Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
1
of
36
EPA­
HSRB­
06­
02
1
2
George
Gray,
Ph.
D.
3
Science
Advisor
4
Office
of
the
Science
Advisor
5
1200
Pennsylvania
Avenue,
NW
6
Washington,
DC
20460
7
8
Subject:
May
2­
3,
2006
EPA
Human
Studies
Review
Board
Meeting
Report
9
10
Dear
Dr.
Gray:
11
12
The
United
States
Environmental
Protection
Agency
(
EPA
or
Agency)
requested
the
13
Human
Studies
Review
Board
(
HSRB)
to
review
scientific
and
ethics
reviews
of
chromium,
14
carbofuran
and
methyl
isothiocyanate.
The
enclosed
HSRB
report
addresses
the
Board's
15
response
to
EPA
charge
questions
for
the
Board's
consideration
at
its
May
2­
3,
2006
meeting.
16
17
A
summary
of
the
Board's
conclusions
on
the
scientific
and
ethical
considerations
of
the
18
human
toxicity
studies
for
the
three
pesticides
are
provided
below.
19
20
Chromium
21
22
Scientific
Considerations
23
 
The
Board
concluded
that
the
1994
Nethercott
et
al.
dermal
sensitization
study
was
24
sufficiently
sound,
from
a
scientific
perspective,
to
be
used
to
estimate
a
safe
level
of
25
dermal
exposure
to
hexavalent
chromium.
26
27
 
The
study
was
properly
designed,
well­
conducted,
and
employed
appropriate
scientific
28
and
clinical
methods
to
determine
a
minimum
elicitation
threshold
for
dermal
29
sensitization
due
to
hexavalent
chromium.
The
MET10
reported
in
the
study
provided
a
30
reasonable
point
of
departure
for
risk
assessment.
31
32
Ethical
Considerations
33
 
The
HSRB
concluded
there
was
insufficient
information
to
determine
whether
the
study
34
failed
to
fully
meet
specific
ethical
standards
prevalent
at
the
time
the
research
was
35
conducted.
36
37
 
The
Board
concurred
with
the
assessment
of
the
Agency
that
there
was
no
clear
and
38
convincing
evidence
that
the
conduct
of
the
research
was
fundamentally
unethical
in
that
39
the
deficiencies
did
not
result
in
serious
harm,
nor
seriously
impair
the
informed
consent
40
of
the
research
subjects
and;
41
42
 
The
Board
determined
that
there
was
not
clear
and
convincing
evidence
that
the
conduct
43
of
the
study
was
significantly
deficient
relative
to
the
ethical
standards
prevailing
when
44
the
study
was
conducted.
45
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
2
of
36
Carbofuran
1
2
Scientific
Considerations
3
4
 
The
HSRB
concluded
that
there
were
numerous
technical
issues
regarding
the
conduct
of
5
the
oral
and
dermal
studies
with
carbofuran
and
that
overall,
the
weakness
of
the
studies
6
far
outweigh
the
strengths.
Accordingly,
the
HSRB
did
not
recommend
any
of
the
oral
or
7
dermal
studies
conducted
with
carbofuran
in
human
subjects
for
the
single
chemical
8
assessment
or
in
informing
the
interspecies
uncertainty
factor
for
the
cumulative
9
assessment.
10
11
Ethical
Considerations
12
 
For
the
oral
study,
there
was
no
evidence
that
the
study
failed
to
fully
meet
specific
13
ethical
standards
prevalent
at
the
time
the
research
was
conducted.
14
15
 
For
the
oral
human
toxicity
study,
there
was
no
clear
and
convincing
evidence
of
16
significant
deficiencies
in
the
ethical
procedures
that
could
have
resulted
in
serious
harm
17
(
based
on
the
knowledge
available
at
the
time
the
study
was
conducted)
nor
that
18
information
provided
to
participants
seriously
impaired
their
informed
consent.
19
20
 
For
the
oral
study
there
was
no
clear
and
convincing
evidence
that
the
research
was
21
fundamentally
unethical
(
e.
g.,
intended
to
seriously
harm
participants
or
that
informed
22
consent
was
not
obtained).
23
24
 
The
HSRB
found
deficiencies
in
both
dermal
human
toxicity
studies
relative
to
specific
25
ethical
standards
prevalent
at
the
time
the
study
was
conducted.
26
27
 
For
both
dermal
human
toxicity
studies,
there
was
clear
and
convincing
evidence
of
28
significant
deficiencies
in
the
ethical
procedures
for
minimizing
risk
that
could
have
29
resulted
in
serious
harm
(
based
on
the
knowledge
available
at
the
time
the
study
was
30
conducted).
The
first
dermal
toxicity
study
was
significantly
deficient
given
the
delay
in
31
the
administration
of
atropine
to
more
than
one
subject
experiencing
the
signs
and
32
symptoms
of
carbamate
toxicity.
The
second
dermal
toxicity
study
was
considered
33
significantly
deficient
in
that
the
lack
of
information
provided
about
the
results
from
the
34
initial
dermal
toxicity
study
seriously
impaired
their
informed
consent.
35
36
 
However,
for
both
dermal
human
toxicity
studies,
there
was
no
clear
and
convincing
37
evidence
that
the
research
was
fundamentally
unethical
(
e.
g.,
intended
to
seriously
harm
38
participants
or
that
informed
consent
was
not
obtained).
39
40
41
Methyl
Isothiocyanate
42
43
Scientific
Considerations
44
 
The
Board
concluded
that
air
concentrations
of
methyl
isothiocyanate
sufficient
to
45
produce
eye
irritation
would
lead
to
a
conservative
and
prudent
point
of
departure
for
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
3
of
36
inhalation
risk
(
i.
e.,
eyes
were
a
sensitive
endpoint
in
relation
to
the
respiratory
system).
1
The
Board
reached
it
decision
based
on
eye
irritation
LOAELs
are
often
lower
than
2
respiratory
irritation
LOAELs
for
irritant
gases.
While
the
use
of
eye
irritation
data
as
a
3
surrogate
for
respiratory
data
is
reasonable
in
this
situation,
one
must
be
cautious
as
only
4
appropriate
controlled
human
studies
of
the
respiratory
system
can
provide
a
final
and
5
definitive
respiratory
point
of
departure,
if
ever
determined.
6
7
Ethical
Considerations
8
 
The
HSRB
determined
there
were
minor
deficiencies
in
the
ethical
procedures
relative
to
9
those
prevalent
at
the
time,
however:
10
11
 
There
was
no
clear
and
convincing
evidence
that
the
conduct
of
the
research
was
12
fundamentally
unethical
(
e.
g.,
the
research
was
intended
to
seriously
harm
participants
or
13
failed
to
obtain
informed
consent)
and;
14
15
 
There
was
no
clear
and
convincing
evidence
that
the
conduct
of
the
study
was
16
significantly
deficient
relative
to
the
ethical
standards
prevailing
when
the
study
was
17
conducted.
18
19
The
Board
also
provided
commentary
of
its
scientific
criteria
for
review
of
human
dosing
20
studies.
The
Board's
criteria
encompassed
the
following:
(
1)
justification;
(
2)
dose
selection;
(
3)
21
endpoint
selection;
(
4)
participants;
(
5)
method;
and
(
6)
statistical
analyses.
In
addition,
the
22
Board
established
criteria
for
evaluating
the
utility
of
single
dose
level
studies.
23
24
In
conclusion,
the
EPA
HSRB
appreciated
the
opportunity
to
advise
the
Agency
on
the
25
scientific
and
ethical
aspects
of
human
subjects
research
and
looks
forward
to
future
26
opportunities
to
continue
advising
the
Agency
in
this
endeavor.
27
28
29
Sincerely,
30
31
32
33
Celia
Fisher,
Ph.
D.
Chair
34
EPA
Human
Studies
Review
Board
35
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
4
of
36
NOTICE
1
2
This
report
has
been
written
as
part
of
the
activities
of
the
EPA
Human
Studies
Review
3
Board,
a
Federal
advisory
committee
providing
advice,
information
and
recommendations
on
4
issues
related
to
scientific
and
ethical
aspects
of
human
subjects
research.
This
report
has
not
5
been
reviewed
for
approval
by
the
Agency
and,
hence,
the
contents
of
this
report
do
not
6
necessarily
represent
the
view
and
policies
of
the
Environmental
Protection
Agency,
nor
of
other
7
agencies
in
the
Executive
Branch
of
the
Federal
government,
nor
does
mention
of
trade
names
or
8
commercial
product
constitute
a
recommendation
for
use.
Further
information
about
the
EPA
9
Human
Studies
Review
Board
can
be
obtained
from
its
website
at
http://
www.
epa.
gov/
osa/
hsrb/.
10
Interested
persons
are
invited
to
contact
Paul
Lewis,
Designated
Federal
Officer,
via
e­
mail
at
11
lewis.
paul@
epa.
gov.
12
13
In
preparing
this
document,
the
Board
carefully
considered
all
information
provided
and
14
presented
by
the
Agency
presenters,
as
well
as
information
presented
by
public
commenters.
15
This
document
addresses
the
information
provided
and
presented
within
the
structure
of
the
16
charge
by
the
Agency.
17
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
5
of
36
United
States
Environmental
Protection
Agency
Human
Studies
Review
Board
1
2
Chair
3
4
Celia
B.
Fisher,
Ph.
D.
Marie
Ward
Doty
Professor
of
Psychology,
Director,
Center
for
Ethics
5
Education,
Fordham
University,
Department
of
Psychology,
Bronx,
NY
6
7
Vice
Chair
8
9
William
S.
Brimijoin,
Ph.
D.,
Chair
and
Professor,
Molecular
Pharmacology
and
Experimental
10
Therapeutics,
Mayo
Foundation,
Rochester,
MN
*
**
11
12
Members
13
14
David
C.
Bellinger,
Ph.
D.,
Professor
of
Neurology,
Harvard
Medical
School
15
Professor
in
the
Department
of
Environmental
Health,
Harvard
School
of
Public
Health
16
Children's
Hospital,
Boston,
MA
17
18
Alicia
Carriquiry,
Ph.
D.,
Professor,
Department
of
Statistics,
Iowa
State
University
19
Snedecor
Hall,
Ames,
IA
20
21
Gary
L.
Chadwick,
PharmD,
MPH,
CIP,
Associate
Provost,
Director,
Office
for
Human
Subjects
22
Protection,
University
of
Rochester,
Rochester,
NY
23
24
Janice
Chambers,
Ph.
D.,
D.
A.
B.
T.,
William
L.
Giles
Distinguished
Professor,
Director,
Center
25
for
Environmental
Health
Sciences,
College
of
Veterinary
Medicine,
Mississippi
State
26
University,
Wise
Center,
Mississippi
State,
MS
*
27
28
Richard
Fenske,
Ph.
D.,
MPH,
Professor,
Department
of
Environmental
and
Occupational
Health
29
Sciences,
University
of
Washington,
Seattle
WA
30
31
Susan
S.
Fish,
PharmD,
MPH,
Professor,
Biostatistics
&
Epidemiology,
Boston
University
32
School
of
Public
Health,
Co­
Director,
MA
in
Clinical
Investigation
33
Boston
University
School
of
Medicine,
Boston,
MA
34
35
Suzanne
C.
Fitzpatrick,
Ph.
D.,
DABT,
Senior
Science
Policy
Analyst,
Office
of
the
36
Commissioner,
Office
of
Science
and
Health
Coordination,
U.
S.
Food
and
Drug
Administration,
37
Rockville,
MD
38
39
Kannan
Krishnan,
Ph.
D.,
Professor,
Département
de
santé
environnementale
et
santé
au
travail,
40
Faculté
de
medicine,
Université
de
Montréal,
Montréal,
Canada
41
42
KyungMann
Kim,
Ph.
D.,
CCRP,
Professor
&
Associate
Chair,
Department
of
Biostatistics
&
43
Medical
Informatics,
School
of
Medicine
and
Public
Health,
University
of
Wisconsin­
Madison,
44
Madison,
WI
**
45
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
6
of
36
Michael
D.
Lebowitz,
Ph.
D.,
FCCP,
Professor
of
Public
Health
&
Medicine.
University
of
1
Arizona,
Tucson,
AZ
2
3
Lois
D.
Lehman­
Mckeeman,
Ph.
D.,
Distinguished
Research
Fellow,
Discovery
Toxicology,
4
Bristol­
Myers
Squibb
Company,
Princeton,
NJ
5
6
Jerry
A.
Menikoff,
M.
D.,
Associate
Professor
of
Law,
Ethics
&
Medicine,
Director
of
the
7
Institute
for
Bioethics,
Law
and
Public
Policy,
University
of
Kansas
Medical
Center,
8
Kansas
City,
KS
9
10
Robert
Nelson,
M.
D.,
Ph.
D.,
Associate
Professor
of
Anesthesiology
and
Critical
Care,
11
Department
of
Anesthesiology
and
Critical
Care,
University
of
Pennsylvania
School
of
12
Medicine,
The
Children's
Hospital
of
Philadelphia,
Philadelphia,
PA
19104
13
14
Sean
M.
Philpott,
Ph.
D.,
Research
Scientist,
David
Axelrod
Institute,
Wadsworth
Center
for
15
Laboratories
and
Research,
New
York
State
Department
of
Health,
Albany,
NY
16
17
Human
Studies
Review
Board
Staff
18
19
Paul
I.
Lewis,
Ph.
D.,
Designated
Federal
Officer,
United
States
Environmental
Protection
20
Agency,
Washington,
DC
21
22
*
Recused
from
carbofuran
discussion
and
deliberation
23
**
Not
in
attendance
at
May
2­
3,
2006
Public
Meeting
24
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
7
of
36
TABLE
OF
CONTENTS
1
2
INTRODUCTION......................................................................................................................
8
3
REVIEW
PROCESS...................................................................................................................
9
4
CHARGE
TO
THE
BOARD
AND
BOARD
RESPONSE.........................................................
10
5
1.
Chromium.........................................................................................................................
10
6
2.
Carbofuran
.......................................................................................................................
16
7
3.
Methyl
Isothiocyanate
.......................................................................................................
26
8
COMMENTARY
ON
SCIENTIFIC
STANDARDS
FOR
HUMAN
DOSING
STUDIES.........
33
9
REFERENCES.........................................................................................................................
35
10
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
8
of
36
INTRODUCTION
1
2
On
May
2­
3,
2006,
the
United
States
Environmental
Protection
Agency's
(
EPA
or
3
Agency)
Human
Studies
Review
Board
(
HSRB)
met
to
review
scientific
and
ethical
issues
4
concerning
human
toxicity
studies
involving
two
pesticide
active
ingredients,
carbofuran
and
5
methyl
isothiocyanate
(
MITC),
and
chromium,
a
constituent
of
wood
preservative
products
6
(
wood
preservatives
are
regulated
as
pesticides
under
the
Federal
Insecticide,
Fungicide,
and
7
Rodenticide
Act).
8
9
The
Pesticide
Registration
Improvement
Act
(
PRIA)
requires
that
EPA
complete
its
10
decision­
making
process
on
certain
types
of
applications
to
register
a
pesticide
product
within
11
specified
amounts
of
time
after
receiving
the
application
for
registration.
In
addition,
PRIA
12
established
deadlines
for
EPA
to
complete
"
reregistration"
of
pesticide
active
ingredients
that
are
13
contained
in
pesticide
products
initially
registered
before
1984.
Reregistration
involves
the
14
systematic
reexamination
of
older
pesticides,
applying
contemporary
scientific
and
regulatory
15
standards.
When
a
pesticide
active
ingredient
is
approved
for
use
on
food,
EPA
combines
16
reregistration
with
the
tolerance
reassessment
process
mandated
by
the
Food
Quality
Protection
17
Act
of
1996
(
FQPA).
18
19
Both
MITC
and
carbofuran
are
undergoing
reevaluation
in
the
reregistration
process.
20
EPA
is
considering
the
human
health
risks
of
chromium
both
in
its
reregistration
program
and
as
21
part
of
its
review
of
an
application
for
registration
pending
under
FIFRA
and
PRIA.
22
23
For
each
of
the
human
studies
under
consideration,
the
Agency
provided
the
Board
with
24
the
complete
study
report
and
any
supplements
available
to
the
Agency.
Each
of
these
studies
25
was
assigned
a
unique
identifier,
the
Master
Record
Identifier
or
MRID,
which
the
EPA,
Office
26
of
Pesticide
Programs
(
OPP)
uses
to
manage
documents
in
its
archive.
When
a
company
submits
27
multiple
documents
pertaining
to
a
single
study,
each
document
is
assigned
a
unique
MRID
as
it
28
is
received
and
catalogued.
Thus
a
study
with
several
supplements,
such
as
the
MITC
study
29
discussed
at
the
meeting,
may
be
associated
with
several
MRIDs.
30
31
For
each
study,
the
Agency
had
provided
a
review
of
the
ethical
conduct
of
the
study.
32
Each
ethics
review
identified
any
deficiencies
noted
in
the
conduct
of
the
specific
study
33
compared
to
both
current
ethical
standards
and
the
ethical
standards
prevailing
at
the
time
the
34
research
was
performed.
EPA
has
intentionally
deferred
making
a
final
determination
of
35
whether
an
individual
study
satisfies
the
ethical
standards
for
acceptability
in
40
CFR
sections
36
26.1704
 
