Document ID: EPA-HQ-OPP-2003-0360-0012
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-06-29T04:00Z

Preliminary
N­
Methyl
Carbamate
Cumulative
Risk
Assessment:
Fact
Sheet
EPA
has
released
its
preliminary
cumulative
risk
assessment
for
the
N­
methyl
carbamate
pesticides.
This
assessment
is
based
on
evaluation
of
the
potential
for
people
to
be
exposed
to
more
than
one
member
of
this
group
of
pesticides
at
a
time
and
considers
exposures
from
food,
drinking
water,
and
residential
sources.
The
assessment
incorporates
regional
exposures
from
residential
and
drinking
water
sources,
as
the
most
appropriate
way
to
account
for
the
considerable
variation
in
potential
exposures
across
the
country.

Because
this
is
a
preliminary
assessment,
it
is
too
soon
to
draw
firm
conclusions
about
risks
or
consider
risk
management
possibilities.
EPA
is
still
reviewing
the
results
and
seeking
scientific
peer
review.
EPA
has
submitted
the
preliminary
risk
assessment
to
the
FIFRA
Scientific
Advisory
Panel
(
SAP),
and
will
evaluate
comments
from
the
public
and
the
SAP,
and
incorporate
additional
data
received.
EPA
will
modify
this
assessment
as
appropriate.
The
revised
cumulative
assessment
will
incorporate
chemical­
specific
Food
Quality
Protection
Act
(
FQPA)
factors.
As
existing
analyses
are
revised
or
new
information
becomes
available,
EPA
will
review
this
assessment
and
make
further
changes
as
appropriate.

Preliminary
Assessment
of
N­
Methyl
Carbamate
Pesticides
This
assessment
is
preliminary
and
subject
to
refinement.
The
Agency
cautions
against
premature
conclusions
based
on
this
preliminary
assessment,
and
against
any
use
of
information
contained
in
these
documents
out
of
their
full
context.
Risk
mitigation
measures
have
already
been
taken
on
some
individual
members
of
this
group
of
pesticides,
through
interim
reregistration
decisions.
The
individual
chemical
assessments
for
other
members
of
this
group
have
not
yet
been
completed.
The
Agency
is
reviewing
the
results
of
the
assessment
to
determine
if
any
issues
may
need
to
be
addressed
related
to
food
commodities,
drinking
water,
and
residential
uses.
However,
EPA
has
confidence
in
the
overall
safety
of
our
food
supply
and
emphasizes
the
importance
of
eating
a
varied
diet
rich
in
fruits
and
vegetables.
At
this
point,
no
target
Margin
of
Exposure
(
MOE)
has
been
established.
Also,
no
FQPA
safety
factor
has
been
incorporated
into
the
assessment.

By
evaluating
the
potential
for
combined
exposures
to
two
or
more
N­
methyl
carbamate
pesticides,
the
assessment
moves
beyond
the
already
high
level
of
protection
of
public
health
provided
by
the
individual
aggregate
assessments.
Looking
at
exposure
over
time
helps
take
into
account
the
potential
effects
of
additional
exposure
before
complete
recovery
from
any
given
exposure.
It
also
evaluates
variation
in
exposure
from
drinking
water
and
residential
uses
in
different
areas
of
the
country.

Defining
Cumulative
Risk
Assessment
A
cumulative
risk
assessment
is
the
process
of
combining
exposure
(
the
amount
of
a
pesticide
to
which
an
individual
is
exposed)
and
hazard
(
the
health
effects
a
pesticide
could
cause)
from
all
substances
that
share
a
common
mechanism
of
toxicity.
The
Food
Quality
Protection
Act
(
FQPA)
directs
EPA
to
consider
the
combined
effects
to
human
health
that
can
result
from
exposure
to
such
pesticides
and
other
substances.

