EPA-HSRB-09-02

Kevin P. Teichman, PhD

Acting Science Advisor

Office of the Science Advisor

1200 Pennsylvania Avenue, NW

Washington, DC 20460 

Subject: June 24-25, 2009 EPA Human Studies Review Board Meeting Report

Dear Dr. Teichman:

	The United States Environmental Protection Agency (EPA or Agency)
requested the Human Studies Review Board (HSRB) to review three
completed studies involving intentional human exposure to the
organophosphate pesticide chlorpyrifos. The Agency proposes to rely on
these three studies, conducted prior to publication of the EPA’s
expanded final rule for protection of subjects in human research (40 CFR
26) on February 6, 2006 (71 Federal Register 24, 6137), in actions under
the pesticide laws. The Agency asked the HSRB to advise the Agency on a
range of scientific and ethics issues regarding how the studies should
be assessed against the provisions in 40 CFR sections 26.1701 –
26.1704 of the final human studies rule.

	The Agency also requested the HSRB to provide scientific and ethics
reviews of one completed and two proposed human studies: a completed
ICR, Inc., (ICR) insect repellent efficacy study (ICR A382); a proposed
Carroll-Loye Biological Research, Inc. (CLBR) insect repellent efficacy
study (LNX-002); and a proposed Agricultural Handler Exposure Task
Force, LLC (AHETF) water-soluble packing mixing and loading scenario and
protocol (AHE-120).

	The enclosed report provides the Board’s response to EPA charge
questions presented at the June 24-25, 2009 meeting.

Assessment of Completed Research Study MRID 124144: Nolan et al. (1982)
Chlorpyrifos: Pharmacokinetics in Human Volunteers Following Single Oral
and Dermal Doses.

Science

The Board concluded that data measuring chlorpyrifos at the limit of
detection in blood and urine are not useful. The measurements of
3,5,6-trichloro-2-pyridinol (TCP) in urine are generally reliable. It is
unclear if the measurement of TCP in blood is useful because of concerns
about the ability of the methods used to detect the appropriate TCP
conjugate.

The Board expressed concern over the variability of the erythrocyte
cholinesterase activity data and the lack of a control group, but
concluded that measurements of cholinesterase activity/inhibition from
Nolan et al. (1982) were likely to be reliable.

The Board concluded that the data are reliable but suggested that the
Agency be cautious in its use of the erythrocyte cholinesterase data.
Since only a single dose level was evaluated, for example, no
dose-response data are available from this study.

Ethics

The Board concurred with the Agency’s assessment that there was
neither clear and convincing evidence that the study was fundamentally
unethical, nor clear and convincing evidence that the study was
significantly deficient relative to the ethical standards prevailing at
the time the Nolan et al. (1982) study was conducted. 

Assessment of Completed Research Study MRID 42062701: Honeycutt and
DeGeare (1993) Worker Reentry Exposure to Chlorpyrifos in Citrus Treated
with Loraban* 4E Insecticide.

Science

The Board concluded that the blood and urine measurements of
chlorpyrifos and/or TCP from Honeycutt and DeGeare (1993) are likely
reliable but of limited value. Board members expressed concerns about: 
1) the small sample size; 2) the background chlorpyrifos exposure not
being properly accounted for; 3) the likely incompleteness of urine
collection; and 4) the high degree of variation seen in the daily
measurements.

The Board concluded that the measurements of cholinesterase
activity/inhibition are likely accurate and reliable but raised concerns
about their utility. Some of the Board’s concerns included: 1) the
lack of an untreated control; 2) the reliance on a single post-exposure
time point; 3) the small sample size; and 4) the dose received by the
subjects varied and was only estimated from dermal dosimetry.

Ethics

The Board concurred with the Agency’s assessment that there neither
was clear and convincing evidence that the study was fundamentally
unethical, nor clear and convincing evidence that the study was
significantly deficient relative to the ethical standards prevailing at
the time the Honeycutt and DeGeare (1993) study was conducted.

Assessment of Completed Research Study MRID 44811002: Kisicki et al.
(1999) A Rising Dose Toxicology Study to Determine the No-Observable
Effect-Levels (NOEL) For Erythrocytes Acetylcholinesterase (AChE)
Inhibition and Cholinergic Signs and Symptoms of Chlorpyrifos at Three
Dose Levels.

Science

Because of concerns about the analytic procedures' potential inability
to control for the glucuronide-conjugated TCP, and apparent
discrepancies in the absorption data when compared with the data from
Nolan et al. (1982), the Board questioned the reliability and utility of
the blood and urine measurements of chlorpyrifos and/or TCP from Kisicki
et al. (1999) for risk assessment purposes.

The Board concluded that these measurements of cholinesterase
activity/inhibition likely represent a reliable set of data, but
cautioned the Agency about relying on data from the incomplete profile
for the one responder at the highest dose level. 

The Board cautioned against relying on the statistical analyses as
presented in the report, recommending that these analyses be replicated
prior to applying these result to any risk assessment or model
development. 

The Board concluded that, in the absence of additional information about
the analytic methods used and the accuracy of the TCP measurements, the
TCP data is of questionable reliability.  If the level of exposure
cannot be confirmed as reliable, then by default the erythrocyte data
should not be used. The Board thus suggested that the Agency be cautious
in its use of the erythrocyte data in light of the variability and
analytical concerns raised.

Ethics

The Board concluded that there neither was clear and convincing evidence
that the study was fundamentally unethical, nor clear and convincing
evidence that the study was significantly deficient relative to the
ethical standards prevailing at the time the Kisicki et al. (1999) study
was conducted.

Assessment of Completed Research Study MRID 47732701: ICR, Inc. Study
A382 – Evaluation of the Efficacy of KBR 3023 (Picaridin; Icaridin) -
Based Personal Insect Repellents (20% Cream and 20% Spray) Against
Stable Flies in the Laboratory.

Science

The Board concurred with the Agency’s assessment that this study
provides scientifically valid results to assess the repellent efficacy
against stable flies of the formulations tested.

The Board recommended correcting several of the statistical analyses
present in the report. For example, the standard error for mean
protection time and resulting confidence interval need to be corrected
to use the estimated standard error, not the planned standard error. 
The report should also be corrected to indicate that the data presented
are for product failure times and not complete protection times.

Ethics

The Board concurred with the Agency’s assessment that the study
submitted for review was conducted in substantial compliance with
subparts K and L of 40 CFR 26.

Assessment of Proposed Carroll-Loye Biological Research Study LNX-002:
Efficacy Test of KBR 3023 (Picaridin; Icaridin) - Based Personal Insect
Repellents (20% Cream and 20% Spray) with Biting Flies Under Field
Conditions.

Science

The Board concurred with the Agency’s assessment that this protocol,
if modified according to HSRB recommendations and conducted accordingly,
will provide scientifically valid results on the efficacy of these two
picaridin-based insect repellent formulations against biting flies. 

The Board recommended that the protocol be revised to address the
following concerns: 1) the standard of biting used may be insufficiently
high to yield valid results and could lead to inappropriately right
censored data; 2) the change from the previously-used paradigm of one
minute exposure of treated limbs out of each 15 minute period to five
minutes in each 30 minute period was not explained or justified; 3) the
varied behaviors and aggressiveness of four different species of biting
flies to be examined; and 4) accurate calculation of mean complete
protection time.

Ethics

The Board concluded that the protocol submitted for review, if modified
in accordance with Agency and HSRB recommendations and conducted
accordingly, is likely to meet the applicable requirements of 40 CFR 26,
subparts K and L.

Assessment of Proposed AHETF Scenario and Protocol AHE-120:
Water-Soluble Packing Mixing and Loading.

Science

Given the lack of existent reliable and sound data in this area, the
Board concurred with the Agency’s assessment that this protocol will
generate data that are scientifically valid. These data may be useful
for assessing the exposure of handlers who mix and load soluble or
wettable powder pesticides in water-soluble packaging. 

The Board cautioned that these data might not be useful for creating
distributions of worker exposure that are scientifically accurate or
that are precise.  Only if worker exposure is found to be proportional
to the amount of active ingredient handled (AaiH) will the study data
likely be generalizable.

The Board recommended that the AHETF and the Agency acknowledge the
limitations of the study design and add appropriate statistical methods
or data management approaches to ensure that, once these data are inside
the AHED® database, the limitations of the original study design are
not forgotten and the data used to generate the typical statistical
distributions without the user's knowledge. 

Ethics

The Board concluded that the protocol submitted for review, if modified
in accordance with Agency and HSRB recommendations and conducted
accordingly, is likely to meet the applicable requirements of 40 CFR 26,
subparts K and L. In particular, the Board recommended that the AHETF
implement the proposed protocol changes designed to address issues of
representativeness language in the informed consent and related
documents.

The Board recommended that the AHETF release individual exposure data
only once the study is complete, except in those instances where data
collected from individuals suggest an unusually high level of exposure
and thus a clear need to mitigate exposure risks.

Sincerely,

Sean Philpott, PhD, MSBioethics

	Chair

	EPA Human Studies Review BoardNOTICE

This report has been written as part of the activities of the EPA Human
Studies Review Board, a Federal advisory committee providing advice,
information and recommendations on issues related to scientific and
ethical aspects of human subjects research.  This report has not been
reviewed for approval by the Agency and, hence, the contents of this
report do not necessarily represent the view and policies of the
Environmental Protection Agency, nor of other agencies in the Executive
Branch of the Federal government, nor does the mention of trade names or
commercial products constitute a recommendation for use.  Further
information about the EPA Human Studies Review Board can be obtained
from its website at http://www.epa.gov/osa/hsrb/.  Interested persons
are invited to contact Paul Lewis, Designated Federal Officer, via
e-mail at lewis.paul@epa.gov.