26.1706,
pending
the
advice
of
the
Board.
37
38
For
most
studies,
the
Agency
develops
documents,
called
Data
Evaluation
Records
39
(
DERs),
containing
a
scientific
review
of
the
study;
the
Board
was
provided
with
one
or
more
40
DERs
for
carbofuran
and
MITC.
DERs
contain
summaries
of
the
study
design,
methods
and
41
results,
describe
potential
deficiencies,
and
provides
conclusions
about
the
usefulness
of
the
42
study
in
risk
assessment.
43
44
In
addition
to
the
DERs,
the
Agency
had
prepared
a
Weight
of
Evidence
(
WOE)
45
memorandum
for
carbofuran
and
MITC
discussing
the
differences
and
similarities
between
the
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
9
of
36
human
and
animal
responses
to
each
chemical
and
characterizing
the
usefulness
of
the
human
1
toxicity
studies
for
human
health
risk
assessment.
The
WOE
memos
expressed
the
Agency's
2
current
scientific
conclusions
on
which
the
Agency
was
soliciting
the
Board's
comments.
To
3
maintain
the
historical
record
of
review,
the
Agency
may,
in
some
cases,
include
a
DER
for
a
4
study
that
expressed
scientific
conclusions
differing
from
those
in
the
WOE
document.
5
6
For
chromium,
the
Agency
provided
a
set
of
documents
which
contained
similar
7
information
to
DERs
and
WOEs,
but
which
had
a
slightly
different
format
and
presentation,
due
8
to
the
procedural
history
of
the
EPA's
review
of
this
chemical.
As
noted
above,
chromium
is
a
9
constituent
in
wood
preservative
products.
The
Agency
has
concern
about
the
potential
for
10
chromium
to
elicit
an
allergic
response
in
sensitized
individuals
who
come
in
contact
with
11
residues
remaining
in
products
made
from
wood
that
has
been
treated
with
chromium­
containing
12
wood
preservatives.
To
assess
the
risk
of
potential
dermal
exposure,
the
Agency
reviewed,
13
among
other
information,
a
study
involving
intentional
exposure
of
sensitized
subjects
to
14
different
levels
of
chromium,
(
Nethercott
et
al.
1994).
This
assessment
was
one
of
the
first
15
assessments
of
this
kind
performed
by
the
Agency,
and
it
raised
significant
scientific
issues.
16
Accordingly,
the
Agency
prepared
a
background
document
for
its
independent,
peer
review
17
advisory
committee,
the
FIFRA
Scientific
Advisory
Panel
(
SAP).
The
SAP
is
a
federally
18
chartered
advisory
committee
of
scientific
experts
who
provide
advice
to
the
Agency
on
19
pesticides
and
pesticide­
related
issues
as
to
their
impact
on
human
health
and
the
environment
of
20
regulatory
actions.
The
Agency
provided
a
copy
of
the
materials
given
to
the
SAP
for
its
review,
21
as
well
as
a
copy
of
the
SAP's
final
report.
After
receiving
the
SAP's
recommendations,
the
22
Agency
sought
review
and
comment
from
other
Agency
scientists
through
the
steering
23
committee
of
the
Agency's
internal
Science
Policy
Council
(
SPC)
to
ensure
consistency
across
24
programs
in
the
approach
to
regulating
substances
that
are
skin
sensitizers.
Using
the
advice
of
25
the
SAP
and
the
steering
committee
of
the
SPC,
the
Agency
developed
a
memorandum
26
describing
how
it
intended
to
use
the
results
of
the
Nethercott
study
to
derive
a
sensitization
27
Reference
Dose.
28
29
The
HSRB
has
reviewed
studies
on
which
the
Agency
proposes
to
rely
in
actions
under
30
the
pesticide
laws
and
studies
that
the
Agency
has
decided
not
to
use
in
its
risk
assessments,
31
either
for
scientific
reasons
or
because
they
do
not
meet
the
standards
in
EPA's
final
human
32
studies
rule,
40
CFR
Part
26.
The
Agency
asked
the
HSRB
to
advise
the
Agency
on
a
range
of
33
scientific
and
ethics
issues
and
on
how
the
studies
should
be
assessed
against
the
provisions
in
40
34
CFR
sections
26.1701
 
