the dioxin TEQ was contributed by non detects. 

Reviewers also questioned why the highest measurements that were observed on 

September 23 were used to extrapolate back to earlier time periods when no data were 

available. One reviewer felt that it would be better to state that concentrations are 

unknown from the time period before monitoring was conducted, as was considered for 

other chemicals. This discussion should be included up front in Section III and reiterated here. 

The reviewer added that the document should state that modeling is currently being done to 

better estimate dioxin releases and concentrations during the first 10 days but that no assessment 

of potential health effects should be conducted at this time. Reviewers concluded the discussion 

of the dioxin monitoring data by reiterating that the table and text should provide more 

clarification on these issues. 

Comments on the dioxin cancer and noncancer health assessments were generally positive, with 

requests that EPA clarify the approaches used. One reviewer noted that the dioxin cancer 

assessments were straightforward for estimating risks from short-term exposures. It was noted 

that a short qualitative discussion should be added to differentiate between potential impacts to 

different populations, such as the difference between a short-term, high exposure to children 

versus to the elderly. For the noncancer assessments, one reviewer commented that EPA’s 

approach using an MOE based on body burdens should be described in more detail because it is 

atypical from approaches used for other chemicals. This MOE (the ratio of body burden where 

effects are found divided by a body burden at a level of interest) discussion might also benefit 

from the addition of information on background body burdens, as well as levels at which effects 

would be of concern. Such a discussion would give context for the degree of concern one might 

have from a 10% increase in body burden. It might also be noted that uncertainties related to 

this analysis, including animal-to-human extrapolation, could add another 10-fold factor, which 

might start to approach body burdens where effects might be observed. One reviewer would 

have liked to have seen a comparison of dioxin levels with health-based benchmarks but 

recognized that EPA does not have noncancer reference values for dioxin. This reviewer asked 

that EPA consider examining the World Health Organization’s tolerable daily intake for dioxin 

26
to see if it might be appropriate if adjusted for this application. 

Overall, reviewers found the dioxin health effect analyses to be acceptable, but a few reviewers 

suggested that EPA revisit a few exposure factors used in the occupational exposure assessment. 

Specifically, several reviewers suggested that a higher exposure frequency be used (12 hrs/day 

and 7 days/wk) because it has been well documented that recovery workers were on site for 

extended periods, with few days off. Similarly, because of the strenuous work performed, 

reviewers suggested that EPA consider using an inhalation rate higher than 1.3 m3/hr, possibly as 

much as twice that value. One reviewer also added that the inhalation rate for the residential 

receptor, 0.55 m3

/hr, might be increased to 0.7 m3/hr. Reviewers suggested that EPA revisit 

these inhalation rates by consulting Exposure Factors Handbook. It was acknowledged, 

however, that if these exposure factors were changed, the results would be only slightly 

impacted. 

An issue was raised during discussion of the dioxin occupational assessment, and discussed in 

more detail during other portions of the meeting, was that the focus of this report should be on 

general population exposures. Occupational exposures should be the topic of another document, 

where a more extensive assessment can be undertaken; therefore, it might benefit this document 

to move some of these analyses to an appendix. Also during this session it was suggested that 

the document set aside a subsection on chemical mixtures and cumulative risk because of 

concerns about interactions among chemicals. Although quantitative analyses, such as 

calculating hazard indices across multiple contaminants, might not be conducted for this report, 

it should be mentioned for consideration in future studies. The assessment approach section 

(Section II) would be an appropriate place to introduce these concepts. 

3.7 Asbestos 

Several criticisms were voiced on the asbestos assessment. It was recommended that EPA use 

the IRIS toxicity values for a health-based assessment, instead of the AHERA approach; revisit 

27
raw data to convert them from s/mm2

 to s/cc; conduct a risk assessment (similar to what was 

done for dioxin); and discuss uncertainties. 

One reviewer expressed concern over EPA’s use of the AHERA standard as the benchmark 

because it is not a health-based value, but rather is based on practicality of measurements in 

asbestos abatement. This reviewer reiterated that the overall approach should be changed to a 

more appropriate procedure for outdoor (ambient) air and risk assessment purposes. This would 

also call for converting the monitoring data presented in s/mm2 (used for the AHERA approach) 

to volumetric units (s/cc or s/mL) for use in the risk assessment with the IRIS unit risk value. 

There were concerns about the use of PCM for measurement for ambient air samples, because it 

could frequently lead to misleading conclusions. The preferred method for ambient (outdoor) air 

would be TEM, which is more sensitive and provides more reliable results for outdoor samples 

that have high concentrations of other fibers. This reviewer acknowledged that the existing 

measurement data can be used for the assessment, possibly by considering calculating an average 

of concentrations for the PCM and TEM measurements. EPA should revisit the raw TEM 

analyses data to obtain the concentrations of fibers longer than 5 μm and the air volume data 

from the sampling. This information can be used to convert the asbestos data to appropriate 

units (s/cc). 

Additional discussion among several reviewers supported using the IRIS value for the asbestos 

risk assessment. One reviewer provided an overview of the suggested approach, which would be 

to use the converted data (reported in s/cc) and the IRIS toxicity value (4x10-5 fibers/mL at a 

target risk value of 1 in 100,000). The assessment should also take into account the less-thanlifetime exposure duration, distinguishing between the lifetime exposure duration used in 

deriving the IRIS value (similar to how an assessment would be done for children). This 

approach would be similar to what EPA used for the dioxin risk assessment. Several of the 

reviewers commented that they believed that the results of this assessment would likely result in 

slightly more conservative health risk estimates. Reviewers also agreed that there should be a 

qualitative discussion on the uncertainties in the risk assessment due to the inherent uncertainties 

28
in the sampling and analysis of asbestos and the conservative assumptions used in the risk 

assessment. 

PM

One of the reviewers also revisited the issue of glass fiber and mineral wool raised earlier in the 

PM discussion, acknowledging that these are large-diameter fibers (unlike those of asbestos) that 

can pose respiratory impacts. This reviewer reported that NIOSH has an occupational exposure 

limit of 3 fibers/cm2

 for glass fiber, which could be adjusted for application for the general 

population. Concentration data for glass fiber could be obtained from the filters collected for 

asbestos measurement, and a qualitative assessment could be added to the discussion to address 

potential health effects. Another approach, which would require more work, would be to use the 

2.5 teflon filters and do an indirect analysis. Such an indirect analysis would be more of a 

future effort rather than being useful for this assessment. Several reviewers attempted to 

characterize potential risks from the glass fibers, which may be responsible for some of the 

respiratory irritation effects. One reviewer commented that there could be some exceedances for 

glass fibers, especially for the recovery workers, but less so for the general population. 

Conclusions for asbestos could not be addressed because of the need for these additional 

analyses. 

3.8 Volatile Organic Compounds 

Reviewer discussion on the VOC assessment raised several concerns about the utility of the 

VOC monitoring data to assess general population exposures because of the locations of sample 

collection, type of samples collected (most data points are for grab samples), and issues related 

to detection limits. All of these issues could impact the conclusions drawn from the assessment; 

therefore, EPA should include appropriate caveats because of the data limitations. Reviewers 

also discussed the benchmarks that should be used to characterize risks to the general public and 

site recovery workers (if retained in this assessment). Overall, reviewers agreed that VOC 

concentrations in outdoor air posed minimal impacts to the general population, but they were 

concerned about the limitations of the monitoring data. 

29
One reviewer stated that the discussion on VOCs was very clear and well laid out, but this 

reviewer did have some concerns with using the data sets provided to draw conclusions on 

exposures and risks to the general populations. This reviewer added that most of the VOC data 

are from grab samples, which were not collected to characterize exposures but were intended to 

inform recovery workers within the restricted zone of the location of hot spots. As a result, the 

locations for most of the sampling were near the sources and plumes of smoldering fires, so they 

are not well suited for characterizing exposures for the general population (or even for recovery 

workers). Although grab samples of VOCs can be valuable for indicating high levels at certain 

locations and give an indication of which chemicals are present, 24-hour samples would be much 

more appropriate for an exposure assessment. Several reviewers were concerned about the 

possibility of inaccurate representation of VOC exposure from grab sample data. 

After discussing the extent of the VOC grab samples, some reviewers felt more comfortable that 

there was reasonable spatial and temporal coverage, such that the data could be used as an upper 

bound estimate, with the proper caveats. Several reviewers reiterated the importance of 

presenting this information in the revised “monitoring design” section of the document to help 

the reader to understand the limitations of the data sets before they are used for the exposure and 

risk assessment. The reviewers also inquired about the extent of the 24-hour samples, 

discovering that those data sets were limited to one day in late September 2001 and a few days in 

December 2001. Reviewers concluded that use of the available data, which are mostly grab 

samples, would be acceptable if the appropriate caveats are included in the discussion on the 

limitations of the data. This should acknowledge that there are few exceedances, even using the 

grab sample data, that would be expected to be higher than levels to which the general 

population would be exposed. For the health effects assessment, reviewers advocated the use of 

the ATSDR Intermediate MRLs (also considering the toxicity information on which they are 

based) with the 24-hour samples to evaluate potential risks to the general public. Another 

reviewer suggested that the grab samples would be useful for comparison to Short Term 

Exposure Limits (STELs) to assess risks for recovery workers (if retained in the assessment). 

30
In general, reviewers found the conclusions to be acceptable, noting that only benzene would be 

of slight concern from the grab samples. When using the 24-hour samples, there were no 

exceedances, based on the ATSDR acute and intermediate MRLs. One reviewer identified a 

potential problem with detection limits for benzene, which raised additional concerns about the 

conclusions. Several reviewers suggested that the last sentences dealing with benzene on page 

110 be revised or deleted, because the conclusion states that exposure to the general population 

within the restricted zone was minimal, but this conclusion is based on few samples. It was 

suggested that this last sentence could be included in the report if the proper caveats are clearly 

stated. Another reviewer suggested taking out the entire last paragraph because it depended too 

much on limited data. It was generally agreed to by all the reviewers that more information be 

provided on the VOC sampling (such as the total number of samples, number below detection 

limits, spatial and temporal distribution, etc.) so that the data are more transparent to the reader 

in understanding the limitations in using these data for assessing general population exposures. 

3.9 Comment on the First Several Days After September 11 

The reviewers felt that the discussion presented in this section could be moved up to the front of 

the document to be included in the monitoring section (Section III). The issues raised are similar 

to the discussion that should be expanded upon in that section, which would provide a better 

description of the data that are available, what time periods can be reliably evaluated, and what 

populations can be evaluated using the data collected. It was suggested earlier that information 

be added to the report on the monitoring program design, including information on what 

monitoring was done and not done. The discussion currently presented in this section would fit 

well in that expanded section. 

3.10 Occupational and Indoor Exposures 

In general, reviewers felt that the occupational and indoor air information presented in the 

document distracted the reader from the primary focus of the document, which is ambient 

(outdoor) exposures to the general population. Reviewers found these assessments to be of 

31
variable quality, which would be expected because of limited data to characterize concentrations 

to which recovery workers in the restricted zone might be exposed. Some reviewers felt that 

these discussions should be removed from the document, and others suggested that they be 

moved to appendices. Most reviewers stated that these issues need to be addressed in a more 

comprehensive manner, which would call for separate stand-alone documents. Because such 

documents might not be developed (at least by EPA), some reviewers suggested that the 

assessments done to date be retained, but be de-emphasized by placing them in the appendix. 

3.10.1 Occupational Exposure Assessment 

Reviewer discussion began with one reviewer suggesting removing the section on occupational 

exposure because there were not a lot of onsite measurements, especially for PM. The reviewer 

claimed that the data collected do not reflect the exposures of on-site recovery workers within 

the restricted zone. Several reviewers agreed that the workers participating in the recovery effort 

were exposed to more extreme conditions than indicated by the data presented (mostly from 

perimeter monitoring locations). The exposure was outdoors, but it was an extremely unique and 

unknown exposure. In addition, the recovery workers were often on site 12 hrs/day for 7 

days/wk and they didn’t use respiratory protection. Another reviewer suggested leaving the 

section in, but removing the references to occupational exposures to PM, because of the data 

shortcomings. Similarly, another reviewer added that the asbestos measurements do not provide 

an adequate characterization of occupational exposures. Limitations in the asbestos data result 

from variability in the PCM analyses, the location of the monitors, and other complexities, which 

call for a more extensive assessment in a separate report. Alternatively, several reviewers 

commented that the dioxin occupational analysis was well developed and appropriate, somewhat 

because on-site measurements were available. This discussion brought up again the suggestion 

that the monitoring methods section be revised to better describe the sampling procedures, 

methods, time frames, etc., which would better illustrate the strengths and weaknesses of the 

various data sets for use in estimating exposures. 

32
Several reviewers felt that the occupational exposure discussion should be removed; however, a 

question was raised asking whether other reviewers would suggest removing this section if 

another assessment were not done focusing on worker exposure. One reviewer noted that the 

downside to keeping this section in the report is that the data do not provide a clear picture of 

conditions for recovery workers and that it distracts the reader from the main focus on outdoor 

exposures of the general population. Several reviewers agreed that “someone needs to do this” 

and suggested that EPA work with NIOSH, OSHA, and other organizations to conduct a more 

extensive assessment. Reviewers did acknowledge, however, that unless there will be a separate 

report on occupational exposure, it would be better to include the available information, but 

possibly de-emphasize this section or put it into an appendix. Many reviewers agreed with this 

sentiment, commenting that such a suggestion would be an acceptable middle ground. 

3.10.2 Indoor Air Exposure Assessment 

Reviewers felt similarly about the indoor exposure discussion, suggesting that it would be best if 

it were taken out and prepared as a separate report. The issues are very complicated and warrant 

more extensive analysis and discussion. In addition, there are many other groups addressing 

aspects of the indoor air issue, including many health studies that might not be completed for 

some time. It was pointed out that the main data set included in this section was the ASTDR 

study, and this creates an uneven match when compared to the rest of the document. It was also 

not clear whether the ASTDR study had been peer reviewed. The indoor air issue is more 

complicated than the ambient air assessment due to the challenges in cleanup and confirmatory 

sampling, which deserves a more extensive treatment in a stand-alone document. 

Many reviewers agreed that the indoor exposure section should be further developed as a 

separate document, or it could be added to what has already been prepared and peer reviewed 

(WTC, 2003). This document could introduce the issue and refer readers to other 

studies/organizations that are addressing ancillary studies. One reviewer cautioned against 

adding web sites for ongoing studies because they can become outdated very quickly. It was 

also suggested that EPA re-examine the indoor air sections in the current draft of the report (e.g., 

33
asbestos assessment) because of errors in the measurements and assessment. Reviewers 

concluded their discussion with a suggestion that EPA work with other organizations with 

responsibilities for the indoor air issue. It might even consider commissioning an independent 

group of experts to further address the indoor air issue, such as the National Academy of 

Sciences. Reviewers wrapped up the discussion and recommended that EPA should move 

forward quickly to determine the most appropriate future activities and mechanisms for 

completing an indoor air health assessment. 