	In preparing this document, the Board carefully considered all
information provided and presented by the Agency presenters, as well as
information presented by public commenters.  This document addresses the
information provided and presented within the structure of the charge by
the Agency.

US ENVIRONMENTAL PROTECTION AGENCY

HUMAN STUDIES REVIEW BOARD

Chair

Sean Philpott, PhD, MS Bioethics, Science and Ethics Officer, Global
Campaign for

Microbiocides, PATH, Washington, DC

Vice Chair

Rebecca Parkin, PhD, MPH, Associate Dean for Research and Public Health
Practice, School of Public Health and Human Services, The George
Washington University, Washington, DC

Members

Janice Chambers, PhD, DABT, William L. Giles Distinguished Professor,
Director, Center for Environmental Health Sciences, College of
Veterinary Medicine, Mississippi State University, Mississippi State, MS


Suzanne C. Fitzpatrick, PhD, DABT, Senior Science Policy Analyst, Office
of the Commissioner, Office of Science and Health Coordination, US Food
and Drug Administration, Rockville, MD *

Dallas E. Johnson, PhD, Professor Emeritus, Department of Statistics,
Kansas State University, Manhattan, KS

Michael D. Lebowitz, PhD, FCCP, Retired Professor of Public Health &
Medicine, University of Arizona, Tucson, AZ 

Lois D. Lehman-Mckeeman, PhD, Distinguished Research Fellow, Discovery
Toxicology, Bristol-Myers Squibb Company, Princeton, NJ 

Jerry A. Menikoff, MD, JD, Director, Office of Human Subjects Research,
Office of the Director, National Institutes of Health, Bethesda, MD

Ernest D. Prentice, PhD, Associate Vice Chancellor for Academic Affairs,
University of Nebraska Medical Center, Omaha, NE *

Linda J. Young, PhD, Professor, Department of Statistics, Institute of
Food and Agricultural Sciences, University of Florida, Gainesville, FL 

Consultants to the Human Studies Review Board

Sidney Green, Jr., PhD, Fellow, ATS, Professor, Department of
Pharmacology, Howard University College of Medicine, Washington, DC

Alan Meisel, JD, Dickie, McCamey and Chilcote Professor of Bioethics,
Professor of Law and Psychiatry, University of Pittsburgh School of Law,
Pittsburgh, PA

Martin A. Philbert, PhD, Director, Center for Risk Science and
Communications, University of Michigan School of Public Health, Ann
Arbor, MI 

William Popendorf, PhD, MPH, Professor, Department of Biology, Utah
State University, Logan, UT 

Lianne (Elizabeth A.) Sheppard, PhD, Professor, Department of
Biostatistics, University of Washington, Seattle, WA

Human Studies Review Board Staff

Paul I. Lewis, PhD, Executive Director, Human Studies Review Board
Staff, Office of the Science Advisor, United States Environmental
Protection Agency, Washington, DC 

* Not in attendance at June 24-25, 2009 Public Meeting

  TOC \o "1-3" \h \z \u   INTRODUCTION 

From June 24-25, 2009, the United States Environmental Protection
Agency’s (EPA or Agency) Human Studies Review Board (HSRB) met to
address scientific and ethical issues concerning: three completed human
toxicity studies involving one pesticide active ingredient –
chlorpyrifos – conducted prior to publication of the EPA’s expanded
final rule for protection of subjects in human research; and one
completed study involving one insect repellent active ingredient –
picaridin – conducted after promulgation of the EPA’s expanded final
human studies rule. In accordance with 40 CFR 26.1602, EPA sought HSRB
review of these completed studies. Each of these studies is discussed
more fully below.

In addition, the Agency submitted two protocols for conducting new
research involving human participants: one study measuring the efficacy
of two registered insect repellents containing picaridin against biting
flies under field conditions; and one study measuring levels of exposure
received by agricultural handlers when mixing and loading pesticides
using water-soluble packing under various conditions. In accordance with
40 CFR 26.1601, EPA sought HSRB review of these proposed protocols. Each
of these studies is discussed more fully below.

REVIEW PROCESS

On June 24-25, 2009, the Board had a public face-to-face meeting in
Arlington, Virginia. Advance notice of the meeting was published in the
Federal Register as “Human Studies Review Board; Notice of Public
Meeting” (74 Federal Register 106, 26861).

During the public meeting, following welcoming remarks from Agency
officials, the Board heard presentations from the Agency on the
following topics: three completed studies involving intentional human
exposure to the organophosphate pesticide chlorpyrifos (Nolan et al.
(1982), Honeycutt and DeGeare (1993), and Kisicki et al. (1999)); a
completed ICR, Inc., (ICR) insect repellent efficacy study (ICR A382); a
proposed Carroll-Loye Biological Research, Inc. (CLBR) insect repellent
efficacy study (LNX-002); and a proposed Agricultural Handler Exposure
Task Force, LLC (AHETF) water-soluble packing mixing and loading
scenario and protocol (AHE-120).

The Board also asked clarifying questions of several study sponsors
and/or research investigators, including:

Dr. Craig Barrow, Consultant to Dow AgroSciences

Dr. Victor Canez, Technical Chair, Agricultural Handler Exposure Task
Force

Dr. Scott Carroll, Principal, Carroll-Loye Biological Research

Dr. Richard H. Collier, Administrative Committee Chair, Agricultural
Handler Exposure Task Force

Mr. Bill Gaynor, Staff Member, ICR

Mr. Shawn King, Director of Operations, Carroll-Loye Biological Research

Dr. Ralph Piedmont, Consultant to ICR

Dr. Ken Racke, Regulatory Specialist, Dow AgroSciences

Dr. Ghona Sangha, Toxicology and Regulatory Consultant, LANXESS Corp.

Oral comments were provided by: 

Dr. Ghona Sangha, Toxicology and Regulatory Consultant, LANXESS Corp.

No written public comments were provided.

For their deliberations, the Board considered the materials presented at
the meeting, oral comments, and Agency background documents (e.g.,
published literature, sponsor and investigator research reports, study
protocols, data evaluation records, and Agency science and ethics
reviews of proposed protocols and completed studies).   A comprehensive
list of background documents is available online at
http://www.regulations.gov. 

CHARGE TO THE BOARD AND BOARD RESPONSE

Assessment of Completed Research Study MRID 124144: Nolan et al. (1982)
Chlorpyrifos: Pharmacokinetics in Human Volunteers Following Single Oral
and Dermal Doses.

Overview of the Study

The HSRB reviewed Nolan et al. (1982) as part of a package of three
studies involving human volunteers exposed to chlorpyrifos that were
proposed for use by EPA to characterize and help interpret
epidemiological and bio-monitoring data for this pesticide.  In
addition, the data from human participants might be used for setting
bounding estimates and developing physiologically based pharmacokinetic
(PBPK) models for chlorpyrifos.

	

	Nolan et al. (1982) summarize the results of a single dose level study
that was designed to compare the fate of chlorpyrifos when administered
orally or dermally to humans. Chlorpyrifos is a highly lipophilic
compound that is rapidly metabolized to 3,5,6-trichloro-2-pyridinol
(TCP) and diethylthiophosphate. TCP is excreted in urine predominantly
as a glucuronide conjugate. Blood and urine levels of chlorpyrifos and
TCP (unconjugated) were determined after oral (0.5 mg/kg) or dermal (5
mg/kg) administration of chlorpyrifos. 

	There were a total of six participants in the Nolan et al. (1982)
study, with one participant (“subject A’) included in the evaluation
of the fate of chlorpyrifos after oral dosing.  However, this
participant received dermal dosages of chlorpyrifos at 0.5 mg/kg in a
preliminary evaluation and was not used in the final analyses of the
dermal fate of chlorpyrifos (n = 5 for the dermal study).  Based on the
urinary excretion of TCP, it was estimated that approximately 70% of the
orally administered dose of chlorpyrifos was absorbed, whereas less than
3% of the dose was absorbed after dermal application. 

Science

	Although presented separately, the same scientific criteria were used
to assess the reliability of the data from all three chlorpyrifos
studies.  These criteria are:

Verification that the administered dose of chlorpyrifos was confirmed in
the study;

Assurance that sample collection (blood and urine) was reliable and
complete;

Validation and appropriateness of the analytical methods for
quantification of chlorpyrifos and TCP in blood and urine; and

Evaluation of the cholinesterase inhibition data (plasma and/or RBC
cholinesterase) for sensitivity, accuracy, reproducibility, timing of
sample collection and proper sample handling for analysis.

Along with other relevant study issues, an assessment of how the Nolan
et al. (1982), as well as the other two chlorpyrifos studies presented,
met these general criteria along with other relevant study issues are
summarized in responses to the Agency’s charge questions below.

Charge to the Board

	Are the blood and urine measurements of chlorpyrifos and/or TCP from
the Nolan et al. (1982) oral and dermal studies reliable?

Board Response to the Charge

HSRB Recommendation 

	The Board concluded that data measuring chlorpyrifos at the limit of
detection in blood and urine are not useful. The measurements of TCP in
urine are generally reliable. It is unclear if the measurement of TCP in
blood is useful because of concerns about the ability of the methods
used to detect the appropriate TCP conjugate.	

HSRB Detailed Recommendations and Rationale 

	Since blood and urinary concentrations of chlorpyrifos were essentially
non-detectable, there is little confidence in these data.  However,
urinary levels of TCP, determined after hydrolysis of the glucuronide
conjugate, were well above the limit of detection. Additionally, the
data suggest relatively high absorption of chlorpyrifos from oral dosing
and considerably less exposure from the dermal route, a pattern that is
biologically plausible.  It is not clear whether the blood levels of TCP
are accurate because the extent to which the glucuronide conjugate of
TCP circulates in the blood and the extent to which the glucuronide
conjugate may be detected in blood. Confirmation of how the blood
samples were handled for analysis may help to increase the confidence in
the reported blood concentrations of TCP.   

