i

Human Health and Ecological Risk Assessment

for the Use of Wildlife Damage Management Methods

by USDA-APHIS-Wildlife Services

Chapter XII

Use of Lead in

Wildlife Damage Management

December 2017

Peer Reviewed Final 

August 2022
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USE OF LEAD IN WILDLIFE DAMAGE MANAGEMENT

EXECUTIVE SUMMARY

Lead is a chemical element that has a variety of usages and is used in ammunition (shot, bullets, 

or pellets) and fishing sinkers. The USDA-APHIS-Wildlife Services (WS) Program uses lead 

ammunition for aerial and ground shooting in certain Wildlife Services (WS) programs, and 

minimal amounts of fishing sinkers for a fish reduction program on the Columbia River. WS use 

of lead has declined as non-lead substitutes have become available, researched, and determined 

to be effective; however, the use of non-lead shot is dependent on availability and whether nonlead ammunition can be safely used to address wildlife damage management actions. Lead 

ammunition use as a percentage of total ammunition used by WS varies from state to state;

however, total lead ammunition use in WS operational activities as a percentage of total lead use 

from ammunition in the United States is very low (~0.002%). The use of lead ammunition and 

weights in WS is expected to continue to decline. A need for additional investigation into the use 

of non-lead ammunition is noted (APHIS 2012, Caudell et al. 2012).

Risk to human health from lead ammunition (e.g., through consumption of carcasses) is

minimized by training WS personnel and the WS carcass disposal policy. In addition, most wildlife 

damage management conducted for animals such as deer, swine, rabbits, or migratory game 

birds (e.g., ducks and native doves) that have the highest likelihood of being consumed are 

conducted mostly on private or secured public lands (e.g., airports), where public access is 

restricted. 

Ecological impacts to aquatic resources are also expected to be minimal based on the low 

potential for exposure to most aquatic biota. In terrestrial systems the greatest potential for 

exposure and risk is to nontarget vertebrates that consume lead ammunition fragments 

inadvertently from the ground or from scavenging carcasses. Risks to nontarget animals are 

reduced when carcasses are removed and when non-lead ammunition can be used. Lead 

ammunition degrades slowly in terrestrial and aquatic environments. Its environmental fate once 

it degrades suggests that the small amounts of lead that may be present in the environment as a 

result of WS activities would not have an adverse impact to soil, air or water quality. Regardless, 

WS is gravitating towards the use of non-lead ammunition and fishing sinkers in wildlife damage 

management and remains committed to working with the U.S. Fish Wildlife Service, other federal 

agencies, and state agencies to proactively manage lead exposure to fish and wildlife.
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Table of Contents

1 INTRODUCTION........................................................................................................................................ 1

1.1 Use Pattern of Lead.......................................................................................................................... 1

2 PROBLEM FORMULATION ...................................................................................................................... 3

2.1 Chemical Description and Product Use............................................................................................ 4

2.2 Physical and Chemical Properties.................................................................................................... 5

2.3 Environmental Fate .......................................................................................................................... 5

2.4 Hazard Identification......................................................................................................................... 6

2.4.1 Toxicokinetics.......................................................................................................................... 6

2.4.2 General Lead Poisoning Effects ............................................................................................. 7

2.4.3 Lead Effects on Neurological Systems ................................................................................... 7

2.4.4 Lead Effects on Cardiovascular Systems ............................................................................... 8

2.4.5 Lead Effects on Renal Systems.............................................................................................. 8

2.4.6 Lead Effects on Immune Systems .......................................................................................... 9

2.4.7 Lead Effects on Hematological Systems ................................................................................ 9

2.4.8 Lead Effects on Reproductive and Developmental Systems................................................ 10

2.4.9 Carcinogenicity and Mutagenicity of Lead ............................................................................ 10

3. DOSE-RESPONSE ASSESSMENT....................................................................................................... 10

3.1 Human Health Dose-Response Assessment................................................................................. 11

3.2 Ecological Effects Analysis............................................................................................................. 11

3.2.1 Aquatic Effects Analysis........................................................................................................ 12

3.2.2 Terrestrial Effects Analysis ................................................................................................... 12

4 EXPOSURE ASSESSMENT.................................................................................................................... 13

4.1 Human Health Exposure Assessment............................................................................................ 13

4.2 Ecological Exposure Assessment .................................................................................................. 15

4.2.1 Aquatic Exposure Assessment ............................................................................................. 15

4.2.2 Terrestrial Exposure Assessment......................................................................................... 15

5 RISK CHARACTERIZATION ................................................................................................................... 16

5.1 Human Health................................................................................................................................. 16