34
3.11 Conclusions/Executive Summary 

In general, the reviewers’ comments on previous sections addressed the contaminant-specific 

and overall conclusions presented in the executive summary. The executive summary will 

change after EPA revises the assessment, based on the panel’s comments. One reviewer felt that 

the second paragraph of the executive summary, which indicated that the report covers the 

inhalation exposures of the general population residing and working in the area, which are 

indoor activities, does not fit with the outdoor assessments, which are the focus of the report. 

Also, the executive summary should be improved to make it suitable to be a stand-alone 

document. One reviewer commented that the executive summary should more clearly indicate 

the time frames when contaminant levels returned to background levels. 

During this final discussion session of the meeting, the Chair facilitated preparation of flip charts 

summarizing the major recommendations from the reviewers (presented in Appendix E). The 

items placed on the flip charts included those issues where the reviewers felt strongly about 

corrections or improvements that should be made by EPA to the document. Following this 

discussion, reviewers made final concluding statements. Overall, the reviewers felt that EPA 

should be commended for its assessment. The document will be well received if time is taken to 

revise and incorporate the proposed recommendations and suggestions. The document needs to 

be refined, with a clearly stated purpose and scope, which should result in an excellent 

assessment. When completed, this document will be the definitive statement on outdoor air and 

the potential health effects from the airborne pollution created by the World Trade Center 

disaster. The document should be completed in a timely manner because of the public’s need for 

information on potential health risks. It would also be desirable to make it the first of a series of 

documents focusing on ambient (outdoor) air exposures for the general population. EPA was 

encouraged to consider further enhancing its separate assessments on indoor air (WTC, 2003) 

and to work with other groups on the occupational exposure issues. In addition, other longerterm studies should be considered, such as conducting toxicity tests on the dusts and 

characterizing other contaminants of concern, to better assess potential health impacts. 

35
4. OBSERVER COMMENTS 

Several opportunities during the two-day meeting were provided for observers to make 

comments and provide feedback on EPA’s document. This section summarizes the statements 

made by observers who spoke during the meeting. Written statements, handouts, and documents 

provided by observers during and following the meeting are presented in Appendix G. 

4.1 First Comment Period 

Mr. Joel Kupferman, of the New York Environmental Law and Justice Project, stated that he was 

an attorney with the firefighter’s union. He commented that EPA did not provide the data that it 

had obtained in a prudent manner. The data that were collected were very revealing and 

exhibited exceedances. He stated that releasing this information after the fact is really only an 

academic exercise. Mr. Kupferman felt that EPA did not go out of its way to obtain data 

and that his organization did. He also commented that only 218 out of 1000 landowners 

responded to questions on why they either did or did not re-open their buildings. Mr. 

Kupferman felt that there was inaccuracy in the monitoring data and indicated that the statement 

had been made that personal monitoring data had been thrown out because it was too high; they 

were dismissed as a spiked sample. Mr. Kupferman noted that studies are still on-going on the 

plume moving towards Brooklyn and that, in addition, trucks were known to have taken things 

from Ground Zero to other areas. Scientists indicate they want lots of data, but none of the site 

workers were registered beforehand so as to keep track of them. Nurses who have come forward 

with respiratory problems have not been included in reports. Mr. Kupferman felt that people 

should have been warned that they could have been exposed to chemical hazards from the World 

Trade Center buildings (e.g., 6800 pounds of mercury) and also that there is a need to better 

understand where the chemicals are moving. Mr. Kupferman offered, upon request by the Chair, 

to provide a list of names of the people he had mentioned who have come forward with 

respiratory illnesses. 

36
Ms. Diane Dreyfus commented that no testing had been done on workers. She also stated that 

Dr. Chatfield was not a good choice for the panel because of his past work for W.R. Grace in the 

Libby, Montana, case. Ms. Dreyfus suggested that another reviewer be added to the panel, Jim 

Millette from EPA Region 8 (who is actually not an EPA employee but is a principal of a private 

corporation, Millette Vanderwood Associates, Inc. [MVA, Inc.]). 

Ms. Ann Warner Arlen stated that she was the Vice-Chair of Community Board #2 (which 

covers Canal Street to 14th and the Bowery to the Hudson River) and reviews projects and brings 

matter of urgency to city agencies. Ms. Arlen raised two points. The first point was that she felt 

that the line drawn at Canal Street was extremely arbitrary. Particles were still found in the air, 

and the smell of fires could be detected beyond this cut-off point. Apartments beyond this area 

were full of fumes, and some people reported coming down with chronic cases of bronchitis and 

sinusitis. High levels of particulates were found near NYU and Beekman as well as in areas in 

Brooklyn and New Jersey; however, these impacted places were left out of the monitoring that 

was performed. The second point was that lessons learned are important in this situation; she 

hoped that responses would be better and stated that there is also a need to commit to doing the 

right thing now. She stated that people were told that “there is nothing to worry about” and that 

she had the feeling that these issues did not matter to the government. Upon request, Ms. Arlen 

offered to provide copies of the NYU/Beekman and University of California, Davis, particulate 

studies (not received as of the finalization of this report). 

Ms. Jo Polett noted that she “is the target audience” because she lives just six blocks north of the 

World Trade Center and returned to her apartment on September 18, 2001, but then had to leave 

in November and only returned again ten days ago. Ms. Polett requested that EPA investigate 

indoor air. She noted that the cleaning efforts in her apartment were not done properly. She had 

no history of respiratory problems but has had recurring problems since returning to her 

apartment. Her apartment had been cleaned in May 2002, but during the subsequent testing, she 

found that one of the fans was never turned on in her apartment and that the others were not 

oscillating, as is required in the testing protocol. She made the point that this makes the 

sampling data useless. Ms. Polett also noted that the ATSDR/NYCDOHMH study referenced in 

37
the report only sampled two buildings and was not representative of what was actually in the 

building. She stated that assessments can not be based on the available indoor air data. 

Although the outdoor air might be acceptable, there are high levels of contaminants in the indoor 

air, so the exposures are ongoing. 

Ms. Kimberly Flynn, of 9/11 Environmental Action, read aloud a letter that she had written on 

behalf of the 9/11 Environmental Action group to the Regional Administrator of EPA Region 2, 

Jane M. Kenny, dated July 14, 2003. The letter was written to formally object to the failure of 

EPA to comply with the “proper, legally mandated public process in its assessment and cleanup 

of hazardous substances released in the World Trade Center disaster.” The letter requested 

implementation of a public process to include affected communities in the decisions being made 

that affect their health and environment. Ms. Flynn noted in the letter that EPA had promised to 

establish a citizen’s advisory group in 2002, but this was never created. The letter also voiced 

objection to the failure of both EPA and Versar to conduct public outreach for the current peer 

review meeting. She noted that community-based organizations and advocacy groups were not 

given the opportunity to nominate qualified experts to serve on the panel nor was the public 

given ample time to review the chosen panelists’ CVs. The letter also noted objections to certain 

panelists who were chosen, based on possible ties to either EPA or major polluting industries 

regulated by EPA. The letter requested (and stated that this request was made in two previous 

letters) that EPA initiate a “legitimate public process” and a comprehensive cleanup of all 

affected residences and workplaces. 

4.2 Second Comment Period 

Ms. Jenna Orkin, of 9/11 Environmental Action, requested that Dr. Thomas Cahill’s PM data be 

included in the PM section of the report. These data were made public in February of last year. 

She pointed out that the PM2.5 data for areas beyond the site have consistently been reported by 

EPA to be at levels that are fine, but she stated that this was not the case. At Stuyvesant High 

School, PM concentrations were much higher than at Ground Zero. Ms. Orkin noted that EPA 

has stated that it does not expect short- or long-term health effects, but she pointed out that there 

38
already are illnesses. She commented that there has not been any effort to do a study on the 

students at the high school. Most of her knowledge on the situation is anecdotal, but she stated 

that students have had respiratory illnesses and that one teacher at the high school was reported 

to have been a lung cancer victim. Ms. Orkin requested that EPA acknowledge the potential 

health effects from the high levels of contaminants. At Stuyvesant High School, asbestos 

concentrations were found to be as high as 123 s/mm2

; however, the contractor hired to sample 

in the high school reported no problems. All of these data are suspect. Ms. Orkin requested that 

a doctor be added to the panel to examine health effects from the World Trade Center. In answer 

to a question from the panel, Ms. Orkin noted that the PM concentrations at the high school were 

provided by sampling overseen by the parent’s association of the high school (ATC–inside 

sampling; ATC and EPA–outside sampling). A question was raised by the panel whether 

Cahill’s data are readily available. It was noted by Ms. Orkin that they were available on the 

web site, http://www.nyenvirolaw.org . 

Dr. Robert L. Jaffe, of Environmental Toxicology Laboratory, questioned whether in vitro tests 

were performed. He noted that pollutant mixtures should have been evaluated, as well as the 

toxicity of small particles and new types of pollutants not previously studied. He suggested that 

if samples are still available, his laboratory could do tests with them. His lab has developed a 

new toxicity test using protozoa. Dr. Jaffe provided information to Versar to pass on to the panel 

describing his lab and testing procedure. 

Ms. Jo Polett spoke for Ms. Nina Lavin, noting that the EPA fact sheet on the report being 

discussed does not say “ambient” in the discussion of potential short- and long-term effects. She 

also suggested that the executive summary be rewritten to add uncertainties on the health effects. 

She provided the peer review panel with copies of a New York Times article from December 28, 

2002, for review, adding that such articles, stating that there are no health effects, hinder cleanup 

of apartments. She provided the panel with the executive summary of the 

ATSDR/NYCDOHMH study as well as supporting data. She requested that the panel review 

the full ATSDR/NYCDOHMH study, which is available on the Internet, as well as the 

underlying data. Ms. Polett posed a question asking whether asbestos really is a good indicator 

39
of World Trade Center contamination, because it is being used to determine the need to clean up 

apartments. 

4.3 Third Comment Period 

Dr. Catherine McVay Hughes, of NYU, has prepared community outreach materials on the 

World Trade Center, highlighting ongoing research projects. She also pointed out that local 

papers have reported on a survey of respiratory problems in residents. She commented that the 

public outreach to the communities needed to be better. Dr. Hughes stated that there needed to 

be a consideration of risks from ingestion of dusts inside homes. This also poses additional risks 

to residents who work in the area, so they are exposed 24 hrs/day. It should also be highlighted 

that the restricted zones were not always effective at keeping people out of the restricted area. 

She pointed out that there are still buildings available for collection of dust samples. One 

suggestion she made was that EPA include, along with meteorological data, temperature maps, 

which could be useful in discussing the fate and transport of pollutants. A panel member asked 

whether there was further information on the respiratory symptom survey, and Dr. Hughes 

directed the panel to the Community Board #1 Web site, http://www.cb1.org , which provides 

the contact information for the District Manager, Paul Goldstein. 

4.4 Fourth Comment Period 

Dr. Marjorie J. Clarke, of Lehman and Hunter Colleges, commented that she was glad to hear the 

panel recommending that more studies be done, particularly indoor air studies involving 

additional organizations. She criticized EPA for releasing conclusions prior to conducting peer 

review of its studies, which resulted in confusion in the public on the potential health effects 

from the World Trade Center. She suggested removing conclusion #3 from the report and 

argued that it was being used to silence the cleanup program advocates. Other concerns were for 

synergistic effects of the complex mixture of pollutants, such that conclusions should not be 

made before the interactions are better understood. Using the precautionary principle should be 

encouraged. In addition, EPA’s premature statements led to bad decisions, including delegating 

40
responsibilities to other authorities for cleanup and other activities, which have resulted in 

increased exposures. 

Ms. Kimberly Flynn suggested a re-writing of the executive summary and conclusion #3 to 

better reflect the information from various doctors on the extent of disease resulting from the 

World Trade Center exposures, even though the available chemical exposure data are limited. 

Qualitative statements should be made on the limited knowledge on chemical mixtures and 

impacts to occupational environmental health. She mentioned a presentation by Steve 

Markowitz that had been given at the New York Academy of Sciences in February 2003 that 

supports that statement. EPA has the opportunity to provide accurate information on risks to 

help restore public confidence and increase public awareness. Ms. Flynn endorsed the panel’s 

recommendation for a separate document on indoor exposures and chronic health effects as well 

as the use of an independent panel to address the indoor air issues related to the cleanup. She 

stated that she hoped the case would be made to re-open the cleanup effort and to re-examine the 

indoor air data. 

Ms. Orkin suggested that the reviewers consult a white paper by Congressman Nadler and also 

the EPA Inspector General’s report of January 27, 2003, which criticizes EPA on apartment 

cleanup. She noted that EPA cleaned very few HVAC systems and left most decisions to the 

residents, who had little information on which to make decisions. EPA’s cleanup was also 

incomplete and insufficient. She commented that the outreach by EPA needs to be more 

extensive to educate the public. Ms. Orkin noted that at Stuyvesant High School, a barge waste 

transport site was located very close by. However, the ventilation system of the school was only 

cleaned after threats were made to sue over elevated lead levels. Ms. Orkin reiterated that, based 

on NIOSH respiratory studies of faculty and staff, as of last May, 60% of them still had 

respiratory symptoms attributed to the World Trade Center. She also encouraged EPA to look at 

shorter asbestos fibers. 

Ms. Jo Polett suggested that the term “ambient” be replaced with “outdoor” to make it clearer to 

the reader what the report addresses. She also advocated that an independent panel address the 

41
indoor air issue and that a community representative be included on the panel. She also provided 

information on the inadequacy of the cleanup and stated that EPA did not address dust inside air 

conditioning systems. Most buildings were not completely cleaned up. EPA’s outreach also 

needed to be improved; the May 2002 mailing was not received by many people, and other 

materials were not helpful. 

42
 REFERENCES

Lioy, P. J.; Weisel, C. P.; Millette, J. R.; Eisenreich, S.; Vallero, D.; Offenberg, J.; Buckley, B.; 

Turpin, B.; Zhong, M.; Cohen, M. D.; Prophete, C.; Yang, I.; Stiles, R.; Chee, G.; Johnson, W.; 

Porcja, R.; Alimokhtari, S.; Hale, R. C.; Weschler, C.; Chen, L. C. (2002) Characterization of 

the dust/smoke aerosol that settled east of the World Trade Center (WTC) in lower Manhattan 

after the collapse of the WTC 11 September 2001. Environ. Health Perspect. 110: 703-714. 

U.S. Environmental Protection Agency (2000). Peer Review Handbook. 2nd Edition. Office of 

Science Policy. EPA 100-B-00-001. 

U.S. Environmental Protection Agency (2002). Exposure and Human Health Evaluation of 

Airborne Pollution from the World Trade Center Disaster. External Review Draft. National 

Center for Environmental Assessment. Office of Research and Development. EPA/600/P2/002A. October 2002. (http://www.epa.gov/ncea/wtc.htm). 

WTC (2003). World Trade Center Indoor Environment Assessment: Selecting Contaminants of 

Potential Concern and Setting Health-Based Benchmarks. Contaminants of Potential Concern 

(COPC) Committee. 

43
APPENDIX A 

Peer Reviewer Biographical Sketches 
Compilation of Biographical Sketches for Peer Reviewers of 

Exposure and Human Health Evaluation of Airborne Pollution from the World Trade Center 

Disaster 

Peer Reviewers 

Eric J. Chatfield, Ph.D.