26.1704
of
EPA's
final
human
studies
rule.
This
report
transmits
the
35
HSRB's
comments
and
recommendations
from
its
May
2­
3,
2006
meeting.
36
REVIEW
PROCESS
37
38
On
May
2­
3,
2006
the
Board
had
a
public
face­
to­
face
meeting
in
Arlington,
Virginia.
39
Advance
notice
of
the
meeting
was
published
in
the
Federal
Register
"
Human
Studies
Review
40
Board:
Notice
of
Public
Meeting
(
71
Federal
Register
19725).
At
the
public
meeting,
following
41
welcoming
remarks
from
Agency
officials,
Celia
B.
Fisher,
HRSB
Chair,
proposed
a
set
of
42
scientific
and
ethics
criteria
consistent
with
the
language
of
71
Federal
Register
6137
to
guide
43
Board
evaluation
of
each
protocol.
The
Chair's
scientific
criteria
asked
the
Board
to
consider
the
44
following
two
questions:
(
1)
did
the
research
design
and
implementation
meet
scientific
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
10
of
36
standards
and
(
2)
Did
the
data
generated
by
the
study
have
implications
for
the
Agency's
Weight
1
of
the
Evidence
(
WOE)
review
and
when
applicable
aspects
of
the
risk
assessment?
The
Chair's
2
ethics
criteria
asked
the
Board
to
consider
three
questions:
(
1)
did
the
study
fail
to
fully
meet
3
specific
ethical
standards
prevalent
at
the
time
the
research
was
conducted;
(
2)
was
the
conduct
4
of
the
study
fundamentally
unethical
(
i.
e.,
specifically
was
there
clear
and
convincing
evidence
5
that
the
research
was
intended
to
seriously
harm
participants
or
failed
to
obtain
informed
6
consent);
and
(
3)
was
the
conduct
of
the
study
significantly
deficient
relative
to
the
ethical
7
standards
prevailing
at
the
time
(
i.
e.,
was
there
clear
and
convincing
evidence
that
identified
8
deficiencies
identified
could
have
resulted
in
serious
harm
based
on
knowledge
available
at
the
9
time
the
study
was
conducted
or
the
information
provided
to
participants
could
seriously
impair
10
informed
consent).
The
Board
then
heard
presentations
from
the
Agency
on
the
following
11
topics:
science
and
ethics
of
chromium
human
studies,
science
and
ethics
of
carbofuran
human
12
studies
and
science
and
ethics
of
methyl
isothiocyanate
human
studies.
The
Board
heard
oral
13
public
comments
from
the
following
individuals:
14
15
Chromium
16
Jennifer
Sass,
Ph.
D.
representing
the
Natural
Resources
Defense
Council
17
18
Carbofuran
19
Donald
Carson,
Ph.
D.
and
Ms.
Jane
McCarty
on
behalf
of
FMC
Corporation
20
Jennifer
Sass,
Ph.
D.
representing
the
Natural
Resources
Defense
Council
21
22
In
addition,
the
Board
received
written
public
comments
from
CRLA
Foundation,
FMC
23
Corporation,
and
the
Natural
Resources
Defense
Council.
Following
Agency
presentations
and
24
public
comments,
the
Board
deliberated
on
the
charge
questions.
For
their
deliberations,
the
25
Board
considered
the
materials
presented
at
the
meeting,
written
public
comments
and
Agency
26
background
documents
on
each
individual
pesticide
(
i.
e.,
pesticide
human
study,
Agency
data
27
evaluation
record
(
DER)
of
the
pesticide
human
study,
weight
of
evidence
review,
risk
28
assessment
and
ethics
review).
29
CHARGE
TO
THE
BOARD
AND
BOARD
RESPONSE
30
31
1.
Chromium
32
33
Charge
to
the
Board
34
35
Hexavalent
chromium
is
a
component
of
a
pesticide
product
intended
to
be
used
as
a
36
wood
preservative.
Members
of
the
general
public
may
experience
dermal
exposure
to
residues
37
of
hexavalent
chromium
remaining
on
wood
treated
with
a
wood
preservative.
Because
38
chromium
has
caused
allergic
contact
dermatitis
(
ACD)
in
occupational
settings,
39
EPA
has
determined
that
it
should
assess
the
potential
for
ACD
in
the
general
public
resulting
40
from
the
use
of
wood
preservatives
containing
chromium.
41
42
In
a
meeting
of
the
FIFRA
Scientific
Advisory
Panel
(
SAP)
in
May
2004,
EPA
obtained
43
independent
peer
review
of
scientific
issues
related
to
the
assessment
of
the
potential
dermal
risk
44
resulting
from
exposure
to
chromium.
See
www.
epa.
gov/
scipoly/
sap/
2004/
final.
doc
The
Agency
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
11
of
36
had
carefully
considered
the
report
of
the
SAP,
as
well
as
the
advice
of
EPA
scientists
through
1
the
steering
committee
of
the
Agency's
Science
Policy
Council.
Taking
all
of
this
into
account,
2
EPA
had
derived
a
"
sensitization
reference
dose"
(
RfD)
based
on
the
10%
Minimum
Elicitation
3
Threshold
(
MET
10)
and
use
of
a
10­
fold
uncertainty
factor
for
potential
variability
within
the
4
human
population
and
other
uncertainties.
See
ADTC
Memorandum,
"
Hexavalent
Chromium
­
5
Finalization
of
Issues
related
to
Quantitation
of
Dermal
Risk
from
exposure
to
treated
wood
6
containing
hexavalent
chromium,"
August
31,
2004.
7
8
Scientific
considerations
9
10
EPA
had
identified
a
study
performed
with
subjects
who
had
documented
sensitivity
to
11
chromium
(
Nethercott,
et
al.,
1994).
The
study
was
conducted
to
identify
a
level
of
exposure
to
12
chromium
below
which
dermal
exposure
did
not
appear
to
elicit
an
ACD
response.
Regarding
13
the
Nethercott
human
study,
the
Agency
had
concluded
that
the
study
contains
information
14
sufficient
for
assessing
human
risk
resulting
from
potential
dermal
exposure.
15
16
Please
comment
on
whether
the
Nethercott
study
was
sufficiently
sound,
from
a
scientific
17
perspective,
to
be
used
to
estimate
a
safe
level
of
dermal
exposure
to
hexavalent
chromium.
18
19
Board
Response
to
the
Charge
20
21
Introduction
22
23
Hexavalent
chromium
(
CrVI)
is
known
to
cause
allergic
contact
dermatitis
(
ACD).
CrVI
24
is
a
component
of
a
pesticide
product
used
as
a
wood
preservative,
and
members
of
the
general
25
public
may
be
exposed
through
contact
with
treated
wood.
ACD
is
a
delayed,
immunologically
26
mediated,
inflammatory
skin
disease
consisting
of
various
degrees
of
erythema,
edema,
and
27
vesiculation.
ACD
is
typically
characterized
by
two
phases,
termed
induction
and
elicitation.
28
Induction
occurs
when
there
was
an
exposure
of
sufficient
magnitude
and/
or
duration
to
activate
29
specific
immune
mechanisms
resulting
in
the
acquisition
of
sensitization,
while
elicitation
occurs
30
from
a
subsequent
exposure
to
the
same
chemical
allergen.
In
general,
the
amount
of
allergen
31
exposure
needed
to
produce
induction
is
greater
than
that
needed
to
produce
elicitation
in
32
previously
sensitized
individuals.
Thus,
the
study
of
elicitation
can
provide
an
appropriate
33
critical
endpoint
for
risk
assessments.
One
approach
to
estimate
an
acceptable
area
dose
for
34
protection
against
elicitation
is
the
determination
of
a
minimum
elicitation
threshold,
or
MET.
35
The
concept
behind
the
MET
is
that
there
was
an
elicitation
threshold
below
which
no
36
sensitization
reaction
is
expected.
37
38
The
EPA
FIFRA
Scientific
Advisory
Panel
met
in
May
2004
to
review
human
and
39
animal
studies
related
to
CrVI
(
SAP,
2004).
In
August,
2004
the
Agency's
Antimicrobials
40
Division
Toxicity
Endpoint
Selection
Committee
issued
a
memorandum
that
summarized
its
41
assessment
of
dermal
risk
from
CrVI
(
ADTC,
2004).
The
Agency
identified
a
study
performed
42
with
human
subjects
who
had
documented
sensitivity
to
chromium
(
Nethercott
et
al.,
1994).
The
43
study
was
conducted
to
identify
a
level
of
exposure
to
chromium
below
which
dermal
exposure
44
did
not
appear
to
elicit
an
ACD
response.
Regarding
the
Nethercott
et
al.
study,
the
Agency
had
45
concluded
that
the
study
contained
information
sufficient
for
assessing
human
risk
resulting
from
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
12
of
36
potential
dermal
exposure.
The
Agency
had
asked
the
HSRB
to
comment
on
whether
this
study
1
was
sufficiently
sound,
from
a
scientific
perspective,
to
be
used
to
estimate
a
safe
level
of
dermal
2
exposure
to
hexavalent
chromium.
3
4
Critique
of
the
1994
Nethercott
et
al.
Study
5
6
The
purpose
of
the
study
was
to
determine
the
MET
as
mass
of
allergen
per
skin
surface
7
area
for
CrVI
by
a
patch
testing
technique.
The
study
also
included
response
to
CRIII,
but
these
8
data
were
not
discussed
here.
Five
concentration
levels
of
CrVI
(
4.4,
0.88,
0.18,
0.088,
0.018
9
µ
g/
cm2)
was
used
in
the
patch
test,
and
"
TRUE­
Test"
patches
were
manufactured
specifically
for
10
use
in
the
study
to
reduce
the
variability
inherent
in
earlier
patch
preparation
methods.
The
11
highest
concentration
(
4.4
µ
g/
cm2)
were
used
as
a
screening
concentration
to
identify
those
who
12
were
sensitized
to
CrVI.
This
first
round
of
testing
involved
102
volunteers
(
78
men
and
24
13
women)
previously
shown
to
be
sensitive
to
developing
allergic
contact
dermatitis
(
ACD)
in
14
response
to
an
allergen.
CrVI
elicited
ACD
in
54
(
39
men
and
15
women)
of
these
102
subjects.
15
Two
lower
concentrations
(
0.018
and
0.088
µ
g/
cm2)
were
tested
in
these
54
volunteers
in
round
16
two.
Those
who
had
no
ACD
response
during
round
two
were
tested
with
the
next
two
higher
17
concentrations
(
0.18
and
0.88
µ
g/
cm2)
in
round
three.
These
concentrations
were
chosen
to
18
provide
a
maximal
ACD
response.
The
study
was
double
blind
as
to
concentration,
and
each
19
concentration
was
matched
with
a
control
(
placebo)
concentration
within
each
volunteer.
Patch
20
concentrations
were
validated
analytically
and
found
to
be
within
Contract
Laboratory
Procedure
21
criteria
for
acceptability.
The
serial
escalation
of
patch
concentration
level
permitted
the
authors
22
to
determine
a
dose­
response
relationship
and
to
calculate
MET
values.
The
authors
calculated
a
23
10%
minimum
elicitation
threshold
(
MET10)
of
0.089
µ
g/
cm2.
24
25
This
study
had
a
number
of
strengths.
It
involved
both
sexes,
the
study
concentrations
26
were
selected
carefully
based
on
previous
studies,
and
the
investigators
determined
a
priori
what
27
sample
size
and
dosing
group
size
were
needed
to
establish
statistical
accuracy
for
the
MET10.
28
Many
elements
of
the
experimental
protocol
(
e.
g.,
employment
of
the
control
patch,
serial
29
increase
of
the
concentration
until
manifestation
of
ACD,
double
blinding
of
patch
concentration
30
levels)
were
thoughtfully
developed.
The
study
was
designed
in
accordance
with
current
31
scientific
standards
to
address
a
clearly
defined
research
question,
included
representative
study
32
populations
for
the
endpoint
in
question,
and
met
requirements
for
adequate
statistical
power.
It
33
appears
to
have
been
conducted
in
accordance
with
recognized
good
clinical
practices,
including
34
appropriate
monitoring
for
safety.
Finally,
the
study
authors
reported
the
design,
conduct
and
35
analysis
very
comprehensively.
36
37
There
are
several
questions
that
can
be
raised
regarding
the
scientific
validity
of
this
38
study.
First,
the
authors
developed
a
cumulative
response
curve
that
included
subjects
who
did
39
not
respond
to
any
of
the
doses
presented
in
rounds
two
and
three.
These
subjects
were
assigned
40
a
minimum
elicitation
threshold
value
of
4.4
µ
g/
cm2,
although
none
were
tested
at
doses
between
41
0.88
and
4.4
µ
g/
cm2.
The
assignment
of
this
MET
value
appeared
arbitrary,
and
potentially
42
distorts
the
shape
of
the
cumulative
response
curve.
However,
this
use
of
the
high
MET
value
43
does
not
affect
the
calculation
of
the
MET10,
and
so
it
was
of
no
consequence
to
the
study's
44
primary
conclusion.
Second,
a
recent
study
by
Hansen
et
al.
(
2003)
reported
a
MET10
of
0.03
45
ug/
cm2
for
18
subjects,
a
value
substantially
lower
than
that
reported
by
Nethercott
et
al.
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
13
of
36
However,
these
two
studies
differed
with
respect
to
the
reading
scale
employed.
The
reading
of
1
the
tests
in
the
Nethercott
et
al.
study
followed
rules
adopted
for
the
diagnostic
patch
test;
that
is
2
to
say,
the
definition
of
a
positive
reaction
was
the
appearance
of
erythema
infiltration
and
3
papules.
This
approach
was
consistent
with
current
international
clinical
standards.
For
the
4
Hansen
et
al.
study,
the
investigators
used
the
same
reading
scale
for
diagnostic
patch
testing,
but
5
for