	

Charge to the Board

	Are the measurements of cholinesterase activity/inhibition from the
Nolan et al. (1982) oral and dermal studies reliable? 

Board Response to the Charge

HSRB Recommendation 

	The HSRB expressed some concern over the variability of the erythrocyte
cholinesterase activity data and the lack of a control group, but
concluded that measurements of cholinesterase activity/inhibition from
Nolan et al. (1982) were likely to be reliable.

HSRB Detailed Recommendations and Rationale 

	A major issue with determination of cholinesterase activity is the
inter-day and inter-assay variability (typically 10-15%) that may be
observed.  In the Nolan et al. (1982) study, plasma cholinesterase
showed marked inhibition (up to approximately 85%) after oral
administration of chlorpyrifos, whereas less plasma cholinesterase
inhibition was noted after dermal application (up to about 25%).  In
contrast, no inhibition of erythrocyte cholinesterase was observed with
either route of administration.  

	The HSRB considered the following limitations or weaknesses of the
cholinesterase measurements in Nolan et al. (1982):

1.	There was no untreated group to control for inter-day laboratory
variations; the subject's response was based only on a change from their
own pretest samples.

2.	The inter-day variability for each subject was high, particularly for
the erythrocyte cholinesterase activity, thereby limiting the
interpretation of the results.

  

3.	Although the method used to measure cholinesterase activity (the
micro-Michel method) is an older method, it was probably the most
reliable at the time.

4.	Since only a single dose level was evaluated, no dose-response data
are available from this study.  

Nevertheless, the results demonstrated that oral administration of
chlorpyrifos caused greater inhibition of plasma cholinesterase than
that observed after dermal application, a result that is consistent with
higher absorption of chlorpyrifos following oral dosing.

Ethics

Charge to the Board 

Is there clear and convincing evidence that the conduct of the Nolan et
al. (1982) study was fundamentally unethical, or significantly deficient
relative to the standards of ethical research conduct prevailing when it
was conducted?

Board Response to the Charge 

HSRB Recommendation

The Board concurred with the Agency’s assessment (Carley 2009a) that
there neither was clear and convincing evidence that the study was
fundamentally unethical, nor clear and convincing evidence that the
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted. 

HSRB Detailed Recommendations and Rationale 

Given that the Nolan et al. study was conducted in 1981 and 1982, the
Board concurred with the Agency’s assessment that the applicable
regulatory standard at that time was FIFRA §12(a)(2)(P). In response to
questions from the Agency, the study sponsor indicated that participants
signed a one-page consent form that gave few details about the study but
affirmed that they had read the study protocol (Dow AgroSciences 2009a).
There had been two ethical reviews of this protocol, one by the Dow
Human Health Research Committee, and a second by the University of
Michigan Ethical Review Committee (The Committee to Review Grants for
Clinical Research and Investigation Involving Human Beings).

1. 	The Board concurred with the conclusions and factual observations of
the ethical strengths and weaknesses of the study, as detailed in the
Agency’s Ethics Review (Carley 2009a).

2.  	The Board concluded that this study met all applicable ethical
requirements for such research involving human participants, in
accordance with the following criteria: 

a. 	Not fundamentally unethical. With regard to determining whether or
not a study is fundamentally unethical, the Board’s standard is to
decide if the research was intended to seriously harm participants, or
if it failed to obtain informed consent, or if it was fundamentally
unethical for other reasons. 

( 	The study was not intended to seriously harm participants. Voluntary
informed consent of participants was obtained. Given that there does not
appear to be clear and convincing evidence that for any other reasons it
might have been fundamentally unethical, the Board concludes that it was
not fundamentally unethical.

b. 	Not significantly deficient. With regard to determining whether a
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted, the Board’s
standard is to determine whether or not any ethical deficiencies
identified could have resulted in serious harm based on knowledge
available to researchers at the time the study was conducted, or whether
the information provided to study participants could seriously impair
informed consent.

( 	Based on toxicological data that was available at the time for
chlorpyrifos, study participants were unlikely to be at risk for serious
side effects given the exposure dose used in this study.

( 	The Board did not have a copy of the protocol that was given to the
prospective participants when obtaining their informed consent, so the
HSRB did not know exactly what information the participants received.
Given that the study was reviewed by two ethics review boards, however,
the Board concluded that there was no clear and convincing evidence that
the information provided to participants could seriously impair informed
consent. With regard to studies that were conducted prior to the
effective date of the Agency’s regulations, the Board does wish to
convey to the Agency the importance of obtaining as much information
about such studies as is reasonably possible. It would have been
desirable for the Board to have had access to the actual study protocol.


Assessment of Completed Research Study MRID 42062701: Honeycutt and
DeGeare (1993) Worker Reentry Exposure to Chlorpyrifos in Citrus Treated
with Loraban* 4E Insecticide.

Overview of the Study

	The study reported by Honeycutt and DeGeare (1993) was a biological
monitoring study to determine potential exposure to chlorpyrifos in
individuals who reenter a citrus grove after agricultural use of
chlorpyrifos.  There were 15 participants in the study, representing
five citrus pickers and ten citrus pruners (five each in wet and dry
conditions, respectively).  Pickers entered the test site 43 days after
application of chlorpyrifos, whereas pruners re-entered two days after
the application of chlorpyrifos.  The exposure period was 5-6 hours, and
the assessment of chlorpyrifos exposure was achieved with whole body
dosimeters, air sampling, leaf punches and quantification of urinary
excretion of TCP. The results from Nolan et al. (1982) justify
monitoring urinary TCP to estimate chlorpyrifos exposure.  The report
included considerable emphasis on the handling of all samples in the
field and a comprehensive summary of all analytical conditions and
methods used in determining chlorpyrifos in all study matrices. 

	

	Both chlorpyrifos and TCP were analyzed with negative ion-chemical
ionization gas chromatography with mass selective detection (GC/MS) and
urinary TCP was quantified after acid hydrolysis employing concentrated
hydrochloric acid with heating for 1-2 hr followed by derivitization
with N-methyl-(N-tertbutyldimethylsilyl)-trifloroacetamide. Analytical
recoveries were reported, and the limit of detection was defined as
three-times higher than the signal to noise ratio.  No limit of
quantitation (LOQ) was provided.

Science

Charge to the Board

	Are the blood and urine measurements of chlorpyrifos and/or TCP from
the Honeycutt and DeGeare (1993) worker biomonitoring study reliable?

Board Response to the Charge

HSRB Recommendation 

	The Board concluded that the data from Honeycutt and DeGeare (1993) are
likely reliable but of limited value. Board members expressed concerns
about:  1) the small sample size; 2) the background chlorpyrifos
exposure not being properly accounted for; 3) the likely incompleteness
of urine collection; and 4) the high degree of variation seen in the
daily measurements.

HSRB Detailed Recommendations and Rationale 

 

	Relevant weaknesses or limitations concerning study conduct and data
reported by Honeycutt and DeGeare (1993) were assessed as follows:   

1.	The strength of this study is that it provides data on real-world
exposures to chlorpyrifos.  However, the critical element regarding
confirmation of the dosage was not achieved in this study because the
purpose of this study was to actually determine the dosage.

2.	Urine samples were collected for 24 hrs prior to reentry and across
12-hr time intervals for up to five days after completion of the 5-6 hr
work period.  However, there is evidence to suggest that urine
collections were not complete.  This conclusion was based on variability
in total urinary creatinine excretion along with several instances in
which incomplete sample collection was noted.  In total, five of 15
participants had total urinary creatinine levels that were significantly
below normal daily reference range for creatinine excretion. In
addition, for nine of 15 study participants the coefficient of
variability exceeded reported urinary creatinine levels by up to
four-fold, suggesting that urine collection was inconsistent at best. In
light of these discrepancies, efforts were made to normalize urinary
excretion data to a population average for creatinine excretion, but the
accuracy and validity of this calculation is unknown, as discussed
further below.  

3.	The control of the participants both prior to and after completion of
the exposure was inadequate.  One worker (Pruner 9) showed maximum
urinary TCP levels on day three of the study suggesting additional
exposure to chlorpyrifos after the test exposure period.  More
importantly, several workers showed detectable levels of urinary TCP in
pretest samples, which was suggested to represent a steady state level
of TCP resulting from occupational exposure.  However, the validity of
this conclusion is unknown, and the possibility that the observed levels
may have resulted from a more recent exposure to chlorpyrifos was not
considered.   

4.	In light of the uncertainties regarding urine sample collection and
subject control, urinary TCP, and hence exposure to chlorpyrifos, were
determined using six different methods including no corrections,
correction for background TCP excretion, correction for creatinine
excretion and combinations of corrections for background and creatinine
levels.  Across the six different methods used, the range of urinary TCP
concentrations was about two-fold for pickers and four-fold for pruners.
 In addition to the range of urinary TCP concentrations and the
uncertainty regarding which method is most accurate, the small sample
size (n = 5 participants per scenario) decreases the confidence of the
final reported values.  

	Thus, although this study provides the potential for assessing
chlorpyrifos exposure from a relevant occupational exposure, the
uncertainty resulting from incomplete urine sample collection,
background exposure to chlorpyrifos, the small sample size,
inter-individual and inter-day variability and the use of six different
calculations to estimate chlorpyrifos exposure undermine confidence in
the reliability of the data.

