Bullet fragmentation and lead deposition in white-tailed deer and domestic sheep

In February 2008, a private physician in North Dakota radiographed hunterharvested venison and found that 60 of 100 packages contained metal fragments. This discovery had implications for public-funded venison donation programs, and it prompted several Midwest states to examine their programs. Approximately 500,000 deer hunters harvest >200,000 deer annually in Minnesota, and the state has a donation program similar to North Dakota’s program. Therefore, we analyzed fragmentation patterns and lead deposition in carcasses of 8 white-tailed deer (Odocoileus virginianus) and 72 domestic sheep (Ovis aries). We fired 5 different bullet types from centerfire rifles, and we also fired projectiles from both a shotgun and a black-powder muzzleloader. Centerfire bullets, which are designed to expand quickly upon impacting the animal, left bullet fragments and lead deposits throughout the entire abdominal cavity of carcasses. We also used 2 types of centerfire bullets that were purportedly designed to resist fragmentation. One of these bullet types had fragmentation patterns and lead deposition rates similar to the rapid-expanding bullets; the other bullet type resisted fragmentation, and no lead was detected in muscle tissue that we sampled. Centerfire bullets made from copper resisted fragmentation, and of course did not deposit any lead in muscle tissues. Projectiles fired from the shotgun and black-powder muzzleloader did deposit lead into carcasses but did not fragment as much as bullets fired from centerfire rifles. Our study suggests that rinsing the abdominal cavity may spread the lead contaminant to other areas of the carcass, thereby worsening the contamination situation. We suggest that hunters who use centerfire rifles and are concerned about lead exposure should purchase a bullet type that resists fragmentation. Key words: bullets, deer, donation, fragmentation, human–wildlife conflicts, hunting, lead, policy, venison W"3)#‐)13,#-
 -##'
 (Odocoileus
 virginianus)
 populations
 throughout
 the
United
 States
 are
 a
wildlife
 success
 story
 (Woolf
 and
Roseberry
 1998),
and
hunting
is
the
primary
tool
used
to
 manage
deer
populations
(Stedman
et
al.
2008).
 However,
 there
 is
 considerable
 discussion
 and
 legitimate
 concern
 about
 whether
 or
 not
 hunters
can
control
deer
populations
(Rutberg
 1997,
Brown
et
al.
2000,
Riley
et
al.
2003).
Given
 the
 national
 decline
 in
 hunter
 numbers
 (U.S.
 Department
 of
 Interior
 2007),
 the
 impacts
 of
 large
 deer
 populations
 will
 present
 future
 challenges
to
wildlife
managers.
In
Minnesota,
 approximately
 500,000
 hunters
 harvest
 >200,000
 deer
 annually;
 thus,
 any
 issue
 that
 may
contribute
 to
declines
 in
hunter
numbers
 is
 important
 given
 the
 need
 to
 manage
 deer
 populations. Lead
 is
 a
 toxic
 metal
 found
 in
 the
 natural
 environment
 (Tsuji
 et
 al.
 1999).
 It
 is
 also
 the
 most
 common
metal
 used
 in
 ammunition
 for
 harvesting
game
species
because
of
its
density
 and
malleability.
While
the
toxicological
effects
 associated
with
 lead
poisoning
of
wildlife
has
 been
documented
(Hunt
et
al.
2006,
Cade
2007),
 liele
research
has
been
conducted
related
to
the
 possible
effects
on
humans
consuming
animals
 shot
with
lead.
Johansen
et
al.
(2006)
concluded
 that
hunters
consuming
animals
shot
with
lead
 had
 high
 blood‐lead
 levels.
 Iqbal
 et
 al.
 (2009)
 found
 that
 people
 who
 consumed
 animals
 harvested
 with
 lead
 ammunition
 had
 blood
 lead
levels
0.30μg
per
deciliter
higher
than
did
 people
who
did
not
consume
animals
shot
with
 lead
 ammunition.
 Thus,
 health
 concerns
 exist
 for
humans
consuming
meat
from
animals
that
 were
harvested
using
lead‐based
ammunition,
 although
the
relationships
and
ramifications
of
 consumption
are
poorly
understood. Although
 few
 studies
 examined
 impacts
 of
 258 Human–Wildlife Interactions 4(2) humans
 consuming
 bullet
 fragments
 in
 food,
 there
 have
 been
 many
 physiology
 studies
 conducted
 about
 the
 toxic
 effects
 of
 lead
 exposure.