definition
of
thresholds
they
used
any
degree
of
reaction,
including
erythematous
and
6
follicular
reactions.
The
logic
for
this
approach
was
that
at
very
low
concentrations
irritation
was
7
not
an
issue,
so
that
the
question
of
threshold
was
not
a
diagnostic
decision.
This
more
sensitive
8
reading
approach,
which
at
present
was
considered
experimental,
accounts
for
the
difference
in
9
MET10
values
reported
in
these
two
studies.
Third,
Nethercott
et
al.
(
1994)
used
patches
that
10
covered
a
very
small
area
of
skin
(
0.81
cm2).
Workers,
and
presumably
members
of
the
public,
11
would
typically
be
exposed
over
a
much
larger
skin
surface
area
than
that
used
in
this
study.
In
12
their
article
Nethercott
et
al.
discussed
the
potential
importance
of
patch
surface
area,
and
13
described
an
additional
experiment
with
four
of
the
study
subjects
who
had
exhibited
MET
14
values
at
0.88
µ
g/
cm2.
In
this
experiment
five
patches
were
used
for
each
subject,
and
the
15
exposure
level
of
CrVI
was
reduced
to
0.18
µ
g/
cm2
for
each
patch.
The
data
that
resulted
from
16
this
experiment
were
not
presented,
but
the
authors
stated
that
"
sub­
MET
concentrations
of
CrVI
17
applied
over
a
larger
skin
surface
area
did
not
elicit
the
positive
responses
seen
when
the
MET
18
concentration
was
applied
in
the
standard
patch."
Current
evidence
indicated
that
the
dose
per
19
unit
area
was
the
most
important
parameter
for
studies
of
this
kind.
But
there
was
no
doubt
that
if
20
an
extended
area
was
exposed,
such
as
the
full
arm,
there
may
be
an
effect
from
absorption
of
an
21
ACD­
producing
compound.
This
type
of
exposure
could
lead
to
a
systemic
contact
dermatitis
22
reaction
with
spreading
of
the
dermatitis
to
a
vesicular
palmar
eczema,
and
eventually
flexural
23
eczema.
Such
systemic
spreads
are
well
known
in
relation
to
major
contact
dermatitis
reactions,
24
as
occur
in
occupational
exposures.
The
Nethercott
et
al.
study,
where
relatively
small
skin
25
surface
areas
were
exposed,
does
not
exclude
that
such
effects
could
happen
if
larger
areas
were
26
exposed.
27
28
HSRB
Consensus
and
Rationale
29
30
The
Board
concluded
that
the
1994
Nethercott
et
al.
dermal
sensitization
study
was
31
sufficiently
sound,
from
a
scientific
perspective,
to
be
used
to
estimate
a
safe
level
of
dermal
32
exposure
to
hexavalent
chromium.
33
34
The
1994
Nethercott
et
al.
study
was
properly
designed,
well­
conducted,
and
employed
35
appropriate
scientific
and
clinical
methods
to
determine
a
minimum
elicitation
threshold
for
36
dermal
sensitization
due
to
hexavalent
chromium.
The
MET10
reported
in
the
study
provided
a
37
reasonable
point
of
departure
for
risk
assessment.
38
39
Charge
to
the
Board
40
41
Ethical
considerations
42
43
The
Agency
requested
that
the
Board
provide
comment
on
the
following:
44
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
14
of
36
a.
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
Nethercott
study
was
1
fundamentally
unethical?
2
3
b.
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
study
was
significantly
4
deficient
relative
to
the
ethical
standards
prevailing
at
the
time
the
research
was
conducted?
5
6
Board
Response
to
the
Charge
7
8
Brief
Overview
of
the
Study
9
10
A
previously­
published
study
involving
dermal
exposure
of
102
healthy
volunteers
to
11
increasing
doses
of
CrVI
was
evaluated,
hereinafter
referred
to
as
Nethercott
et
al.
1994.
he
study
12
sponsor
was
unknown,
but
is
likely
to
be
either
the
Chem
Risk
Division
of
McLaren/
Hart
13
Environmental
Engineering,
Alameda
CA,
or
a
client
of
McLaren/
Hart.
The
study
was
14
conducted
in
1992
at
five
U.
S.
and
one
Canadian
academic
institution:
the
Cleveland
Clinic
15
Foundation
(
Cleveland,
OH),
Johns
Hopkins
University
(
Baltimore,
MD),
Pennsylvania
State
16
University
(
Hershey,
PA),
Stanford
University
(
Palo
Alto,
CA),
the
University
of
British
17
Columbia
(
Vancouver,
BC),
and
the
University
of
Louisville
(
Louisville,
KY).
The
study
was
18
conducted
after
the
promulgation
of
federal
protections
for
the
protection
of
human
participants
19
in
research
(
i.
e.
Common
Rule)
(
§
45CFR46;
adopted
by
the
EPA
in
1991
and
published
at
20
§
40CFR26),
so
the
regulatory
requirements
of
the
Common
Rule
were
applicable.
Furthermore,
21
all
five
US
academic
institutions
participating
had
a
valid
Multiple
Project
Assurance
of
22
Compliance
with
U.
S.
Department
of
Health
and
Human
Services
(
DHHS)
Regulations
for
23
Protection
of
Human
Research
Subjects
at
the
time
the
study
was
performed.
The
University
of
24
British
Columbia,
in
contrast,
held
a
Cooperative
Project
Assurance
at
that
time,
allowing
its
25
participation
in
DHHS­
recognized
research
programs
and
documenting
the
University
of
British
26
Columbia's
commitment
to
the
protection
of
human
research
subjects
in
accordance
with
27
§
45CFR46.
28
29
Critique
of
Study
30
31
The
Board
concurred
with
the
factual
observations
of
the
strengths
and
weaknesses
of
the
32
study,
as
detailed
in
USEPA
(
2006a).
However,
further
comments
were
raised
regarding:
1)
33
whether
the
documentation
and
process
of
study
subject
enrollment
was
sufficient
to
meet
34
prevailing
standards
of
voluntary
informed
consent
and
2)
whether
the
repeat
high­
dose
oral­
35
exposure
protocols
used
were
designed
to
minimize
risks
to
study
participants.
36
37
1)
Voluntary
Informed
Consent
38
39
The
Common
Rule
provides
a
comprehensive
framework
for
initial
and
continuing
40
review
of
research
involving
human
subjects.
In
order
to
ensure
that
a
study
like
Nethercott
et
al.
41
was
performed
ethically,
the
Common
Rule
requires
that:
1)
people
who
participate
as
subjects
42
in
research
are
selected
equitably
and
give
informed
and
voluntary
written
consent;
and
2)
43
research
involving
human
subjects
be
reviewed
and
approved
by
an
independent
oversight
group
44
such
as
an
Institutional
Review
Board
(
IRB).
As
published,
however,
the
Nethercott
et
al.
study
45
did
not
contain
sufficient
information
for
the
Board
to
adequately
determine
whether
or
not
the
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
15
of
36
informed
consent
process
used
to
enrolled
study
participants
met
the
standards
outlined
in
1
§
45CFR46.
All
that
is
known
about
the
informed
consent
process
is
that
"
all
volunteers
provided
2
their
doctors
with
written
consent
to
participate
in
the
study"
(
Nethercott
et
al.
1994).
3
4
Given
the
paucity
of
documentation,
the
Board
concluded
there
was
no
evidence
that
the
5
voluntary
informed
consent
process
used
failed
to
meet
the
regulatory
and
ethical
standards
6
applicable
to
research
conducted
in
the
United
States
and
Canada
in
1992.
All
six
academic
7
institutions
participating
in
this
study
had
an
assurance
of
compliance
with
DHHS
Regulations
8
for
Protection
of
Human
Research
Subjects
at
the
time,
requiring
independent
review
of
the
9
research
protocol
and
consent
documents
by
IRBs.
These
review
boards
were
expected
to
10
approve
a
study
involving
human
subjects
only
if:
1)
the
risks
to
subjects
were
minimized
by
11
using
procedures
which
were
consistent
with
sound
research
design
and
which
do
not
12
unnecessarily
expose
subjects
to
risk;
and
2)
the
risks
to
subjects
were
reasonable
in
relation
to
13
anticipated
benefits
to
subjects,
if
any,
and
the
importance
of
the
knowledge
that
may
reasonably
14
be
expected
to
result
(
see,
e.
g.,
§
45CFR46.111).
The
HSRB
believed
that
it
was
unlikely
that
all
15
six
of
these
IRBs
would
overlook
deficiencies
in
the
consent
process
that
would
seriously
impair
16
the
voluntary
informed
consent
of
the
research
subjects.
17
18
2)
Minimization
of
Risks
to
Study
Participants
19
20
The
Nethercott
et
al.
study
employed
a
three­
step
exposure
protocol.
Initially,
102
21
volunteers
were
screened
for
hexavalent
chromium
sensitivity
by
dermal
exposure
using
a
22
chromium
concentration
equivalent
to
the
standard
dose
used
in
patch
testing
for
skin
allergies
23
(
4.4
µ
g
Cr(
VI)/
cm2).
Pregnant
women,
individuals
receiving
immunosuppressive
or
steroid
24
medications,
and
patients
with
recent
or
concurrent
dermatological
conditions
were
excluded
25
from
study
participation.
54
chromium­
sensitive
subjects
were
identified
by
Nethercott
et
al.
26
These
chromium­
sensitive
subjects
then
participated
in
up
to
two
rounds
of
additional
testing.
In
27
the
first
round,
subjects
were
exposed
to
0.018
and
0.088
µ
g
CrVI/
cm2
using
a
skin
patch
28
approach.
Five
subjects
developed
allergic
contact
dermatitis
to
one
or
both
of
these
lower
doses;
29
these
subjects
were
excluded
from
further
testing.
Subjects
who
failed
to
respond
to
either
the
30
0.018
or
0.088
µ
g
dose,
however,
were
subsequently
exposed
to
ten­
fold
higher
doses
(
0.18
or
31
0.88
µ
g
Cr(
VI)/
cm2.
27
subjects
developed
allergic
contact
dermatitis
to
one
or
both
of
these
32
higher
doses.
33
34
In
sensitized
individuals,
chromium
exposure
elicits
an
allergic
contact
dermatitis
similar
35
to
a
poison
oak
or
poison
ivy
rash.
The
result
typically
is
an
itching,
red
rash
with
bumps
or
36
blisters;
these
transient
symptoms
usually
are
mild
and
can
be
treated
with
calamine
lotion
and
37
hydrocortisone
cream.
The
use
of
patch
testing,
even
when
it
knowingly
results
in
allergic
38
contact
dermatitis,
thus
meets
the
generally
accepted
definition
of
minimal
risk.
Furthermore,
Dr.
39
Torkil
Menne,
a
consultant
to
the
HSRB,
commented
that
most
studies
designed
to
determine
the
40
minimum
elicitation
threshold
to
a
dermal
sensitizing
agent
like
chromium
have
used
a
single­
41
step
protocol
in
which
study
subjects
were
exposed
to
the
entire
range
of
dermal
concentrations
42
in
a
single
round
of
testing.
The
study
exclusion
criteria
and
the
use
of
a
three­
step
exposure
43
protocol,
involving
initial
screening
of
subjects
for
chromium
sensitivity
followed
by
additional
44
rounds
of
testing,
using
doses
significantly
smaller
than
those
routinely
employed
for
allergy
45
testing
and
excluding
reactive
study
participants
from
further
exposure,
seems
designed
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
16
of
36
specifically
to
minimize
the
risk
of
serious
harm
to
research
participants.
Thus,
the
Board
1
believed
that
there
was
not
was
clear
and
convincing
evidence
that
these
studies
could
have
2
resulted
in
serious
harm
based
on
the
knowledge
available
to
the
investigators
at
the
time.
3
4
HSRB
Consensus
and
Rationale
5
6
The
Board
concurred
with
the
assessment
of
the
Agency
that
there
was
no
clear
and
7
convincing
evidence
that
the
conduct
of
the
research
was
fundamentally
unethical
in
that
the
8
deficiencies
did
not
result
in
serious
harm,
nor
seriously
impair
the
informed
consent
of
the
9
research
subjects.
10
11
The
Board
determined
that
there
was
no
clear
and
convincing
evidence
that
the
conduct
12
of
the
study
was
significantly
deficient
relative
to
the
ethical
standards
prevailing
when
the
study
13
was
conducted.
14
15
The
Board
based
these
two
determinations
on
its
conclusion
that
this
study
appeared
to
16
have
not
deviated
significantly
from
the
ethical
standards
prevailing
when
the
study
was
17
conducted.
However,
this
conclusion
was
based,
in
part,
on
a
process
that
was
hampered
by
a
18
lack
of
supporting
documentation
concerning
independent
ethical
review
by
the
study
19
investigators'
home
institutions.
The
Board
strongly
recommended
that
for
all
studies
submitted
20
to
the
HSRB,
the
Agency
make
a
good
faith
effort
to
obtain
such
documentation
in
the
future.
21
22
2.
Carbofuran
23
24
Charge
to
the
Board
25
26
Carbofuran
is
an
N­
methyl
carbamate
(
NMC)
pesticide
whose
primary
toxic
effect
is
27
neurotoxicity
caused
by
the
inhibition
of
the
enzyme,
acetylcholinesterase,
via
carbamylation
28
followed
by
rapid
recovery.
Carbofuran
can,
at
sufficiently
high
doses,
lead
to
a
variety
of
29
clinical
signs.
The
Agency
is
conducting
acute,
aggregate
(
single
chemical,
multi­
route)
and
30
worker
risk
assessments
of
carbofuran.
In
addition,
carbofuran
is