Charge to the Board

	Are the measurements of cholinesterase activity/inhibition from the
Honeycutt and DeGeare (1993) worker biomonitoring study reliable? 

Board Response to the Charge

HSRB Recommendation 

	The Board concluded that the laboratory data are likely accurate and
reliable but raised concerns about their utility. Some of the Board’s
concerns included: 1) the lack of an untreated control group; 2) the
reliance on a single post-exposure time point; 3) the small sample size;
and 4) the dose received by the subjects varied and was only estimated
from dermal dosimetry

HSRB Detailed Recommendations and Rationale 

	Plasma and blood cholinesterase activities were determined pre-exposure
(typically 2 occasions prior to exposure) and 24 hr after working in the
citrus grove.  The modified Ellman procedure was used to determine
cholinesterase activities. Overall, no significant changes in plasma or
erythrocyte cholinesterase activities were observed.  The following
limitations concerning plasma and erythrocyte cholinesterase activities
reported by Honeycutt and DeGeare (1993) were identified:   

Only one post-exposure sample was collected for analysis (24 hr). 
Additional sampling would have been helpful, as it is not clear whether
the 24 hr time point was most appropriate for analysis.

Considerable variability was noted across the samples.  In six of the
workers, the two pre-dose measurements were not within 15% of each
other, thereby confounding the accuracy of the baseline activities, and
in three of the pruners, post-exposure erythrocyte cholinesterase levels
were actually increased by more than 20% over baseline values. 
Collectively, there is considerable uncertainty in the baseline data.

 No data from an unexposed group of control subjects was used to control
for inter-day variability in the assay.  It was noted that the practice
of including laboratory controls for intra-assay variability is
published, standard practice for this assay.

The small group size further confounds the interpretation of the highly
variable results.

	Thus, the HSRB concluded that the experimental evidence suggesting that
plasma and erythrocyte cholinesterase activities were not significantly
altered in the pickers and pruners exposed to chlorpyrifos in this study
were likely to be accurate.  However, the Board also cautioned that the
reliability of the data was limited because of the issues noted above
including analysis at only a single time point after exposure, the small
sample size, the high degree of intra- and inter-subject variability and
the lack of an untreated control.

Ethics

Charge to the Board

Is there clear and convincing evidence that the conduct of the Honeycutt
and DeGeare (1993) study was fundamentally unethical, or significantly
deficient relative to the standards of ethical research conduct
prevailing when it was conducted?

Board Response to the Charge 

HSRB Recommendation

The Board concurred with the Agency’s assessment (Carley 2009b) that
there neither was clear and convincing evidence that the study was
fundamentally unethical, nor clear and convincing evidence that the
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted. 

HSRB Detailed Recommendations and Rationale 

This study was initiated in 1991 in California. As a result, it was
subject to the California Code of Regulations, Title 3, Section 6710, as
amended September 26, 1988, which required pre-approval of the study by
the Director of the California Department of Pesticide Registration, and
by an Institutional Review Board approved by the US Department of Health
and Human Services. It was also subject to FIFRA § 12(a)(2)(P).  The
study was reviewed and approved by the Committee on Human Subjects
Research at the University of California, San Francisco. 

1. 	The Board concurred with the conclusions and factual observations of
the ethical strengths and weaknesses of the study, as detailed in the
EPA’s Ethics Review (Carley 2009b).

2.  The Board concluded that this study met all applicable ethical
requirements for such research involving human participants, in
accordance to the following criteria: 

a. 	Not fundamentally unethical. With regard to determining whether or
not a study is fundamentally unethical, the Board’s standard is to
decide if the research was intended to seriously harm participants, or
if it failed to obtain informed consent, or if it was fundamentally
unethical for other reasons.

 ( 	The study was not intended to seriously harm participants. Voluntary
informed consent of participants was obtained. Given that there does not
appear to be clear and convincing evidence that for any other reasons it
might have been fundamentally unethical, the Board concludes that it was
not fundamentally unethical.

b. 	Not significantly deficient. With regard to determining whether a
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted, the Board’s
standard is to determine whether or not any ethical deficiencies
identified could have resulted in serious harm based on knowledge
available to researchers at the time the study was conducted, or whether
the information provided to study participants could seriously impair
informed consent.

( 	Based on toxicological data that was available at the time for
chlorpyrifos, study participants were unlikely to be at risk for serious
side effects given the exposure dose used in this study.

Exposure took place while participants were performing activities that
were the same as those they regularly performed as part of their usual
employment as citrus workers. Accordingly, it does not appear that there
were ethical deficiencies that could have resulted in serious harm.

( 	The volunteers were briefed about the design of the study and the
risks relating to participation, and they signed consent forms
containing that information. As the Agency noted (Carley 2009b), there
was misleading information in some of the forms, such as comments that
the residue from the spraying of the pesticide would have disappeared by
the time they entered the groves. That misinformation was certainly
inappropriate but does not, in and of itself, provide clear and
convincing evidence that the informed consent process was seriously
impaired.

( 	The study participants were employed by Mr. Gary Austin of
Leffingwell Ag Sales Co., and he recruited them himself. It is unclear
to what extent these participants might therefore have been vulnerable
to his influence in deciding to enter the study. Nonetheless, this type
of arrangement does not appear to be unusual at that time. 

( 	The privacy of participants was compromised by the fact that their
full names and Social Security numbers were included in an appendix to
the study report. This is inappropriate, but would not appear to
constitute clear and convincing evidence of an ethical deficiency that
resulted in serious harm to these participants.

Assessment of Completed Research Study MRID 44811002: Kisicki et al.
(1999) A Rising Dose Toxicology Study to Determine the No-Observable
Effect-Levels (NOEL) For Erythrocytes Acetylcholinesterase (AChE)
Inhibition and Cholinergic Signs and Symptoms of Chlorpyrifos at Three
Dose Levels.

Overview of the Study

	This study was a double blind, randomized and placebo-controlled rising
dose study designed to determine the no-observable effect level (NOEL)
for inhibition of erythrocyte acetylcholinesterase in human volunteers. 
The dosages used in the study were 0.5, 1 and 2 mg/kg, with the starting
dose of 0.5 mg/kg based on the results of Nolan et al. (1982) discussed
previously.  In addition to assessing cholinesterase activity, blood and
urine were collected and analyzed for chlorpyrifos and TCP to help
define the pharmacokinetic properties in humans.  Finally, paraoxonase
status of each subject was determined (but will not be discussed here).

	

	Chlorpyrifos was administered orally in a gelatin capsule with 0
(lactose), 0.5 and 1 mg chlorpyrifos/kg administered in Phase I of the
study followed by a second phase that include 0 (control) and 2 mg/kg
dosages.  There were six male and six female participants for each dose
level.  Subjects were confined to the testing facility overnight prior
to treatment through the first 48 hr after dosing.  Additional samples
were collected thereafter at 24 hr intervals through 168 hr (one week)
post dosing.  Blood, collected pre-dose (-10 and 0 hr) and at 2, 4, 8,
24, 36, 48, 72, 96, 120, 144 and 168 hr post treatment, was used for
determining erythrocyte acetylcholinesterase activity and chlorpyrifos
and TCP levels.  Voided urine was collected at 12 hr intervals starting
48 hr prior to dosing and through the 168 hr dosing period (with the
exception that immediately after dosing urine was collected at 0-6 and
6-12 hr).

Science

Charge to the Board

	Are the blood and urine measurements of chlorpyrifos and/or TCP from
the Kisicki et al. (1999) oral study reliable and appropriate for use in
characterizing the results of epidemiological studies with chlorpyrifos?


Board Response to the Charge

HSRB Recommendation 

	Because of concerns about the analytic procedures' potential inability
to control for the glucuronide-conjugated TCP, and apparent
discrepancies in the absorption data when compared with the data from
Nolan et al. (1982), the Board questioned the reliability and utility of
the blood and urine measurements of chlorpyrifos and/or TCP from Kisicki
et al. (1999) for risk assessment purposes.

HSRB Detailed Recommendations and Rationale 

	With respect to the general elements considered in the evaluation of
the scientific reliability of the chlorpyrifos exposure data, this study
provided clear documentation of the administered dose. Chlorpyrifos was
added to a gelatin capsule normalized with lactose powder and the weight
of the filled capsule was determined.  There was one noted discrepancy
that one participants in the 2 mg/kg dose group may have received a
lower dose (1.63 mg/kg) based on conflicting data on body weight and
administered dose data, but overall the documentation of the
administered dose was satisfactory.

	There was also generally good reliability with respect to sample
collections.  Participants remained in the testing facility for the
first 48 hrs after dosing and 48 of the 60 subjects provided all
periodic urine samples.  Urine collections were judged to be complete
based on creatinine excretion for 19 of the 60 subjects. One participant
in the 2-mg/kg-dose group failed to return for sample collection and
clinical monitoring after the initial 48 hr post-dosing period.

	Chlorpyrifos and TCP were measured in blood and urine with GC/MS
detection, and TCP was derivatized with
N-methyl-(N-tertbutyldimethylsilyl)-trifloroacetamide.  In general,
these methods were similar to those described by Honeycutt and DeGeare
with the exception that stable labels of chlorpyrifos and TCP (13C
and/or 15N-labeled) were used as internal standards in the present
analyses.    