Chatfield Technical Consulting Limited

Mississauga, Ontario L5B 1Y8 Canada

Michael Dourson, Ph.D.

Toxicology Excellence for Risk Assessment

Cincinnati, OH 45223

Alison Geyh, Ph.D.

Johns Hopkins University School of Public Health

Baltimore, MD 21205 

Gary Hunt, M.S.

TRC Environmental Corporation

Lowell, MA 01852

Patrick L. Kinney, Sc.D.

Mailman School of Public Health at Columbia University

New York, NY 10032

Margaret MacDonell, Ph.D.

Argonne National Laboratory

Argonne, IL 60439

Clifford P. Weisel, Ph.D.

Environmental & Occupational Health Sciences Institute (EOHSI)/UMDNJ

Piscataway, New Jersey 08854

A-1
Eric J. Chatfield, B.A., M.A., Ph.D. 

Dr. Chatfield received his B.A., M.A. and Ph.D. from Cambridge University in the United 

Kingdom. His B.A. and M.A. were in Natural Sciences and included mineralogy and 

crystallography; his Ph.D. thesis was in Colloid Science, and was based on studies of particulate 

hydrosols and aerosols. From 1958 to 1968, Dr. Chatfield was with the Nuclear Safety Section 

of the United Kingdom Atomic Energy Authority where his work involved studies of particle 

size distribution of aerosols, using electron microscopy and diffraction, and included design and 

execution of field studies of the dispersion of airborne particulate. From 1968 to 1985 he was 

Head of the Electron Optical Laboratory at the Ontario Research Foundation. Dr. Chatfield is 

currently President and Principal Analyst of Chatfield Technical Consulting Limited which he 

formed in 1986 to specialize in asbestos analysis and research. 

Dr. Chatfield has been developing methods for determination of asbestos since 1970, including a 

method for determination of asbestos in resilient flooring materials to provide quantitative results 

and to overcome the problem of false-negative results often obtained by routine PLM, a 

gravimetric method which provides reliable quantification of low concentrations of asbestos in 

building materials such as plasters, cementitious and texture materials, a method using PLM and 

SEM for screening of vermiculite samples for the presence of amphiboles, and preparation of 

reference standard suspensions for quality assurance in TEM analysis of water samples. 

For the U.S. EPA, Dr. Chatfield developed the analytical method for determination of asbestos in 

water, a standard operating procedure for collection and analysis of air samples for asbestos, an 

analytical methodology for sampling and analysis to provide results for airborne asbestos with 

sufficient sensitivity and precision to permit risk assessment determination, a quality assurance 

guideline for TEM asbestos laboratories, and an analytical method for determination of asbestos 

in vermiculite. Dr. Chatfield was a member of the Select Committee which drafted the U.S. EPA 

AHERA TEM Analytical Methodology for asbestos abatement site clearance. 

Dr. Chatfield is Project Leader of the International Organization for Standardization (ISO) 

Working Groups which have developed 3 analytical methodologies for measurement of airborne 

asbestos in ambient atmospheres, and are currently developing a sampling strategy for 

measurement of asbestos in building atmospheres. He is also a member of the ASTM 

Committee which is developing reference analytical methods for measurement of asbestos in 

dust and in air. Dr. Chatfield was a member of the Der Verband der Chemischen Industrie e.V. 

Working Group which developed a standard procedure for measurement of asbestos in parenteral 

medicines. 

Dr. Chatfield was a consultant to The Royal Commission on Matters of Health and Safety 

Arising from the Use of Asbestos in Ontario, and prepared advisory reports on both PCM and 

TEM measurements of asbestos in air. He was editor of "Asbestos Fibre Measurements in 

Building Atmospheres", prepared for Health and Welfare Canada. Dr. Chatfield was a member 

of the Literature Review Panel and the TEM Analysis Steering Committee of the Health Effects 

Institute - Asbestos Research. Dr. Chatfield is a Technical Advisor and Laboratory Assessor for 

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the Hong Kong Laboratory Accreditation Scheme (HOKLAS) asbestos analysis accreditation 

programs, has provided training courses in TEM analysis for asbestos, has been a consultant to a 

number of laboratories concerning set-up, equipment requirements and operation of a TEM 

analysis service for asbestos, and on behalf of the U.S. EPA, he has conducted audits of 

laboratories performing TEM analysis for asbestos for EPA programs. Dr. Chatfield has been an 

expert witness on asbestos measurement for a number of court cases. Dr. Chatfield is a Fellow 

of the Chemical Institute of Canada. He has over 60 publications relating specifically to asbestos 

measurement. 

Michael L. Dourson, Ph.D., DABT 

Dr. Dourson directs Toxicology Excellence for Risk Assessment (TERA), a nonprofit 

corporation dedicated to the best use of toxicity data for estimating risk assessment values. 

TERA's projects include the development of complex risk assessments, such as soluble nickel 

salts, research into improvements of risk methods, such as comparative dietary risk for fish 

consumption, and education and outreach on risk assessment values through lectures and data 

bases, such as the International Toxicity Estimates for Risk (ITER). TERA prizes the 

development of partnerships between government agencies and industry. 

Dr. Dourson has a Ph.D. in Toxicology, University of Cincinnati (1980) and is a Diplomate of 

the American Board of Toxicology and served on its Board as President, Vice President and 

Treasurer. He has published more than 50 papers on risk assessment methods, co-authored over 

100 government risk assessment documents, and made over 80 invited presentations. 

For fifteen years, Dr. Dourson held leadership roles in the U.S. Environmental Protection 

Agency, as chair of EPA's Reference Dose (RfD) Work Group, charter member of the EPA's 

Risk Assessment Forum and chief of the group that helped create the Integrated Risk 

Information System (IRIS) in 1986. Dr. Dourson won 4 EPA Bronze medals during his tenure. 

Professional affiliations include past presidents of the Dose-Response Specialty Group of the 

Society for Risk Analysis, of the Society of Toxicology's Specialty Section on Risk Assessment 

and of the Ohio Chapter of the Society for Risk Analysis. Current affiliations include 

membership on the editorial board of three journals. Dr. Dourson previously chaired a panel that 

peer reviewed EPA’s World Trade Center Indoor Air Assessment: Selecting Contaminants of 

Potential Concern and Setting Health-Based Benchmarks. 

Alison S. Geyh, Ph.D. 

Alison S. Geyh is an assistant professor at the Johns Hopkins Bloomberg School of Public 

Health (JHSPH), Department of Environmental Health Sciences in Baltimore MD. Her work 

related to the World Trade Center disaster has included area monitoring and exposure 

assessment of one group of workers at the disaster site, and a health assessment of approximately 

8000 workers who were involved in the clean up and recovery effort. Other research interests 

include assessing the impact of vehicle-related air pollution on the health and environment of 

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inner city residents and an exploration into the specific chemical composition of metal species 

found in particulate matter. Before moving to JHSPH, she was a Staff Scientist at the Health 

Effects Institute where she was project officer for several studies focused on issues of exposure 

to particulate matter. She holds a doctorate in physical organic chemistry from Brandies 

University and conducted postdoctoral research at Department of Environmental Health of the 

Harvard School of Public Health in Boston, MA. 

Gary Hunt, M.S. 

Mr. Gary Hunt is a Vice President of Air Toxics Programs and Director of Air Toxics

Monitoring within TRC in their Lowell, MA office. He works principally in the toxic air

pollutant area and, in particular, the characterization, quantification and control of toxic air

pollutant emissions from stationary and fugitive sources (esp. combustion) , as well as their

distribution, occurrences, transport and fate in the atmosphere. Areas of particular interest and

professional activity presently include the following:

Characterization, Quantification and Control of Toxic Air Pollutant Emissions

Environmental Monitoring (Multimedia) in the Vicinity of Combustion/Incineration Facilities

(MSW, Hazardous Waste)

Waste Incineration – Emissions Testing Programs (Trial Burns, Performance Testing,

Compliance Testing; RCRA/TSCA/MSW/BIF)

Toxics Monitoring – Indoor/Workplace Air (e.g., PCB Fires)

Ambient Monitoring for PCDDs/PCDFs, PAHs and other semivolatile organics

Odor Diagnostics and Abatement – Air Emissions From Industrial Facilities

Fugitive Dust Emissions (MSW Landfills, Quarries, Etc.)

PCDDs/PCDFs Emissions From Industrial Sources – Characterization, Diagnostics 

Ambient Monitoring of Toxic Air Pollutants

Litigation Support/Expert Testimony

Title V/CAA Compliance Monitoring Programs (CAM, PM, MACT)

Air Permitting (Title V, BACT, RACT, etc.)

Analytical Methods Development

Mr. Hunt, who holds a B.S. in chemistry from Villanova University and an M.S. in

Environmental Sciences from Rutgers University, has more than 25 years of experience in air

quality consulting. He is an internationally recognized expert in the field of toxic air pollutants.

Mr. Hunt is a Qualified Environmental Professional (QEP) and Fellow Member of the Air &

Waste Management Association, as well as a faculty member of A&WMA’s CAM workshop

series. He is also a member of the American Chemical Society, Sigma XI, the Water

Environment Federation, and the American Society of Mechanical Engineers. Mr. Hunt has

authored more than 100 journal manuscripts and symposia presentations on environmental

topics.

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Patrick L. Kinney, Sc.D. 

Dr. Kinney is an air pollution epidemiologist with a strong interest in exposure assessment. He 

has carried out numerous epidemiologic studies addressing the human health effects of air 

pollution, including studies of the effects of ozone and particulate matter on children's lung 

function, on pulmonary inflammation in adult joggers, and on daily mortality in large cities. His 

recent work has focused on characterizing levels and determinants of indoor, outdoor, and 

personal exposures to air pollution in the underprivileged neighborhoods of NYC, including 

studies of indoor allergens, diesel vehicle emissions, volatile organic compounds, PAHs, and 

other air toxins. He directed an NIEHS-funded intervention trial seeking ways to reduce 

exposures to indoor allergens among asthmatic children living in Northern Manhattan and the 

South Bronx. He also is the P.I. of a study entitled "Urban Air Toxics Exposures of High School 

Students," funded by the National Urban Air Toxics Research Center. The study characterized 

air toxin exposures among minority high school students living in New York City and Los 

Angeles. Dr. Kinney co-directs the Exposure Assessment Cores of the Columbia Center for 

Children’s Environmental Health and the Center for Environmental Health in Northern 

Manhattan. 

Margaret MacDonell, Ph.D. 

Margaret MacDonell is manager of the environmental health risk section of the environmental 

assessment division at Argonne National Laboratory. She has a Ph.D. from Northwestern and an 

M.S. from Notre Dame in civil / environmental health engineering, and a B.S. from Notre Dame 

in biology (with honors). Her work at Argonne has focused on risk assessments for 

contaminated sites, primarily for federal cleanup programs with an emphasis on Department of 

Energy (DOE) facilities. In addition to interacting with regulators and the public in evaluating 

multi-pathway risks, she has also conducted risk training workshops for federal, state, and tribal 

risk program managers as well as risk workshops for the local community at a contaminated site. 

Margaret is an adjunct professor at Northwestern University (teaching risk analysis and 

environmental impact assessment in the Technological Institute) and president of the Chicago 

Regional Chapter of the Society for Risk Analysis. She serves on the editorial board of 

international environmental journal and is a participant in various cumulative risk initiatives, 

including the interagency Mixed Exposures Research Group, American Chemistry Council Risk 

Assessment Methods Technical Implementation Panel, and collaborative DOE-Environmental 

Protection Agency interagency agreement on screening guidance for cumulative risk assessment. 

Clifford P. Weisel, Ph.D. 

Clifford P. Weisel, Ph.D. is a Professor in Environmental and Community Medicine at the 

University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School and 

Deputy Director of the Exposure Measurement and Assessment Division of the Environmental 

and Occupation Health Sciences Institute. Dr. Weisel also holds appointments at the Graduate 

Faculty of Rutgers University and the School of Public Health of UMNDJ and directs the 

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Doctoral Graduate Study option in Exposure Assessment, jointly given by the Graduate School 

of Biomedical Sciences of UMNDJ and the Department of Environmental Sciences of Rutgers 

University. He was the treasurer of the International Society of Exposure Assessment and an 

associate editor of the Journal of Exposure Analysis and Environmental Epidemiology and the 

Journal of the Air Waste and Management Association. 

Dr. Weisel has conducted research to evaluate multi-route exposures to volatile organic 

compounds and trace metals using direct exposure measurements and biomarkers of exposures. 

His broad areas of interest are analyzing the relationship among ambient, indoor and personal air 

pollutants; the effect of air pollutants on asthmatics; multi-route exposure to disinfection byproducts in drinking water; how the body burden of contaminants and their metabolites vary to 

reduce uncertainty in extrapolating basic mechanistic data determined at high concentrations in 

animals to environmental exposures in humans; measuring biomarkers and variations in 

metabolic rates for use in pharmacokinetic models in humans at environmentally relevant levels; 

and application of genomics to understand gene-environmental interactions. 

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APPENDIX B 

List of Observers 
Technical Peer Review Meeting on the Draft Document Entitled: Exposure and Human 

Health Evaluation of Airborne Pollution from the World Trade Center Disaster 

July 14-15, 2003 

OBSERVERS 

Name Organization 

Sara Allen Ecology & Environment, Inc. 

Belina Anderson New York City Law Department 

Michael Brown U.S. EPA - ORD 

Nancy Clark NYC DOHMH 

Marjorie J. Clarke Lehman and Hunter Colleges 

Nathalie Cohen New York City Law Department 

Bernard Cooney N.Y. Environm. Law and Justice Project 

Avidan Cover New York City Law Department 

Diane Dreyfus Little Italy Neighbors Association 

George C.D. Duke New York City Law Department 

Aura Engel N. Y. Environ.Law and Justice Project 

Barbara A. Finazzo U.S. EPA - Region 2 

Kimberly Flynn 9/11 Environmental Action 

Robin Forst Council Member Gerson 

Herman Gibb U.S. EPA - NCEA 

Paul Gingrass Zelle Hofmann 

Virali Gokaldas Natural Resources Defense Council 

Hiller Hammer A.K.R.F. 

Jenny Ho Environmental Defense 

Robert L. Jaffe Environmental Toxicology Laboratory 

Joel R. Kupferman N.Y. Environ. Law & Justice Project 

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OBSERVERS 

Name Organization 

Diane Levy Columbia University 

Carrie Loewenherz NYC DOHMH 

Matthew Lorber U.S. EPA - NCEA 

Faye Lubinof New York City Law Department 

Amy Mahl Ecology and Environment, Inc. 

Shek Mark U.S. EPA - OIG 

Stephen Mazzalonga New York City Law Department 

Kelly R McKinney New York City Department of Health 

Catherine McVay Hughes New York University 

Mary Means EPA 

Yosef Moshe NYELJP 

Morton Orentlicher Ecology & Environment, Inc. 