The
potential
risk
presented
by
a
pesticide
depends
on
the
toxicity
of
the
pesticide
and
the
amount
of
the
pesticide
to
which
a
person
is
exposed.
It
is
important
to
note
that
a
pesticide
having
low
toxicity
but
the
potential
for
high
exposure
can
present
a
risk
similar
to
that
of
a
pesticide
having
high
toxicity
but
very
little
potential
for
exposure.
Since
people
can
be
exposed
to
several
pesticides
that
act
the
same
way
in
the
body
at
the
same
time
through
various
foods,
drinking
water,
and
from
uses
in
and
around
the
home,
school,
or
recreational
areas,
it
is
also
necessary
to
assess
the
effects
of
cumulative
exposure.

Potential
Health
Effects
of
the
N­
Methyl
Carbamate
Pesticides
The
N­
methyl
carbamate
pesticides
affect
the
nervous
system
by
reducing
the
ability
of
cholinesterase,
an
enzyme,
to
function
properly
in
regulating
a
neurotransmitter
called
acetylcholine.
Acetylcholine
helps
transfer
nerve
impulses
from
a
nerve
cell
to
a
muscle
cell
or
another
nerve
cell.
If
acetylcholine
is
not
properly
controlled
by
cholinesterase,
the
nerve
impulses
or
neurons
remain
active
longer
than
they
should,
overstimulating
the
nerves
and
muscles
and
causing
symptoms
such
as
weakness
or
paralysis
of
the
muscles.

There
are
other
pesticides
which
are
considered
'
carbamate'
pesticides.
However,
only
the
N­
methyl
subclass
of
pesticides
is
considered
in
this
cumulative
risk
assessment.
The
Nmethyl
carbamates
share
the
ability
to
inhibit
cholinesterase
through
a
specific
pathway.
Other
'
carbamate'
pesticides
do
not
share
the
same
common
mechanism.

In
general,
cumulative
risk
assessments
consider
currently
registered
N­
methyl
carbamates
unless
they:

 
are
being
phased
out
according
to
specific
legal
agreements
or
 
pose
negligible,
if
any,
potential
for
exposure,
based
on
results
of
their
individual
risk
assessments
The
full
risk
assessment
provides
details
about
the
pesticides
included
and
excluded.

(
For
more
details,
see
the
Federal
Register
Notice
announcing
availability
of
the
carbamate
cumulative
assessment
group:
http://
www.
epa.
gov/
fedrgstr/
EPAPEST
2004/
February/
Day­
04/
p2157.
htm)
EPA's
Approach
to
Conducting
Cumulative
Risk
Assessment
EPA's
approach
to
cumulative
risk
assessment
relies
on
a
careful
review
of
the
data
on
toxicity
of
individual
pesticides
and
information
on
potential
for
exposure.

Before
beginning
the
cumulative
assessment
process,
EPA
generally
assesses
risks
associated
with
individual
pesticides.
For
each
individual
pesticide,
EPA
performs
an
aggregate
risk
assessment
(
considering
all
combined
sources
of
exposure).
In
the
aggregate
assessment,
EPA
considers
exposures
to
the
individual
pesticide
from
food,
drinking
water,
and
residential
uses.
At
this
stage,
if
risks
exceed
EPA's
level
of
concern,
the
Agency
would
take
steps
to
reduce
risks
associated
with
the
chemical
to
acceptable
levels.
EPA's
revised
guidance
on
aggregate
risk
assessment
("
General
Principles
for
Performing
Aggregate
Exposure
and
Risk
Assessment")
is
available
on
the
web
at
www.
epa.
gov/
pesticides/
trac/
science.

The
process
generally
follows
these
steps:

 
Identify
Pesticides
with
a
Common
Mechanism
EPA
identifies
pesticides
that
have
a
common
mechanism
of
toxicity.
Once
identified,
these
pesticides
are
called
a
"
common
mechanism
group."
Such
a
group
consists
of
pesticides
for
which
scientifically
reliable
data
demonstrate
that
the
same
toxic
effect
occurs
in
or
at
the
same
organ
or
tissue
by
essentially
the
same
sequence
of
major
biochemical
events.
EPA
guidance
on
the
process
for
identifying
whether
pesticides
have
a
common
mechanism
("
Guidance
for
Identifying
Pesticides
and
Other
Substances
that
Have
a
Common
Mechanism
of
Toxicity")
is
available
on
the
web
at
www.
epa.
gov/
pesticides/
trac/
science.