 Exposure
 to
 lead
 has
 been
 found
 to
 adversely
 affect
 neural
 systems,
 kidney
 structure,
 bones,
 blood
 formation,
 and
 nerve
 transmission
(Canfield
et
al.
2003,
Menke
et
al.
 2006).
The
most
significant
toxic
effects
of
lead
 exposure
 are
 among
 children,
 which
 include
 neuro‐cognitive
 and
 neuro‐developmental
 disorders
 caused
when
 low
 blood
 lead
 levels
 were
observed
 (Canfield
et
al.
2003,
Lanphear
 et
 al.
 2005,
 Kordas
 et
 al.
 2006,
 Menke
 et
 al
 2006).
 Consequently,
 these
 physiological
 studies
also
demonstrate
that
exposure
to
lead
 bullet
 fragments
 pose
 human
 health
 risks
 for
 individuals. White‐tailed
deer
are
considered
 light,
 thin‐ skinned
game,
and
ammunition
manufacturers
 market
 bullets
 that
 are
 designed
 to
 expand
 rapidly
 upon
 penetration.
 Bullets
 of
 this
 type
 are
oHen
marketed
for
use
while
hunting
mid‐ sized
deer
species
(Odocoileus
spp.),
pronghorn
 (Antilocapra
 americana),
 bighorn
 sheep
 (Ovis
 canadensis),
and
other
species
typically
ranging
 in
weight
 from
 34
 to
 136
 kg.
We
will
 refer
 to
 these
 types
of
bullets
as
 rapid
expansion
 (RE)
 bullets
throughout
this
paper. Alternatives
 to
 RE
 bullets
 exist
 for
 larger
 game
 animals
 and
 are
 usually
 marketed
 as
 having
 properties
 that
 allow
 for
 slower
 expansion.
 These
 bullets
 are
 designed
 to
 penetrate
into
the
body
aHer
striking
thick
skin,
 heavy
 bone,
 or
 thick
muscle
 tissue.
 Bullets
 of
 this
type
usually
include
lead,
but
are
designed
 to
resist
fragmentation
and
are
oHen
described
 as
retaining
>90%
of
their
weight
aHer
striking
 the
 animal.
 This
 type
 of
 bullet
 is
 typically
 recommended
 for
 hunting
 large
 mammals
 such
 as
 elk
 (Cervus
 canadensis),
 moose
 (Alces
 alces)
and
other
species
weighing
>226
kg.
We
 will
refer
to
these
types
of
bullets
as
controlled‐ expansion
(CE)
bullets
throughout
this
paper. Several
 manufacturers
 also
 market
 bullets
 that
are
not
lead‐based
but
are
designed
for
both
 mid‐sized
 and
 large
 mammals.
 These
 bullets
 are
 made
 entirely
 from
 copper
 or
 a
 copper‐ based
alloy
and
are
presumed
 to
be
nontoxic.
 Throughout
this
paper
refer
to
these
bullets
as
 copper
(Cu)
bullets. Hunters
 oHen
 use
 shotguns
 that
 fire
 slugs
 and
black‐powder
muzzleloading
rifles
for
deer
 hunting.
Both
weapons
fire
projectiles
of
larger
 mass
and
at
lower
velocities
than
most
bullets
 fired
from
centerfire
rifles
and,
thus,
may
have
 different
 fragmentation
 paeerns.
 Lead‐based
 shotgun
 slugs
 are
 the
 most
 common
 type
 of
 shotgun
 projectiles
 used
 for
 deer
 hunting.
 Based
on
our
observations
over
the
last
15
years,
 hunting
with
black‐powder
muzzleloaders
has
 been
 increasing
 in
popularity,
and
many
state
 wildlife
 agencies
 have
 observed
 an
 increased
 number
 of
 deer
 harvested
 by
 this
 method.
 There
 are
 essentially
 2
 types
 of
muzzleloader
 (MZ)
bullets.
The
first
is
a
bullet
that
equals
the
 size
of
 the
caliber
and
 is
designed
specifically
 for
 black‐powder
 muzzleloader
 firearms.