a
member
of
the
N­
methyl
31
carbamate
common
mechanism
group
and
is
thus
included
in
the
cumulative
(
multi­
chemical,
32
multi­
route)
risk
assessment
for
the
NMCs.
33
34
Scientific
considerations:
35
36
The
Agency's
WOE
document
and
DERs
for
carbofuran
described
the
study
design
and
37
results
of
a
carbofuran
human
oral
study
and
two
human
dermal
toxicity
studies.
The
WOE
38
document
also
discusses
the
Agency's
conclusions
that
these
studies
were
useful
in
establishing
39
points
of
departure,
both
oral
and
dermal,
for
the
single
chemical
assessment
and
in
informing
40
the
interspecies
uncertainty
factor
for
the
cumulative
assessment.
41
42
Please
comment
on
the
scientific
evidence
that
supports
these
conclusions.
43
44
Board
Response
to
the
Charge
45
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
17
of
36
Study
Overview
1
2
Three
separate
studies
(
one
oral,
two
dermal)
were
carried
out
with
carbofuran
in
human
3
subjects.
The
study
details
are
described
separately
below.
4
5
Overview
of
Oral
Study
6
7
The
oral
study
conducted
with
carbofuran
was
carried
out
in
nine
healthy
male
volunteers
8
using
an
ascending
dose
schedule
and
single
doses
of
0.05,
0.1
and
0.25
mg/
kg
(
1976).
The
goal
9
of
this
study
was
to
determine
the
threshold
for
toxicity
following
a
single
oral
dose.
Initially,
the
10
study
was
conducted
in
an
open
design
(
subject
and
investigator
knew
that
carbofuran
was
11
ingested)
until
a
dose
level
produced
symptoms
determined
to
be
intolerable
(
described
below).
12
Once
the
intolerable
dose
was
achieved
(
0.25
mg/
kg),
the
study
was
completed
in
a
randomized,
13
double
blind
manner.
Carbofuran
was
administered
as
a
single
dose
in
a
capsule
immediately
14
following
breakfast,
after
which
subjects
remained
under
observation
for
24
hours.
Blood
15
samples
were
collected
for
analysis
of
plasma
and
RBC
cholinesterase
activity
at
0.5,
1,
2,
3,
6
16
and
24
hours
after
dosing.
The
baseline
level
of
RBC
cholinesterase
activity
was
established
17
from
a
predose
sample
collected
immediately
prior
to
dosing.
For
each
subject,
additional
18
physiological
parameters
including
ECG,
blood
pressure,
pupil
size
and
accommodation
and
the
19
Fukuda
step
test
were
collected,
and
subjects
were
monitored
continuously
for
additional
20
symptoms
of
toxicity,
including
sweating,
salivation,
headaches
and
nausea
and
vomiting
21
throughout
the
24­
hour
post­
dosing
period.
A
complete
clinical
chemistry
profile
was
performed
22
predose
and
at
24
hours.
The
next
highest
dose
was
not
initiated
until
data
from
the
24­
hour
23
post­
treatment
period
were
evaluated.
Plasma
and
RBC
cholinesterase
levels
were
determined
24
using
a
modification
of
the
Ellman
colorimetric
method
with
propionylthiocholine
as
substrate.
25
Subjects
were
allowed
to
smoke
during
the
24­
hour
sample
collection
period.
26
27
After
administration
of
the
0.05
mg/
kg
dose
(
2
subjects),
no
symptoms
were
noted
and
28
RBC
cholinesterase
activity
was
decreased
by
11
or
22%
from
baseline
(
plasma
cholinesterase
29
was
decreased
by
32
and
36%,
respectively).
Accordingly,
the
dose
was
escalated
to
0.1
mg/
kg
30
(
2
subjects).
In
this
leg
of
the
study,
one
subject
exhibited
an
abnormal
vestibular
mechanism
31
prior
to
dosing
and
showed
further
deterioration
after
exposure
to
carbofuran.
This
subject
also
32
showed
changes
in
cardiovascular
parameters
including
sinus
bradycardia
and
sinus
arrhythmia.
33
Two
subjects
presented
with
mild
symptoms
including
headache
(
1
subject)
or
lightheadedness
34
(
the
other
subject).
RBC
cholinesterase
activity
decreased
33
and
31%,
respectively,
whereas
35
plasma
cholinesterase
activity
was
more
variable
(
decreased
56
and
35%,
respectively).
Based
36
on
these
results,
the
dose
was
escalated
to
0.25
mg/
kg
(
2
subjects)
where
marked
symptoms,
37
including
drowsiness,
nausea,
vomiting,
headache,
salivation,
and
sinus
bradycardia
were
noted.
38
Accordingly,
this
dose
level
was
considered
to
have
achieved
the
level
of
intolerable
symptoms,
39
and
an
additional
2
subjects
were
exposed
to
this
level
along
with
one
control
subject
in
a
double
40
blinded
manner.
At
this
dose
level,
RBC
cholinesterase
inhibition
ranged
from
46­
63%
and
41
plasma
cholinesterase
inhibition
ranged
from
33­
100%.
42
43
Overview
of
Dermal
Studies
44
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
18
of
36
The
dermal
studies
conducted
with
carbofuran
(
1977
and
1978)
involved
application
of
1
the
compound
to
the
backs
of
subjects
for
4
hours.
The
two
studies
were
similar
in
design,
but
2
differed
with
respect
to
the
commercial
formulations
tested
and
the
mass
applied
per
unit
area
of
3
skin.
4
5
The
1977
dermal
study
(
i.
e.,
first
dermal
study)
was
carried
out
as
a
single,
ascending
6
dose
study
and
was
designed
to
determine
the
threshold
for
toxicity
under
conditions
of
normal
7
and
elevated
temperatures.
Carbofuran
was
provided
in
labeled
capsules
containing
75.4%
8
carbamate
powder
or
placebo.
This
powder
was
applied
to
the
backs
of
each
subject
over
an
area
9
described
by
a
paper
template
and
was
then
mixed
with
either
water,
an
artificial
sweat
medium,
10
or
normal
saline
to
insure
adhesion.
Under
normal
temperature
conditions
(
approximately
70
°
F
11
and
35%
humidity),
the
doses
evaluated
were
2,
4,
8
and
32
mg/
kg
(
2
subjects
per
dose
level),
12
whereas
under
elevated
temperature
conditions
(
approximately
90
°
F
and
68­
89%
humidity),
the
13
doses
evaluated
were
0.5,
1
and
2
mg/
kg
(
2
subjects
per
dose
level).
A
control
group
(
2
subjects)
14
was
included
in
the
high
temperature
leg
of
this
study.
For
the
high
temperature
conditions,
15
subjects
were
also
made
to
exercise
by
riding
a
stationary
bicycle
(
5
minutes
of
exercise
16
followed
by
15
minutes
of
rest)
throughout
the
entire
4­
hour
exposure
period.
The
parameters
17
outlined
above
under
the
overview
of
the
oral
study
were
performed
on
all
subjects
in
this
study.
18
19
Under
normal
temperature
conditions,
no
symptoms
were
noted
at
any
dose
level,
and
20
changes
in
RBC
and
plasma
cholinesterase
were
variable.
RBC
cholinesterase
inhibition
did
not
21
exceed
24%
(
observed
at
32
mg/
kg).
Plasma
cholinesterase
activity
was
highly
variable,
with
a
22
maximal
inhibition
of
33%
noted
at
the
4
mg/
kg
dose,
whereas
only
0
or
2
%
inhibition
was
23
reported
in
the
2
subjects
dosed
with
32
mg/
kg.
24
25
Under
conditions
of
high
temperature
and
humidity,
symptoms
were
observed
in
the
two
26
subjects
dosed
at
2
mg
carbofuran/
kg.
One
subject
at
this
level
exhibited
severe
symptoms
27
(
including
hazy
vision,
vomiting,
defecation
with
muscle
cramps
and
chills)
and
required
28
atropine
(
at
3
separate
times)
to
ameliorate
symptoms.
Maximal
inhibition
of
RBC
29
cholinesterase
activity
at
this
dose
level
was
45
and
65%
in
the
2
subjects
(
4
hours),
whereas
30
plasma
cholinesterase
inhibition
was
maximal
at
24
hours
(
12
and
16
%,
respectively).
31
32
The
1978
dermal
study
(
i.
e.,
second
dermal
study)
was
carried
out
as
a
single,
ascending
33
dose
study
and
was
conducted
under
conditions
of
elevated
temperature
and
humidity
as
34
described
above.
The
carbofuran
used
in
this
study
was
a
formulation
containing
44%
active
35
ingredient
and
was
applied
at
a
concentration
of
approximately
0.5
mg/
cm2
using
a
50%
dilution
36
of
the
formulation.
The
doses
evaluated
were
0.5,
1,
2
and
4
mg/
kg
(
2
subjects
per
dose
level).
37
There
was
no
control
group.
The
same
parameters
outlined
above
under
the
overview
of
the
oral
38
study
were
performed
on
all
subjects
in
this
study.
39
40
One
subject
dosed
at
0.5
mg/
kg
reported
nausea
after
treatment
and
the
other
subject
41
noted
burning
at
the
application
site.
In
contrast,
neither
subject
dosed
with
1
or
2
mg/
kg
42
experienced
any
symptoms.
A
dose
of
4
mg/
kg
resulted
in
symptoms
of
nausea,
dizziness
and
43
weakness
in
both
subjects,
and
atropine
was
administered
to
these
subjects.
Inhibition
of
RBC
44
cholinesterase
activity
showed
some
evidence
of
dose­
dependence
but
was
variable,
ranging
45
from
22
and
7%
to
61
and
49%
in
the
2
subjects
treated
with
0.5
and
4
mg/
kg,
respectively.
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
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or
Quote
19
of
36
Plasma
cholinesterase
levels
were
highly
variable,
with
33
and
46%
inhibition
observed
at
0.5
1
mg/
kg
and
6
and
9%
at
4
mg/
kg,
respectively.
2
3
Critique
of
the
Oral
and
Dermal
Studies
Conducted
with
Carbofuran
4
5
In
the
three
studies
described
above,
the
major
strength
of
the
work
was
that
the
6
experimental
design
included
the
evaluation
of
at
least
three
dose
levels
from
which
dose
7
response
relationships
could
be
evaluated.
Furthermore,
the
study
outcomes
were
generally
8
consistent
with
fundamental
principles
of
xenobiotic
disposition
including
observations
that
9
exposure
from
the
oral
route
likely
exceeded
that
from
the
dermal
route
(
reflected
by
the
10
observation
of
toxicity
at
much
lower
oral
doses)
and
that
dermal
exposure
was
increased
in
an
11
environment
of
increased
temperature
and
humidity.
However,
in
evaluating
all
of
the
studies,
12
numerous
weaknesses
were
noted
by
the
HSRB.
These
weaknesses
included:
13
14
1)
There
was
no
justification
or
rationale
for
the
selection
of
doses
used
in
any
of
the
15
three
studies.
16
17
2)
The
sample
size
was
very
small
(
typically
two
subjects
per
dose
or
condition)
with
few
18
or
no
controls
(
no
more
than
two
control
subjects
in
any
study).
Such
a
design
prevented
19
evaluation
of
statistical
significance
for
any
parameter
measured
in
the
studies.
20
21
3)
The
values
obtained
for
RBC
and
plasma
cholinesterase
levels
were
highly
variable.
22
Factors
that
contributed
to
this
variability
included
the
small
sample
size,
the
inclusion
of
only
a
23
single
baseline
sample
collected
immediately
prior
to
dosing
used
to
compare
all
post­
dosing
24
samples,
the
small
number
of
control
subjects,
and
an
uncommon
method
for
analytical
25
determination
of
cholinesterase
activities.
The
contribution
of
potential
laboratory
error
cannot
26
be
ruled
out.
27
28
4)
Plasma
cholinesterase
levels
were
highly
variable
in
all
studies
so
as
to
preclude
any
29
useful
interpretation.
In
general,
plasma
cholinesterase
levels
were
not
consistent
with
changes
30
in
RBC
cholinesterase
activities.
31
32
5)
One
subject
who
presented
with
abnormal
vestibular
mechanisms
in
the
pre­
dose
33
evaluation
was
used
in
the
oral
study
and
showed
serious
symptoms
after
treatment.
34
35
6)
Subjects
were
allowed
to
smoke
during
the
study
period.
36
37
While
the
oral
and
dermal
studies
shared
these
common
weaknesses,
there
were
also
38
serious
limitations
regarding
the
application
of
carbofuran
in
the
conduct
of
the
dermal
studies.
39
In
particular,
it
is
known
that
dermal
absorption
is
influenced
by
the
concentration
of
compound
40
applied
per
unit
surface
area
of
skin,
and
it
was
clear
that
the
studies
were
extremely
different
in
41
this
regard.
For
example,
as
shown
in
the
Table
1
below
in
the
first
dermal
study
(
high
42
temperature/
humidity),
the
mass
loading
range
was
6,000
to
12,000
µ
g
carbofuran/
cm2.
These
43
extremely
high
loading
levels
were
not
appropriate
for
evaluating
potential
dermal
absorption
44
from
occupational
or
environmental
exposure
to
carbofuran.
In
the
first
dermal
study,
the
45
greatest
skin
surface
area
treated
in
the
normal
temperature
leg
of
this
study
was
40
cm2;
a
mass
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
20
of
36
of
3,264
mg
was
applied
to
this
area,
equivalent
to
a
loading
of
81,600
µ
g
carbofuran/
cm2.
In
1
contrast,
mass
loading
was
controlled
to
achieve
approximately
500
µ
g
carbofuran/
cm2
at
all
2
dose
levels
in
the
second
dermal
study.
3
4
5
Table
1.
Calculation
Of
Loading
Levels
For
Carbofuran
For
Subjects
In
The
First
Dermal
Study
6
(
High
temperature/
humidity
conditions)
7
8
Subject
Dose
Body
Wt
Mass
Template
Loading
(
mg/
kg)
(
kg)
(
mg)
(
cm2)
(
ug/
cm2)