Jenna Orkin 9/11 Environmental Action 

La-Verne Parris Environmental Defense 

Joseph Pinto U.S. EPA - NCEA 

Jo Polett Downtown Resident - 9/11 Environmental 

Action 

Peter Preuss U.S. EPA - NCEA 

Hara Robrish New York City Law Department 

Jessica Rosenzweig Council Member Gerson 

Amy Rozenfeld New York City Law Department 

Alex Salvagno AAR Environmental 

Rudy Sanfilippo Uniformed Firefighters Association 

Susan Smollens New York City Law Department 

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OBSERVERS 

Name Organization 

Steven Tishco New York City Law Department 

Diane Van Dyke N. Y. Environ. Law and Justice Project 

Ann Warner Arlen Community Board #2 Manhattan 

Josh Weinberg N. Y. Environ. Law and Justice Project 

Henry Willis RAND 

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APPENDIX C 

Agenda 
United States 

Environmental Protection Agency 

Office of Research and Development 

Technical Peer Review Meeting on the 

Draft Document Entitled 

Exposure and Human Health Evaluation of Airborne 

Pollution from the World Trade Center Disaster 

Sofitel New York Hotel 

45 West 44th St. 

New York, NY 10036 

Agenda 

MONDAY, JULY 14, 2003 

8:30AM Registration Begins 

9:00AM Welcome, Introductions, and Conflict of Interest Discussion 

David Bottimore, Versar, Inc. 

9:15AM Welcome Peter Preuss, Director, National Center for Environmental 

Assessment (NCEA), Office of Research and Development, U.S. Environmental 

Protection Agency 

9:20AM Chair’s Introduction Michael Dourson, Workshop Chair 

9:30AM Background on WTC Assessment Matthew Lorber, U.S. EPA/NCEA 

10:00AM Peer Reviewer Q&A Session on Background Presentation 

10:30AM Break 

10:45AM Observer Comment Period 

11:15AM Discussion Session - Purpose and Scope of Assessment 

12:15PM Lunch 

1:15PM Discussion Session - Exposure Assessment and Risk Characterization 

Approach 

2:15PM Discussion Session - Monitoring Data 

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3:15PM Break 

3:30PM Discussion Session - Particulate Matter 

4:30PM Observer Comment Period 

5:00PM Wrap-Up of First Day 

TUESDAY, JULY 15, 2003

8:30AM EPA and/or Observer Comments 

9:00AM Discussion Session1 

– Metals 

– PCBs and Dioxins 

– Asbestos 

12:00PM Lunch 

1:00PM Discussion Session - VOCs 

1:45PM Discussion Session - Occupational and Indoor Exposures 

2:30PM Break 

2:45PM Discussion Session - Conclusions/Executive Summary 

3:30PM Observer Comment Period 

4:00PM Summary of Comments and Recommendations on WTC Document and 

Writing Assignments for Workshop Report 

5:00PM Adjourn 

1

 The Chair will determine the appropriate time for the break during this discussion period. 

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APPENDIX D 

PowerPoint Presentations 
I. Introductory Talk by David Bottimore, Versar 

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D-2
II. Overview Presentation of Document by Matthew Lorber, EPA 

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APPENDIX E 

Flip Charts from Meeting 
Major Recommendations from Reviewers at Close of Meeting 

In the afternoon of the second day of the peer review meeting, the Chair led a brief session with 

the reviewers to recap some of the major recommendations and suggestions that were provided 

during the meeting. 

• Replace AHERA asbestos standard with IRIS value; conduct analysis as for dioxin and 

PCB cancer evaluation 

• Clarify dioxin monitoring and MOE discussion; revise exposure scenarios for WTC 

worker and resident 

• Revise PCB noncancer benchmark 

• Review data of potential inconsistencies of PM2.5 data; incorporate data on PM10 

• State monitoring program design up front; state COPC not addressed (e.g., PAHs) 

• Rank benchmarks for health; adjust OELs for duration and sensitivity; compare 

exceedances with tox or epi. data 

• Define populations of concern (e.g., are “illegal” residents consider resident-worker 

scenarios) 

• Keep text focused on out-door air; state text as interim subject to change; link to other 

efforts 

• Enhance VOC discussion with LOD, then caveat conclusions as appropriate; revise tables; 

give “n” for samples 

• Enhance ongoing effort on indoor environment; consider independent group analysis (e.g., 

NAS) 

E-1
APPENDIX F 

Written Comments from Reviewers 
Review by 

Eric J. Chatfield, Ph.D. 

Exposure and Human Health Evaluation of Airborne Pollution 

from the World Trade Center Disaster. Report NCEA-W-1395, 

EPA/600/P-2/002A 

Initial Comments by Eric J. Chatfield, 2003 June 29 

I would suggest that the title of the report be changed to: 

AMeasurements of Ambient Airborne Pollution and Evaluation of the Potential Health Impacts 

from the World Trade Center Disaster@. 

This title would emphasize that the measurements under consideration are for ambient air, and 

introduction of the word Apotential@ conveys the acknowledged fact that there is a great deal of 

uncertainty in the interpretation, particularly for September 11 and the early days afterwards. 

Overall, the draft report effectively summarizes a great deal of data collected from 

diverse sources, and the general conclusions reached appear to be consistent with the available 

data. However, I believe the report could be improved by re-organizing the sections into the 

following topics: 

1. Executive Summary 

2. Purpose 

3. Rationale for Selection or Rejection of Pollutants to be measured 

4. Measurements of Pollutants 

5. Discussion 

6. Conclusions and Recommendations 

In a report such as this, the Executive Summary is particularly important, in view of the 

wide audience who may read this report. Many readers will read only the Executive Summary, 

and will not read the more detailed discussions later in the report. It is therefore most important 

that this section be as free-standing as possible. The Executive Summary should carefully 

discriminate between firm conclusions and other areas about which there is uncertainty or 

insufficient knowledge. It should also be clear that the general conclusions of the report refer 

only to exposures from ambient (outdoor) atmospheres, and not to the indoor atmospheres of 

buildings in which deposited pollutants were unchanged by weathering. I believe that the 

Executive Summary should also include reference to the limitations of some of the measurement 

methods. 

Early in the document, there should be a detailed discussion of the contaminants 

considered to be of concern, the rationale for selection of those to be measured, and the rationale 

for those excluded. For example, glass fiber and mineral wool are known to have been major 

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components of the dust cloud from the collapse of the World Trade Center towers, but the only 

consideration given to them seems to be as a constituent of the particulate material (PM) 

measurements. These fibers do not normally contribute significantly to the airborne particulate 

material in urban environments, and it is therefore questionable whether the NAAQS screening 

benchmark for PM used in the report is a sufficiently protective value, given the irritating nature 

and composition of the dust that was generated by the collapse of the towers. 

The use of screening benchmarks based on occupational PELs or TLVs should be 

re-examined. Given the unprecedented nature of the events and the need for some rational basis 

for interpretation of data, the PELs and TLVs provide a good starting point. For ionizing 

radiation, the practice is to adjust such benchmarks for application to the general public by 

taking account of the working week vs. the full year and the normal years worked vs. the normal 

life expectancy, and then reducing these modified PELs and TLVs by a further factor of 10. 

The presentation and interpretation of the asbestos data needs to be re-examined. The 

practice of using phase contrast microscopy (PCM) as a screening measurement for ambient air 

samples could frequently lead to misleading conclusions. In general building atmospheres and in 

the outside atmosphere, there has usually been very little correlation between PCM results and 

transmission electron microscopy (TEM) results obtained from the same or parallel-collected 

samples. Accordingly, there is no reason to believe that samples showing elevated PCM fiber 

counts would necessarily coincide with those showing elevated TEM asbestos fiber counts. 

High PCM fiber counts could represent nothing more than an elevation in the number of paper 

fibers or naturally-occurring organic fibers, and elevations in asbestos fibers could have been 

overlooked. It has long been generally recognized that PCM is not a suitable means for 

measurement of asbestos in ambient atmospheres, however for some reason it was applied in this 

report. 

All of the TEM data for asbestos are presented in terms of structures/mm2

 (s/mm2) on the 

collection filters. There appears to be no reason to do this, and reporting the data in terms of 

structures/cc (s/cc) would be far more useful and scientific. The AHERA clearance value of 

70 s/mm2

 is actually based on the average of 5 samples, and is itself only an initial screening test 

which substitutes for a statistical comparison of sets of 5 indoor and 5 outdoor samples. The 

value of 70 s/mm2

 is not a health-based standard, and it was derived solely from the asbestos 

contamination that existed on filter media available in 1987. The asbestos contamination on air 

sampling filters in current use is virtually undetectable, and as a consequence the continued use 

of the 70 s/mm2

 criterion amounts to an acceptance of a clean air standard of approximately 

0.02 s/cc. Also, the AHERA protocol is intended to simulate the worst case situation indoors by 

use of aggressive air sampling after extensive cleaning of all surfaces. The outside results 

tabulated in this report would likely have been different if surfaces had been disturbed with leaf 

blowers close to and up-wind of the sampling location. Moreover, there appears to be variation 

in the analytical sensitivities of the analyses, which are dependent on the air volumes collected 

and on the area of the TEM specimens examined. I would recommend that all data expressed in 

terms of s/mm2

 be converted into air concentrations expressed as s/cc, with additional reporting 

of the concentrations of fibers longer than 5 μm. Assuming that all TEM analyses were 

performed in accordance with the AHERA method, the concentrations of fibers longer than 5 μm 

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should be available in the data, and these would provide a limited basis for risk estimation which 

cannot be performed using values in terms of s/mm2

. 

F-3
Exposure and Human Health Evaluation of Airborne Pollution from the 

World Trade Center Disaster. Report NCEA-W-1395, EPA/600/P-2/002A 

Supplementary Comments by Eric J. Chatfield, 2003 October 12 

The following are supplementary comments on the EPA report. These additional 

comments were too detailed in nature to be included in my initial comments, and they were not 

discussed at the Peer Review Meeting because they did not fall under any of the general charges 

to the reviewers, but they may be helpful to EPA during the revision of the report. 

1. In the List of Acronyms and Abbreviations, “f” should refer to “fibers”, rather than to 

“fibers of asbestos”, the letter “L” in “REL” and “STEL” I believe is “Limit”, rather than 

“Level”, “TEM” is “Transmission Electron Microscopy”, and “XRF” is “x-ray 

fluorescence”. 

2. In the Executive Summary on Page 1, Paragraph 2, Line 3, it is stated that “It is an 

assessment of the inhalation exposure and potential human health risk incurred by the 

general population residing and working in the vicinity of the WTC.” This statement 

requires some additional clarification, because most people residing and working near the 

WTC spend most of their time indoors, and indoor exposures are not the primary focus of 

this report. 

3. On Page 2, in Line 8 of Paragraph 2, the sentence beginning “Dioxin and VOC’s...” 

needs to be re-worded. As it stands, the sentence can be taken to mean that these 

pollutants are produced only from fuels. There were many other potential sources in the 

WTC buildings. 

4. On Page 2, the final paragraph contains the expression “in the surrounding community”. 

It would be good if this could be better defined. 

5. On Page 9, Line 2, it is stated that PCM is used to identify structures greater than 5 :m in 

length. PCM does not have the ability to identify anything. 

6. On Page 9, Line 3, the statement in parentheses is incorrect. TEM is used to detect and 

identify asbestos structures greater than 0.5 :m in length 

7. On Page 9 in the final line of Paragraph 1, a reference for the value of 0.003 f/cc as 

typical of urban background should be given, particularly since it is used in the report as 

a definition of background. In fact, I remain uncomfortable with the concept of using 

PCM as a measurement method for asbestos in the general environment. I recognize that 

it may have been useful for rapid measurements in the early hours after the collapse, but 

the authors should be careful to not place too much reliance on the PCM measurements, 

either outdoors or indoors. In the measurements we made in the apartments, I never even 

contemplated the use of PCM. 

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8. On Page 9 of the report, in the 3rd Paragraph, it is stated that “One apartment was highly 

affected by the collapse of the WTC towers with completely shattered windows and dust 

piled throughout the apartment. The other was in a building that had little exterior 

damage.....”. In fact, I was present at the sampling and only one small window had been 

broken in the first apartment, and the opening had been sealed with plastic sheet and 

adhesive tape. The other building had no exterior damage. 

9. On Page 10 of the report in the first paragraph, some reference to the method of analysis 

of the bulk samples should be given, and a caution on the reliability of these data. It is 

well known that measurements by PLM in the range below about 5% are quite unreliable, 

and it is unlikely that the figures quoted to two significant digits are meaningful. 

Moreover, I think that asbestos was likely present in all of the bulk samples collected, 

and that the failure to detect asbestos in many of the settled indoor dust samples or the 

outdoor samples was a question of deficiencies in either the analytical method, or the 

conduct of the method. 

10. On Page 11, Paragraph 2, Line 9, the method of analysis should be stated.. 

11. On Page 17, the last entry in Table 1 is incorrect. The AHERA clearance standard is not 

“a level of concern”. Abatement activities were not undertaken to reduce air 

concentrations, because abatement decisions were not made on the basis of measured air 

concentrations. It is incorrect to say that school children were not allowed back in until 

several consecutive readings were less than the AHERA standard. In fact, the clearance 

decision is based on the average of 5 simultaneously collected samples in the work area 

being lower than 70 s/mm2

. Even that value is considered to be an “initial screening 

test”. 

12. On Page 70, there is a blank cell for the Barclay & West Broadway location on 9/27 in 

the final column. 

13. On Page 86 at the beginning of the 2nd paragraph, the word “classified” would be more 

appropriate than “characterized”. 

14. On Page 86 in the 3rd Paragraph, it is stated that “Both asbestosis and benign pleural 

plaques result in reduced breathing capacity and mortality”. I suggest that this be rephrased, since it currently means that asbestosis and pleural plaques result in reduced 

mortality, which I do not believe is the case. 

15. On Page 87 in Section IV.e.1, it is stated with respect to PCM: “It counts all fibrous 

structures with a minimum diameter of 0.3 :m and has a magnification range of 100 ­

400X”. The minimum diameter is usually taken to be 0.25 :m in the U.S., and counts 

are made at a fixed magnification of between 400 and 450. Later in the same paragraph, 

it is stated that “PCM results are reported on a mass-per-volume basis, ....”. This is not 

correct - PCM results are never reported in that manner. 

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16. On Page 88 in the first paragraph, there needs to be some mention of the fact that the 

AHERA method specifies the use of aggressive sampling to create the worst case 

situation. 

17. On Page 88 in the 3rd line of the first paragraph, it is stated: “The AHERA Final Rule 

establishing a 70 s/mm2

 standard for asbestos in schools.....”. The AHERA Final Rule 

actually established an indoor-outdoor comparison as the clearance criterion. The 

70 s/mm2

 criterion is an “initial screening test”. In this paragraph, it should also be 

mentioned that the air sampling is to be conducted under aggressive conditions. 

18. On Page 88 in the final three sentences of Paragraph 2, it is an over-simplification to state 

that there is not a good correlation between PCM and TEM measurements. When the 

direct-transfer TEM method is used, and the PCM size fraction of fibers is measured 

using TEM, the correlation can be very close. It is true to say that, in the general 

environment, there is generally little correlation between PCM measurements and TEM 

measurements of all fiber sizes. There are two reasons for this: the PCM measurements 

include fibers other than asbestos, and the TEM measurement includes asbestos fibers 

outside of the visible range for PCM. In fact, there is no reason to expect a correlation. 

