Page
1
of
9
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
February
14,
2002
MEMORANDUM
SUBJECT:
Propionic
Acid.
HED
Science
Assessment
for
Tolerance
Reassessment
Eligibility
Decision.
PC
Code
077702.
DP
Barcode
D279285.

FROM:
Christina
Jarvis,
Environmental
Protection
Specialist
Reregistration
Branch
II
Health
Effects
Division
(
7509C)

THROUGH:
Alan
Nielsen,
Branch
Senior
Scientist
Reregistration
Branch
II
Health
Effects
Division
(
7509C)

TO:
Joseph
Nevola,
Chemical
Review
Manager
Special
Review
Branch
Special
Review
and
Reregistration
Division
(
7508W)

Attached
is
the
tolerance
reassessment
decision
document
for
propionic
acid,
prepared
by
the
Health
Effects
Division
(
HED).
This
decision
document
updates
the
tolerance
exemptions
for
propionic
acid
issued
by
the
EPA
in
May,
1984,
based
on
a
review
of
the
toxicology
database
and
available
information
on
propionic
acid.
In
summary,
HED
concludes
that
propionic
acid
and
its
sodium
and
calcium
salts
are
exempt
from
all
tolerance
requirements
when
used
as
an
active
ingredient
and/
or
as
inert
ingredients.
Furthermore,
a
FQPA
safety
factor
analysis
is
not
required
for
propionic
acid.
Page
2
of
9
1.0
EXECUTIVE
SUMMARY
1.1
Background
Information
and
Statement
of
Purpose
The
Reregistration
Eligibility
Decision
(
RED)
Document
for
propionic
acid
(
PC
Code
077702)
was
completed
in
September
1991
and
concluded
that
all
products
containing
propionic
acid
as
the
active
ingredient
were
eligible
for
reregistration.
However,
since
the
RED
was
issued
prior
to
the
passage
of
the
Food
Quality
Protection
Act
(
FQPA)
of
1996,
a
tolerance
reassessment
eligibility
decision,
or
TRED,
is
now
required
by
the
Agency
for
propionic
acid.
This
document
addresses
possible
exposures
to
residues
of
propionic
acid
in
food,
drinking
water,
and
from
residential
sources
as
pursuant
to
FQPA,
and
makes
a
conclusion
on
the
tolerance
reassessment
of
propionic
acid.

1.2
Regulatory
History
Active
Ingredient
Status
Propionic
acid
was
first
registered
for
pesticidal
use
in
the
early
1970'
s.
As
an
active
ingredient,
it
is
formulated
into
products
that
control
fungi
and
bacteria
in
stored
grains,
hay,
storage
areas
for
silage
and
grains,
poultry
litter,
and
poultry
and
livestock
drinking
water.

Calcium
and
sodium
propionate
(
salts
of
propionic
acid)
are
not
currently
registered
for
use
as
pesticide
active
ingredients.
The
tolerance
exemptions
that
were
established
for
calcium
and
sodium
propionate
in
40
CFR
180.2(
a)
and
40
CFR
180.1015
have
been
revoked.

Inert
Status
Propionic
acid,
calcium
propionate,
and
sodium
propionate
may
be
found
as
inert
ingredients
in
various
pesticide
formulations.
An
inert
ingredient
is
defined
by
the
Agency
as
"
any
ingredient
in
the
product
that
is
not
intended
to
affect
a
target
pest."
The
law
does
not
require
inert
ingredients,
or
"
other
ingredients,"
to
be
identified
by
name
and
percentage
on
the
label,
but
the
total
percentage
of
such
ingredients
must
be
declared.

Propionic
acid
and
sodium
propionate
are
both
identified
on
the
Agency's
"
List
4B"
of
inert
ingredients.
Inert
ingredients
listed
on
List
4B
have
sufficient
data
to
substantiate
they
can
be
used
safely
in
pesticide
products.
When
an
inert
reaches
List
4B,
no
further
regulatory
action
is
anticipated.