 
Perform
a
Cumulative
Assessment
After
establishing
the
common
mechanism
group,
EPA
performs
the
cumulative
risk
assessment
in
four
steps:

1.
Hazard
Assessment
and
Characterization
­
This
step
identifies
the
potential
health
effects
that
can
be
caused
by
a
pesticide.
For
the
cumulative
assessment,
this
includes
the
potential
for
health
effects
from
exposure
to
multiple
pesticides
with
a
common
mechanism
of
toxicity,
including
consideration
of
conditions
that
will
allow
the
effects
to
cumulate
and
whether
specific
subgroups
might
have
increased
sensitivity
to
the
common
toxic
effect.

2.
Dose­
Response
Assessment
and
Characterization
­
This
step
determines
the
relative
toxic
strength
of
each
pesticide
included
in
the
assessment
and
establishes
a
dose
that
is
used
to
estimate
the
potential
combined
risk.
3.
Exposure
Assessment
and
Characterization
­
This
step
assesses
who
is
potentially
exposed,
how
they
might
be
exposed,
and
how
much
of
the
pesticide
people
could
be
exposed
to
through
food,
drinking
water,
and
various
non­
agricultural
uses,
such
as
use
in
and
around
the
home.
For
the
cumulative
assessment,
EPA
will
assess
the
potential
for
humans
to
be
exposed
to
multiple
members
of
the
common
mechanism
group
at
the
same
time
and
whether
there
are
regional
or
subpopulation
concerns.

4.
Risk
Characterization
­
This
step
identifies
the
strengths
and
weaknesses
of
the
analysis,
potential
sources
of
risk,
and
any
subpopulations
that
are
at
increased
risk.
It
describes
the
Agency's
confidence
in
the
results
as
well
as
assumptions
used
and
uncertainties
in
the
analysis.

The
first
two
steps
include
use
of
a
weight­
of­
the­
evidence
approach
to
determine
the
harmful
effect
that
occurs
through
a
common
mechanism
of
toxicity
and
to
establish
a
common
measure
of
toxic
potency.
A
weight­
of­
the­
evidence
approach
involves
reviewing
all
pertinent
data
and
information,
assessing
the
strengths
and
weaknesses
of
the
data,
and
reaching
conclusions
based
on
the
overall
picture
provided
by
the
data,
rather
than
based
on
any
one
specific
study.
One
way
of
comparing
toxic
potency
is
by
selecting
one
pesticide
as
the
"
index"
pesticide
(
generally
the
one
for
which
the
Agency
has
the
best
information
on
effects
at
a
variety
of
doses)
and
comparing
the
other
pesticides
to
it
to
determine
their
relative
potency
(
e.
g.,
one
might
be
half
as
toxic
as
the
index
pesticide,
while
another
might
be
twice
as
toxic).

Steps
3
and
4
include
estimating
exposure
and
risks
for
the
food,
drinking
water,
and
residential/
non­
occupational
pathways.
EPA
combines
these
exposures
using
a
calendarbased
software
modeling
tool
that
allows
the
user
to
develop
exposure
estimates
for
a
period
of
time,
such
as
a
day,
a
week,
or
a
month.

EPA
has
published
guidance
on
conducting
cumulative
risk
assessments.
This
guidance
has
been
reviewed
by
the
FIFRA
Scientific
Advisory
Panel.
The
revised
guidance
is
available
on
EPA's
Web
site
at
http://
www.
epa.
gov/
pesticides/
trac/
science/
cumulative_
guidance.
pdf
(
PDF,
90
pp.,
490
KB,
about
PDF).

Combining
Results
of
the
Food,
Water,
and
Residential
Assessments
EPA
is
undertaking
regional
risk
assessments
for
potential
exposures
from
drinking
water
and
residential
pesticide
uses.
These
regional
assessments
will
allow
the
Agency
to
take
into
account
the
variation
in
uses
of
pesticides
across
the
country,
as
well
as
the
differences
both
in
sources
of
drinking
water
and
in
the
potential
for
presence
of
pesticide
residues
in
water
sources.