	In reviewing this study, the HSRB identified several limitations or
issues that may impact the overall reliability of the data.  These
included:

1.	The amount of chlorpyrifos absorbed after oral administration in the
present study was markedly lower than that reported by Nolan et al.
(1982).  A dose of 0.5 mg/kg was common to both studies, with Nolan et
al. reporting approximately 70%, and Kisicki et al. reporting
approximately 35% absorbed.  The rationale provided for this large
difference was that chlorpyrifos was administered using lactose tablets
and gelatin capsules in the Nolan et al. and Kisicki et al. studies,
respectively.  Kisicki et al. suggested that oral absorption is slowed
by the dissolution of the gelatin capsule with a concurrent reduction in
the total amount absorbed.  Although the Board agreed that absorption of
chlorpyrifos from the gelatin capsule might be slower than that from a
lactose tablet, there was some skepticism that the difference in dosage
form would yield the large discrepancy in total percent absorbed in the
two studies.

2.	In the methodological details provided for the analysis of urinary
levels of TCP, there was no indication that urine samples were subjected
to acid hydrolysis required to liberate the glucuronide conjugate of
TCP, which is the major urinary metabolite of chlorpyrifos.  This is an
important distinction, as both Nolan et al. (1982) and Honeycutt and
DeGeare (1993) indicated that urine samples were treated with
concentrated sulfuric or hydrochloric acid and heated in order to
hydrolyze the glucuronide conjugate and liberate TCP which is then
derivatized (in the methods used by Honeycutt and DeGeare and Kisicki et
al.).  In the analytical portion of the Kisicki et al. study (Brzak
2000), there is a clear designation that blood samples were treated with
concentrated hydrochloric acid prior to extraction, but no similar
details are provided for the analysis of the urine samples.  Although it
seems unlikely that this important (and necessary) step was omitted, the
lack of explicit indication of this critical analytical step raises some
doubt that it was done.  If urine samples were not properly hydrolyzed
prior to analysis, then the validity and reliability of these data are
uncertain.  Furthermore, since urinary TCP is used to estimate oral
absorption of chlorpyrifos, it is possible that differences in sample
handling may explain or at least contribute to the lower percent
absorption reported by Kisicki et al.

   

3.	The total mass balance (total recovery of the administered
chlorpyrifos) was not determined. Inclusion of total recovery could
increase the confidence in the estimated percent of absorption in the
study and possibly clarify whether there was an issue with the TCP
analysis conducted by Kisicki et al.

4.	There were several questions regarding the designation and use of
alternate participants in the study.  The basis for participant
replacement and verification of body weight and dose administered to the
alternate participants were not adequately provided. 

Because of concerns about the analytic procedures' potential inability
to control for the glucuronide-conjugated TCP, and apparent
discrepancies in the absorption data when compared with the data from
Nolan et al. (1982), the Board thus questioned the reliability and
utility of the blood and urine measurements of chlorpyrifos and/or TCP
from Kisicki et al. (1999) for risk assessment purposes.

Charge to the Board

	Are the measurements of cholinesterase activity/inhibition from the
Kisicki et al. (1999) oral study reliable? 

Board Response to the Charge

HSRB Recommendation 

	The Board concluded that these measurements likely represent a reliable
set of data, but cautioned the Agency about relying on data from the
incomplete profile for the one responder at the highest dose level. The
Board also cautioned against relying on the statistical analyses as
presented in the report.

HSRB Detailed Recommendations and Rationale 

	In this study, erythrocyte acetylcholinesterase activities were
determined pre-dose (2 samples) and 2, 4, 8, 12, 24, 36, 48, 72, 96,
120, 144 and 168 after dosing (Ellman method).  Plasma cholinesterase
activity was not measured.  The results showed a relatively high degree
of variability, and samples collected at 96 hr (Phase I; 0, 0.5 and 1
mg/kg) were judged to be low relative to all other treatment times. One
participant in the 1-mg/kg dose group showed a 24.5% decrease in
activity at the 96 hr time point.  However, given the decreased activity
observed in the entire group of samples collected at 96 hr along with
the fact that peak inhibition would be expected to occur before 96 hr,
this result was not considered to be a real finding.   Only one
participant in the 2-mg/kg-dose group showed a reduction in erythrocyte
cholinesterase activity in the study, with a nadir (72% of her baseline
level) observed 12 hr after treatment.  However, this volunteer did not
return for blood collections after the initial 48 hr period, resulting
in an incomplete profile. This participant did not appear to show
adverse clinical signs associated with cholinesterase inhibition.  Based
on the reduction in erythrocyte cholinesterase activity in this subject,
the NOEL for enzyme inhibition was considered to be 1 mg/kg.

	In reviewing this study, the Board identified several limitations or
issues that may impact the overall reliability of the data.  These
included:

1.	There was generally poor documentation provided for the grouping or
batch processing of the blood samples. Given the recognized inter-day
and inter-assay variability associated with the Ellman method, this is a
critical weakness.  The study records were noted to be insufficient to
confirm that samples were batched correctly to allow the proper
utilization of the unexposed control data to correct for day-to-day or
batch-to-batch variations in the mean lab results.  This limitation is
particularly important to detect or to quantify accurately small changes
within an exposed population.

2.	The interpretation of the results is centered on the single
individual who showed more than a 25% inhibition of erythrocyte
cholinesterase activity at the 2-mg/kg-dose level.  The conclusions
regarding both the duration and magnitude of inhibition depend upon the
inclusion of this participant, and the lack of follow-up in this
participant beyond 48 hr thereby limits the interpretation of the
results.  

3.	The reported statistical analyses of these data are highly
problematic, and the results in Appendix 3 were judged to be clearly
wrong.  Specifically, it was noted that a univariate repeated measures
ANOVA was performed (Kisicki et al. 1999, 25), and Appendix 3 summarizes
the results of such analyses (Kisicki et al. 1999, 151-158, 184-188,
206-211).  Although it is not possible to replicate these analyses, the
report suggests that the variable being analyzed is the Normalized
Percent of Baseline (Kisicki et al. 1999, 24).  The report indicates
that the Group Mean Square (Kisicki et al. 1999, 157) is 19.1207 while
the Error Mean Square is 52,835,395,914.644.  It is virtually impossible
that these two values can be this different for real data.  Furthermore,
the corresponding Individual Hour Error Mean Squares from the
corresponding mixed model analysis range from about 14.39 to 48.26. 
These are much more reasonable values.  The report (Kisicki et al. 1999,
25) also indicates that mixed effects models were used where gender and
treatment were considered to be fixed factors, and that time was
considered to be a random continuous covariate.  According to the mixed
model analyses reported in Appendix 3, time is not being considered a
random continuous covariate.  Time is treated as a continuous covariate,
but not as a random continuous covariate.  Overall, the Board concluded
that the statistical analyses are likely incorrect, and there should be
some effort to perform correct analyses before relying on these data.

4.	Plasma cholinesterase activity was not determined in the study.  It
is recognized that the erythrocyte cholinesterase activity is more
biologically relevant for assessing potential adverse effect of
chlorpyrifos, and as such, the lack of data on plasma cholinesterase is
not a serious limitation.  However, given the issues raised concerning
sample handling, batch processing and statistical evaluations, inclusion
of plasma cholinesterase may have helped to assess the overall
reliability of the data.

	The Board thus concluded that the measurements of erythrocyte
acetylcholinesterase activities were generally reliable.  However, Board
members cautioned that the incomplete profile obtained from the only
subject who showed inhibition at the 2 m/kg dose level limited the
utility of the data. Moreover, the Board recommended that, although the
data might be reliable, the statistical analyses in general and
particularly for the data in Appendix 3 should be replicated prior to
applying these results to any risk assessment or model development.

Ethics

Charge to the Board 

Is there clear and convincing evidence that the conduct of the Kisicki
et al. (1999) study was fundamentally unethical, or significantly
deficient relative to the standards of ethical research conduct
prevailing when it was conducted?

Board Response to the Charge 

HSRB Recommendation

The Board concluded that there neither was clear and convincing evidence
that the study was fundamentally unethical, nor clear and convincing
evidence that the study was significantly deficient relative to the
ethical standards prevailing at the time the research was conducted. 

HSRB Detailed Recommendations and Rationale 

According to documents supplied by the sponsor (Juberg and Mattsson
2009a, Juberg and Mattsson 2009b), the study was conducted in accordance
with US Food and Drug Administration rules relating to the protection of
human subjects, as codified at 21 CFR parts 50 and 56, and in accordance
with the International Guidelines for Human Testing promulgated in the
Declaration of Helsinki (as amended in 1996). In addition, the study was
subject to FIFRA  § 12(a)(2)(P). The protocol and related study
documents were reviewed and approved by the MDS Harris Institutional
Review Board. The consent of all participants was obtained and
documented through the use of a consent form approved by that IRB.

1. 	The Board concurred with most of the conclusions and factual
observations of the ethical strengths and weaknesses of the study, as
detailed in the EPA’s initial Ethics Review (Carley 2009c). The Board
disagreed, however, with the Agency’s initial conclusion that the
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted.  After considering
additional supplementary information provided to the Agency on June 23,
2009 and described in detail below (Kisicki 2009), the Board found no
clear and convincing evidence that the study was fundamentally unethical
or significantly deficient in its design and conduct. Following the
public meeting, additional supplementary material (including copies of
MDS Harris Laboratories screening and consent logs) was submitted to the
Agency for review. Although the Board shares the Agency’s concerns
that these supplementary documents still raise concerns about the
recruitment and consent process (Carley 2009e), the information
contained therein do not meet the evidentiary standard of clear and
convincing evidence that the study was fundamentally unethical or
significantly deficient relative to the ethical standards prevailing at
the time. It is possible, for example, that the deficiencies noted in
the logs are the result of sloppy record keeping rather than a serious
impaired participant recruitment, consent and screening process.

2.  The Board concluded that this study met all applicable ethical
requirements for such research involving human participants, in
accordance to the following criteria: 

a. 	Not fundamentally unethical. With regard to determining whether or
not a study is fundamentally unethical, the Board’s standard is to
decide if the research was intended to seriously harm participants, or
if it failed to obtain informed consent, or if it was fundamentally
unethical for other reasons.