Calcium
propionate
is
identified
on
the
Agency's
"
List
3"
of
inert
ingredients,
meaning
that
it
is
of
"
unknown
toxicity."
While
the
Agency
has
reclassified
many
List
3
inerts
as
List
4B
inerts,
it
is
uncertain
whether
or
not
calcium
propionate
is
one
of
these
inerts.
The
Office
of
Pesticide
Program's
Inerts
Workgroup
recommends
that
calcium
propionate
be
classified
as
a
List
4B
inert
ingredient.
Page
3
of
9
Affirmation
as
GRAS
In
May
1984,
propionic
acid,
calcium
propionate,
and
sodium
propionate
were
affirmed
as
Generally­
Recognized­
As­
Safe
(
GRAS)
by
the
Food
and
Drug
Administration
(
FDA)
for
use
as
direct
food
additives
(
i.
e.,
as
chemical
preservatives
and
antimicrobial
agents
in
food).
The
specifications
for
the
affirmation
of
propionic
acid,
calcium
propionate,
and
sodium
propionate
as
GRAS
chemicals
are
listed
in
21
CFR
184.1081,
184.1221,
and
184.1784,
respectively,
and
can
be
summarized
as
follows:
"
The
ingredient
is
used
in
food
with
no
limitation
other
than
current
good
manufacturing
practice."

Tolerance
Exemptions
The
following
tolerance
exemptions
for
propionic
acid
are
listed
in
40
CFR
180.1023:

1.
Residues
in/
on
the
following
raw
agricultural
commodities
following
postharvest
application
(
as
a
fungicide):
alfalfa,
barley
grain,
Bermuda
grass,
bluegrass,
brome
grass,
clover,
corn
grain,
cowpea
hay,
fescue,
lespedeza,
lupines,
oat
grain,
orchard
grass,
peanut
hay,
peavine
hay,
rye
grass,
sorghum
grain,
soybean
hay,
sudan
grass,
timothy,
vetch,
and
wheat
grain.

2.
Residues
in/
on
meat
and
meat
byproducts
of
cattle,
sheep,
hogs,
goats,
horses,
and
poultry,
milk,
and
eggs
when
applied
as
a
bactericide/
fungicide
to
livestock
drinking
water,
poultry
litter,
and
storage
areas
for
silage
and
grain.

3.
Residues
in/
on
the
following
raw
agricultural
commodities
following
postharvest
application
(
as
a
fungicide):
cottonseed,
peanuts,
rice
grain,
and
soybeans.

Propionic
acid
is
also
exempt
from
the
requirement
for
a
tolerance
when
used
in
accordance
with
good
agricultural
practice
as
inert
(
or
occasionally
active)
ingredients
in
pesticide
formulations
applied
to
growing
crops
or
to
raw
agricultural
commodities
after
harvest
as
described
in
40
CFR
180.1001(
c).

1.3
Use
Profile
Active
Ingredient
Uses
Propionic
acid
is
a
fungicide
and
bactericide
registered
to
control
fungi
and
bacteria
in
stored
grains,
hay,
grain
storage
areas,
poultry
litter,
and
drinking
water
for
livestock
and
poultry.
A
search
of
REFS
on
11/
07/
01
shows
propionic
acid
is
formulated
as
a
soluble
concentrate
(
10
percent
a.
i.
to
70.5
percent
a.
i.),
ready­
to­
use
solution
(
39.2
percent
a.
i.
to
100
percent
a.
i.),
and
as
a
granular
(
one
formulation;
15
percent
a.
i.).
The
Agency
notes
that
REFS
incorrectly
lists
Page
4
of
9
EPA
Reg.
No.
53824­
2
(
P­
7
Grain
Preservative)
as
a
granular
formulation.
A
review
of
the
P­
7
Grain
Preservative
label
shows
that
it
is
actually
a
liquid.
The
are
currently
17
active
products
containing
propionic
acid.

Labels
state
that
propionic
acid
may
be
applied
using
a
low­
pressure
spray
system
equipped
with
adequately
arranged
and
calibrated
nozzles
to
provide
the
desired
coverage
to
grain
as
it
is
moved
into
storage,
or
to
hay
just
prior
to
baling
and
stacking.
For
use
on
poultry
litter,
it
is
diluted
with
water
and
applied
to
the
surface
of
the
litter
as
a
spray.
For
grain
storage
areas
(
silos),
it
is
diluted
with
water
and
applied
to
the
surfaces
of
the
storage
areas
as
a
spray.
Propionic
acid
is
poured
directly
into
drinking
water
for
livestock
and
poultry.
Other
application
methods
may
include
low­
and
high­
pressure
hand
wands,
and
a
backpack
sprayer.