1
0
63
0
2
0
65
0
3
0.5
72
36
6
6,000
4
0.5
66
33
5.72
5,769
5
1
74
74
8.55
8,655
6
1
64
64
7.94
8,060
7
2
74
148
12.16
12,171
8
2
78
156
12.49
12,490
9
A
primary
deficiency
of
the
first
dermal
study
was
that
it
did
not
provide
a
realistic
10
worker
exposure
scenario;
that
is,
the
exposures
of
the
subjects
in
these
experiments
did
not
11
correspond
to
exposures
likely
to
be
seen
among
workers.
Large
amounts
of
carbofuran
(
up
to
12
3,000
mg)
were
applied
to
a
relatively
small
skin
surface
area
(
6­
40
cm2)
in
the
experiments,
13
whereas
we
typically
see
much
larger
skin
surface
areas
exposed
to
smaller
amounts
among
14
workers
(
e.
g.,
1­
10
µ
g/
cm2).
For
example,
the
hands,
a
skin
surface
commonly
exposed
to
15
pesticides,
have
a
total
surface
area
of
990
cm2
(
EPA
Exposure
Factors
Handbook,
1997).
16
Dermal
dosing
studies
require
careful
consideration
of
three
factors:
mass
applied
to
the
skin,
17
surface
area
treated,
and
the
duration
of
exposure.
Therefore,
the
skin
loadings
and
skin
surface
18
areas
exposed
in
both
carbofuran
dermal
studies
were
not
appropriate
for
determination
of
a
19
NOAEL
or
a
LOAEL
for
risk
assessment
purposes.
20
21
HSRB
Consensus
and
Rationale
22
23
The
EPA
concluded
that
the
oral
and
dermal
studies
conducted
with
carbofuran
in
human
24
subjects
were
useful
in
establishing
points
of
departure,
both
oral
and
dermal,
for
the
single
25
chemical
assessment
and
in
informing
the
interspecies
uncertainty
factor
for
the
cumulative
26
assessment.
27
28
However,
while
these
studies
were
informative,
the
HSRB
concluded
that
there
were
29
numerous
technical
issues
regarding
the
conduct
of
the
oral
and
dermal
studies
with
carbofuran
30
and
that
overall,
the
weakness
of
the
studies
far
outweigh
the
strengths.
The
weaknesses
31
included
the
small
sample
size,
the
lack
of
control
subjects,
the
highly
variable
results
for
RBC
32
cholinesterase
activity
and
the
inappropriate
application
methods
used
in
the
dermal
studies.
33
Accordingly,
the
HSRB
did
not
recommend
any
of
the
oral
or
dermal
studies
conducted
with
34
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
21
of
36
carbofuran
in
human
subjects
for
the
single
chemical
assessment
or
in
informing
the
interspecies
1
uncertainty
factor
for
the
cumulative
assessment.
2
3
Additional
Considerations:
Potential
For
The
Carbofuran
Human
Studies
Data
4
5
The
Board
provided
additional
analysis
in
response
to
the
Agency's
charge
to
the
Board
6
concerning
the
potential
for
the
data
in
human
subjects
for
carbofuran
to
be
applied
to:
(
1)
the
7
calculation
of
a
benchmark
dose
(
BMD10)
and
identification
of
the
BMD10L
(
lower
confidence
8
limit);
(
2)
the
identification
of
a
NOAEL
or
LOAEL
for
effects
or
(
3)
the
comparison
to
other
9
species
for
possible
adjustments
to
uncertainty
factor
for
the
cumulative
assessment.
10
11
The
HSRB
provided
the
following
additional
perspective
relative
to
the
Agency's
12
question:
13
14
The
utility
of
the
human
studies
with
carbofuran
was
limited
by
the
very
small
sample
15
size
used
in
all
of
the
studies.
The
Agency
proposed
to
use
the
RBC
cholinesterase
data
for
16
determination
of
the
BMD10L.
However,
under
conditions
where
the
group
size
was
only
two,
it
17
would
be
imperative
to
have
highly
accurate,
valid,
reliable
and
consistent
measures
of
RBC
18
cholinesterase
activity
in
both
control
and
carbofuran­
treated
subjects.
This
rigor
was
simply
not
19
achieved
in
the
human
studies.
Rather,
RBC
cholinesterase
activities
were
compared
to
a
single
20
baseline
value,
were
highly
variable
across
subjects,
including
controls,
and
did
not
show
any
21
consistency
with
plasma
cholinesterase
levels.
As
such,
although
a
BMD10L
could
be
calculated,
22
the
magnitude
of
the
error
in
the
derived
values
would
preclude
a
reliable,
meaningful
23
assessment.
Therefore,
the
HSRB
reiterated
its
recommendation
that
the
human
data
should
not
24
be
used
for
calculation
of
the
BMD10.
25
26
In
a
similar
manner,
the
small
sample
size,
compounded
by
the
lack
of
consistent
changes
27
in
cholinesterase
activities
in
all
studies,
the
inappropriate
methods
used
for
dermal
application
28
of
the
compound
in
the
dermal
studies
and
the
inclusion
of
at
least
one
subject
who
presented
29
with
abnormal
vestibular
function
in
a
pre­
dose
assessments
limited
the
general
utility
of
the
30
data.
Collectively,
the
weaknesses
in
the
carbofuran
human
studies
conduct
and
outcomes
cast
31
doubt
on
the
utility
of
the
data
for
identifying
a
NOAEL
or
LOAEL
or
for
comparing
across
32
species
in
consideration
of
the
interspecies
uncertainty
factor
for
the
cumulative
risk
assessment.
33
Thus
the
HSRB
recommended
that
the
human
data
should
not
be
used
for
these
evaluations.
34
35
Charge
to
the
Board
36
37
Ethical
Considerations
38
39
The
Agency
requested
that
the
Board
provide
comment
on
the
following:
40
41
Oral
Toxicity
Study:
42
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
human
oral
study
43
conducted
with
carbofuran
was
fundamentally
unethical?
44
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
22
of
36
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
oral
study
was
significantly
1
deficient
relative
to
the
ethical
standards
prevailing
at
the
time
the
research
was
conducted?
2
3
Dermal
Toxicity
Studies:
4
Is
there
clear
and
convincing
evidence
that
the
conduct
of
either
of
the
human
dermal
5
studies
conducted
with
carbofuran
was
fundamentally
unethical?
6
7
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
dermal
studies
was
8
significantly
deficient
relative
to
the
ethical
standards
prevailing
at
the
time
the
research
was
9
conducted?
10
11
Board
Response
to
the
Charge
12
13
Study
Overview
14
15
There
were
three
studies
involving
either
oral
or
dermal
administration
of
carbofuran:
an
16
oral
toxicity
study
performed
in
1976
(
IRB
Review
dated
March
31,
1976;
Final
Report
dated
17
September
17,
1976);
a
dermal
toxicity
study
performed
in
late
1976
and
early
1977
(
IRB
18
Review
dated
August
25,
1976;
Final
Report
dated
March
18,
1977);
and
a
second
dermal
19
toxicity
study
conducted
in
late
1977
(
REC
Review
date
unknown;
Final
Report
dated
February
20
15,
1978).
21
22
The
location
for
the
research
was
the
Quincy
Research
Center
in
Kansas
City,
Missouri.
23
All
three
studies
were
under
the
direction
of
a
single
principal
investigator,
John
D.
Arnold,
MD.
24
The
research
appeared
to
have
been
performed
under
contract
to
the
Midwest
Research
Institute,
25
also
located
in
Kansas
City.
The
responsible
institutional
review
board
was
the
Community
26
Review
Committee,
Inc.,
again
located
in
Kansas
City.
The
research
sponsor
was
FMC
27
Corporation,
located
in
Philadelphia,
Pennsylvania
with
the
manufacturing
facility
apparently
28
located
in
Middleport,
New
York.
29
30
No
ethical
or
regulatory
standards
were
mentioned
in
any
of
the
study
documents.
Given
31
the
dates
of
the
research
studies,
Section
12
of
FIFRA
applied
to
the
research.
In
addition,
the
32
1975
version
of
the
Declaration
of
Helsinki
was
available
at
the
time.
33
34
Critique
of
Studies
35
36
The
following
comments
apply
to
all
three
studies.
37
38
1)
The
fact
that
these
studies
have
never
been
published
should
not
be
used
as
the
sole
39
criterion
to
determine
whether
the
purpose
of
the
research
was
to
obtain
generalizable
40
knowledge.
Publication
is
neither
a
necessary
nor
sufficient
criterion
of
whether
or
not
the
41
research
was
designed
to
allow
for
either
a
descriptive
or
causal
inference.
42
43
2)
The
risks
were
minimized
by
the
study
design
(
setting
aside
the
actual
conduct),
44
assuming
that
there
was
a
valid
scientific
purpose
in
escalating
the
dose
until
achieving
a
"
lowest
45
observable
adverse
effect
level"
(
LOAEL).
Examples
of
the
procedures
that
were
incorporated
to
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
23
of
36
minimize
risk
included
the
presence
of
a
supervising
physician
who
was
readily
available
for
24
1
hours
after
dosing,
confinement
of
the
subjects
for
24
hours,
abstinence
from
alcohol
during
the
2
study,
the
exclusion
of
other
drugs
within
two
weeks
of
performing
the
study,
the
availability
3
and
administration
of
atropine
(
discussed
further
below),
and
a
delay
in
dose
escalation
(
at
least
4
in
the
oral
toxicity
study)
until
the
24
hour
clinical
data
was
available.
In
addition,
subjects
only
5
received
the
active
compound
once
during
each
research
study.
6
7
3)
Measurements
of
RBC
cholinesterase
inhibition
should
serve
as
an
adequate
surrogate
8
measure
of
toxicity,
obviating
the
need
to
induce
clinical
signs
and
symptoms
of
cholinergic
9
toxicity.
The
question
however
in
judging
these
three
studies
was
whether
this
standard
was
10
either
appreciated
or
applicable
in
1976
and
1977.
The
fact
that
the
research
was
designed
to
11
cause
clinical
signs
and
symptoms
of
cholinergic
toxicity
as
the
study
endpoint
does
not,
in
and
12
of
itself,
establish
that
the
interests
of
the
subjects
did
not
prevail
over
other
interests.
The
13
Common
Rule
allows
for
the
balancing
of
the
risks
of
research
against
the
knowledge
that
may
14
reasonably
be
obtained.
The
central
question
then
was
whether
the
risks
were
reasonable,
not
15
whether
the
research
was
designed
to
elicit
clinical
toxicity.
16
17
4)
With
respect
to
informed
consent,
the
list
of
signs
and
symptoms
of
cholinergic
18
toxicity
found
in
the
consent
documents
was
fairly
complete.
The
consent
documents
were
fairly
19
straightforward
about
the
fact
that
the
testing
involved
a
pesticide
and
that
the
research
would
be
20
of
no
benefit
to
the
subject.
The
freedom
to
withdraw
was
emphasized,
along
with
the
fact
that
21
additional
testing
to
ensure
the
safety
of
subjects
would
be
requested
by
the
supervising
22
physician.
In
spite
of
these
strengths,
the
consent
documents
failed
to
provide
a
description
of
23
the
study
design
(
i.
e.,
dose
escalation)
and
the
anticipated
endpoint
of
clinical
toxicity.
The
24
phrase
"
we
do
not
expect
any
serious
complications"
is
clearly
open
to
interpretation.
Some
25
would
and
some
would
not
consider
the
clinical
signs
and
symptoms
of
cholinergic
stimulation
26
"
serious."
Regardless,
the
phrase
does
introduce
a
framing
of
these
stated
risks
as
"
non­
serious."
27
Given
the
research
design,
the
consent
documents
would
have
been
improved
if
they
had
been
28
explicit
about
the
dose
escalation,
the
place
of
the
specific
subject
within
that
dose
escalation,
29
and
the
fact
that
someone
would
eventually
have
a
100%
chance
of
experiencing
clinical
30
toxicity.
Although
these
changes
are
an
admirable
standard
going
forward,
the
consent
31
documents
used
for
the
oral
and
first
dermal
toxicity
study
met
(
and
some
might
argue
exceeded)
32
the
standards
prevalent
in
1976
and
1977.
However,
as
discussed
below,
the
consent
document
33
for
the
second
dermal
toxicity
study
was
seriously
deficient.
34
35
The
Board
had
specific
comments
about
the
conduct
of
each
of
the
studies
that
can
be
36
addressed
under
the
general
topic
of
the
reasonableness
of
the
risks
(
and
the
efforts
to
reduce
37
those
risks)
that
the
subjects
experienced
in
the
conduct
of
this
research.
38
39
1)
Was
it
appropriate
to
expose
additional
subjects,
in
the
oral
toxicity
study,
to
a
dose
40
which
had
already
been
shown
to
cause
clinical
toxicity
if
the
scientific
purpose
was
to
establish
41
a
LOAEL?
Given
the
criticism
of
attempting
to
determine
a
"
no
observable
adverse
effect
level"
42
(
NOAEL)
using
a
small
sample
size,
the
design
chosen
in
these
three
studies
to
elicit
a
LOAEL
43
may
be
more
reliable.
However
the
small
sample
size,
when
combined
with
the
variability
and
44
unreliability
of
the
RBC
cholinesterase
measurements,
undermine
confidence
that
the
study
was
45
designed
to
establish
the
real
LOAEL.
The
repeat
administration
of
the
test
substance
absent
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
24
of
36
dose
escalation
was
used
in
other
cholinesterase
inhibitor
studies,
but
the
endpoint
driving
the
1
decision
to
not
escalate
dosing
was
the
more
sensitive
endpoint
of
the
degree
of
RBC
2
cholinesterase
inhibition.
3
4
2)
There
was
documentation
(
in
a
letter
dated
October
26,
1976)
of
the
decision
to
start
at
5
the
2.0
mg/
kg
dose
in
the
low­
temperature
and
low­
humidity
phase
of
the
first
dermal
toxicity
6
study.
Although
the
responsible
IRB
was
not
consulted
(
for
which
there
were
no
procedural
7
guidelines
in
1976),
was
the
decision
to
bypass
the
16
mg/
kg
dose
in
favor
of
a
32
mg/
kg
dose
in
8
the
low
temperature
and
humidity
phase
of
the
dermal
toxicity
study
reasonable?
If
the
dose­
9
response
relationship
based
on
the
percent
RBC
acetyl
cholinesterase
inhibition
was
linear,
yet
10
the
onset
of
clinical
signs
and
symptoms
reflects
a
threshold
response,
this
decision
could
have
11
placed
the
subjects
given
the
higher
dose
at
greater
risk
even
though,
in
retrospect,
the
32
mg/
kg
12
dose
was
well
tolerated.
13
14
3)
The
administration
of
atropine
as
an
antidote
to
cholinergic
toxicity
may
have
been
15
delayed
for
one
or
more
of
the
subjects
in
the
high­
temperature
and
high­
humidity
phase
of
both
16
dermal
toxicity
studies.
Although
mention
was
made
of
written
instructions
for
the
17
administration
of
atropine,
these
instructions
were
not
included
in
the
submitted
documentation.
18
The
question
then
was
whether
there
could
be
any
justification
for
the
delay
in
the
administration
19
of
atropine.
Two
possible
justifications
might
be:
(
1)
the
signs
and
symptoms
were
from
non­
20
muscarinic
cholinergic
receptors
and
thus
would
not
be
responsive
to
atropine
(
which
was
not
21
the
case);
or
(
2)
the
supervising
physician
was
concerned
that
any
resulting
tachycardia
or
other
22
side­
effects
from
the
administration
of
atropine
would
be
of
greater
risk
(
highly
unlikely).
After
23
considerable
reflection,
the
Board
could
find
no
scientific
or
clinical
reason
to
delay
the
24
administration
of
atropine.
25
26
4)
Study
participants
were
not
fully
informed
of
the
risks