 The
 second
 type
 is
 smaller
 in
 diameter
 and
 was
 originally
 designed
 for
 a
 handgun
 that
 is
 inserted
 into
 a
 plastic
 jacket
 so
 that
 the
 size
 matches
 the
 diameter
 of
 the
 bore
 of
 the
 muzzleloader.
 To
our
knowledge,
no
studies
have
been
pub‐ lished
 that
 examined
 the
 variability
 of
 bullet
 fragmentation
 and
 deposition
 using
 different
 categories
of
bullet
and
firearm
classifications.
 The
objectives
of
our
study
were
to:
(1)
provide
 a
 standardized
basis
 of
 examination
of
differ‐ ent
bullet
types;
(2)
describe
general
bullet
per‐ formance,
 variability,
 and
 differences
 among
 firearm
 types;
 and
 (3)
 provide
 information
 to
 hunters
so
that
informed
choices
can
be
made
 about
 selecting
a
bullet
 if
 lead
deposition
 is
 a
 concern. Background Several
 midwestern
 states
 have
 publicly
 funded
 venison
 donation
 programs.
 While
 these
 programs
 vary
 slightly,
 the
 primary
 intent
 is
 to
 provide
 surplus
 hunter‐harvest
 venison
 to
 the
 public.
 In
 2007,
 Minnesota
 deer
 hunters
 donated
 1,996
 deer
 to
 food
 pantries,
 which
 yielded
 an
 estimated
 35,500
 kg
 of
 venison.
 In
 February
 2008,
 a
 private
 physician
in
North
Dakota
reported
observing
 radiographic
 evidence
 of
 metal
 in
 60
 of
 100
 samples
of
donated
venison
collected
from
food
 pantries.
The
State
of
North
Dakota
confirmed
 the
 presence
 of
 lead
 in
 these
 samples
 and
 suspended
the
state
venison
donation
program.
 Due
to
the
similarities
in
state
venison
donation
 programs
 in
Minnesota
 and
 North
 Dakota,
 a
 decision
was
made
to
examine
a
portion
of
the
 venison
remaining
at
Minnesota
food
pantries.
 259 Bullet fragmentation • Grund et al. A
random
sample
of
 238
packages
of
venison
 was
 removed
 from
 Minnesota
 food
 pantries
 and
 subsequently
 examined
 by
 radiography
 to
 determine
 the
 presence
 of
 metal.
 Overall,
 radiographic
 evidence
 revealed
 32%
 of
 the
 inspected
packages
contained
metal
fragments,
 and,
 consequently,
 the
 remaining
 venison
 at
 area
food
pantries
was
recalled
and
destroyed
 (L.
Cornicelli,
Minnesota
Department
of
Natural
 Resources,
unpublished
report).
The
discovery
 of
 lead
 in
 venison
 prompted
 the
 Minnesota
 Department
 of
Natural
 Resources
 to
 examine
 the
broader
issue
of
bullet
fragmentation
with
 the
goal
of
providing
hunters
with
a
baseline
of
 information
regarding
the
most
popular
bullet
 types. Hunt
et
al.
(2006)
used
radiographs
to
study
 bullet
 fragmentation
 paeerns
 in
 both
 hunter‐ harvested
 deer
 carcasses
 and
 offal
 piles
 and
 confirmed
that
metal
fragments
existed
within
 both.
While
the
study
demonstrated
the
presence
 of
 bullet
 fragments,
 its
 findings
 were
 limited
 because
 hunters
 killed
 deer
 under
 variable
 conditions.
 For
 example,
 hunters
 harvested
 deer
 using
different
 calibers
 that
 had
 varying
 bullet
weights
 and
bullet
velocities,
 estimated
 shot
distances
of
37
to
>200
m,
and
no
deer
were
 harvested
using
shotguns
or
muzzleloaders.
We
 presume
that
differences
in
rifle
caliber,
bullet
 weight,
design,
bullet
velocities,
shot
distances,
 and
shot
placement
will
likely
influence
bullet
 fragmentation
 paeerns.
 Consequently,
 it
 was
 not
 possible
 to
 distinguish
 fragmentation
 paeerns
associated
with
different
bullet
types,
 shot
 distances,
 and
 shot
 placement
 based
 on
 their
results.