 ( 	The study was not intended to seriously harm participants. Voluntary
informed consent of participants was obtained. Given that there does not
appear to be clear and convincing evidence that for any other reasons it
might have been fundamentally unethical, the Board concludes that it was
not fundamentally unethical.

b. 	Not significantly deficient. With regard to determining whether a
study was significantly deficient relative to the ethical standards
prevailing at the time the research was conducted, the Board’s
standard is to determine whether or not any ethical deficiencies
identified could have resulted in serious harm based on knowledge
available to researchers at the time the study was conducted, or whether
the information provided to study participants could seriously impair
informed consent.

( 	Based on toxicological data that was available at the time for
chlorpyrifos, study participants were unlikely to be at risk for serious
side effects given the exposure dose used in this study.

(	Participants underwent some screening tests (urine and blood sampling)
prior to signing the written consent form. According to materials
provided to the EPA and made public on the day of the Board’s
discussion of this study (Kisicki 2009), volunteers were given a copy of
the approved consent form and required to listen to an audiotape about
the study before they agreed to undergo the screening procedures. Later
documents submitted to the Agency (Radke 2009), however, raise questions
as to whether all potential study participants or alternates underwent
voluntary informed consent prior to screening. Although the failure to
have potential participants and alternates sign an informed consent form
prior to screening could be a violation of applicable FDA regulations,
given these circumstances it does not appear that the informed consent
process was serious impaired. 

There were various sentences in the informed consent form that appear
inappropriate, such as characterizing the study compound as one that
improves performance on tests of mental functioning. In addition,
portions of that form were written at an inappropriately high reading
level. Taken as a whole, however, the informed consent document does
appear to have provided prospective subjects with an accurate and
understandable picture of the likely risks from participation – which
were very low. Thus, it does not appear that the form, as written,
seriously impaired the informed consent process.

Assessment of Completed Research Study MRID 47732701: ICR, Inc. Study
A382 – Evaluation of the Efficacy of KBR 3023 (Picaridin; Icaridin) -
Based Personal Insect Repellents (20% Cream and 20% Spray) Against
Stable Flies in the Laboratory.

Overview of the Study

	A382 was a laboratory study conducted by ICR to assess the efficacy of
two formulations containing the repellent picaridin against
laboratory-reared stable flies. The study followed the protocol
previously reviewed by the HSRB and recommended for acceptance with some
suggested modifications.  

	The study used a dosimetry phase for dose determination. The initial
study had to be aborted because the stable flies did not show sufficient
biting pressure for a valid repellency test. Adjustments were
subsequently made in the husbandry of the flies to insure that they were
sufficiently hungry to bite the test subjects in the testing period, and
the data from the second test, along with the dosimetry results, were
presented. Complete protection times were calculated.

Science

Charge to the Board

Is the ICR study A382 sufficiently sound, from a scientific perspective,
to be used to assess the repellent efficacy of the tested formulations
against stable flies in the laboratory? 

Board Response to the Charge  

HSRB Recommendation 

	The Board concurred with the Agency’s assessment (Sweeney 2009) that
this study provides scientifically valid results to assess the repellent
efficacy against stable flies of the formulations tested. However, some
of the data presentation requires revision.

HSRB Detailed Recommendations and Rationale

	ICR was responsive to Board concerns and recommendations of the
previous Board review (EPA HSRB 2008). These responses included the use
of a dosimetry phase for dose determination and the inclusion of
individuals from racial minorities in the test population. The study
also used the time to first bite as the criterion, and not the time to
first confirmed bite, which was also a Board recommendation for
participant protection. The study included 12 participants (seven
females and five males). One female participant served as an untreated
control to verify landing pressure. The total number of study
participants is higher than the EPA guidelines recommend. Study
documents (Gaynor 2009, Gaynor et al. 2009) indicated that, according to
ICR’s database, landings underestimate bites. Thus, bites were
selected as the endpoint despite earlier Board recommendations
concerning participant safety (EPA HSRB 2008). Nevertheless, in order to
obtain scientifically valid data useful for regulatory purposes, the use
of confirmed bites is acceptable. The Margins of Exposure (MoEs) were
adequate for protection of participants from the potential toxicity of
the repellent.

	Statistical analyses were generally appropriate. However, the standard
error for mean protection time and resulting confidence interval need to
be corrected to use the estimated standard error, not the planned
standard error.  It would also be helpful to present the range of values
observed in the data. For study planning, basing sample size
calculations on an estimated standard deviation from stable fly data
would have been more appropriate than using a published estimate from
mosquito data. Lastly, Table 4 in the submitted report should be
corrected to indicate that the data presented are for product failure
times and not complete protection times.

Ethics

Charge to the Board

	Does available information support a determination that study ICR A382
was conducted in substantial compliance with subparts K and L 40 CFR
Part 26?

Board response to the Charge

HSRB recommendation

	The Board concurred with the Agency’s assessment (Carley 2009d) that
the study submitted for review was conducted in substantial compliance
with subparts K and L of 40 CFR 26.

HSRB Detailed Recommendations and Rationale

	The documents provided by ICR (Gaynor 2009, Gaynor et al. 2009) state
that each study was conducted in compliance the requirements of the US
EPA Good Laboratory Practice (GLP) Regulations for Pesticide Programs
(40 CFR 160). Additional regulations – 40 CFR 26 subparts K and L; and
FIFRA § 12(a)(2)(P – are also applicable. The study was reviewed and
approved by a commercial human subjects review committee, Essex
Institutional Review Board, Inc. (EIRB, Inc.) of Lebanon, NJ. 

1. 	The Board concurred with the conclusions and factual observations of
the ethical strengths and weaknesses of the study, as detailed in the
EPA’s Ethics Review (Carley 2009d). The completed study met all
applicable ethical requirements for research involving human
participants, in accordance with the following criteria as developed by
the Board:

a.	Acceptable risk-benefit ratio. The risks to study participants were
minimized appropriately and were justified by the potential societal
benefits, particularly data on the efficacy of these new formations as
personal insect repellents.

Minor and pregnant or lactating women were excluded from participation,
with pregnancy either confirmed by over-the-counter pregnancy testing on
the day of study or by opt-out. The potential stigma resulting from
study exclusion due to pregnancy was also appropriately minimized.

Based on toxicological data currently available for picaridin, coupled
with appropriate exclusion criteria, study participants were unlikely to
be at risk of adverse side effects with exposure.

Clear stopping rules and medical management procedures were in place,
with no adverse events related to product exposure reported.

The study uses first bite as an endpoint. Stable fly bites, however,
usually cause only minor symptoms and are readily treated with
over-the-counter antipruritic lotions.

 

The study was conducted with laboratory-raised flies free of known
pathogens. This latter point, in particular, resulted in the one notable
change to the protocol. At its initial review, the HSRB recommended that
the stable flies be raised on 10% sucrose rather than bovine blood
meals, thus minimizing the risk of potential zoonoses (EPA HSRB 2008).
As a result, the first planned test of picaridin as a repellent for
stable flies failed. Specifically, the trial had to be aborted due to
insufficient landing pressure. Upon consulting with an entomologist, ICR
researchers concluded that the stable flies “[overfed] on the 10%
sucrose solution, which then interfered with their normal inclination to
land and take a blood meal” (Gaynor et al. 2009). This was addressed
by: 1) changing the feeding regimen to dry sugar cubes; 2) increasing
the numbers of stable flies used per cage; and 3) increasing the length
of participant exposure to stable flies to determine attractiveness.
These changes were submitted to EIRB, Inc. as protocol amendments and
approved prior to implementation. This protocol change was unlikely to
have increased the risk of study participants or compromised the
informed consent process.

b.	Voluntary and informed consent of all participants

The study protocol included several mechanisms designed to minimized
coercive recruitment and enrollment.

Monetary compensation was not so high as to unduly influence
participants.

c.	Equitable study participant selection and recruitment

In response to HSRB concerns, ICR modified their recruitment strategy to
identify study participants more representative of the racial and ethnic
distribution of likely repellent users.

2.	The Board also recommended that, for future intentional dosing
studies, the sponsor work with the IRB of record to address some of the
gaps of submitted information noted in the EPA’s Ethics Review (Carley
2009d). 

a.	Several Board members raised concerns about the quality of IRB review
and the qualifications of IRB members to review insect repellent
protocols, given the failure of EIRB, Inc. to provide the sponsor or the
Agency with a description of IRB member qualifications and detailed
meeting minutes that provide a description of IRB deliberations and
debate of intentional exposure protocols. It is unlikely that these
deficiencies placed study participants at risk or compromised the
informed consent process, but they do represent a deviation from the
expectations of 40 CFR 26.

b.	The sponsor and IRB of record should ensure that all telephone
scripts and other recruitment materials, and informed consent documents
be reviewed prior to study initiation to ensure that the information
contained in each is accurate.  For example, the telephone script
submitted to the IRB for review and approval failed to note two
significant changes to the study design: the change on the duration of
attractiveness testing; and the change to pregnancy screening protocol
that allowed women who are physically incapable of having children
(i.e., post-menopausal or surgically sterilized) to opt-out of
over-the-counter pregnancy testing. This deviation, however, was
unlikely to have compromised the informed consent process as potential
study participants were informed of these protocol changes later when
formally consented at the ICR facility.

Assessment of Proposed Carroll-Loye Biological Research Study LNX-002:
Efficacy Test of KBR 3023 (Picaridin; Icaridin) - Based Personal Insect
Repellents (20% Cream and 20% Spray) with Biting Flies Under Field
Conditions.