of
the
study.
It
should
have
27
been
clear
to
study
investigators
that
the
escalating
dose
design
used
was
likely
to
result
in
28
serious
harm
to
some
research
subjects.
For
example,
several
participants
who
received
a
2.0
29
mg/
kg
dose
of
carbofuran
during
the
high­
temperature
and
high­
humidity
phase
of
the
first
30
dermal
toxicity
study
exhibited
clear
clinical
signs
and
symptoms
of
carbamate
poisoning,
31
requiring
administration
of
atropine
as
an
antidote.
Plasma
and
red
cell
cholinesterase
inhibition
32
data
also
was
obtained
from
these
individuals,
with
participants
demonstrating
46%
and
65%
33
peak
red
cell
inhibition
respectively.
In
the
subsequent
second
dermal
toxicity
study,
however,
34
the
data
from
the
first
dermal
toxicity
study
were
not
used
either
to
develop
clear
stopping
35
criteria
or
to
modify
the
dosing
protocol,
thus
exposing
study
participants
to
an
unacceptable
36
level
of
risk.
The
two
participants
in
the
high­
temperature
and
high­
humidity
second
dermal
37
toxicity
study
who
received
a
2.0
mg/
kg
dose
of
carbofuran
did
not
exhibit
any
clinical
38
symptoms
of
carbamate
poisoning.
These
individuals
did,
however,
exhibit
peak
red
cell
39
cholinesterase
inhibition
of
40%
and
42%
respectively,
similar
to
the
level
of
inhibition
seen
in
40
one
of
the
symptomatic
participants
in
the
first
dermal
toxicity
study.
These
data
suggest
that
the
41
LOAEL
for
carbofuran
was
at
or
near
2.0
mg/
kg.
Nevertheless,
the
decision
was
made
to
expose
42
two
subjects
to
a
dose
of
4.0
mg/
kg
carbofuran,
once
again
resulting
in
severe
clinical
symptoms
43
indicative
of
carbamate
poisoning
and
requiring
administration
of
atropine
as
an
antidote.
In
light
44
of
the
clinical
and
biomarker
data
obtained
from
the
first
dermal
toxicity
study,
it
should
have
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
25
of
36
been
obvious
to
study
investigators
that
exposure
of
additional
research
subjects
to
a
dose
of
4.0
1
mg/
kg
carbofuran
was
likely
to
have
resulted
in
serious
harm
to
these
two
study
participants.
2
3
This
conclusion,
coupled
with
the
observation
that
the
consent
documents
from
the
4
second
dermal
toxicity
study
explicitly
stated
study
investigators
"[
did]
not
expect
a
serious
5
complications"
raises
serious
questions
about
the
informed
consent
process.
At
least
some
study
6
participants
were
likely
to
experience
clinical
signs
indicative
of
carbamate
toxicity.
To
imply
7
otherwise
in
the
informed
consent
documents
suggests
that
the
consent
process
was
severely
8
flawed.
Study
participants
were
denied
access
to
information
that
might
have
influenced
their
9
decision
to
voluntarily
enroll
in
the
second
dermal
toxicity
study.
10
11
HSRB
Consensus
and
Rationale
12
13
Oral
Toxicity
Study
14
15
For
the
oral
study,
there
was
no
evidence
that
the
study
failed
to
fully
meet
specific
16
ethical
standards
prevalent
at
the
time
the
research
was
conducted.
17
18
There
was
no
clear
and
convincing
evidence
that
the
research
was
fundamentally
19
unethical
(
e.
g.,
intended
to
seriously
harm
participants
or
that
informed
consent
was
not
20
obtained).
21
22
There
was
no
clear
and
convincing
evidence
of
significant
deficiencies
in
the
ethical
23
procedures
that
could
have
resulted
in
serious
harm
(
based
on
the
knowledge
available
at
the
24
time
the
study
was
conducted)
nor
that
information
provided
to
participants
seriously
impaired
25
their
informed
consent.
26
27
Dermal
Toxicity
Studies
28
29
The
HSRB
found
deficiencies
in
both
dermal
human
toxicity
studies
relative
to
specific
30
ethical
standards
prevalent
at
the
time
the
study
was
conducted.
31
32
The
majority
of
the
Board
concluded
there
was
no
clear
and
convincing
evidence
that
the
33
research
was
fundamentally
unethical
(
e.
g.,
intended
to
seriously
harm
participants
or
that
34
informed
consent
was
not
obtained).
In
light
of
the
results
obtained
from
the
first
dermal
toxicity
35
study,
one
Board
member
concluded
that
the
second
dermal
toxicity
study
was
fundamentally
36
unethical
in
design.
The
Board
member
believed
that
this
study
was
neither
designed
to
37
minimize
the
risk
of
serious
harm
to
participants
nor
to
ensure
an
adequate
informed
consent.
38
39
For
both
dermal
toxicity
studies,
there
was
clear
and
convincing
evidence
of
significant
40
deficiencies
in
the
ethical
procedures
for
minimizing
risk
that
could
have
resulted
in
serious
41
harm
(
based
on
the
knowledge
available
at
the
time
the
study
was
conducted).
The
first
dermal
42
toxicity
study
was
significantly
deficient
given
the
delay
in
the
administration
of
atropine
to
43
more
than
one
subject
experiencing
the
signs
and
symptoms
of
carbamate
toxicity.
The
second
44
dermal
toxicity
study
was
considered
significantly
deficient
by
a
majority
of
Board
members
in
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
26
of
36
that
the
lack
of
information
provided
about
the
results
from
the
initial
dermal
toxicity
study
1
seriously
impaired
their
informed
consent.
2
3
4
3.
Methyl
Isothiocyanate
(
MITC)
5
6
Charge
to
the
Board
7
8
MITC
is
an
irritating
compound
that
has
a
limited
animal
database
for
toxicity
via
9
inhalation,
the
key
route
of
exposure.
MITC
can
be
used
as
a
pesticide
directly
to
treat
wood
10
poles,
but
the
major
pathway
of
exposure
to
MITC
is
from
degradation
of
several
fumigant
11
pesticides
(
i.
e.,
metam
sodium,
metam
potassium,
and
dazomet).
Due
to
its
volatility,
MITC
has
12
the
potential
to
move
off­
site,
which
can
result
in
exposure
to
bystanders
near
treated
areas
and,
13
through
ambient
air,
to
people
far
away
from
treated
areas.
Use
of
the
soil
fumigants
also
results
14
in
exposure
to
those
handling
the
pesticides
or
working
in
treated
fields.
15
16
Scientific
considerations
17
18
The
Agency's
WOE
document
and
DER
for
MITC
describe
the
study
design
and
results
19
of
the
MITC
odor
threshold
and
eye
irritation
human
studies.
The
WOE
document
also
discusses
20
the
Agency's
conclusions
that
the
eye
irritation
study
is
useful
for
the
assessment
of
potential
21
effects
on
bystanders
and
workers
from
exposures
to
MITC
during
acute
(
1­
day)
intervals.
The
22
Agency
had
concluded
that
the
odor
threshold
study
is
less
useful
than
the
eye
irritation
study
for
23
assessing
the
human
health
effects
of
MITC,
since
the
odor
detection
threshold
for
humans
is
24
higher
than
the
level
that
causes
eye
irritation.
The
Agency
had
decided,
however,
to
use
the
25
results
of
the
eye
irritation
study
for
assessing
the
inhalation
exposure
of
MITC.
26
27
Please
comment
on
the
scientific
evidence
that
supports
this
conclusion.
28
29
Board
Response
to
the
Charge
30
31
Introduction
32
33
MITC
is
the
primary
and
key
degradate
of
these
fumigant
pesticides
(
i.
e.,
metam
sodium,
34
metam
potassium
and
dazomet).
As
a
gas
injected
into
soil,
it
can
kill
soil­
borne
pests,
such
as
35
insects,
microorganisms,
weeds,
and
nematodes.
The
fumigant
dissipates
from
the
soil
in
a
few
36
days
to
a
couple
of
weeks.
37
38
According
to
the
EPA
Weight
of
Evidence
(
WOE)
document
(
USEPA
2006b)
"
The
39
mode
of
toxic
action
for
MITC
is
not
known
at
this
time.
MITC
is
primarily
an
irritating
40
compound
that
produces
non­
specific
systemic
effects
in
oral
toxicity
studies
such
as
changes
in
41
body
weight,
food
consumption,
and
hematological
parameters.
Following
air
exposures
to
42
MITC,
consistent
effects
are
observed
in
rats
and
humans.
For
example,
clinical
signs
and
43
pathological
changes
of
the
respiratory
tract
consistent
with
an
irritant
have
been
observed
in
44
laboratory
studies
in
rat.
Humans
exposed
to
MITC
complain
of
symptoms
such
as
itchy
and
45
burning
eyes,
rash
and
burning
skin,
nausea,
scratchy
throat,
salivation,
coughing,
and
shortness
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
27
of
36
of
breath.
In
acute
toxicity
testing
with
animals,
MITC
is
considered
Acute
Toxicity
Category
I
1
(
corrosive)
for
skin
and
eye
irritation."
Since
the
animal
studies
were
either
long­
term
inhalation
2
or
oral
studies,
they
were
not
considered
for
a
point
of
departure
and
therefore
would
be
less
3
protective
of
human
health.
Thus,
the
Board
recommended
the
eye
irritation
LOAL
as
a
point
of
4
departure.
5
6
Brief
Overview
of
Study
7
8
The
EPA
WOE
extracted
a
description
of
the
odor
and
eye
irritation
study
(
Russell
and
9
Rush
1996)
directly
from
the
Risk
Characterization
Document
for
MITC
of
the
Department
of
10
Pesticide
Regulation,
Cal
EPA
(
July
25,
2003,
pp
53­
59),
which
was
considered
accurate
and
11
quoted
herein.
12
13
"
In
order
to
determine
the
NOEL
for
human
eye
irritation
produced
by
MITC
vapors,
as
14
well
as
its
odor
threshold,
human
volunteers
were
exposed
to
air
concentrations
of
MITC
in
a
15
laboratory
setting
(
Russell
and
Rush,
1996).
The
study
specifically
focused
on
assessing
these
16
parameters
at
different
times
of
exposure.
An
olfactometer
was
used
which
permitted
the
17
operator
to
dispense
the
test
material
through
a
manifold
system.
The
test
material
could
thus
be
18
diluted
over
a
100­
fold
concentration
range.
The
material
was
dispensed
by
diffusion
from
a
19
glass
vessel
which
could
be
maintained
at
any
temperature
±
0.1
°
C
over
a
range
of
30
to
70
°
C.
A
20
Total
Hydrocarbon
Analyzer
(
THA)
was
used
to
monitor
the
flow
of
test
material
during
the
21
exposure
period.
In
addition,
carbon
tube
samples
were
drawn
once
the
system
was
equilibrated
22
prior
to
exposure,
and
at
the
end
of
the
exposure.
The
test
material
was
desorbed
from
the
carbon
23
and
analyzed
by
gas
chromatography.
Every
effort
was
undertaken
to
minimize
the
reaction
of
24
the
test
material
with
the
tubing
and
other
equipment
used
in
the
delivery
system".
25
26
"
In
the
olfactory
threshold
study,
33
individuals
(
16
males,
17
females)
with
a
mean
age
27
of
25
years
(
range,
18
to
34
years)
were
tested.
They
were
exposed
to
three
positive
control
28
odorants,
pyridine,
acetic
acid,
and
n­
butyl
alcohol
as
well
as
to
MITC.
The
technician
chose
the
29
odorant
and
concentration
level.
The
odorant
was
dispensed
in
double
blind
fashion
from
one
of
30
three
presentation
ports.
The
subject
was
responsible
for
identifying
from
which
of
the
31
presentation
ports
the
odorant
was
dispersed.
A
30­
second
rest
period
between
exposures
was
32
permitted
in
order
to
allow
the
subject
to
recover
prior
to
the
next
exposure.
The
operator
tested
33
each
subject
over
the
range
of
concentrations
for
each
odorant
until
he
was
assured
that
the
34
threshold
had
been
adequately
ascertained.
A
standard
procedure
was
employed
in
order
to
make
35
this
determination."
36
37
"
In
the
NOEL
determination
for
eye
irritation,
the
olfactometer
was
modified
by
38
attaching
goggles
to
the
presentation
line.
This
permitted
the
test
material
to
be
directed
only
to
39
the
eyes.
Five
parameters
were
used
to
ascertain
an
irritation
response:
1.
the
subjects'
subjective
40
estimation
of
irritation
(
using
the
"
Likert"
scale);
2.
photographs
of
the
subjects'
eyes
prior
to
41
and
after
exposure;
3.
blink
rate
as
measured
by
electromyography;
4.
effect
upon
visual
acuity;
42
5.
tear
production.
Both
a
positive
control
(
acetic
acid)
and
a
negative
control
(
air)
were
43
employed.
Baseline
responses
for
each
of
the
assessment
parameters
were
determined
under
pre­
44
exposure
conditions
("
zero­
time
controls")
and
upon
exposure
to
the
negative
control
("
air­
only
45
controls")
for
the
prescribed
period.
A
positive
irritation
response
was
based
on
three
criteria:
1.
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
28
of
36
the
average
response
must
be
quantitatively
greater
than
the
pre­
exposure
response;
2.
the
1
average
response
must
be
greater
than
pre­
exposure
and
greater
than
could
be
expected
2
statistically
from
individual
to
individual
differences
within
the
group;
3.
the
average
treated
3
response
must
be
greater
than
the
air­
only
group's
response
and
greater
than
could
be
expected
4
from
individual
differences
observed
within
the
group.
Seventy
individuals
(
38
males,
32
5
females)
with
a
mean
age
of
32
years
(
range,
18­
67
years;
median
age,
28
years)
were
exposed
to
6
air,
MITC,
and/
or
acetic
acid.
Between
9
and
16
subjects
were
examined
under
each
dose/
time
7
period
combination.
Three
exposure
periods,
14
minutes,
4
hours
and
8
hours
were
used.
In
the
8
eight
hour
test,
subjective
responses,
blink
rates
and
tearing
were
assessed
at
0,
1.5,
3,
3.5,
6
and
9
8
hours
(
tearing
was
not
measured
at
3.5
hours).
Two
15­
minute
rest
breaks
and
a
30­
minute
10
lunch
break
were
permitted
during
the
8­
hour
period.
In
the
four
hour
test,
these
same
parameters
11
were
assessed
at
0,
1,
2,
3
and
4
hours
(
tearing
was
not
measured
at
0,
2
and
3
hours).
In
the
14­
12
minute
exposure
protocol,
subjective
responses
and
blink
rates
were
measured
at
0,
1,
4
and
14
13
minutes
after
the
start
of
exposure.
Tearing
was
measured
at
14
minutes
only.
Visual
acuity
and
14
ocular
morphology
were
assessed
at
the
beginning
and
end
of
each
exposure
period.
All
analyses
15
were
performed
in
a
double­
blind
manner."
T­
tests
were
used
to
compare
responses
at
each
16
computed
concentration
level
for
each
time
period
to
both
air
control
results
and
zero­
time
17
results.
Both
were
significant
and
positive
but
responses
to
the
control
substance
were
not
as
18
dramatic.
19
20
Critique
of
the
Study
21
22
Introduction
23
24
Table
2
shows
what
the
investigators
called
the
NOEL,
which
the
Agency's
Data
25
Evaluation
Record
and
WOE
call
the
NOAEL
and
LOEL
respectively
(
EPA's
RfC
methodology
26
document
included
eye,
nasal,
and
throat
irritation
in
its
list
of
adverse
effects).
27
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
29
of
36
1
Table
2.
Summary
Of
MITC
Eye
Irritation
Effects
From
Human
Subjects
2
3
Exposure
time
NOAEL
(
ppm)
LOAEL
(
ppm)
Source
of
observed
Effect
1
minute
3.3
­
­
4
minutes
0.6
1.9
Subjective
eye
irritation
14
minutes
0.6
1.9
Subjective
eye
irritation
1
hour
0.23
a
0.8
Subjective
eye
irritation
1.5
hours
0.22
a
­
­

