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1
of
5
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
Date:
March
24,
2006
Subject:
Issues
to
Consider
in
Commenting
on
the
Preliminary
Risk
Assessments
for
the
Organic
Arsenic
Herbicides
(
Case
Numbers
2080
and
2395)

From:
Lance
Wormell,
Chemical
Review
Manager
Reregistration
Branch
2
Special
Review
and
Reregistration
Division
To:
Organic
Arsenic
Herbicides
Docket
(
EPA­
HQ­
OPP­
2006­
0201)

The
Environmental
Protection
Agency's
(
EPA
or
"
the
Agency")
Office
of
Pesticide
Programs
(
OPP)
has
completed
its
preliminary
risk
assessments
in
support
of
the
reregistration
eligibility
decision
(
RED)
for
cacodylic
acid
(
DMA),
monosodium
methanearsonate
(
MSMA),
disodium
methanearsonate
(
DSMA),
and
calcium
methanearsonate
(
CAMA),
collectively
referred
to
as
the
"
organic
arsenic
herbicides."
These
and
other
support
documents
are
now
available
for
public
comment.
Reviewers
may
submit
comments
to
public
docket
#
EPA­
HQ­
OPP­
2006­
0201
on
the
web
at
http://
www.
regulations.
gov/.

SECTION
I:
BACKGROUND
EPA
is
developing
a
RED
for
the
organic
arsenic
herbicides
cacodylic
acid,
MSMA,
DSMA,
and
CAMA.
The
Food
Quality
Protection
Act
(
FQPA)
requires
EPA
to
consider
all
potential
sources
of
exposure
to
the
organic
arsenic
herbicides
as
well
as
exposure
to
metabolites
and/
or
transformation
products
of
organic
arsenic.
Since
there
is
potential
for
the
organic
arsenic
herbicides
to
transform
to
inorganic
arsenic
in
the
environment,
EPA
has
also
considered
the
risk
resulting
from
exposure
to
inorganic
arsenic.

Publishing
preliminary
risk
assessments
and
risk
mitigation/
exposure
reduction
options
for
public
comment
is
part
of
EPA's
modified
Four­
Phase
public
participation
process.
The
Agency
uses
this
process
to
involve
the
public
in
developing
pesticide
reregistration
and
tolerance
reassessment
decisions.
As
announced
in
the
Federal
Register,
EPA
has
published
the
organic
arsenic
herbicides
preliminary
risk
assessments
for
public
comment.
EPA
is
also
seeking
input
on
the
questions
presented
in
this
document
to
Page
2
of
5
potentially
address
uncertainties
and
aid
the
Agency
in
making
its
reregistration
eligibility
decision.

There
has
been
extensive
public
discussion
and
elucidation
of
issues
related
to
the
hazard/
toxicity
associated
with
the
organic
arsenic
herbicides,
particularly
at
the
EPA's
September
2005
Arsenic
Scientific
Advisory
Board
meeting
(
http://
www.
epa.
gov/
sab/
panels/
arsenic_
review_
panel.
htm).
EPA
acknowledges
that
there
are
uncertainties
associated
with
the
conversion
and
fate
of
the
organic
arsenic
herbicides
in
the
environment.
The
Agency
is
seeking
information
on
arsenic
buildup
in
soil,
arsenic
contribution
to
water,
arsenic
exposure
to
homeowners,
and
arsenic
exposure
to
non­
target
species.
EPA
is
requesting
input
from
the
public,
stakeholders,
and
other
state
and
Federal
agencies.