Application
rates
of
propionic
acid
depend
on
the
moisture
content
of
the
grain
at
the
time
it
is
placed
in
storage,
and
also
vary
depending
on
whether
the
grains
are
in
"
open"
storage
or
"
closed"
storage.
A
review
of
the
17
current
propionic
acid
labels
shows
that
application
rates
range
from
1.25
lb
ai/
gallon
(
approximately
6
lbs.
ai/
ton
of
grain)
to
8.28
lb
ai/
gallon
(
approximately
31
lbs.
ai/
ton
of
grain).

Other
Uses
(
including
use
as
a
direct
food
additive)

Naturally­
occurring
propionic
acid
is
consumed
by
humans
in
animal
and
dairy
products,
such
as
butter
and
cheese
(
swiss
cheese
may
contain
as
much
as
one
percent
propionic
acid).
Propionic
acid
and
its
salts
are
also
consumed
as
added
ingredients
in
other
foods.
For
example,
propionic
acid
and
its
salts
may
be
used
as
chemical
preservatives
in
jams,
jellies,
and
jelly­
filled
baked
goods,
and
as
antimicrobial
agents
in
cheese
and
bread.
When
used
as
a
direct
food
additive,
propionic
acid
and
its
salts
are
"
generally
recognized
as
safe"
for
human
consumption
(
21
CFR
184.1081,
184.1221,
and
184.1784).
Propionic
acid
is
also
a
normal
component
of
metabolism
in
the
human
body.
Page
5
of
9
2.0
PHYSICAL/
CHEMICAL
PROPERTIES
SUMMARY
Chemical
Name:
Propionic
Acid
Chemical
Structure:

Empirical
Formula:
CH
3
CH
2
COOH
Molecular
Weight:
74.08
Boiling
Point
(
oC):
140.7
Melting
Point
(
oC):
­
21.5
Vapor
Pressure:
3
mm
Hg
at
20oC
P
ow:
2.1
CAS
Number:
79­
09­
4
PC
Code:
077702
Propionic
acid
is
a
colorless,
oily
liquid
at
room
temperature
with
a
rancid,
pungent
odor.
It
is
completely
soluble
in
water,
ethanol,
chloroform,
and
diethyl
ether.
Propionic
acid
occurs
naturally
in
animals
and
in
dairy
products
in
small
amounts.

3.0
HAZARD
CHARACTERIZATION
At
the
time
that
the
propionic
acid
RED
was
completed
in
1991,
the
toxicological
database
was
determined
to
be
adequate
for
the
purposes
of
supporting
reregistration
eligibility,
and
no
further
toxicity
data
on
propionic
acid
were
required
by
the
Agency.
A
comprehensive
open
literature
search,
conducted
from
1991
(
the
date
of
the
RED)
to
the
present
and
including
databases
such
as
Medline
and
Toxline,
has
not
revealed
any
new
studies
on
propionic
acid
that
would
alter
the
toxicological
conclusions
of
the
RED.
A
search
of
the
Pesticide
Data
Management
System
(
PDMS)
conducted
in
April,
2001
has
also
not
revealed
any
new
toxicity
studies
that
would
have
a
significant
impact
on
the
toxicological
findings
for
propionic
acid.
Therefore,
the
Agency
concludes
that
the
toxicology
determinations
made
in
the
propionic
acid
RED
(
September
1991)
are
still
valid.
A
summary
of
these
toxicology
findings
is
presented
below:

3.1.
Hazard
Profile
3.1.1
Acute
Toxicity
Technical
propionic
acid
is
of
moderate
to
low
acute
toxicity
via
the
oral,
dermal,
and
inhalation
routes
of
exposure
(
toxicity
category
of
III),
and
is
not
a
skin
sensitizer.
However,
propionic
acid
is
acutely
toxic
in
eye
and
dermal
irritation
tests
(
toxicity
category
1).
Page
6
of
9
3.1.2
Subchronic
Toxicity
No
subchronic
toxicity
data
are
available
on
propionic
acid
itself;
however,
data
on
calcium
and
sodium
propionate
can
be
used
to
assess
subchronic
toxicity.
Rats
fed
calcium
or
sodium
propionate
at
one
percent
of
the
diet
(
equivalent
to
750
mg/
kg/
day
of
propionic
acid)
for
four
weeks
followed
by
three
percent
(
equivalent
to
1200
mg/
kg/
day
of
propionic
acid)
for
three
weeks
showed
no
changes
in
weight
gain
compared
to
the
controls.
Rats
fed
five
percent
propionic
acid
in
the
diet
(
approximately
5000
mg/
kg
body
weight)
for
110
days
developed
lesions
of
the
forestomach.