The
Agency's
food
risk
assessment
for
the
N­
methyl
carbamate
pesticides
is
based
primarily
on
residues
reported
in
the
U.
S.
Department
of
Agriculture's
Pesticide
Data
Program.
The
estimate
of
food
exposure
is
conducted
on
a
national
basis,
since
most
food
commodities
are
available
in
all
areas
of
the
country.
EPA
will
combine
this
national
food
assessment
with
the
regional
drinking
water
and
residential
results.

Using
the
results
of
the
cumulative
risk
assessment
in
making
tolerance
reassessment
decisions
FQPA
requires
EPA
to
consider
the
cumulative
effects
of
substances
that
share
a
common
mechanism
of
toxicity
in
making
decisions
about
the
safety
of
pesticide
residues
in
food.
The
current
risk
assessment
is
a
preliminary
version;
it
will
not
be
used
in
making
risk
management
decisions.
EPA's
tolerance
reassessment
decisions
for
the
Nmethyl
carbamate
pesticides
will
take
into
account
the
public
comment
and
scientific
consultation
planned
for
the
next
few
months.
When
the
risk
assessment
is
revised,
EPA
will
require
any
unacceptable
risks
to
be
reduced
to
acceptable
levels.
In
the
meantime,
EPA
has
already
taken
significant
actions
and
continues
to
act
on
risks
associated
with
individual
pesticides,
based
on
the
risk
assessments
for
those
pesticides.

Data
Sources
Used
for
the
Preliminary
Assessment
EPA
has
attempted
to
obtain
the
best
available
data
to
use
in
each
component
of
this
risk
assessment.
The
sources
of
data
vary
for
the
food,
water,
and
residential
components
of
the
risk
assessment.

The
sources
of
data
for
the
food
component
include:

 
USDA's
Pesticide
Data
Program
 
USDA's
Continuing
Survey
of
Food
Intake
by
Individuals
 
The
Food
and
Drug
Administration
Center
monitoring
data
For
the
water
component
of
the
assessment:

 
USDA
Agricultural
Chemical
Usage
Reports
for
Field
Crops,
Fruits,
and
Vegetables
 
USDA
Typical
Planting
and
Harvesting
Dates
for
Field
Crops
and
Fresh
Market
and
Processing
Vegetables
 
Local
sources
for
refinements
 
Monitoring
studies
from
USGS
and
other
sources
For
the
residential/
non­
occupational
component:

 
Doane­
Golftrak
 
Outdoor
Residential
Exposure
Task
Force
(
ORETF
Survey)
 
Studies
from
scientific
literature
(
for
more
detail,
refer
to
the
preliminary
assessment
document
available
from
the
SAP
meeting
Web
page.)
 
Exposure
Factors
Handbook
 
REJV
Survey
Key
Steps
Taken
to
Date
to
Develop
the
Methods
Used
in
Cumulative
Risk
Assessment
EPA
used
an
open
process
in
developing
cumulative
risk
assessment
methods
and
approaches,
beginning
shortly
after
the
1996
enactment
of
the
Food
Quality
Protection
Act.
EPA
held
numerous
public
meetings
on
various
components
of
the
methods
used
in
the
risk
assessment:

 
More
than
30
consultations
with
the
FIFRA
Scientific
Advisory
Panel
on
various
issues
related
to
scientific
methods
used
in
the
assessment.
 
The
International
Life
Sciences
Institute
(
ILSI)
held
workshops
with
EPA
and
other
scientists
on
topics
related
to
cumulative
risk
assessment.

In
addition,
EPA
released
for
public
comment
10
science
policy
papers
related
to
the
cumulative
process
over
the
past
several
years,
including
the
draft
guidance
on
cumulative
risk
assessment
for
comment
on
June
30,
2000.

For
More
Information
 
For
information
on
assessing
cumulative
pesticide
risk,
visit:
http://
www.
epa.
gov/
pesticides/
cumulative/.
 
The
preliminary
risk
assessment
is
available
from
the
SAP
meeting
Web
page.
 
Information
about
the
SAP
meeting
and
related
information
are
available
at:
http://
www.
epa.
gov/
oscpmont/
sap/#
august.
 
Additional
background
documents
will
be
posted
as
they
become
available.