Below
are
several
terms
and
definitions
to
keep
in
mind
when
reading
and
commenting
on
the
risk
assessments:

Organic
arsenic:
The
"
organic"
form
of
arsenic
includes
the
pesticides
cacodylic
acid,
MSMA,
DSMA,
and
CAMA;
organic
arsenic
compounds
can
also
be
found
naturally
in
the
environment.
Inorganic
arsenic:
Found
naturally
in
the
environment,
the
"
inorganic"
form
of
arsenic
is
the
more
toxic
form
and
is
known
to
cause
cancer
in
humans.
Total
arsenic:
"
Total"
arsenic
is
used
to
describe
all
the
arsenic
present
in
a
sample
regardless
of
its
form
(
i.
e.,
organic
arsenic
+
inorganic
arsenic);
EPA
and
state/
Federal
agencies
measure
and/
or
establish
regulatory
limits
in
soil
and
water
for
total
arsenic.
Transformation:
The
process
of
arsenic
changing
forms
(
i.
e.,
organic
to
inorganic
or
vice
versa).
Speciating:
Quantifying
the
concentration
of
inorganic
and
organic
arsenic
in
a
soil
or
water
sample
(
as
opposed
to
only
total
arsenic);
"
speciated"
data
provide
a
breakdown
of
organic
and
inorganic
arsenic
whereas
"
unspeciated"
data
provide
only
total
arsenic.
Soil
Screening
Level
(
SSL):
Risk­
based
concentrations
for
contaminants
established
by
EPA's
Office
of
Solid
Waste
and
Environmental
Response
(
OSWER)
to
identify
areas,
chemicals,
and
pathways
of
concern
at
National
Priority
List
sites
that
need
further
investigation
and
those
that
require
no
further
attention
under
the
Comprehensive
Environmental
Response,
Compensation,
and
Liability
Act
(
CERCLA);
the
arsenic
SSL
(
0.4
ppm)
is
not
a
national
target
cleanup
level.
Maximum
Contaminant
Level
(
MCL):
Established
by
EPA's
Office
of
Water
(
OW),
the
arsenic
MCL
in
water
(
10
ppb)
is
set
to
protect
consumers
served
by
public
water
systems
from
the
effects
of
chronic
exposure
to
arsenic;
public
drinking
water
facilities
must
supply
water
with
levels
of
arsenic
at
or
below
the
MCL.
Methylation
and
demethylation:
The
chemical
process
that
transforms
metals
such
as
arsenic
by
the
addition
(
methylation)
or
removal
(
demethylation)
of
methyl
groups
(
CH3)
to
the
molecule.
Monomethyl
methanearsonate
(
MMA):
MMA
refers
to
organic
arsenic
compounds
with
a
single
methyl
group;
in
these
assessments,
the
term
"
MMA"
is
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3
of
5
used
collectively
to
refer
to
MSMA,
DSMA,
and
CAMA
(
salts
of
MMA
that
readily
dissociate
to
MMA
in
water).
Dimethyl
methanearsonate
(
DMA):
DMA
refers
to
organic
arsenic
compounds
with
two
methyl
groups
such
as
cacodylic
acid;
since
cacodylic
acid
is
the
only
registered
dimethyl
organic
arsenic
herbicide,
DMA
and
cacodylic
acid
are
used
interchangeably
in
these
assessments.

SECTION
II:
QUESTIONS
This
section
provides
questions
to
elicit
and
guide
comments
on
EPA's
preliminary
risk
assessments.
The
questions
focus
on
five
issues:
arsenic
buildup
in
soil,
arsenic
contribution
to
water,
arsenic
exposure
to
homeowners,
arsenic
exposure
to
non­
target
species,
and
additional
information.
Note
that
these
questions
are
offered
for
comment
and
are
not
meant
to
imply
that
EPA
intends
to
complete
or
require
any
of
the
measures
herein.
When
submitting
comments,
please
identify
the
question(
s)
you
are
addressing
and
include
discussions,
explanations,
and
references
where
possible.

1.
Arsenic
buildup
in
soil
from
the
use
of
organic
arsenic
herbicides
Application
of
organic
arsenic
herbicides
may
lead
to
buildup
of
total
arsenic
in
soil.
a.
What
measures
would
reduce
the
likelihood
that
arsenic
would
buildup
in
soil
as
a
result
of
continued
organic
arsenic
herbicide
use?
b.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
reduce
the
likelihood
of
arsenic
buildup
in
soil?
c.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?