 Similarly,
 Dobrowolska
 and
 Melosik
 (2008)
 analyzed
lead
concentrations
in
muscle
tissues
 of
wild
boar
 (Sus
 scrofa)
 and
 red
deer
 (Cervus
 elaphus)
 harvested
 by
 hunters
 in
 Poland.
 The
 authors
 concluded
 that
 muscle
 tissue
 closer
 to
wounds
had
higher
 concentrations
 of
 lead.
 However,
 their
 samples
were
 also
 taken
 from
 animals
 harvested
 with
 bullets
 of
 different
 calibers
and
types.
The
authors
concluded
that
 caliber
and
bullet
type
would
be
an
important
 factor
 related
 to
 the
 extent
 of
 contamination,
 but
 their
 study
was
 designed
 to
 confirm
 that
 meat
 derived
 from
 animals
 shot
 with
 lead‐ based
 bullets
 would
 be
 contaminated
 with
 lead.
Their
study
was
not
designed
to
address
 the
 variability
 associated
 with
 fragmentation
 paeerns
 of
 different
 types
 of
 bullets
 and
 firearms. Hunt
et
 al.
 (2009)
 conducted
a
 study
where
 all
hunters
used
a
Remington
Magnum
7‐mm
 caliber
 bullet,
 as
 well
 as
 a
 bullet
 of
 identical
 mass
to
harvest
white‐tailed
deer.
The
authors
 concluded
 that
 individuals
 risk
 exposure
 to
 lead
 when
 they
 consume
 venison
 from
 deer
 killed
 with
 standard
 lead‐based
 rifle
 bullets.
 However,
 their
 study
 did
 not
 test
 different
 bullet
types.
Thus,
there
is
a
lack
of
information
 about
which
 types
 of
 bullets
 individuals
who
 are
 concerned
 about
 lead
 exposure
 should
 purchase
for
hunting.
 Methods Our
research
was
conducted
in
July
2008
with
 the
goal
of
producing
preliminary
results
before
 the
fall
2008
Minnesota
deer
season
(November
 8,
2008).
We
used
euthanized,
domestic
 sheep
 (Ovis
aries)
as
surrogates
for
white‐tailed
deer.
 Domestic
 sheep
 are
 ruminants,
 anatomically
 similar
 to
 deer,
 and
 were
 readily
 available.
 Each
sheep
carcass
was
harnessed
in
a
sternal
 recumbent
 position
 and
 then
 shot
 broadside
 in
the
thoracic
cavity
at
50
m.
In
all
cases,
 the
 scapula
 was
 positioned
 forward
 so
 that
 the
 bullet
 did
 not
 strike
 the
 scapula.
AHer
 being
 shot,
 sheep
 were
 immediately
 transported
 to
 a
 necropsy
 laboratory
 at
 the
 University
 of
 Minnesota,
 Veterinary
 Diagnostic
 Laboratory
 (UMN‐VDL)
for
fragmentation
analysis.
 We
tested
2
types
of
RE
bullets
(RE1
and
RE2),
 2
types
of
CE
bullets
(CE1
and
CE2),
and
1
type
 of
Cu
bullet
 to
make
bullet
 type
 comparisons
 using
 a
 centerfire
 rifle
 chambered
 in
 .308
 (7.62mm)
 Winchester
 (Table
 1).
 All
 centerfire
 rifle
 bullets
 were
 commercially
 available
 cartridges,
and
weighed
10
g
(150
grains).
For
 centerfire
 rifles,
 10
 sheep
 were
 shot
 for
 each
 bullet
brand
group
(n
=
50
sheep).
An
additional
 10
 sheep
were
 shot
using
a
12‐gauge
 shotgun
 that
fired
slugs
weighing
28
g
(1
ounce).
A
0.50
 caliber
 muzzleloader
 rifle
 was
 used
 to
 test
 2
 types
of
MZ
bullets.
One
type
of
muzzleloader
 bullet
(MZ1)
weighed
16
g
(245
grains),
and
the
 other
type
(MZ2)
weighed
19
g
(300
grains).
Six
 sheep
were
shot
using
MZ1
bullets,
and
6
sheep
 were
shot
using
MZ2
bullets. To
make
 comparisons
 to
deer
 carcasses,
we
 examined
8
deer
that
were
killed
in
April
2008
 as
 part
 of
 a
 disease
 management
 program
 260 Human–Wildlife Interactions 4(2) conducted
 by
 the
 Minnesota
 Department
 of
 Natural
Resources.