Although it is not the responsibility of the authors of this report, I believe that the 

ATSDR procedure to obtain what are termed “TEM units” by multiplying PCM data by 

60 is totally invalid. It needs to be clarified as to what these “TEM units” are - are they 

for all fiber sizes greater than 0.5 :m in length, or are they all fibers longer than 5 :m? 

19. On Page 88 in the 3rd paragraph, it is stated that “.... structures meeting a minimum 

diameter of >0.3 :m with length >5 :m are counted as PCM equivalent (“PCME”) 

fibers”. NIOSH 7402 defines “PCME” fibers as those longer than 5 :m and thicker than 

0.25 :m, and ISO 10312 defines them as longer than 5 :m and thicker than 0.2 :m. 

20. On Page 89 in the first paragraph, on line 4, the AHERA clearance criterion is actually 

based on the average of a single set of 5 samples. There is no requirement for such TEM 

readings to be “consistently” below 70 s/mm2

, just that the average of the clearance set be 

below this value. 

21. On Page 89, Paragraph 4, Line 5, it should be stated that the mass concentration of 

30,000 ng/m3

 was derived only for chrysotile, and the data on which this value is based 

have a very large range. I have already commented in Item 18 about the multiplier used 

to convert PCM to TEM data. 

22. On Page 91 in the first paragraph, reference is made to sampling stations set up in public 

schools. It is not clear whether these were external samples or actually inside the 

buildings. If they were inside, was the sampling aggressive or passive? The sampling 

conditions should be stated, since the AHERA protocol specifically requires aggressive 

sampling. 

23. On Page 128 in the 2nd paragraph of Section VI.b.1, the description of how PLM 

distinguishes between fiber types requires revision - it is not correct. I doubt that a 

simple, one sentence description is even possible, and a more detailed explanation would 

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be out of place. I suggest that the sentence be truncated to: “PLM can distinguish 

between fiber types in a bulk sample.”. I also suggest that a caution be added regarding 

the inaccuracy and unreliability of routine PLM measurements in the vicinity of 1%. As 

stated in Item 9, it is my opinion that the failure to detect asbestos in 82% of the 

residential units, and in 8 of the outdoor samples was more a question of limitations of 

the analytical method and the conduct of the method. 

24. On Page 128 in the final paragraph, it states that “All air filter samples were analyzed 

first using PCM to determine if fibrous materials were present. It seems highly 

questionable to use a method, already admitted to have little correlation with TEM data, 

as a screening method for selection of samples for subsequent TEM analysis. Under this 

protocol, the existence of a few cellulose fibers could trigger analysis by TEM, and a 

sample containing considerable numbers of thin chrysotile fibers could be overlooked. 

Again, the ATSDR work is simply being reviewed by the authors of this report. 

25. On Page 133, on the 5th line the report states: “A small-scale monitoring study of two 

residential buildings was conducted by contract (Chatfield and Kominsky, 2001).” The 

statement is incorrect - the work was not done under contract; all individuals involved in 

the study donated their time and the analytical costs to conduct this study. 

26. On Page 133 in the 2nd paragraph, it is stated that the TEM analyses were conducted 

using AHERA counting protocols. In fact, ISO 10312 was used. The end result, 

however, would be similar. Chrysotile is also spelled incorrectly at the beginning of the 

3rd sentence. 

27. On Page 133 in the final paragraph, it should be mentioned that amphibole asbestos 

(amosite and actinolite/richterite) at concentrations of approximately 0.02% was also 

detected in these outdoor dust samples. 

28. On Page 134, it is not clear whether the air sampling referred to was aggressive or 

passive. This should be clarified, because it affects the interpretation of the data. In fact, 

whether the air sampling was aggressive or passive should be stated for all of the 

asbestos air sampling data. 

29. On Page 135, various dates are quoted. It would be helpful if the year was added to each 

of these dates. 

30. On Page 135, the first sentence of Paragraph 4 needs to be re-worded. One suggestion 

would be to insert the word “who” or “that” between “people” and “may” on Line 2 of 

this paragraph. 

F-7
Review by 

Michael Dourson, Ph.D. 

F-8
Pre Meeting Comments 

General comments 

The report is a nice description of likely risks to exposures during and after the time of 

the WTC collapse. It strikes the appropriate balance between readability and more 

extensive information. The overall findings shown on page 2 seem appropriate in 

general, although they should be revisited, perhaps, for each specific chemical. Since the 

report focuses on the “outdoor” environment, this should be part of the report’s title. 

I was not sure of the reason why only these chemicals were selected. From a previous 

EPA report on the WTC disaster chemicals such as Be, Hg, PAH were also considered. 

In addidtion, what is the comparison, if any, between the health benchmarks of region 2 

(Appendix A) and those used here? What was the logic for not using the Region 2 values 

directly? Moreover, I was surprised that a mixtures risk assessment was not attempted, 

nor was the dermal pathway seemingly a concern. 

Specific comments 

(Page 5) 

I agree with the conclusion on lead, especially since adverse effect is due more to 

continuous exposure. 

(Page 6) 

How did these air samples for nickel compare to EPA’s developing RfC? (Presumably 

ATSDR did not have an intermediate MRL.) Should not EPA normalize the nickel 

OSHA PEL of 1 mg/m3

 for continuous exposure and divide by 10H for sensitive 

individuals? 

(Page 7) 

The comparisons of safe dose for PCBs do not make me happy. How were PELs 

adjusted for continuous exposure and sensitive individuals, if at all? See Appendix A (A4) for alternative values.

(Page 13) 

It seems appropriate to limit this text to outdoor air as EPA has done, especially since 

EPA already has a text on indoor environment. However, this would be a good place to 

link to other related work and consider the dermal route and a mixtures risk assessment. 

This might also be the place to incorporate or acknowledge health information in 

workers, nurses and others qualitatively assessed after the first several days of the 

disaster. 

F-9
(Page 17) 

The choice of safe doses such as the RfC automatically accounts for the protection of

sensitive populations. However, this is not necessarily true with other choices, such as 

with ACGIH’s TLVs. How does EPA account for this difference? Please make this 

distinction. See for example the following chart where I have marked whether or not the 

sensitive individual has been protected (marked with a *). 

Short-Term Exposures 

No. OSHA Permissible Exposure Limit PEL 

No. OSHA Short Term Exposure Limit (STEL) 

Yes* ATSDR Acute inhalation Minimal Risk Level (MRL) 

Yes* ATSDR Immediate inhalation Minimal Risk Level (MRL) 

Yes* EPA-STSC Provisional Subchronic Reference Concentration (RfC) 

Give RfC Definition from IRIS. 

No ACGIH Threshold limit value (TLV) 

No NIOSH Recommended Exposure Level (REL) 

Yes* EPA Asbestos Hazard Emergency Response Act (AHERA) level 

of concern 

Yes EPA Air Quality Index (AQI) 

Yes EPA National Ambient Air Quality Standard (NAAQSA) 

Long-Term Exposures 

Yes EPA Reference Concentration (RFC) Please give RfC definition. 

Yes EPA Cancer Slope Factor (SF) 

Yes EPA Unit Risk (UR) 

Yes EPA Maximum Contaminant Level (MCL) 

(Page 23) 

EPA states that screening benchmarks vary among chemicals on line 2. Have health 

guidelines been normalized among chemicals? For example, the OSHA PEL ≠ an acute 

ATSDR MRL? I would encourage EPA to develop a ranking among health values, and 

reasons why of course, similar to what EPA Region 2 and others did for indoor air. 

(Page 23) 

I suggest that EPA state its logic for choice among safe doses here. Specific changes to 

this text would be in the 3rd paragraph: 6th line: reference level by a small amount for a 

...... In the 7th line: standards, which are more applicable to the exposures experienced 

in this disaster. In the fourth 4th paragraph: last line: ...criteria, or has adapted these 

criteria to fit the given situation and population. 

(Page 24) 

Please summarize your position on particulate matter at the start of this section. 

(Page 40) 

Please add to the end of line 11: but not for all chemicals. In the 2nd paragraph please 

show me this comparison. 

F-10
(Page 41) 

2nd paragraph, lines 8-10: please note that this is for acute exposure to PM 2.5 only. 

Last paragraph, Line 7: How was dose equalized among humans and mice?

Last Paragraph, Last sentence: any interspecies adjustment used here? 

(Page 64) 

IV.b.2. Why not use the chromium and nickel RfCs?

(Page 68) 

3rd paragraph, last sentence: please change six orders of magnitude to four. 

An alternate RfC for PCBs might be: 

RfC = NOAEL 9,000 mg/m3 divided by (10H X 10A)= 90 ng/ m3 

This value is slightly less than 153 ng/m3 that EPA chose. 

(Page 75) 

Please clarify Table 4 on page 83 by showing what values are ND and which are 

measured. 

(Page 80) 

This definition of MOE is not as per EPA (see background document 1 on IRIS). 

Furthermore, this definition only works for body burdens if it is directly proportional to 

dose. Is this expected? 

(Page 81) 

3rd paragraph: I would be more interested in exceedence of an RfD or RfC from an 

ingested or inhaled dose, than what is happening with body burdens. 

(Page 95) 

What would be the exceedence based on the IRIS value of 4 x 10-5 f/ml at 1 x 10-5 excess 

cancer risk? Why not estimate the incremental excess lifetime risk as for dioxin? 

(Page 105) 

3nd full paragraph: EPA states that the analytical method can not detect benzene 

concentrations below 0.02 ppm, but then gives concentrations less than 0.02 ppm (see p. 

115). Hmm... 

(Page 106) 

2nd full paragraph: EPA concludes that the exceedences of benzene are not a public 

health risk. What is risk at 6-fold higher than short-term MRL? (See p. 115) 

(Page 107) 

Last paragraph: so what is the provisional subchronic RfC for chloromethane?

(Page 110) 

Last sentence: EPA’s conclusion on VOCs can be further supported by an analysis of 

excess cancer risk. 

F-11
Review by 

Alison Geyh, Ph.D. 

F-12
Comments on “Exposure and Human Health Evaluation of Airborne Pollution from the World 

Trade Center Disaster” 

NCEA-W-1395 

EPA/600/P-2/002A 

Date: 28 June 03 

Reviewer: A.S. Geyh 

The report, on “Exposure and Human Health Evaluation of Airborne Pollution from the World 

Trade Center Disaster” is the first summary of air contaminant data collected in response to the 

events of September 11, 2001. What follows are general comments about the report with some 

specific suggestions about the presentation of the data and results. A more detailed set of 

comments about this report from this reviewer will be offered at the meeting in NYC set for July 

14 and 15. 

General comments: 

The report appears to the best of my understanding to have considered all the available data 

collected post 9/11 as well as historical data collected in and around the NYC area. 

The use of available standards and benchmarks was appropriate overall. However, for some of 

the contaminants, such as the VOCs, it may be best to not try to put the results into a health 

context because of the sampling method and the original purpose for that sampling. 

1. From my overall reading of this report there appears to be 3 key objectives 

1. To describe the data collection effort in response to the disaster 

2. To put the post 9/11 airborne contaminant data into historical perspective 

3. To assess to the extent possible the health implications from exposure to 

these airborne contaminants at the levels measured for the general population. 

The third objective is clearly stated in the first paragraph of section I. The other 2 objectives are 

implied. I believe it is important to state them explicitly. In addition, I believe the data will speak 

for themselves in terms of their limitations and so the first paragraph could be condensed to 

listing these objectives along with the last sentence of paragraph 1 starting with “ Accordingly, 

this report attempts to take a practical.....” 

If it is true that this assessment is focused on the general population, it would be best to leave 

out any discussion of exposure of the on site rescue/recover/cleanup workers. As we are 

learning there was a very steep concentration gradient from the center of the pile toward the 

perimeter, and the perimeter sites as well, as the 290 Broadway site, do no well reflect 

concentrations in the middle of the site and thus exposure on the site. As stated in the Lorber and 

Gibbs memo of 3 June 2003 good data on the worker population are limited and other agencies 

such as OSHA and NIOHS have conducted analyses of worker exposure at the WTC that may be 

more complete. 

F-13
The brief review of the OSHA and NIOHS data in section VI should be left out as it is too brief 

to give a good picture of what these agencies did and how there results could be integrated with 

the EPA data. In addition, if the focus of this report is the general population in Lower 

Manhattan these sections may not be relevant. 

The presentation of data on the indoor environments would be better served by a separate report 

that is solely devoted to all the issues related to EPA becoming involved with indoor air quality 

and apartment clean up. 

Under section IV “ Evaluation” subsections IVb(metals) – IVf(VOCs) were extremely well 

presented starting with a brief, but complete description of the health concerns related to the 

particular contaminant, background levels measured in and around the NYC area and also in 

other parts of the US, a description of the monitoring methods at the site, the number of samples 

collected, how the values measured compare with historical data and available benchmarks. 

However, section IVa, the section describing the PM results is not as well organized and as a 

result is confusing. Some significant restructuring along the lines of the other sections would 

help the reader understand this very complicated data set and the implication of the 

concentrations actually measured. For example, in this section, the initiation of sampling for PM 

started some time after 9/11 but it is not stated when each site was set up and when actual data 

collection commenced by site. It is also not stated what PM were sampled for (PM2.5, PM10, 

both, TSP??) at any of the site except the 290 Broadway site. No end dates for sample collection 

are given ( this information is also not offered in Appendix B). Sampling frequency is not given. 

Was sampling only done by TEOM or were filter based samples collected as well? It would also 

be helpful to have a summary of results before the discussion of the implication of exposure to 

PM by the community is started. Although this would probably entail a length table it would be 

helpful to the reader in terms of understanding what concentrations were measured. 

Specific comments for section IVa 

This section of the report spends a fair amount of space on estimating exposure during the first 

day and 2-3 days after the event. The numbers offered from this exercise are very approximate 

and represent only a very first cut at understanding people’s exposures during this time period. 

As a result the subsequent health assessment is couched in the conditional ( exposures may have 

been, potential health effects could be, it is possible, etc). As stated in the report, a significant 

amount of modelling work is currently being conducted to estimate concentrations on the day of 

and 2-3 days after from satellite data and other data sources. The results of these models will like 

give more robust estimates of exposure than are presented here and it might be best to wait for 

those result before embarking on a discussion of exposure and health effects during that time 

period. 

The use of the Lioy et al. analysis of the settled dust samples to describe the composition of the 

airborne PM needs to be considered more carefully. By definition, settling is as size selective 

process for PM and so the smaller particles will naturally be under represented in a settled dust 

sample. In addition, on a mass basis the smaller particles contribute very little to the over all 

F-14
mass and so the size distribution evaluation of a settled dust will find a small contribution of the 

mass due to small PM. Therefore, care must be taken in the extrapolation these results of this 

analysis of what was in the air during that time period. 

Finally, the section entitled “ High Temporal Resolution Analysis” states that it may be 

important for the health assessment to understand PM concentrations on a more highly resolved 

time scale, however the section does not discuss what temporal resolution is being considered 

that is different from 24 hr integrated measurements. In addition, the time period of Oct 3-5 is 

cited as a period of importance for understanding what was going on on a time scale less than 

24hrs. Data collected by Cahill et al. are offered as evidence of the usefulness of having more 

resolved data but those data are not described in terms of time (or size) resolution. 