2.
Arsenic
contribution
to
water
from
the
use
of
organic
arsenic
herbicides
Application
of
organic
arsenic
herbicides
may
increase
total
arsenic
in
water.
a.
What
measures
could
reduce
the
amount
of
arsenic
in
water
as
a
result
of
continued
organic
arsenic
herbicide
use?
b.
In
what
way
would
limiting
organic
arsenic
herbicide
use
in
areas
vulnerable
to
leaching
or
runoff
be
feasible
and
would
it
help
reduce
the
amount
of
arsenic
contribution
to
water?
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of
5
c.
In
what
way
would
limiting
organic
arsenic
herbicide
use
in
areas
vulnerable
to
leaching
or
runoff
reduce
the
amount
of
arsenic
in
water
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?
d.
In
what
way
would
buffer
zones
in
areas
near
or
adjacent
to
water
bodies
reduce
the
amount
of
arsenic
contribution
to
water?
e.
In
what
way
would
buffer
zones
in
areas
near
or
adjacent
to
water
bodies
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?
f.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
reduce
amount
of
arsenic
contribution
to
water?
g.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?

3.
Arsenic
exposure
to
homeowners
from
the
use
of
organic
arsenic
herbicides
Application
of
organic
arsenic
herbicides
in
the
residential
setting
may
contribute
to
the
buildup
of
total
arsenic
in
soil.
a.
What
measures
would
reduce
the
exposure
to
homeowners
as
a
result
of
continued
organic
arsenic
herbicide
use?
b.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
residential
lawns
in
one
year/
season
reduce
exposure
to
homeowners?
c.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
residential
lawns
in
one
year/
season
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
lawn
care?
d.
In
what
way
would
labeling
the
organic
arsenic
herbicides
as
restricted
use
reduce
exposure
to
homeowners?
Restricted
use
pesticides
may
only
be
applied
by
certified
pesticide
applicators
or
under
the
supervision
of
a
certified
applicator.
e.
In
what
way
would
labeling
the
organic
arsenic
herbicides
as
restricted
use
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
lawn
care?
f.
In
what
way
would
physical
barriers
(
e.
g.,
tarps)
placed
over
residential
lawns
treated
with
cacodylic
acid
for
lawn
renovation
reduce
exposure
to
homeowners?
g.
In
what
way
would
posting
signs
prohibiting
access
to
lawns
treated
with
cacodylic
acid
or
CAMA
reduce
exposure
to
homeowners?

4.
Arsenic
exposure
to
non­
target
organisms
from
the
use
of
organic
arsenic
herbicides
Page
5
of
5
Application
of
organic
arsenic
herbicides
may
lead
to
risk
exceedances
for
terrestrial
nontarget
organisms.
a.
What
measures
would
reduce
the
exposure
to
non­
target
organisms
as
a
result
of
continued
organic
arsenic
herbicide
use?
b.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
reduce
exposure
to
non­
target
organisms?
c.
In
what
way
would
limiting
the
maximum
amount
of
organic
arsenic
herbicide
that
may
be
applied
to
a
site
in
one
year/
season
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?
d.
In
what
way
would
buffer
zones
reduce
exposure
to
non­
target
organisms?
e.
In
what
way
would
buffer
zones
conflict
with
current
growing
practices
or
otherwise
unduly
interfere
with
crop
production?

5.
Additional
information
about
the
organic
arsenic
herbicides
a.
For
each
organic
arsenic
herbicide,
what
additional
estimates
and/
or
data
are
available
on
the
annual
volume
of
pesticide
used
on
golf
courses,
residential
lawns
by
homeowners,
and
residential
lawns
by
professional
applicators?
b.
Are
there
other
environmental
fate
data
not
cited
in
the
preliminary
assessments
that
EPA
should
consider?
c.
What
information
is
available
on
best
management
practices
for
using
organic
arsenic
herbicides
(
e.
g.,
recommended
application
methods/
times
and
storage/
disposal
instructions)?
How
could
this
information
be
disseminated
to
increase
consumer
awareness
of
potential
hazards?
d.
What
alternatives,
either
chemical
or
non­
chemical,
exist
for
agricultural
and
residential
uses
of
the
organic
arsenic
herbicides?