2
hours
0.23
a
0.8
Subjective
eye
irritation
and
blink
rate
3
hours
0.23
a
0.8
Subjective
eye
irritation
and
blink
rate
3.5
hours
0.22
a
­
­

4
hours
0.23
a
0.8
Subjective
eye
irritation
6
hours
0.22
a
­
­

8
hours
0.22
a
­
­

a
The
slightly
different
values
obtained
at
the
low
dose
NOAEL
level
(
0.22
and
0.23
ppm)
reflected
4
the
fact
that
they
were
derived
from
tests
performed
on
different
days.
5
6
7
As
the
WOE
stated
"
Exposure
to
0.8
ppm
(
800
ppb)
MITC
resulted
in
a
statistically
8
significant
positive
response
based
on
averaging
the
subjective
assessments
by
the
subjects
using
9
the
Likert
scale
methodology.
As
many
as
8
out
of
9
subjects
showed
a
positive
response
at
1
10
and
2
hours,
the
first
two
time
points
examined
[
and
also
at
3
&
4
hours].
Shorter
exposures
to
11
0.6
ppm
did
not
result
in
statistically
significant
Likert
scale
changes,
though
1
of
9
individuals
12
appeared
to
respond
at
4
and
14
minutes.
Exposure
to
1.9
ppm
or
3.3
ppm
MITC
for
4
or
14
13
minutes
resulted
in
positive
subjective
responses
at
4
and
14
minutes.
At
1
minute
of
exposure,
14
levels
as
high
as
3.3
ppm
did
not
evoke
a
statistically
significant
positive
response."
15
16
"
Mean
blink
rate
determinations
at
0.8
ppm
were
statistically
significantly
increased
at
17
the
2­
and
3­
hour
time
points
compared
both
to
air­
only
and
zero­
time
controls.
Statistical
18
significance
was
not
achieved
at
1
and
4
hours,
though
a
positive
response
was
indicated
in
19
several
individuals.
The
blink
response
to
0.6
ppm
and
1.9
ppm
at
1,
4
and
14
minutes
did
not
20
show
a
positive
response.
At
3.3
ppm,
statistical
significance
was
achieved
at
4
and
14
minutes.
"
21
The
Board
agreed
with
the
Agency's
conclusion
that
"
A
strong
suggestion
of
a
response
was
also
22
present
at
1
minute,
though
it
was
not
statistically
significant."
In
addition,
the
subjective
(
Likert
23
scale)
responses
were
the
most
sensitive
and
most
variable.
The
eye
blink
rate
was
the
next
most
24
sensitive.
The
other
tests
were
not
as
sensitive
and
usually
were
not
significant.
25
26
The
Board
agreed
with
the
Agency
conclusions
as
noted
in
their
DER:
27
28
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
30
of
36
"°
For
a
one­
minute
exposure,
the
NOAEL
for
eye
irritation
is
3.3
ppm
due
to
a
lack
of
response
1
in
any
parameter
tested."
2
3
"°
For
exposures
4­
14
minutes,
the
NOAEL
for
eye
irritation
is
0.6
ppm
based
on
responses
on
4
the
Likert
subjective
scale
at
1.9
ppm.
"
5
6
"°
For
exposures
of
1­
8
hours,
based
on
the
statistically
significant
subjective
(
Likert
scale)
7
responses
at
0.8
ppm
MITC
at
1­
4
hours
and
the
statistically
significant
eyeblink
responses
at
2
8
and
3
hours,
0.22
ppm
was
designated
as
the
NOAEL
for
this
study.
The
NOAEL
for
eye
9
irritation
was
consistent
for
the
1­
8
hour
measurements.
It
is
reasonable
to
assume
that
exposures
10
up
to
24
hours
would
likely
yield
a
similar
response."
11
12
Finally,
in
terms
of
the
olfactory
threshold
study,
the
Board
agreed
with
the
Agency's
13
conclusion
that
"
The
observed
odor
threshold
for
MITC
ranged
from
0.2
to
8
ppm
with
a
14
geometric
mean
of
1.7
ppm."
15
16
Strengths
of
the
study
17
18
The
studies
were
well­
designed,
equipped,
carefully
controlled
and
performed
by
19
experienced
investigators
at
a
respected
institute.
The
lowest
concentration
tested
was
the
largest
20
sample
size.
Exclusion
criteria
were
appropriate:
abnormal
irritation,
contacts,
frequent
21
headaches,
recent
asthma
attacks,
and
pregnancy.
22
23
Weaknesses
of
the
study
24
25
The
eye
irritation
studies
did
not
have
a
sufficient
number
of
subjects
in
each
of
the
26
experiments
and
phases.
In
addition
there
was
no
information
on
the
susceptibility
status
of
27
individuals
tested
nor
information
on
within
subject
variation.
Another
shortcoming
is
that
eye
28
irritation
does
not
predict
dermal
nor
respiratory
effects.
Thus,
there
may
be
lower
NOAELs
for
29
these
latter
effects.
30
31
Two­
tailed
t­
tests
were
used
to
compare
the
responses
of
subjects
receiving
different
32
doses
of
MITC
despite
the
presence
of
substantial
skew
in
the
data
of
some
groups,
with
some
33
standard
deviations
exceeding
the
corresponding
means.
This
was
most
common
among
the
34
subjects
receiving
the
lower
doses,
an
issue
of
particular
concern
insofar
as
the
goal
of
the
study
35
was
to
identify
a
NOAEL.
A
nonparametric
test
would
have
been
a
more
appropriate
choice.
In
36
addition,
because
responses
were
measured
repeatedly
on
the
same
subjects
over
time,
a
37
statistical
approach
that
took
this
into
account
would
also
have
been
more
appropriate
than
the
38
series
of
independent
t­
tests
that
were
carried
out.
39
40
The
investigators
were
rather
rigid
in
their
approach
to
the
interpretation
of
p­
values.
For
41
instance,
a
group
difference
for
which
the
p­
value
was
0.052
was
not
considered
evidence
of
an
42
effect.
On
the
other
hand,
the
investigators
clearly
stated
their
criteria
for
interpretation
and
43
applied
these
rules
consistently.
Moreover,
inspection
of
the
tables
indicated
that
the
conclusions
44
reached
would
not
have
differed
even
if
a
somewhat
more
liberal
criterion
of
statistical
45
significance
had
been
applied.
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
31
of
36
1
This
issue
does
raise
a
more
general
concern
relating
to
the
size
of
the
study
sample.
The
2
investigators
provided
no
rationale
for
the
sample
size
that
was
used
nor
power
calculations,
3
despite
the
important
influence
that
sample
size
has
on
whether
a
group
difference
reaches
some
4
level
of
statistical
significance.
The
inclusion
of
a
small
number
of
additional
subjects
in
the
5
different
groups
could
well
have
caused
some
of
the
borderline
p­
values
to
fall
to
a
level
that
6
would
have
met
the
investigators'
criteria
for
significance
and,
potentially,
change
the
inferences
7
drawn,
as
demonstrable
by
re­
calculations
of
significance.
Thus
it
is
important
that
one
could
be
8
confident
that
the
sample
size
was
adequate
for
the
assessment
of
the
study
hypotheses.
Ideally,
9
the
investigators
should
have
begun
by
specifying
the
magnitude
of
the
response
that
they
10
consider
meaningful
and
want
to
be
able
to
detect,
should
it
exist
(
e.
g.,
a
50%
increase
in
the
11
response,
a
doubling
of
the
response,
etc).
Then,
after
making
additional
assumptions,
they
12
could
calculate
the
number
of
subjects
that
would
be
necessary.
As
stated,
this
was
not
done.
13
14
HSRB
Consensus
and
Rationale
15
16
The
Board
concluded
that
air
concentrations
of
methyl
isothiocyanate
sufficient
to
17
produce
eye
irritation
would
lead
to
a
conservative
and
prudent
point
of
departure
for
inhalation
18
risk
(
i.
e.,
eyes
were
a
sensitive
endpoint
in
relation
to
the
respiratory
system).
The
Board
19
reached
its
decision
based
on
eye
irritation
LOAELs
are
often
lower
than
respiratory
irritation
20
LOAELs
for
irritant
gases
(
WHO
1979ab,
NRC
1986;
WHO/
EURO
1986).
While
the
use
of
eye
21
irritation
date
as
a
surrogate
for
respiratory
data
is
reasonable
in
this
situation,
one
must
be
22
cautious
as
only
appropriate
controlled
human
studies
of
the
respiratory
system
can
provide
a
23
final
and
definitive
respiratory
point
of
departure,
if
ever
determined
(
NAS
1975).
24
25
Charge
to
the
Board
26
27
Ethical
considerations
28
29
The
Agency
requests
that
the
Board
provide
comment
on
the
following:
30
31
a.
Is
there
clear
and
convincing
evidence
that
the
conduct
of
the
human
eye
irritation
32
study
with
MITC
was
fundamentally
unethical?
33
34
b.
Is
there
clear
and
convincing
evidence
that
the
conduct
of
this
study
was
significantly
35
deficient
relative
to
the
ethical
standards
prevailing
at
the
time
the
research
was
conducted?
36
37
Board
Response
to
the
Charge
38
39
Brief
Overview
of
the
Study
40
41
The
human
eye
irritation
study
was
conducted
in
1993
through
1995.
The
study
was
42
performed
in
Davis,
California
by
researchers
at
the
Sensory
Testing
Laboratory,
School
of
43
Medicine,
University
of
California,
Davis,
together
with
the
Western
Research
Center
of
Zeneca
44
Ag
Products,
Richmond,
California.
The
study
sponsor
was
the
Metam
Sodium
Task
Force
45
(
representing
chemical
manufacturers),
whose
mailing
address
is
in
care
of
Zeneca
Ag
Products
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
32
of
36
of
Wilmington,
Delaware.
The
documents
provided
by
the
sponsor
specifically
state
that
the
1
research
was
conducted
in
compliance
with
the
Declaration
of
Helsinki
(
presumably
the
1989
2
version,
though
no
date
is
specified)
and
the
Human
Subject's
Bill
of
Rights
(
a
provision
of
3
California
law).
The
study
was
reviewed
and
approved
by
the
Human
Subjects
Review
4
Committee
at
the
University
of
California,
Davis,
an
institution
which
held
a
Multiple
Project
5
Assurance
with
the
U.
S.
Department
of
Health
and
Human
Services.
The
documentation
6
provided
by
that
Committee
indicated
that
it
reviewed
this
study
pursuant
to
the
standards
of
the
7
Common
Rule
(
45
C.
F.
R.
Part
46,
Subpart
A)
and
determined
it
to
be
in
compliance
with
that
8
Rule.
9
10
The
Board's
comments
only
relate
to
the
human
eye
irritation
study,
and
not
to
the
11
human
odor
threshold
study
conducted
by
the
same
group
of
investigators.
Consistent
with
the
12
charge
presented
to
the
Board
by
the
EPA,
the
Board
made
no
comments
with
regard
to
the
13
human
odor
threshold
study.
14
15
Critique
of
Study
16
17
The
Board
concurred
with
the
factual
observations
of
the
strengths
and
weaknesses
of
the
18
human
eye
irritation
study,
as
detailed
in
USEPA
(
2006c).
The
Board
concurred
with
the
19
Agency's
conclusion
that
although
there
were
deficiencies
with
regard
to
the
applicable
ethical
20
standards
prevailing
at
the
time
this
study
was
conducted,
those
deficiencies
were
relatively
21
minor.
In
addition
to
the
deficiencies
specified
in
USEPA
(
2006c),
the
Board
wanted
to
comment
22
on
two
additional
aspects
of
the
study:
23
24
1.
The
Human
Subjects
Review
Committee
asked
the
investigators
to
add
a
provision
to
25
the
protocol
and
the
consent
form
indicating
that
"
if
significant
irritation
is
experienced,
no
26
higher
dose
will
be
administered."
The
revised
protocol
never
provided
any
specific
criteria
for
27
determining
how
it
would
be
determined
whether
a
subject
was
experiencing
significant
28
irritation.
It
was
appropriate
that
such
stopping
rules
be
relatively
specific,
if
possible.
29
30
2.
The
original
protocol
for
the
eye
irritation
study
involved
exposing
subjects
to
MITC
31
for
a
series
of
two­
minute
periods,
with
twenty­
minute
breaks
between
each
exposure.
In
the
32
study
investigator's
memorandum
to
the
IRB
dated
August
17,
1994,
requesting
renewal
of
the
33
protocol,
the
investigator
indicated
that
he
had
apparently
finished
conducting
at
least
part
of
the
34
study
as
initially
described,
and
that
it
was
"
going
well
without
any
ill
effects."
He
submitted
a
35
protocol
amendment
so
that
he
might
study
the
effects
of
longer
exposure
to
MITC
(
up
to
eight
36
hours
at
a
time).
In
the
document
submitted
to
the
EPA
describing
the
results
of
this
series
of
37
studies,
however,
no
data
were
provided
as
to
the
results
of
the
short­
term
study.
On
page
26
of
38
the
submitted
documents,
which
outlines
when
subjects
were
exposed
to
this
agent
and
for
what
39
periods
of
time,
there
was
mention
only
of
the
8­
hour,
4­
hour,
and
14­
minute
exposure
periods.
40
The
tables
accompanying
the
report
only
gave
details
of
the
results
of
those
longer
exposure
41
periods.
Since
the
longer
exposures
were
premised
on
the
favorable
results
from
the
short­
term
42
exposures,
it
would
have
been
appropriate
for
the
report
to
have
also
included
details
relating
to
43
the
results
from
the
short­
term
(
two­
minute)
trials.
The
absence
of
such
details
makes
it
difficult
44
to
determine
any
ethical
irregularities
that
might
have
been
revealed
by
such
additional
45
information.
46
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
33
of
36
1
HSRB
Consensus
and
Rationale
2
3
The
Board
concluded
that:
4
5
There
was
no
clear
and
convincing
evidence
that
the
conduct
of
the
research
was
6
fundamentally
unethical
(
e.
g.,
the
research
was
intended
to
seriously
harm
participants
or
failed
7
to
obtain
informed
consent).
8
9
There
was
no
clear
and
convincing
evidence
that
the
conduct
of
the
study
was
10
significantly
deficient
relative
to
the
ethical
standards
prevailing
when
the
study
was
conducted.
11
12
The
Board
based
these
two
determinations
on
its
conclusion
that
this
study,
based
on
the
13
evidence
presented,
appeared
to
have
had
only
relatively
minor
deviations
from
the
ethical
14
standards
prevailing
when
the
study
was
conducted.
15
16
COMMENTARY
ON
SCIENTIFIC
STANDARDS
FOR
HUMAN
DOSING
STUDIES
17
18
The
Chair
asked
the
Board
to
articulate
the
set
of
scientific
standards
that
has
and
will
19
continue
to
guide
Board
decision­
making
for
human
dosing
studies.
Following
Board
20
deliberation,
scientific
standards
for
human
dosing
studies
in
general
and
for
single
dose
studies
21
in
particular
were
adopted.
22
23
Scientific
Standards
for
Human
Dosing
Studies
24
25
1.
Justification
26
27
 
Is
the
scientific
question
worthwhile?
28
 
Are
human
subjects
necessary
to
answer
the
question?
29
 
Is
potential
risk
serious
or
irreversible?
30
31
2.
Dose
Selection
32
33
 
Sufficient
to
test
the
question?
(
single
dose
in
most
cases
is
not
sufficient
to
determine
34
NOAEL
and
LOAEL)
35
 
Based
on
appropriate
data
(
e.
g.
preclinical;
previous
studies)
36
37
3.
Endpoint
Selection
38
39
 
Consistent
with
the
aim
of
the
study?
40
 
Appropriate
to
answer
questions
about
human
responses
(
e.
g.,
sensitivity,
accuracy,
validity,
41
replicability)?
42
 
Measured
accurately
and
reliably
with
good
quality
assurance?
43
 
Participants
44
 
Characteristics
generalizable
to
question
asked?
45
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
34
of
36
 
Appropriate
inclusion/
exclusion
criteria?
1
 
Are
measurements
taken
at
appropriate
times
to
answer
the
study
question?
2
3
4.
Method
4
5
 
Is
the
sample
size
sufficient?
6
 
Is
selection
of
control
and
experimental
groups
appropriate?
7
 
Is
the
staging
of
dose
intervals,
dose
amounts,
and
type
of
exposure
sufficient
to
answer
the
8
question?
9
 
Is
there
quality
assurance
for
observations,
instruments
and
data?
10
11
5.
Statistical
Analyses
12
13
 
Can
data
be
statistically
analyzed?
14
 
Is
the
statistical
method
appropriate
to
answer
the
question?
15
16
Scientific
Standards
for
Single
Dose
Level
Study
17
18
Board
definition
of
single
dose
level
study
­
individual
study
that
uses
one
dose
level
irrespective
19
of
the
number
of
subjects,
frequency
of
dosing
or
inclusion
of
a
control
or
placebo.
20
21
1.
In
general,
single
dose
level
studies
have
limited
utility
22
23
 
Such
studies
cannot
be
used
in
isolation
to
establish
a
NOAEL
or
LOAEL
24
 
In
rare
instances
they
may
have
utility
if
interpreted
within
the
context
of
one
or
more
25
supplementary
studies
that
provide
information
at
other
dose
levels
under
analogous
26
conditions.
27
28
2.
Single
dose
level
studies
may
be
able
to
answer
a
very
focused
question
29
30
 
However
in
such
instances
its
utility
will
depend
upon
the
robustness
of
study
design,
the
31
rationale
for
the
study
and
whether
the
study
design
was
consistent
with
the
rationale.
32
 
Evaluation
of
robustness
will
include
questions
of:
control,
relevant
endpoints,
evidence
that
33
measures
can
identify
an
adverse
effect
or
detect
a
change,
use
of
a
surrogate
marker
that
is
34
quantifiable
and
recognized
as
an
established
function
of
the
compound
and
other
criteria
for
35
scientific
validity.
36
37
3.
A
single
dose
level
study
may
have
utility
if
it
provides
evidence
of
adverse
effects
observed
38
at
lower
levels
than
other
studies
have
indicated.
39
40
41
Proposed
Final
Draft
v.
1
Dated
June
14,
2006;
Do
Not
Cite
or
Quote
35
of
36
REFERENCES
1
2
3
ADTC.
2004.
Memorandum:
Hexavalent
Chromium
­
Finalization
of
Issues
related
to
4
Quantitation
of
Dermal
Risk
from
exposure
to
treated
wood
containing
hexavalent
chromium,
5
Antimicrobials
Division
Toxicity
Endpoint
Selection
Committee,
August
31.
6
7
Hansen
MB.
Johansen
JD.
Menné
T.
2003.
Chromium
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significance
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both
CR(
III)
and
8
Cr(
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Contact
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49:
206­
212.
9
10
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of
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1975.
Principles
for
Evaluating
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in
the
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11
12
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J.
Paustenbach
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Adams
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dermatitis
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16
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Environmental
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13.
html
19
20
Russell
MJ
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TI.
(
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Methyl
Isothiocyanate:
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human
olfactory
21
detection
threshold
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MRID
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25
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26
4­
6,
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28
United
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Environmental
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Methyl
29
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Eye
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Odor
Threshold.
30
31
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2006a.
EPA's
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Hexavalent
Chromium
Human
Sensitization
32
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34
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United
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Protection
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Weight
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3