F-15
Review by 

Gary Hunt, M.S. 

F-16
Preliminary Review 

Exposure and Human Health Evaluation of Airborne Pollution from the World Trade 

Center Disaster (EPA/600/P-2/002A; October 2002) 

Prepared by Gary T Hunt/TRC Corporation 

The text to follow was based upon review of the External Review Draft of the EPA document as 

titled above (EPA/600/P-2/002A; October 2002) as well as, public review comments received by 

EPA contained in a Supplemental Document (June 2003). 

The EPA document provides a significant amount of information in support of the primary stated 

objective of the project, which was an assessment of potential human health impacts associated 

with exposure to emissions from the collapse of the World Trade Center on September 11, 2003 

(pg 13). It should be noted that the assessment focuses deliberately on exposure associated with 

direct inhalation of air emissions from the WTC site commencing on September 18 2001. This 

reviewer finds this report to be a very comprehensive document addressing large quantities of 

data collected by a number of agencies engaged in the monitoring effort. The report does a good 

job of identifying the point in time when air quality in the vicinity of the WTC site had returned 

to normal or background levels. Unfortunately, due to the emergency nature of the event itself 

and logistics issues there are little or no data available representing inhalation exposure during 

the critical hours and days immediately following the 9/11 disaster. 

Perhaps the most critical question that needs to be asked in any study of this nature is what is the 

ultimate end use of the data? Based upon my review of the data in the EPA report as well as the 

attendant public review comments it is obvious that there is much disagreement over the end use 

of the data collected and ultimately the purpose and objectives of the program itself. As a result, 

data currently do not exist to satisfy a “ wish list” of program objectives. Accordingly, it is this 

reviewer’s recommendation that one of the charges of the forthcoming Workshop (July 14 and 

15 2003) should be to reexamine the purpose and objectives of the EPA study and redefine these 

if warranted. These goals and objectives when clearly defined will dictate data needs. More 

specifically, do we have the data needed to satisfy program objectives and if not what course of 

action should be taken to gather the necessary data. For example, the October 2002 report does 

not adequately characterize current and future human exposure associated with inhalation of 

dusts present in the environment around the WTC site and the NYC Metropolitan area. These 

dusts likely represent a significant source of secondary exposure long after air emissions from 

the primary WTC Site had ceased in 2002. 

Other recommendations for discussion on the agenda of the forthcoming Workshop including 

some justification for each are as follows: 

• The target compound list of parameters monitored while quite comprehensive did not 

consider a number of critical compounds and compound classes of toxicological 

significance from a human health perspective that might also be contained in WTC air 

emissions. Mercury was not included nor were brominated POPs. The latter class of 

compounds includes PBDEs and other bromine substituted organics likely formed from 

F-17
combustion of materials impregnated with bromine containing flame retardants. Data 

presented in the report do identify significant levels of elemental bromine in selected 

particulate samples collected in ambient air and dusts in and around the WTC Site. 

• No data on PAHs are contained in the report. These perhaps represent the class of 

semivolatile organic compounds most likely present in the highest concentrations in air 

emissions from the WTC particularly during fires and combustion conditions. 

• Due to the dynamic nature of the disaster and the lack of steady state combustion 

conditions in the days and months following 9/11 additional products of combustion 

analyses are warranted. These analyses if deemed warranted could likely be conducted on 

samples or sample extracts maintained in archival storage at the participating 

laboratories. The necessary data for products of incomplete combustion and in particular 

organics could be developed using existing GC/MS electronic data files. 

• The data contained in the report are still too preliminary to support reliable quantitative 

predictions of potential human health risks (pg 24 EPA Report). The reviewer agrees 

with this statement. That stated the report should be viewed as a work in progress. 

Conclusions and recommendations based upon the available data should be limited to the 

quality of ambient air in and around the WTC site. As a result, broader conclusions about 

the effects of long-term exposure to entrained dusts and human health effects over time 

associated with the initial acute exposure to WTC air emissions cannot be supported by 

the data presented. The Workshop should consider addressing this charge as well in its 

deliberations on July 14 and 15 2003. 

• It is well known that the calendar period of September 11-18 2001 was poorly 

represented in the available data-base. Due to the emergency nature of the event and 

logistics problems likely hampered the response times to deploy sampling equipment to 

the site. A lesson learned from the WTC disaster is to put the necessary planning and 

systems in place in the very near future so as to be ready for emergency monitoring on an 

as needed basis. This should include availability of portable instrumentation (e.g. battery 

powered) and “ real time” monitors that can be readily deployed to respond to any 

national emergency. 

F-18
November 18 2003 

Peer Review Addendum 

Exposure and Human Health Evaluation of Airborne Pollution from the World 

Trade Center Disaster (EPA/600/P-2/002A; October 2002) 

Prepared by Gary T Hunt/TRC Corporation 

Information Sources 

The review to follow herein was based upon information provided to this reviewer from a 

number of sources. These sources include: 

 Review of the External Review Draft of the EPA document as titled above 

(EPA/600/P-2/002A; October 2002). 

 Public review comments received by EPA contained in a Supplemental 

Document (June 2003). 

 Participation in Peer Review Meeting , which took place in New York City on July 

14-15 2003. 

 Review of Summary Report of the USEPA Technical Peer Review Meeting; 

September 11 2003 Draft Version. 

 Review of Executive Summary of the USEPA Technical Peer Review Meeting, 

October 28 2003 Draft. 

 Observers Comments offered during the Peer Review Meeting and subsequent 

to the July 14-15 2003 meeting. 

 Journal article provided by Dr Clifford Weisel which appeared in Environmental 

Health Perspectives Volume 110 Number 7 July 2002. 

 Short papers and oral presentations which appeared on the agenda of the Dioxin 

2003 conference in Boston Ma during the period August 24-29 2003. 

 Package of materials provided by Versar on August 11 2003. 

Summary Comments and Findings 

1. Purpose and Objectives of Program- Data End Uses

 The EPA document , which was the focus of the Peer Review Meeting provides a 

significant amount of information in support of the primary stated objective of the 

project, which was an assessment of potential human health impacts associated 

with exposure to emissions from the collapse of the World Trade Center on 

September 11, 2003 (pg 13). It should be noted that the assessment focuses 

deliberately on exposure associated with direct inhalation of air emissions from 

the WTC site commencing on September 18 2001. This reviewer finds this report 

to be a very comprehensive document addressing large quantities of data 

collected by a number of agencies engaged in the monitoring effort. The report 

does a good job of identifying the point in time when air quality in the vicinity of 

F-19
the WTC site had returned to normal or background levels. Unfortunately, due to 

the emergency nature of the event itself and logistics issues there are little or no 

data available representing inhalation exposure during the critical hours and days 

immediately following the 9/11 disaster. 

 Based upon my review of the information sources cited above it is obvious that 

there is much disagreement over the end use of the data collected and ultimately 

the purpose and objectives of the program itself. As a result, data currently do 

not exist to satisfy a “ wish list” of program objectives. Accordingly, I would 

recommend that the Peer Review Summary Report and perhaps Executive 

Summary contain a section regarding the end use of the data and what it can 

and cannot be used for. This is particularly relevant in light of what the former 

EPA Administrator, Ms Whitman, said about the health impacts associated with 

WTC air emissions based upon the data contained in the EPA Report that was 

the subject of the Peer Review. She drew more global conclusions about the 

significance of the data than the data could justifiably support. These same 

sentiments were echoed in the Observers Presentations and comments rendered 

during the July 14-15 Peer Review Proceedings. 

 The October 2002 EPA report does not adequately characterize current and 

future human exposure associated with inhalation of dusts present in the 

environment around the WTC site and the NYC Metropolitan area. These dusts 

likely represent a significant source of secondary exposure long after air 

emissions from the primary WTC Site had ceased in 2002. 

 That being said I would recommend that the section to be added to the EPA Final 

Report regarding suggested end uses of the data include the following: The data 

contained in this report are recommended for use in examining human health 

effects associated with direct inhalation of regulated air pollutants present in the 

ambient air in the aftermath of the WTC disaster. These data which focus on 

atmospheric concentrations of primarily regulated air pollutants cannot be used 

for inhalation exposure in the hours and in some cases days immediately 

following the WTC disaster nor can they be used in assessing exposures not 

related to direct inhalation of air emissions from the WTC site. For example, 

these data cannot provide a reliable benchmark for secondary exposure 

associated with inhalation of dusts deposited in indoor environments after their 

initial release during the WTC disaster. 

 The October 2002 EPA report should be viewed as a work in progress. 

Conclusions and recommendations based upon the available data should be 

limited to the quality of ambient air in and around the WTC site. As a result, 

broader conclusions about the effects of long-term exposure to entrained dusts 

and human health effects over time associated with the initial acute exposure to 

WTC air emissions cannot be supported by the data presented. 

F-20
2. Target Parameters- Compounds of Interest Monitoring Program 

 No rationale has been provided in the information sources cited regarding the 

basis for the selection of target parameters. In the opinion of this peer reviewer it 

appears that the target parameters were limited to primarily regulated air 

pollutants monitored using traditional or readily available sample collection and 

analyses procedures. The Peer Review Committee has directed EPA to address 

the rationale for the selection of target parameters in further editions of the Final 

Report. 

 Combustion by products formed during the WTC initial collapse and more so in 

the numerous fires which took place in the ensuing months following 9/11 were 

not adequately addressed at any time during the monitoring program. 

Measurements were limited to PCDDs and PCDFs and even these were 

hampered by abnormally high detection limits and the unavailability of data for 

several weeks following the initial collapse. 

 The WTC collapse and ensuing numerous fires , which persisted until December 

19, 2001 constitutes a unique environmental disaster unprecedented in history. It 

is highly likely that significant quantities of combustion by products currently 

regulated and many new compounds at present unknown were introduced into 

the environment vicinal to the WTC site and the New York City Metropolitan area. 

These by products include but are not limited to the following types of 

semivolatile organic compounds: PAHs, PCBs, PBDEs, PCNs. 

 In addition, it is likely that the WTC fires introduced many combustion by 

products into the environment whose toxicity to humans as individual compounds 

or as a composite mixture of compounds is unknown at the present time. Recent 

publications cited in the above information sources have provided the chemical 

characterization of a wide variety of these classes of compounds. These 

compounds were identified in both films deposited on Lower Manhattan windows 

as well as dusts and smoke aerosols deposited in weather protected locations 

east of the WTC site. 

 The latter publication included analysis of both indoor and outdoor dusts 

representative of materials that settled immediately following the explosion and 

fire and concurrent collapse of the WTC. (Lioy et al Environmental Health 

Perspectives Volume 110/Number 7 July 2002). The results of these analyses, 

while limited to three samples, illustrate the chemical complexity of the mixtures 

released and provide some indication of the types of acute exposures 

experienced by residents, commuters and rescue workers in the minutes and 

hours immediately following the WTC collapse. Further these data should help 

us better appreciate the risks associated with longer term exposures to the dusts 

generated by the WTC disaster, and in particular exposure to dusts in work areas 

and residential properties downwind of the WTC site. These types of data are 

F-21
currently unavailable through the EPA data base that was the subject of the Peer 

Review Meeting. 

 The data from these studies further support the need to have the interiors of 

buildings affected by these dusts and associated HVAC systems cleaned so as 

to minimize the longer-term risks for building occupants. 

 The target compound list of parameters monitored while quite comprehensive did 

not consider a number of critical compounds and compound classes of 

toxicological significance from a human health perspective that might also be 

contained in WTC air emissions. Mercury was not included nor were brominated 

POPs. The latter class of compounds includes PBDEs and other bromine 

substituted organics likely formed from combustion of materials impregnated with 

bromine containing flame retardants. Data presented in the report do identify 

significant levels of elemental bromine in selected particulate samples collected 

in ambient air and dusts in and around the WTC Site. 

 No data on PAHs are contained in the report. These perhaps represent the class 

of semivolatile organic compounds most likely present in the highest 

concentrations in air emissions from the WTC particularly during fires and 

combustion conditions. 

 Due to the dynamic nature of the disaster and the lack of steady state 

combustion conditions in the days and months following 9/11 additional products 

of combustion analyses are warranted. These analyses if deemed warranted 

could likely be conducted on samples or sample extracts maintained in archival 

storage at the participating laboratories. The necessary data for products of 

incomplete combustion and in particular organics could be developed using 

existing GC/MS electronic data files. 

 The window films data (Dioxin 2003) can be used to back calculate gas-phase 

concentrations for a variety of semivolatile organics found in these samples. 

These include PBDEs, PCBs, PAHs, and PCNs. The window films serve as a 

convenient passive sampler representative of atmospheric concentrations on an 

historical basis. These samples accordingly may provide a means to establish 

human inhalation exposure over time for gas phase concentrations of a variety of 

semivolatile organic compounds present in the atmosphere. 

 The results of the window film analyses suggest that a large quantity of 

combustion products were released by the WTC disaster and that the deposition 

of these contaminants occurred primarily within a 1 kilometer radius of the WTC 

site. 

F-22
6. Lessons Learned and Implications for the Future 

It is well known that the calendar period of September 11-18 2001 was poorly 

represented in the available data-base. Due to the emergency nature of the 

event and logistics problems likely hampered the response times to deploy 

sampling equipment to the site. A lesson learned from the WTC disaster is to put 

the necessary planning and systems in place in the very near future so as to be 

ready for emergency monitoring on an as needed basis. This should include 

availability of portable instrumentation (e.g. battery powered) and “ real time” 

monitors that can be readily deployed to respond to any national emergency. 

F-23
Review by 

Patrick L. Kinney, Sc.D. 

F-24
Initial Comments on 

Exposure and Human Health Evaluation of Airborne Pollution from the World Trade Center 

Disaster 

EPA/600/P-2/002A External Review Draft 

Patrick L. Kinney, Sc.D. 

July 6, 2003 

This document summarizes results of EPA’s comprehensive evaluation of potential health effects 

associated with air pollution emissions from the World Trade Canter collapse. Extensive air 

monitoring data collected by EPA and other agencies are reviewed and analyzed to examine 

trends over time and space, and to determine whether and to what extent health benchmark 

concentrations were exceeded. The report focuses on a subset of pollutants that are thought to be 

of greatest health concern: particulate matter (PM), metals (including lead, chromium, and 

nickel), polychlorinated biphenyls (PCBs), dioxin-like compounds, asbestos, and volatile organic 

compounds (VOCs). 

Critique: 

EPA’s effort to carry out a comprehensive evaluation of air pollution health risks associated with 

the 9/11 disaster is commendable. The document will be of tremendous value to a variety of 

stakeholders, including the general public, policy makers, scientists and the news media. The 

overall quality of the report is high. The choice of pollutants to focus on makes sense. In 

general, the data are chosen, analyzed and interpreted appropriately; judgments as to health risks 

are well reasoned. I believe that the overall conclusions of the evaluation are reasonable given 

the available data, i.e., (paraphrasing) that 1) persons caught in the initial dust cloud associated 

with the collapse were probably exposed to very high concentrations of a wide range of 

pollutants, and that acute and possibly chronic health problems may be associated with these 

exposures; 2) after this initial phase, concentrations of air pollutants in off-site residential zones 

were often elevated compared to upwind sites but that these exceedences gradually diminished 

after 1-3 months following 9/11 and that the risks of adverse health effects from the elevated 

levels of exposure were generally low. The report is careful to point out that these are 

preliminary conclusions based on available data and that conclusions could change when new 

information becomes available. 