Propionic
acid
was
given
in
the
feed
to
dogs
at
220,
735,
or
2066
mg/
kg/
day
for
90
days.
The
high
dose
dogs
showed
reduced
food
consumption,
increased
incidence
of
epithelial
hyperplasia
in
the
esophagus,
and
increased
nitrite
in
the
urine.
These
effects
were
no
longer
present
in
dogs
held
for
a
six
week
recovery
period.
A
limited
study
with
calcium
propionate
in
dogs
for
90
days
showed
vomiting
and
diarrhea
in
animals
fed
2523
mg/
kg/
day.

It
is
noted
that
when
a
human
adult
male
was
fed
6.0
grams
sodium
propionate
a
day,
the
only
effect
noted
was
slightly
alkaline
urine.

3.1.3
Chronic
Toxicity,
Reproduction,
and
Teratology
Twenty
male
rats
per
group
were
fed
four
percent
propionic
acid
in
the
diet
for
two
years.
The
highest
dose
animals
had
hyperplasia
and
hyperplastic
ulcers
in
the
forestomach.
Available
data
on
calcium
and
sodium
propionate
indicate
the
following:

°
Rats
fed
bread
containing
sodium
propionate
(
4000
mg/
kg/
day)
for
a
year
showed
no
adverse
effects,
nor
did
rats
fed
a
similar
diet
for
32
weeks,
other
than
an
initial
depression
of
growth.

°
No
maternal
or
fetal
effects
were
seen
upon
feeding
calcium
propionate
to
pregnant
animals
at
rates
up
to
300
mg/
kg/
day
for
rats
and
mice,
or
up
to
400
mg/
kg/
day
for
hamsters
and
rabbits.

°
No
teratogenicity
was
found
in
developing
chick
embryos
when
up
to
100
mg/
kg
calcium
propionate
was
injected
into
the
yolk
or
air
cell,
although
there
was
increased
mortality
at
5
and
10
mg/
kg.

3.1.4
Mutagenicity
Propionic
acid
gave
negative
results
in
mutagencity
assays
in
five
strains
of
S.
typhimurium
and
one
strain
of
S.
cerevisiae,
with
and
without
activation.

Additional
data
on
calcium
and
sodium
propionate
indicated
that
both
tested
negative
for
mutagenicity
in
S.
typhimurium
and
S.
cerevisiae.

3.1.5
Metabolism
Page
7
of
9
Propionic
acid
is
rapidly
absorbed
from
the
mammalian
gastrointestinal
tract.
Propionic
acid
is
a
normal
intermediary
metabolite
in
the
body.
It
is
utilized
by
most
organs
and
tissues,
and
can
be
metabolized
to
glucose,
carbohydrates,
amino
acids,
and
lipids.
It
is
produced
in
large
quantities
in
ruminants,
and
is
one
of
the
metabolic
products
from
the
breakdown
of
several
amino
acids
in
nonruminants.
Propionic
acid
is
formed
in
the
oxidation
of
fatty
acids
and
from
the
side
chain
of
cholesterol.

3.2
FQPA
Considerations
Based
on
a
review
of
available
toxicology
data,
and
based
on
general
knowledge
of
propionic
acid,
HED
concludes
that
a
FQPA
safety
factor
analysis
for
propionic
acid
is
not
required.
Propionic
acid
is
of
very
low
acute
toxicity
via
the
oral,
dermal,
and
inhalation
routes
of
exposure.
The
toxicology
database
is
complete,
and
no
data
gaps
have
been
identified.
There
are
no
indications
of
special
sensitivity
of
infants
or
children
resulting
from
exposure
to
propionic
acid.
HED's
review
of
propionic
acid
reaffirms
the
FDA
GRAS
designation.

3.3
Dose
Response
Assessment
Toxicity
endpoints
for
use
in
risk
assessment
have
not
been
established
for
propionic
acid,
due
to
its
low
toxicity.