Deer
were
shot
with
a
.308
 (7.62
mm)
Winchester
 using
 RE1
 bullets
 over
 bait
 at
 an
 average
 distance
 of
 about
 110
 m
 (range
=
80
–
175
m).
Deer
were
killed
in
variable
 conditions,
and
not
all
bullets
struck
the
thoracic
 cavity.
These
intact
deer
carcasses
were
frozen
 until
 July
2008
and
were
not
eviscerated
until
 they
thawed
and
were
examined
for
this
study.
 Our
 intent
 was
 to
 approximate
 paeerns
 of
 fragmentation
for
deer
that
would
be
harvested
 during
 fall
 hunting
 seasons.
 Therefore,
 we
 examined
 lead
 deposition
 in
 a
 manner
 that
 would
be
consistent
with
how
a
hunter
would
 handle
 a
 deer
 carcass.
 Thus,
we
 removed
 the
 hide
and
viscera
prior
to
analysis.
To
determine
 bullet
 direction
 (entry
 to
 exit),
 we
 inserted
 a
 carbon
fiber
 tube
 through
 the
wound
channel
 then
 took
 a
 ventral‐dorsal
 (VD)
 view
 and
 a
 lateral
 view
 (LV)
 radiograph
 image
 on
 the
 exit
 side
 of
 the
 carcass.
 When
 carcass
 length
 exceeded
the
imaging
radius
of
the
scanner,
we
 took
2
radiographs
of
each
view
then
tiled
the
 images
 together
 prior
 to
 analysis.
 Fragments
 were
most
visible
on
VD
radiographic
images.
 Thus,
 we
 used
 VD
 radiographic
 images
 to
 enumerate
 total
 number
 of
 bullet
 fragments
 in
each
carcass.
No
aids
were
used
to
magnify
 the
 fragments
 while
 the
 counting
 was
 being
 performed.
In
addition
to
total
fragment
counts,
 we
counted
the
number
of
bullet
fragments
<5cm
 from
the
exit
wound.
All
radiographic
 images
 were
 coded,
 so,
 the
 individual
 observing
 the
 image
did
not
know
which
bullet
brand
group
 was
being
analyzed. We
studied
lead
contamination
levels
(ppm)
 throughout
carcasses
using
similar
procedures
 as
those
outlined
in
Dobrowolska
and
Melosik
 (2008).
 We
 collected
 muscle
 tissue
 samples
 along
 the
 abdominal
 cavity
 at
 perpendicular
 distances
 of
 5,
 25,
 and
 45
 cm
 from
 the
 exit
 wound
 on
 each
 carcass
 (Figure
 1).
 Tissue
 samples
 were
 taken
 by
 cueing
 through
 the
 carcass
 and
 entirely
 removing
 a
 2.5‐
 H
 2.5‐
 cm
 section
 of
 muscle
 at
 the
 aforementioned
 distances
from
the
exit
wound
sites.

All
muscle
 tissue
samples
were
analyzed
by
University
of
 Minnesota,
 Veterinary
 Diagnostic
 Laboratory
 Table
1.
Bullet
types,
average
velocity
of
projectiles
in
meters
per
second
(±SD),
weight
retention
as
 advertised
by
manufacturer,
and
description
of
lead
composition
within
projectile
(Bullet
types:
RE
=
 rapid
expansion;
CE
=
controlled
expansion;
Cu
=
copper;
MZ
=
muzzleloader.) Treatment Bullet
type Velocity1 Advertised
weight
 retention Lead
description Nosler Ballistic Tip RE1 876 ± 10 50% Lead throughout core Remington Core Lokt RE2 885 ± 17 50% Lead
throughout
core Winchester
XP3 CE1 894 ± 20 Near 100% Copper in front half of bullet, lead at base of bullet Hornady Interbond CE2 855 ± 12 >90% Lead core bonded to jacket Barnes TSX Cu 871 ± 30 Near 100% No lead Reminton Foster Slug Slug 452 ± 38 N/A 100% lead Powerbelt Aero-Tip MZ1 484 ± 3 N/A Lead
throughout
core Hornady XTP MZ2 475 ± 16 N/A Lead throughout core 1Bullet
velocity
determined
via
chronograph
placed
3
meters
from
the
shooting
bench.