Specific comments: 

p. 6, 1st paragraph, last full line: eliminate ‘month’ 

p. 6, 2nd paragraph, second line: the fact that the OSHA PEL of 1 mg/m3 was never exceeded 

seems fairly irrelevant, given that we know that generic PM2.5 can cause adverse health effects 

at levels at or below the NAAQS. This brings up a more general point, which is that somewhere 

early in the executive summary there needs to be a short paragraph explaining why occupational 

F-25
standards may not be directly relevant to general population health risk assessment, including 

issues of voluntary and compensated risks vs. involuntary risks, healthy workers vs. widely 

varying susceptibilities in general population. This very important point will not be obvious to 

the general reader. It’s discussed later in the report, but not mentioned in the E.S. It might be 

useful to give some examples of acute air standards for which both occupational and ambient 

standards exist, such as PM2.5 or SO2, to illustrate how different the numbers can be. 

p. 6 last line: again for the general reader, it would be best to present concentrations in simple 

and consistent units. Instead of 1*103

 ng/m3, why not say 1000 ng/m3 or, better yet, 1 ug/m3. 

p. 7 first line: same issue for 50 ug/m3. 

p. 7, last paragraph: state the dioxin LODs 

p. 9, lines 3 and 4: ‘used to identify structures less than 0.5 um in length’ is confusing. It 

implies that TEM ignores anything longer than 0.5, which I don’t think is the case. In fact, I 

thought that the AHERA protocol involved counting structures as small as 0.5 but not less than 

that size. 

p. 10, first paragraph, last line: It would be good to append a concluding sentence to the effect 

that these data support the conclusion that the WTC collapse resulted in increased indoor 

asbestos levels in lower manhattan. 

p. 11. first paragraph, 8 lines from bottom: the September date is missing. 

p. 12, third paragraph, line 1: include ‘visitors’ as another at risk population.

p. 16, line 1: the use of a health benchmark in a screening exercise is only valid if the health 

benchmark is appropriate for the population at risk, which I think is somewhat problematic here 

where occupational benchmarks are being used to screen risks in the general population. Need 

to include a few lines justifying this approach and discussing whether it’s likely to be 

conservative or not. 

p. 32, conclusion bullet (3), line 2: in addition to quoting the distance in blocks, I think it would 

be helpful to include distance in meters or km. 

p. 32, last paragraph: Need to mention the problem that it’s difficult or impossible reproduce the 

original PM airborne size distribution based on resuspension of settled dust, since the smallest 

particles have a tendency to stick very persistently to larger particles. Thus, these kind of data 

will tend to overestimate the fraction of PM in the larger size ranges and underestimate the PM 

in the smaller size ranges. 

p. 35, third paragraph: There needs to be references to specific figures in this lengthy 

paragraph. 

F-26
Review by 

Clifford P. Weisel, Ph.D. 

F-27
Critique of EPA Draft Report: “Exposure and Human Health Evaluation of Airborne Pollution

from the World Trade Center Disaster”

Clifford P. Weisel, Ph.D.

August 21, 2003

The draft report describes the US EPA health assessment of published and publically 

available ambient air concentration data collected in and near lower Manhattan following the 

World Trade Center (WTC) disaster. A large amount of data was reviewed for selected toxic 

substances predicted to be most likely to have possible adverse health impacts on individuals 

who entered ground zero or lived in the nearby community. Exposure to ambient pollutants to 

both residents and workers (such as clean up workers) were considered and compared to 

standards or “typical” urban ambient levels. A limited examination of exposure to ground zero 

workers and indoor air concentrations was done as part of this report, but a full evaluation of 

workers and indoor environments was beyond the scope of the report and are expected to be 

presented elsewhere. 

Recommendation: Since the report is predominantly focused on ambient air concentrations, it is 

suggested that the title be changed to more clearly reflect this. 

Recommendation: More details should be provided on the selection of which toxic substances 

were analyzed and included in the report. A listing in the appendix of all the toxic substances 

data have been collected, time periods, numbers and locations for the outdoor air would be 

useful. 

The report notes that there is a lack of air monitoring data in the days immediately 

following September 11, and for some contaminants for more than a week. A more detailed 

analysis and justification should be provided for the concentration used to evaluate the health 

impacts for the time period between September 11 and the first available measurement. As is 

indicated on Page 11, “air concentrations within and very near Ground Zero would have been at 

least at these high levels (Measured on September 23 for dioxin) and probably higher during the 

first several days after September 11.” However, on page 78, the dioxin air concentrations 

between September 12 and 23 were assumed to be equal to the September 23 measurement. The 

assumption that the first measured concentration is representative of concentration for the entire 

time interval may not be correct, if the emission source strengths declined during that time 

period or the meteorology varied. This should be discussed in more detail for each of the 

pollutants examined and upper bound estimates of what air concentrations could exist and 

whether they may be of concern presented. 

Recommendation: The ambient air concentrations should not be predicted for time periods prior 

to the start of sampling as there is current way to properly estimate those concentration. Under 

prediction could result in erroneously suggesting that the exposure was non-problematic when 

this was not the case. 

The choice of comparison data and health based standard to be used for comparison to 

the air measurements is important in establishing a risk estimate and when discussing results in 

publically available reports. For the particulate matter, one of the comparison data set chosen 

was collected at the NYU Medical Center in August 1976. These data may not be appropriate 

for comparison as some of the concentrations measured were at levels that have health concerns 

F-28
and the substances were subsequently listed as air toxics or Hazardous Air Pollutants in the 1990 

Clean Air Act Amendments. Thus, saying exposure to similar levels in the past is not 

reassuring. 

Recommendation: Do not use the 1976 data for comparison. 

The report also correctly cautions about using occupational standards as a basis for 

environmental health criteria on page 23. However, that caution is less clear in other places in 

the report, such as on page 68 where the last paragraph begins “Occupational exposure limits 

provide an additional perspective by which to evaluate potential non-cancer health effects ... “ 

Further, even using the TWA for the cleanup workers may be problematic since there were 

reports of their activities exceeding the 10 hour day - 5 day maximum that the standards are 

based on. Rescue workers reported working double shifts, working more than 5 days per week 

and staying in the area between shifts. These exposures would not provide the body the 

recuperation time that is assumed in the standards. 

Recommendation: Care should be taken in applying the TWA for occupational to the 

environmental settings, even when using safety factors. Whenever these comparisons are done 

the appropriate caveats should be restated to minimize the chance that the statements will be 

taken out of context. 

The conclusions on page 33 about the WTC emissions changing because of the changes 

in the metal content of the particulate matter during the Fall needs clearer justification and 

support. 

Recommendation: Include the auxiliary data and discussions about the spatial distribution that 

were presented at the meeting to justify the text discussion of source emissions from on site. 

Include at least a paragraph about all of the metals that were measured, even if figures and/or 

tables of them are not included. 

The description of the dioxin measurements on the EPA samplers, which collected 7 

cu.m. of air, is technically correct. However, due to the low volume the results need more 

careful discussion. The samples with very high concentrations should be highlighted and the 

implications of these values, greater than measured in just about any other ambient air sample 

needs to be presented clearly, along with a reconsideration of whether they may present a health 

risk. 

Recommendation: Reorganize the discussion and tables to clarify which samples were below 

detection because of the low volume collected and how the difference in detection limits 

between the two types of samples that were collected need to be considered in the comparison. 

Align the dates in Table 4 for the three sites so they can be more readily compared. 

In the section on Potential Human Health for Dioxin the exposure scenarios and 

ventilation rates need to be reviewed. 

The limited discussion of the indoor air and occupational exposures while commendable 

may be problematic. 

Recommendation Occupational: For the occupational exposures, see if a more comprehensive 

report is being planned in deciding what should or should not be included here. It is probably 

F-29
best to exclude or at least place in even stronger context the VOC measurements made for source 

emission evaluation as they are not applicable for exposure estimates without extensive 

modeling. Similarly, the measurements made for worker exposure determination need to be 

separated from the environmental exposures that occurred off-site more clearly. It may pay to 

discuss exposures to individuals who returned to their residences on-site or in the restricted zone 

prior to complete authorization using the worker exposure measurements. 

Recommendation Indoor: A separate indoor exposure and risk report should be prepared that at 

the minimum has an oversight board with, if not prepared by, non-EPA scientists and community 

representatives to expand the breadth of the report to address community concerns and facilitate 

an atmosphere of trust between the community and EPA scientists. The section on indoor air 

should be carefully reviewed so as not to provide more emphasis to draft reports that have not 

been peer-reviewed. Having them included here provides an appearance of a peer-reviewed 

status possibly providing them with undue legitimacy. 

A review of the PM conclusions needs to be done after the data has been evaluated. 

Several members of the audience mentioned samples collected at Stuyvesant HS, which was 

apparently done by DEP with coordination by the NYC Board of Education. (see 

http://www.nyc.gov/html/dep/html/airmonit.html for example and at some EPA web sites). 

These should be mentioned for completeness. 

F-30
The following are supplementary comments on the EPA report. These additional 

comments were too detailed in nature to be included in my initial comments, and they were not 

discussed at the Peer Review Meeting because they did not fall under any of the general charges 

to the reviewers, but they may be helpful to EPA during the revision of the report. 

1. In the List of Acronyms and Abbreviations, “f” should refer to “fibers”, rather than to 

“fibers of asbestos”, the letter “L” in “REL” and “STEL” I believe is “Limit”, rather than 

“Level”, “TEM” is “Transmission Electron Microscopy”, and “XRF” is “x-ray 

fluorescence”. 

2. In the Executive Summary on Page 1, Paragraph 2, Line 3, it is stated that “It is an 

assessment of the inhalation exposure and potential human health risk incurred by the 

general population residing and working in the vicinity of the WTC.” This statement 

requires some additional clarification, because most people residing and working near the 

WTC spend most of their time indoors, and indoor exposures are not the primary focus of 

this report. 

3. On Page 2, in Line 8 of Paragraph 2, the sentence beginning “Dioxin and VOC’s...” 

needs to be re-worded. As it stands, the sentence can be taken to mean that these 

pollutants are produced only from fuels. There were many other potential sources in the 

WTC buildings. 

4. On Page 2, the final paragraph contains the expression “in the surrounding community”. 

It would be good if this could be better defined. 

5. On Page 9, Line 2, it is stated that PCM is used to identify structures greater than 5 :m in 

length. PCM does not have the ability to identify anything. 

6. On Page 9, Line 3, the statement in parentheses is incorrect. TEM is used to detect and 

identify asbestos structures greater than 0.5 :m in length 

7. On Page 9 in the final line of Paragraph 1, a reference for the value of 0.003 f/cc as 

typical of urban background should be given, particularly since it is used in the report as 

a definition of background. In fact, I remain uncomfortable with the concept of using 

PCM as a measurement method for asbestos in the general environment. I recognize that 

it may have been useful for rapid measurements in the early hours after the collapse, but 

the authors should be careful to not place too much reliance on the PCM measurements, 

either outdoors or indoors. In the measurements we made in the apartments, I never even 

contemplated the use of PCM. 

8. On Page 9 of the report, in the 3rd Paragraph, it is stated that “One apartment was highly 

affected by the collapse of the WTC towers with completely shattered windows and dust 

piled throughout the apartment. The other was in a building that had little exterior 

damage.....”. In fact, I was present at the sampling and only one small window had been 

F-31
broken in the first apartment, and the opening had been sealed with plastic sheet and 

adhesive tape. The other building had no exterior damage. 

9. On Page 10 of the report in the first paragraph, some reference to the method of analysis 

of the bulk samples should be given, and a caution on the reliability of these data. It is 

well known that measurements by PLM in the range below about 5% are quite unreliable, 

and it is unlikely that the figures quoted to two significant digits are meaningful. 

Moreover, I think that asbestos was likely present in all of the bulk samples collected, 

and that the failure to detect asbestos in many of the settled indoor dust samples or the 

outdoor samples was a question of deficiencies in either the analytical method, or the 

conduct of the method. 

10. On Page 11, Paragraph 2, Line 9, the method of analysis should be stated.. 

11. On Page 17, the last entry in Table 1 is incorrect. The AHERA clearance standard is not 

“a level of concern”. Abatement activities were not undertaken to reduce air 

concentrations, because abatement decisions were not made on the basis of measured air 

concentrations. It is incorrect to say that school children were not allowed back in until 

several consecutive readings were less than the AHERA standard. In fact, the clearance 

decision is based on the average of 5 simultaneously collected samples in the work area 

being lower than 70 s/mm2

. Even that value is considered to be an “initial screening 

test”. 

12. On Page 70, there is a blank cell for the Barclay & West Broadway location on 9/27 in 

the final column. 

13. On Page 86 at the beginning of the 2nd paragraph, the word “classified” would be more 

appropriate than “characterized”. 

14. On Page 86 in the 3rd Paragraph, it is stated that “Both asbestosis and benign pleural 

plaques result in reduced breathing capacity and mortality”. I suggest that this be 

re-phrased, since it currently means that asbestosis and pleural plaques result in reduced 

mortality, which I do not believe is the case. 

15. On Page 87 in Section IV.e.1, it is stated with respect to PCM: “It counts all fibrous 

structures with a minimum diameter of 0.3 :m and has a magnification range of 

100 - 400X”. The minimum diameter is usually taken to be 0.25 :m in the U.S., and 

counts are made at a fixed magnification of between 400 and 450. Later in the same 

paragraph, it is stated that “PCM results are reported on a mass-per-volume basis, ....”. 

This is not correct - PCM results are never reported in that manner. 

16. On Page 88 in the first paragraph, there needs to be some mention of the fact that the 

AHERA method specifies the use of aggressive sampling to create the worst case 

situation. 

F-32
17. On Page 88 in the 3rd line of the first paragraph, it is stated: “The AHERA Final Rule 

establishing a 70 s/mm2

 standard for asbestos in schools.....”. The AHERA Final Rule 

actually established an indoor-outdoor comparison as the clearance criterion. The 

70 s/mm2

 criterion is an “initial screening test”. In this paragraph, it should also be 

mentioned that the air sampling is to be conducted under aggressive conditions. 

18. On Page 88 in the final three sentences of Paragraph 2, it is an over-simplification to state 

that there is not a good correlation between PCM and TEM measurements. When the 

direct-transfer TEM method is used, and the PCM size fraction of fibers is measured 

using TEM, the correlation can be very close. It is true to say that, in the general 

environment, there is generally little correlation between PCM measurements and TEM 

measurements of all fiber sizes. There are two reasons for this: the PCM measurements 

include fibers other than asbestos, and the TEM measurement includes asbestos fibers 

outside of the visible range for PCM. In fact, there is no reason to expect a correlation. 