Overview of the Study

The protocol describes a study to test the efficacy of two formulations
(lotion and spray) of 20% picaridin in the field against at least one of
4 species of biting flies. Dosimetry data recently accumulated in a
previous study (LNX-001) would be used for dose selection. One habitat
is proposed. Ten test subjects and two untreated controls would be
tested in a suitable environment that had adequate biting pressure of
biting flies but relatively few mosquitoes. Repellent-treated skin would
be exposed for 5 minutes in each 30-minute interval until repellent
failure. The endpoint would be the “Lite with Intent to Bite”
(LIBe), and the criterion for data to calculate complete protection time
would be first confirmed LIBe.

Science

Charge to the Board

	If the proposed field repellency study protocol LNX-002 is revised as
suggested in EPA’s review and if the research is performed as
described: Is the research likely to generate scientifically reliable
data, useful for assessing the efficacy of the tested materials in
repelling biting flies in the field? 

Board Response to the Charge  

HSRB Recommendation 

The Board concurred with the Agency’s assessment (Carley and Sweeney
2009) that this protocol will provide scientifically valid results on
the efficacy of two picaridin formulations against biting flies, with
modification as noted below. Additional Board review of the protocol is
not required prior to study implementation.

HSRB Detailed Recommendations and Rationale

	The protocol submitted for review had many similarities to previously
reviewed CLBR protocols and completed studies involving mosquitoes. The
format of the protocol description was revised to provide greater
clarity. The study protocol and associated documents incorporated many
of the Board’s previous comments and recommendations. The endpoint was
LIBe, which the Board has previously expressed preference for because of
the lesser risk to study participants than bites.   

	Agency reviewers identified two concerns: 1) the standard of biting of
one LIBe in five minutes was not well justified and may be
insufficiently high to yield valid results and could lead to
inappropriately right censored data; and 2) a change of the
previously-used paradigm of one minute exposure of treated limbs to
insects out of each 15 minute period to five minutes in each 30 minute
period was not explained or justified (Carley and Sweeney 2009). The
Board concurred with both of these concerns, and recommended that they
be addressed in the revised protocol as possible.

	Additional Board recommendations concerned two issues: 1) the
particular species on which data would be accumulated; and 2) the
calculation of complete protection time.  

With respect to the species tested, although four types of biting flies
were proposed as possible insects to be monitored it was pointed out
that these four species display varied behaviors and aggressiveness.
When questioned, the Agency indicated that it already had some useful
data on some species of biting flies – such as stable flies –
accumulated in the laboratory. The Agency thus expressed interest in
obtaining data from other species that cannot be readily studied in
laboratory tests. The Board thus recommended that the study be conducted
only if black flies (preferably) and/or biting midges were present in
sufficient numbers at the field site. Accumulated data should be
acquired on one or both of these species, as well as any other species
of biting flies that may also be present.  If black flies or biting
midges are not available in sufficient numbers and with sufficient
biting pressure at the field site, other types of biting flies should
not be considered acceptable substitutes. 

	Echoing earlier concerns about the types of calculations and
statistical analyses that will be conducted on these insect repellency
data, the Board recommended that the protocol be amended to explain
better how mean complete protection time will be calculated accurately
using the appropriate types of statistical analyses. Mean protection
time versus the duration of the study should be clarified, particularly
as it affects the prevalence of censored data. The study’s duration
should be sufficiently long to ensure that the repellent will fail for a
substantial portion of study participants, thereby limiting the
occurrence of right-censored data. The protocol should also be revised
to clarify how the analysis will proceed in the presence of censored
data (using Maximum-likelihood or Kaplan-Meier methods).

	In the context of this and other insect repellency studies, the Agency
is again urged to update its guidance to sponsors so that they can
conduct tests and analyze the resultant data in a useful and accurate
manner.

Ethics

Charge to the Board

	If the proposed field repellency study protocol LNX-002 is revised as
suggested in EPA’s review and if the research is performed as
described: Is the research likely to meet the applicable requirements of
40 CFR part 26, subparts K and L?

Board response to the Charge

HSRB recommendation

	The Board concluded that the protocol submitted for review, if modified
in accordance with EPA (Carley and Sweeney 2009) and HSRB
recommendations, is likely to meet the applicable requirements of 40 CFR
26, subparts K and L.

HSRB Detailed Recommendations and Rationale

	The submitted documents assert that the study will be conducted in
accordance with the ethical and regulatory standards of 40 CFR 26,
Subparts K and L, as well as the requirements the US EPA’s GLP
Standards described at 40 CFR 160, and the California State EPA
Department of Pesticide Regulation study monitoring (California Code of
Regulations Title 3, Section 6710) (Carroll 2009). The requirements of
FIFRA §12(a)(2)(P) also apply. The protocol was reviewed and approved
by an independent human subjects review committee, Independent
Investigational Review Board, Inc. (IIRB, Inc.), of Plantation, FL prior
to submission.

1. 	The Board concurred with the conclusions and factual observations of
the ethical strengths and weaknesses of the study, as detailed in the
EPA’s Ethics Review (Carley and Sweeney 2009). The proposed study is
likely to meet the applicable ethical requirements for research
involving human participants, in accordance with the following criteria:

a.	Acceptable risk-benefit ratio. The risks as noted in the study
protocol are five-fold: 1) allergic reaction to test materials
themselves; 2) exposure to biting arthropods; and 3) possible exposure
to arthropod-borne diseases; 4) physical stress from the test
conditions; and 5) psychological stress and/or breach of confidentiality
for pregnancy test results. These risks are minimized appropriately and
are justified by the potential societal benefits, particularly data on
the efficacy of these new formations as personal insect repellents.

Based on toxicological data currently available for picaridin, coupled
with appropriate exclusion criteria, study participants are unlikely to
be at risk of adverse side effects with exposure.

The study is designed to minimize the likelihood of biting fly and
mosquito bites, through the use of: LIBes rather than actual confirmed
bites as a study endpoint; pre-bite removal and joint observation; clear
stopping rules; limited exposure periods. Study participants will be
trained in proper insect observation and handling techniques.

Biting fly and mosquito bites, should they occur, are usually mild and
easily treated with over-the-counter steroidal creams. The study will
also exclude participants who have a history of severe skin reactions to
such bites.

To minimize the risk that study participants will be exposed to
pathogens like West Nile Virus – not transmitted by the biting flies
in question but via other arthropods that may be present at the field
sites – the study will be conducted only in areas where known
vector-borne diseases have not been detected by county and state health
or vector/mosquito control agencies for at least two weeks. The study is
also planned for a location where mosquitoes are not abundant and at a
time of year in which most arthropod-borne pathogens are not usually
detected. Finally, mosquitoes that land with the intent to bite will be
collected and subjected to multiplex RT-PCR assays for several known
arthropod-borne pathogens—including West Nile Virus, Western Equine
Encephalitis Virus, and St. Louis Encephalitis Virus—with clear plans
to contact study participants and alert them if a transmissible pathogen
is detected.

The potential risks to participants from environmental stress are
minimized by the provision of a climate controlled rest area, food,
water and medical supplies, and by careful monitoring for signs of
dehydration, heat stress and hypothermia. Appropriate stopping rules and
medical management procedures are in place.

Minor and pregnant or lactating women are excluded from participation,
with pregnancy either confirmed by over-the-counter pregnancy testing on
the day of study or by opt-out. The potential stigma resulting from
study exclusion due to pregnancy is also appropriately minimized.

b.	Voluntary and informed consent of all participants

The study protocol includes several mechanisms designed to minimize
coercive recruitment and enrollment.

Monetary compensation is not so high as to unduly influence
participants.

c.	Equitable selection of study participants

The majority of research participants will be recruited from the
University of California at Davis student population. Study participants
are likely to represent the appropriate ethnic and racial diversity of
individuals in and around the University, but the use of this
convenience sample may limit the broad applicability of the study
results to the general population. The investigators in the protocol
have noted this fact.

2.	The Board recommended that the study protocol be modified to address
the few concerns noted in the EPA’s Ethics Review (Carley and Sweeney
2009). In addition, the Board recommended that the investigators clarify
of what “3rd party” medical coverage means, as listed in the current
informed consent document.

Assessment of Proposed AHETF Scenario and Protocol AHE-120:
Water-Soluble Packing Mixing and Loading.

Overview of the Study

	This proposal presents an agricultural handler exposure scenario
involving mixing/loading of pesticides enclosed in water-soluble packets
(WSP). The protocol calls for study participants to mix and load one of
two WSP-enclosed surrogate pesticides (acephate and carbaryl) into a
variety of tanks containing water in a variety of agricultural spraying
operations. A total of 25 participants (described in the protocol as
“Monitoring Units” [MUs]) will be observed; 5 volunteers each from
five different growing regions will be enrolled using a purposive
sampling method.

	Dermal exposure will be measured by a whole body dosimeter (WBD) worn
beneath the subject’s outer clothing. Hand wash and face/neck wipe
samples will also be collected prior to, during, and after completion of
pesticide loading and mixing procedures. Airborne concentrations of the
surrogate will be monitored in the participant’s breathing zone using
an OSHA Versatile Sampler (OVS) tube sample collector connected to a
personal sampling pump. Additional measures will also record
environmental conditions at the time of monitoring, and observers will
make field notes, photographs and videos of participant activity
throughout the monitoring event.

	The results of sample analysis under the mixing/loading of
water-soluble packets scenario, and will be posted to the AHED®
database, where they will be available to the EPA and other regulatory
agencies for statistical analysis. The proposed documentation will
report a confidence-interval-based approach to determine the relative
accuracy for the arithmetic mean and 95th percentile of unit exposures.
The Agency proposes to use these data to estimate daily dermal and
inhalation exposures of agricultural handlers who are mixing/loading
pesticides in water-soluble packets under a variety of mixing and
loading scenarios.