4.0
EXPOSURE
ASSESSMENT
4.1
Dietary
Exposure
Products
containing
propionic
acid
are
registered
for
use
as
fungicides
and
bactericides
on
stored
grains,
hay,
grain
storage
areas,
poultry
litter,
and
drinking
water
for
livestock
and
poultry.
Propionic
acid
is
exempt
from
tolerances
following
postharvest
application
(
as
a
fungicide)
on
the
following:
alfalfa,
barley
grain,
Bermuda
grass,
bluegrass,
brome
grass,
clover,
corn
grain,
cottonseed,
cowpea
hay,
fescue,
lespedeza,
lupines,
oat
grain,
orchard
grass,
peanuts,
peanut
hay,
peavine
hay,
rice
grain,
rye
grass,
sorghum
grain,
soybean
hay,
soybeans,
sudan
grass,
timothy,
vetch,
and
wheat
grain.
Tolerance
exemptions
are
also
in
place
for
residues
of
propionic
acid
in/
on
meat
and
meat
byproducts
of
cattle,
sheep,
hogs,
goats,
horses,
and
poultry,
milk,
and
eggs
when
applied
as
a
bactericide/
fungicide
to
livestock.

Propionic
acid
and
its
salts
are
also
added
directly
to
food
as
chemical
preservatives
and
antimicrobial
agents.
For
example,
propionic
acid
and
its
salts
may
be
added
to
jam­
and
jellyfilled
baked
goods
(
such
as
doughnuts),
pizza
crust,
various
cheeses,
and
breads.
The
use
of
propionic
acid,
calcium
propionate,
and
sodium
propionate
as
direct
food
additives
is
affirmed
by
the
FDA
as
"
generally
recognized
as
safe."
Dairy
products
(
such
as
milk
and
cheese)
may
also
contain
propionic
acid
as
a
naturally­
occurring
component.

Since
residues
from
the
pesticidal
use
of
propionic
acid
are
considered
negligible,
the
likelihood
of
Page
8
of
9
any
significant
dietary
exposure
to
humans
is
very
low.
Potential
exposure
and
risk
from
the
use
of
propionic
acid
as
a
direct
food
additive
is
also
considered
to
be
very
low.
This
conclusion
is
strengthened
by
the
presence
of
propionic
acid
as
a
normal
component
of
metabolism
in
the
human
body,
and
because
propionic
acid
is
a
naturally
occurring
component
in
dairy
products
such
as
butter
and
cheese.

When
considered
together,
these
facts
all
support
HED's
conclusion
that
dietary
exposure
and
dietary
risk
to
propionic
acid
is
extremely
low.
A
dietary
risk
assessment
has
not
been
conducted
and
is
not
required.

4.2
Drinking
Water
Exposure
Environmental
fate
data
requirements
for
propionic
acid
have
been
waived
based
on
its
labeled
use
pattern.
Information
on
environmental
fate
was
found
in
previous
reviews
conducted
by
the
Environmental
Fate
and
Effects
Division
(
EFED)
and
in
open
literature.
In
summary,
biodegradation
of
propionic
acid
is
likely
to
be
the
most
important
degradation
pathway
in
aerobic
soil
and
water.
Propionic
acid
is
used
as
a
carbon
source
by
microbes
which
rapidly
mineralize
to
the
metabolic
products
of
carbon
dioxide
and
water.
Propionic
acid
is
expected
to
be
highly
mobile
in
soil.

EFED
has
conducted
a
review
of
propionic
acid
(
both
as
an
active
ingredient
and
as
an
inert
ingredient)
to
determine
potential
concentrations
in
drinking
water.
Based
on
its
review,
EFED
has
concluded
that
propionic
acid
drinking
water
concentrations
as
a
result
of
its
use
as
an
active
ingredient
are
expected
to
be
negligible.

EFED
believes
that
propionic
acid
exposures
in
drinking
water
will
be
driven
more
by
its
use
as
an
inert
ingredient
than
by
its
use
as
an
active
ingredient.
Concentrations
of
propionic
acid
in
drinking
water,
when
applied
as
an
inert
ingredient,
were
calculated
using
screening­
level
modeling
(
FIRST
and
SCI­
GROW).
Estimated
concentrations
are
as
follows:
92
ppb
(
acute)
and
6
ppb
(
chronic)
in
surface
water,
and
1.3
ppb
(
acute
and
chronic)
in
ground
water.
It
is
important
to
note
that
these
these
concentrations
are
based
on
a
number
of
uncertainties,
such
as
an
assumed
maximum
application
rate
of
1
lb
ai/
acre
and
limited
fate
data.
Since
HED
does
not
have
any
information
on
what
products
are
formulated
with
propionic
acid
as
an
inert
ingredient,
or
the
actual
rate
at
which
propionic
acid
is
applied
as
an
inert
ingredient.
Therefore,
no
further
analysis
has
been
conducted.