Although it is not the responsibility of the authors of this report, I believe that the 

ATSDR procedure to obtain what are termed “TEM units” by multiplying PCM data by 

60 is totally invalid. It needs to be clarified as to what these “TEM units” are - are they 

for all fiber sizes greater than 0.5 :m in length, or are they all fibers longer than 5 :m? 

19. On Page 88 in the 3rd paragraph, it is stated that “.... structures meeting a minimum 

diameter of >0.3 :m with length >5 :m are counted as PCM equivalent (“PCME”) 

fibers”. NIOSH 7402 defines “PCME” fibers as those longer than 5 :m and thicker than 

0.25 :m, and ISO 10312 defines them as longer than 5 :m and thicker than 0.2 :m. 

20. On Page 89 in the first paragraph, on line 4, the AHERA clearance criterion is actually 

based on the average of a single set of 5 samples. There is no requirement for such TEM 

readings to be “consistently” below 70 s/mm2

, just that the average of the clearance set be 

below this value. 

21. On Page 89, Paragraph 4, Line 5, it should be stated that the mass concentration of 

30,000 ng/m3

 was derived only for chrysotile, and the data on which this value is based 

have a very large range. I have already commented in Item 18 about the multiplier used 

to convert PCM to TEM data. 

22. On Page 91 in the first paragraph, reference is made to sampling stations set up in public 

schools. It is not clear whether these were external samples or actually inside the 

buildings. If they were inside, was the sampling aggressive or passive? The sampling 

conditions should be stated, since the AHERA protocol specifically requires aggressive 

sampling. 

23. On Page 128 in the 2nd paragraph of Section VI.b.1, the description of how PLM 

distinguishes between fiber types requires revision - it is not correct. I doubt that a 

simple, one sentence description is even possible, and a more detailed explanation would 

be out of place. I suggest that the sentence be truncated to: “PLM can distinguish 

between fiber types in a bulk sample.”. I also suggest that a caution be added regarding 

F-33
the inaccuracy and unreliability of routine PLM measurements in the vicinity of 1%. As 

stated in Item 9, it is my opinion that the failure to detect asbestos in 82% of the 

residential units, and in 8 of the outdoor samples was more a question of limitations of 

the analytical method and the conduct of the method. 

24. On Page 128 in the final paragraph, it states that “All air filter samples were analyzed 

first using PCM to determine if fibrous materials were present. It seems highly 

questionable to use a method, already admitted to have little correlation with TEM data, 

as a screening method for selection of samples for subsequent TEM analysis. Under this 

protocol, the existence of a few cellulose fibers could trigger analysis by TEM, and a 

sample containing considerable numbers of thin chrysotile fibers could be overlooked. 

Again, the ATSDR work is simply being reviewed by the authors of this report. 

25. On Page 133, on the 5th line the report states: “A small-scale monitoring study of two 

residential buildings was conducted by contract (Chatfield and Kominsky, 2001).” The 

statement is incorrect - the work was not done under contract; all individuals involved in 

the study donated their time and the analytical costs to conduct this study. 

26. On Page 133 in the 2nd paragraph, it is stated that the TEM analyses were conducted 

using AHERA counting protocols. In fact, ISO 10312 was used. The end result, 

however, would be similar. Chrysotile is also spelled incorrectly at the beginning of the 

3rd sentence. 

27. On Page 133 in the final paragraph, it should be mentioned that amphibole asbestos 

(amosite and actinolite/richterite) at concentrations of approximately 0.02% was also 

detected in these outdoor dust samples. 

28. On Page 134, it is not clear whether the air sampling referred to was aggressive or 

passive. This should be clarified, because it affects the interpretation of the data. In fact, 

whether the air sampling was aggressive or passive should be stated for all of the 

asbestos air sampling data. 

29. On Page 135, various dates are quoted. It would be helpful if the year was added to each 

of these dates. 

30. On Page 135, the first sentence of Paragraph 4 needs to be re-worded. One suggestion 

would be to insert the word “who” or “that” between “people” and “may” on Line 2 of 

this paragraph. 

F-34
APPENDIX G 

Comments and Written Materials from Observers 
List of Comments and Materials Submitted by Public Observers 

Comments and Materials Submitted Prior to and at Peer Review Meeting 

7/14/03 Letter re: EPA/Versar Peer Review, from 9/11 Environmental Action. Statement by 

Kimberly Flynn, on behalf of 9/11 Environmental Action, July 14, 2003. 

Statement by Jenna Orkin, 9/11 Environmental Action, at EPA Peer Review Meeting. July 14, 

2003. 

Materials provided by Jo Polett on July 14, 2003, at Peer Review Meeting: (1) Executive 

Summary to ATSDR report on WTC, (2) Letter to DOH from Nina Lavin (on residence 1), (3) 

Results of air and settled dust sampling at residence 1, (4) Indoor air quality survey of 

residence 1, (5) Indoor air quality survey of residence 1. 

Sediment and Tetramitus Toxicity in NYC Drinking Water, Appendices I, II, IV. Fact Sheets 

by Robert L. Jaffe, Ph.D., Environmental Toxicology Laboratory, LLC 

Flagellate Swimming Patterns as an Early Warning Signal for Terrorist Poisoning of Air and 

Drinking Water. Phase II White Paper. Paper by Robert L. Jaffe, Ph.D., Environmental 

Toxicology Laboratory, LLC 

Environmental Health Effects of WTC. EOHSI Website, University Research. Provided by 

Catherine McVay Hughes, NYU, on July 15,2003. 

World Trade Center Environmental Impact Research Community Update. Brochure, Fall 

2002. http://niem.med.nyu.edu/wtc.pdf. Provided by Catherine McVay Hughes, NYU, on 

July 15, 2003. 

Further Comments on EPA document for peer review :Exposure and Human Health 

Evaluation of Airborne Pollution from the WTC Disaster. Statement by Marjorie J. Clarke, 

Ph.D. July 15, 2003. 

No Serious Health Risk for Public from Ground Zero, EPA Reports. New York Times, 

December 28, 2002. 

Status of EPA Office of Inspector General Investigation of EPA’s Handling of WTC Fallout. 

January 27, 2003. EPA/OIG. 

Occupational and Environmental Health Impact of the World Trade Center Collapse, 

February 2003. Abstract to presentation by Steven Markowitz, N.Y. Academy of Sciences. 

February 3, 2003. 

Do Lower Manhattan Cleanup Right. NYCOSH. William Henry. Fact Sheet. August, 2002. 

We Protect More Than the Environment. . . EPA Flyer 

G-1
Downtown Favors West St. Tunnel, Poll says . .. Downtown Express Online. May 2003 

Predicting Health Impacts of the World Trade Center Disaster, January 2002. Article. 

Produced by R. Wallace and DW Wallace. N.Y. State Psychiatric Institute and School of 

Public Health, Columbia University. Provided by Joel Kupferman, Esq. July 14, 2003. 

Comments on the EPA Office of Inspector General’s 1/27/03 interim report titled: 

“EPA’s Response to the World Trade Center Towers Collapse” A DOCUMENTARY BASIS 

FOR LITIGATION. July 4, 2003. Prepared by Cate Jenkins, Ph.D., US Environmental 

Protection Agency. 

Comments and Materials Submitted Following Peer Review Meeting 

NYC Council Hearing on Post-9/11 Remediation of WTC: Problems with EPA's Scopes of 

Work; EPA’s Outreach. December 19, 2002. Statement by Marjorie J. Clarke, Ph.D. 

NYS Assembly's second hearing on Air Quality issues surrounding the World Trade Center 

collapses and fires, April 12, 2002. Statement by Marjorie J. Clarke, Ph.D. 

Additional comments concerning the document: Exposure and Human Health Evaluation of 

Airborne Pollution from the World Trade Center Disaster. Post meeting comment submitted 

by Jenna Orkin, 9/11 Environmental Action. July 24, 2003. 

EPA Public Comment /WTC Health Consequences. Post meeting comment submitted by 

Carla Breeze & Wayne Decker, Neighborhood Environmental Watch. July 18, 2003. 

Post Meeting Comments by Diane Dreyfus. July 16, 2003. 

Respiratory Problems for Downtown Residents. From Downtown Dispatch - Summer 2003, 

by Community Board #1. Submitted by Diane Dreyfus. July 31, 2003. 

Independence Plaza Tenants’ Association’s Report on Cleaning/Testing for Review by the 

NCEA Peer Review Panel. Letter from Patricia Dillon, for the IPNTA Environmental 

Committee, to David Bottimore, Versar Inc. July 22, 2003. With 2 attachments (1) Letter to 

Ms. Christine Todd Whitman, Administrator, U.S. Environmental Protection Agency. June 6, 

2003. From Ms. Deborah Dolan, Duane Street Associates, and Diane Lapson, IPNTA 

Environmental Committee. (2) Letter to EPA Region 2 on cleaning/testing reports on 80 N. 

Moore and 310 Greenwich St. buildings. From Deborah Dolan, Hudson River Management 

LLC. 

Meeting Follow up - WTC Public Comments to EPA. Submitted by Rachel Lindov. July 22, 

2003. 

G-2
Asbestos Fiber Length as Related to Potential Pathogenicity: A Critical Review. By Ronald F. 

Dodson, Ph.D., FCCP, FAHA; Mark A.L. Atkinson, M.A., D.Phil.; and Jeffrey L. Levin, 

M.D., M.S.P.H. Pre-publication copy, American Journal of Industrial Medicine. 

Submitted by Marjorie Clarke, July 24, 2003. 

Public comments regarding the July 2003 Peer Review of the EPA study entitled: 

EXPOSURE AND HUMAN HEALTH EVALUATION OF AIRBORNE POLLUTION 

FROM THE WORLD TRADE CENTER DISASTER. Submitted by Bob Van Dyke, From 

the Ground Up. August 1, 2003. 

Question on Use of Ambient Monitoring Network Data, submitted by Henry H. Willis, Ph.D., 

RAND, July 14, 2003. 

Reply to Question on Use of Ambient Monitoring Network Data by Matthew Lorber, U.S. 

EPA, to Henry H. Willis, Ph.D., RAND. July 18, 2003. 

LATEST EPA "All Clear"& Safe to Live Downtown NOT TRUE. Comments submitted by 

Ari Porter, July 15, 2003. 

NCEA peer review comment; PCBs, PCDD/Fs, PBBs, PBDD/fs; background levels. 

Submitted by Paul Bartlett, CBNS, Queens College. July 25, 2003. With attached journal 

article POLYCHLORINATED BIPHENYL (PCB) CONCENTRATIONS IN 

ATMOSPHERICALLY DERIVED ORGANIC FILMS FROM LOWER MANHATTAN AFTER 

SEPTEMBER 11, 2001, Craig M. Butt, Jennifer Truong, Miriam L. Diamond, and Gary A. 

Stern. ORGANOHALOGEN COMPOUNDS Vol. 59, Pages 219-222 (2002). 

G-3
Submission of public comment: 2002. EXPOSURE AND HUMAN HEALTH 

EVALUATION OF AIRBORNE POLLUTION FROM THE WORLD TRADE CENTER 

DISASTER (EXTERNAL REVIEW DRAFT). 01 Oct 2002. Comments submitted by Joel 

Kupferman, Esq., New York Environmental Law & Justice Project. August 1, 2003. With 23 

attachments. 

A - Toxics Targeting for WTC Complex 

B - PortAuthorityVSallied 

C - Kupferman9-19-01-nearWTC 

D - Gonzales-Fallout-Chapter3 

D1 - EPA-Daily-Summary-Oct2-2001 

E - NIEHS Report-on WTC-Workers 

E1 - CCRworkersafetyCritique 

F - HealthStudyFreshKills 

G - 92802Bulksample333RectorStreet 

G1 - Amex testing & cleanup 

H - DEP demand 

I - Ladder25results73102 

J - CONTAMINTED HOUSES AND RIG 

K - TheAsbestosNightmare 

L - WINDBORNE POLLUTANTS TRAVEL 

M - 150FrankllinStreetTestResults 

N - 105DuaneStreetResults 

O - asbestosdustsamplingEwing 

P - WallaceHealthImpacts 

Q - DailyNewsFireMaySmolder 

R - PREZANTLETTERFIREFIGHTERHEALTH 

S - PublicHealthFalloutfromSeptember11 

NY COSH. Technical Peer Review of Exposure and Human Health Evaluation of Airborne 

Pollution from the WTC Disaster. Letter with 17 articles and reports attached. 

1. Four HHE reports by NIOSH, one each for Borough of Manhattan Community college, 

Stuyvesant High, Office of Attorney General of State of NY, and offices of NYC 

clerical workers. 

2. Assessing Health of Immigrant Workers Near Ground Zero: Preliminary Results of the 

WTC Day Laborer Medical Monitoring Project, 2002. Amer. J. Ind. Med, 00:1-2. 

3. Levin, Herbert. WTC Worker and Volunteer Medical Screening Program-Report of 

Initial Findings to Nat’l Inst. For Occup. Safety and Hlth of the Centers for Disease 

Control and Prevention, January 2003. 

4. Chatfield, Kominsky. Summary Report: Characterization of Particulate Found 

in apartments After Destruction of the World Trade Center, October, 2001. 

G-4
5. Ewing. Asbestos in Settled Dust Concentrations in NYC Before September, 11, 

2001. Abstract. Conference Paper July, 2002 by ASTM Committee D22 on 

Sampling and Analysis of Atmospheres. 

6. Phase 2 Sampling and Quality Assurance Project Plan, Rev. 0, for Libby, 

Montana-Environ. Mon. For Asbestos, Evaluation of Exp. To Airborne 

Asbestos Fibers During Routine and Special Activities, March 2001. 

7. Amphibole Mineral Fibers in Source Materials in Residential and Commercial 

Areas of Libby Pose an Imminent and Substantial Endangerment to Public 

Health, December, 2001. 

8. Asbestos Rules and Regulations, city of NY, Dept. Environ. Protection. 

9. Documents (Partial) Obtained from Freedom of Information Law Request from 

NYC Dept. Of Environmental Protection, February 2003. NY Law and 

Environmental Justice Project. 

10. Report of Findings: Building Air Quality Assessment, November 2001, August 

2002. Excerpts of 2 reports for high-rise commercial bldg. In Lower 

Manhattan. 

11. Summary Data ASTM D5755-95 Standard Method for Microvacuum Sampling 

and Indirect Analysis of Asbestos in Settled Dust by TEM, February 2003. 

12. Letter dated January 2002 describing results of air monitoring for asbestos in a 

World Financial Center Bldg. 

13. Letter dated December 2002 describing results of 3 rounds of sampling for lead 

dust in a large institutional building four blocks from Ground Zero. 

14. Re: Environmental dust and Debris Sampling and Evaluation, Letter dated 

November 2001. 

15. Two environmental sampling reports for apartments on Harrison Street, dated 

November 2002 and January 2003. 

16. Letter and environmental sampling results from ETNY Consulting and 

Monitoring, to Ms. Ilona Kloupte, a resident at 300 Albany Street 

17. Summary of TEM Results for Asbestos (ASTM D5755 Dust Microvac) for 2 

apartments on Duane Street. 

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