Science

Charge to the Board

	If the proposed mix/load WSP field study protocol AHE120 is revised as
suggested in EPA’s review and if the research is performed as
described: Is the research likely to generate scientifically reliable
data, useful for assessing the exposure of handlers who mix and load
soluble or wettable powder pesticides in water-soluble packaging? 

Board Response to the Charge

HSRB Recommendation 

Given the lack of existent reliable and sound data in this area, the
Board concurred with the Agency’s assessment (Evans and Sherman 2009)
that this protocol will generate data that are scientifically valid and
that may be useful for assessing the exposure of handlers who mix and
load soluble or wettable powder pesticides in water-soluble packaging.
The Board cautioned, however, that these data might not be useful for
creating distributions of worker exposure that are scientifically
accurate or that are precise. Only if worker exposure is found to be
proportional to the amount of active ingredient handled (AaiH) will the
study data likely be generalizable.

The Board also recommended a number of protocol modifications, as listed
below. Additional Board review of the protocol is not required prior to
study implementation.

HSRB Detailed Recommendations and Rationale

	The Board concluded that the proposed monitoring and quality assurance
and control methods appear adequate, particularly in the supplemental
SOPs provided by the AHETF in response to the Agency’s initial science
and ethics review (Collier 2009b; Evans and Sherman 2009).  The protocol
and supplemental SOPs adequately address a number of key scientific
issues, including: the scientific objective, the quantification of the
test materials, the data collection and compilation methods and summary
of test results, the justification for selection of the test substances,
and the QA/QC requirements. The Board also commended the AHETF and the
Agency for taking the time to plan, test, and revise different scenarios
and approaches, and for pilot testing some aspects of these and related
protocols. The protocol presented to the Board was well thought out and
written as a result.

	The Board did raise a number of concerns, however, about the perceived
inadequacies in the study design, including issues of sample size and
the use of inappropriate statistical analyses. The Board raised many of
these issues previously when it reviewed earlier AHETF protocols. Both
the AHETF and the Agency will need to acknowledge the limitations of the
study design that occur in the AHETF handling scenarios and either
change their goals accordingly, or add appropriate statistical methods
or data management approaches to extrapolate from the data obtained from
these limited scenarios to the wider regulatory purposes that these data
will be used for. Some Board members expressed the concern, for example,
once these data are inside the AHED® database, some users may overlook
the limitations of the original study design and use the data to
generate the typical statistical distributions in error.

	Illustrating this point, the Board raised concerns about the types of
statistical analyses proposed for the water-soluble packing scenario
presented here. The proposed study will rely on a purposive sampling
strategy, for example, but the researchers propose to treat the
monitoring data as if “it were collected as a two-stage random sample
from an infinite population” (Collier 2009a). The Board questioned the
validity of this approach, noting that the data will be collected from a
non-random non-population based sample. There is no statistical theory
that can be applied to non-random samples of this type. Thus, the
statistical analyses proposed, including mixed model approaches, are not
valid.

	The Board also raised concerns about the key objective of the study –
namely, to determine the relationship between measured worker exposure
and AaiH. In particular, the Board disagreed with the Agency’s
assessment that “past studies have shown that AaiH is strongly
associated with exposure and is a meta-factor associated with
differences in equipment and spraying practices” (Evans and Sherman
2009). To expect a linear relationship between AaiH and worker exposure
seems logical; one should expect that a consistently small fraction of
the amount of pesticide that a worker handles would be deposited onto
their skin. Data previously presented by the AHETF to the Agency’s
FIFRA Scientific Advisory Panel (SAP), however, did not demonstrate a
linear relationship between worker exposures of the amount of active
ingredient handled. There are a number of factors that may explain why
there is not a clear linear relationship between measured worker
exposure and AaiH, including ecological, engineering, and statistical
factors. As submitted, the AHETF protocol will not be able to
distinguish between these different factors nor allow researchers to
determine the true relationship between exposure and AaiH. For example,
there are a number of uncontrolled ecological variables that may
influence worker exposure, including: environmental conditions, the
types of equipment used, the types of crops treated, grower preferences,
etc. Indeed, some workers will likely experience mixing and loading
conditions that are atypical for normal use of the active ingredient
being monitored. Myriad sources of natural variation are likely to have
a marked impact on worker exposure. Given the relatively small sample
size of each monitoring cluster in this exposure scenario, these sources
of natural variation will likely introduce considerable estimation bias
into the final data. 

	Finally, current consensus is that estimates of the geometric mean, the
arithmetic mean, and the 95th percentile need to be accurate within
three-fold of the actual population value. The current protocol includes
no methods to validate the actual population data and determine whether
the resulting estimates fall within this necessary range.

Ethics

Charge to the Board

	If the proposed mix/load WSP field study protocol AHE120 is revised as
suggested in EPA’s review and if the research is performed as
described: Is the research likely to meet the applicable requirements of
40 CFR part 26, subparts K and L?

Board response to the Charge

HSRB recommendation

	The Board concluded that the protocol submitted for review, if modified
in accordance with EPA (Evans and Sherman 2009) and HSRB
recommendations, is likely to meet the applicable requirements of 40 CFR
26, subparts K and L.

HSRB Detailed Recommendations and Rationale

	The submitted documents assert that the study will be conducted in
accordance with the ethical and regulatory standards of 40 CFR 26,
Subparts K and L, as well as the requirements the US EPA’s GLP
Standards described at 40 CFR 160 (Collier 2009a). The requirements of
FIFRA §12(a)(2)(P) and, where applicable, the California State EPA
Department of Pesticide Regulation study monitoring (California Code of
Regulations Title 3, Section 6710) also apply. The protocol was reviewed
and approved by an independent human subjects review committee, IIRB,
Inc. of Plantation, FL prior to submission.

1. 	The Board concurred with the conclusions and factual observations of
the ethical strengths and weaknesses of the study, as detailed in the
EPA’s Ethics Review (Evans and Sherman 2009). The proposed study is
likely to meet the applicable ethical requirements for research
involving human participants, in accordance with the following criteria:

a.	Acceptable risk-benefit ratio. The risks as noted in the study
protocol are five-fold: 1) heat-related illness; 2) accidental exposure
to the surrogate chemicals; 3) injury associated with scripted field
activities; 4) allergic reaction to surfactants using for hand washing;
5) psychological stress and/or breach of confidentiality for pregnancy
test results. These risks are minimized appropriately and are justified
by the potential societal benefits, particularly data on occupational
exposure of agricultural workers to pesticides during mixing and loading
activities.

The greatest risk to participants is that of heat-related illness, given
that the participants will be required to wear two layers of clothing
during the scenario activities. This risk is lessened but not eliminated
by the application of appropriate stopping rules (including cessation of
all monitoring activities when the ambient heat-index exceeds 105(F) and
frequent monitoring of participants. Participants will be given frequent
breaks, access to ample amounts of water or sports drinks, and educated
about the dangers and symptoms of heat-related illness. Appropriate
medical management procedures are also in place.

The surrogate materials consist of two common pesticides, acephate and
carbaryl, both of which have been extensively tested. The participants
will only be exposed to concentrations of the surrogate compound at
accepted exposure thresholds. 

Participants will be selected from volunteers with experience handling
these or similar compounds in WSP mixing and loading scenarios. Thus,
all of the participants will have extensive experience in using these or
similar products, and thus unlikely to misuse them in a way that might
increase their likelihood of being accidentally exposed.

Participants will be reminded about safe handling practices and
procedures, wear appropriate PPE, and will be monitored for any
accidental or unintended product exposure.

Allergic reactions to the surfactants used in hand washing are usually
mild and easily treated with over-the-counter steroidal creams. The
study will exclude participants who have a history of severe skin
reactions to such detergents.

Minor and pregnant or lactating women are excluded from participation,
with pregnancy either confirmed by over-the-counter pregnancy testing on
the day of study or by opt-out. The potential stigma resulting from
study exclusion due to pregnancy is also appropriately minimized.

b.	Voluntary and informed consent of all participants

There is the possibility that the participants in this study might
represent particularly vulnerable populations, susceptible to coercion
and undue influence. The study protocol, however, includes several
mechanisms designed to minimize coercive recruitment and enrollment.

Monetary compensation is not so high as to unduly influence
participants.

Spanish translations of the informed consent documents, informational
packets, and recruitment flyers were provided. Researchers will be
working with local Spanish-speaking community members to ensure that the
appropriate regional dialect of Spanish is used.

c.	Equitable selection of study participants

The study is designed to recruit an appropriately diverse population of
participants who represent skilled agricultural workers in the 5 study
locations.

Community representatives and advocates are appropriately involved in
the recruitment and enrollment of study participants.

2.	The Board recommended that the study protocol be modified to address
the few concerns noted in the EPA’s Ethics Review (Evans and Sherman
2009). In addition, the Board also addressed three concerns of the
Agency and the sponsors (Collier 2009c) with respect to
representativeness, language, and release of individual exposure data.

The Board recommended that the AHETF implement the proposed protocol
changes designed to address issues of representativeness.

As noted above, the Board concluded that the proposed protocol changes
designed to address concerns of language in the informed consent and
related documents are likely to yield translations that are written in
the appropriate regional dialect of Spanish.

The Board commended the Task Force for wanting to release individual
exposure data to participants promptly but recommended that these data
only be released once the study is complete, except in those instances
where data collected from individuals suggest an unusually high level of
exposure and thus a clear need to mitigate exposure risks.

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Proposed Final Draft Dated August 18, 2009; Do Not Cite or Quote

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