4.3
Non­
Occupational
(
Residential)
Exposure
Propionic
acid
is
not
registered
for
any
non­
occupational
(
residential)
uses.
Post­
application
exposure
of
homeowners
to
residues
of
propionic
acid
is
also
not
expected
to
occur,
as
propionic
acid
is
used
mainly
on
stored
grains
and
in
grain
storage
areas.
Due
to
the
use
pattern
of
propionic
acid,
exposure
from
spray
drift
is
also
not
expected
to
be
of
concern.
Therefore,
nonoccupational
exposure
was
not
considered
in
this
tolerance
reassessment.
Page
9
of
9
5.0
CONCLUSIONS
Based
on
its
low
toxicity,
limited
use
pattern,
and
affirmation
as
a
GRAS
chemical
when
used
as
a
food
additive,
propionic
acid
is
not
expected
to
result
in
any
adverse
health
effects
via
the
food,
drinking
water,
or
residential
exposure
pathways.
There
is
a
possibility
of
eye
and
skin
irritation
to
occupational
handlers;
this
was
mitigated
through
the
reregistration
process,
on
a
product­
byproduct
basis,
by
the
requirement
for
personal
protective
equipment
on
existing
propionic
acid
labels.
A
review
of
the
toxicology
database,
with
an
emphasis
on
sensitivity
of
infants
and
children,
shows
no
significant
findings
since
the
date
of
the
original
propionic
acid
RED
from
1991.
HED
concludes
that
a
FQPA
safety
factor
analysis
is
not
required
for
propionic
acid.
Propionic
acid,
calcium
propionate,
and
sodium
propionate
will
be
exempt
from
all
tolerance
requirements.

The
Agency
notes
that
propionic
acid
and
its
calcium
and
sodium
salts
are
included
on
the
Agency's
list
of
chemicals
included
in
the
High
Production
Volume
(
HPV)
Challenge
Program.
HPV
chemicals
are
those
that
are
manufactured
or
imported
into
the
United
States
in
volumes
greater
than
one
million
pounds
per
year.
There
are
approximately
3,000
HPV
chemicals
that
are
produced
or
imported
into
the
United
States.
The
HPV
Challenge
Program
is
a
voluntary
partnership
between
industry,
environmental
groups,
and
the
EPA
which
invites
chemical
manufacturers
and
importers
to
provide
basic
hazard
data
on
the
HPV
chemicals
they
produce/
import.
The
goal
of
this
program
is
to
facilitate
the
public's
right­
to­
know
about
the
potential
hazards
of
chemicals
found
in
their
environment,
their
homes,
their
workplace,
and
in
consumer
products.

The
Agency
has
received
at
least
one
full
commitment
from
a
company
or
consortium
to
sponsor
propionic
acid
and
its
calcium
salt
as
part
of
the
Agency's
HPV
Challenge
Program.
The
sodium
salt
is
not
currently
being
sponsored;
however,
it
is
within
the
scope
of
the
HPV
Challenge
Program
and
is
currently
available
for
sponsorship.

Based
on
toxicity
data
already
submitted
on
propionic
acid,
and
the
completeness
of
the
propionic
acid
toxicity
data
base
(
including
subchronic,
chronic,
reproduction,
teratology,
and
mutagenicity
studies),
the
Agency
feels
confident
in
proceeding
with
this
tolerance
reassessment
decision.
Any
submission
of
data
by
current
or
future
sponsors
of
propionic
acid
and
its
sodium
and
calcium
salts
as
part
of
the
HPV
Challenge
Program
may,
in
the
future,
be
used
by
the
Office
of
Pesticide
Programs
to
revise
or
update
their
tolerance
reassessment
decision
for
propionic
acid
and
its
sodium
and
calcium
salts
as
deemed
necessary
and
appropriate.