5.2 Ecological ....................................................................................................................................... 17

5.2.1 Aquatic .................................................................................................................................. 17

5.2.2 Terrestrial.............................................................................................................................. 17

6 UNCERTAINTIES AND CUMULATIVE IMPACTS.................................................................................. 17

7 SUMMARY............................................................................................................................................... 18

8 LITERATURE CITED............................................................................................................................... 19

9 PREPARERS: WRITERS, EDITORS, REVIEWERS .............................................................................. 23

9.1 APHIS WS Methods Risk Assessment Committee........................................................................ 23

9.2 Internal Reviewers.......................................................................................................................... 25

9.3 Peer Review ...................................................................................................................................26

9.3.1 Peer Reviewers’ Agencies Selected by the Association of Fish and Wildlife Agencies.......26

9.3.2 Comments.............................................................................................................................26
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1 INTRODUCTION

This human health and ecological risk assessment provides a qualitative evaluation of potential 

risks and hazards to human health, the environment, and nontarget fish and wildlife as a result of 

exposure to lead from the proposed use of lead ammunition (i.e., shot, bullets, or pellets) for aerial 

or ground-based shooting and fishing weights (sinkers) for fishing by the U.S. Department of 

Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Wildlife Services (WS) 

Program. This risk assessment provides: (a) problem formulation to identify hazards and evaluate 

potential exposures by identifying possible exposed populations and exposure pathways; (b) a 

dose-response assessment; and (c) a risk characterization which combines information from the 

exposure and toxicity assessments to assess the potential for adverse human health and 

ecological risks. A discussion of the uncertainties associated with the risk assessment and 

cumulative effects is also included. 

The methods used to assess human health effects follow regulatory guidance and methods, and 

conform to other Federal agencies guidance, such as the National Research Council (1983) and 

U.S. Environmental Protection Agency (USEPA), Office of Pesticide Programs (USEPA 1989, 

2017c). The methods used to assess the ecological risk to nontarget species generally follow 

USEPA (1989, 2017c) ecological risk assessment methods. The nonchemical or non-lead 

hazards from aerial or ground-based shooting are evaluated separately in other risk assessments 

including “The Use of Aircraft in Wildlife Damage Management by WS” and “The Use of Firearms 

in Wildlife Damage Management by WS.”

WS uses lead, as well as non-lead, ammunition in wildlife damage management (WDM) including 

ground-based, aerial and harassment shooting, and shooting to euthanize animals caught in 

nonlethal snares and traps. WS selects ammunition types based on availability, relevant laws and 

regulations, and the practical, humane, effective, and environmentally safe ammunition for each 

specific project and location. Additionally, WS uses minor amounts of lead in a northern 

pikeminnow reduction project in the form of lead sinkers and some of these weights are lost while 

fishing. 

1.1 Use Pattern of Lead

Firearm use is tracked in the WS Management Information System (MIS1

) for many WS WDM 

operations. However, the MIS does not track the type of firearm or ammunition used during WDM 

operations, the number of shots fired, or all firearm usage. Therefore, lead usage is unknown, but 

it can be estimated based on conservative assumptions. In general, the typical use pattern of 

firearms for different WDM operations is similar. For example, the vast majority of birds are taken 

with shotguns, large mammals with rifles, and small mammals with .22 caliber rifles. Air rifles

(pneumatics) are tracked separately in the MIS and are used mostly for small mammals and birds. 

Animals caught in other WDM methods such as cage and foothold traps, and cable restraints are 

generally euthanized with a gunshot to the brain, typically accomplished with a .22 caliber pistol.

The amount of lead varies considerably with the type of ammunition used, the WDM operation 

being conducted, and legal requirements (e.g., migratory bird permits require the use of lead-free 

shot); most shotgun use is conducted with lead-free ammunition.

1 MIS - Computer-based Management Information System used for tracking APHIS-WS WDM activities nationwide. MIS reports will not be 

referenced in the text or Literature Cited Section because MIS reports are not kept on file. A database is kept that allows queries to be made to 

retrieve the information needed.
2 

From FY112 to FY15, WS used several types of firearms, pneumatics, and fishing that used lead 

in WDM as the primary method or possibly to euthanize animals caught with other methods (Table 

1). Firearms3 used by WS included shotguns and rifles from the ground and air, and pistols and

pneumatics from the ground. If the primary method was a firearm or pneumatics, it was recorded 

as “firearm” or “pneumatics” in the MIS. However, many animals are taken with other WDM 

methods such as foothold and cage traps and euthanized with firearms, but the firearm use is not 

recorded. Additionally, WS conducts a fishing program for northern pikeminnows that uses lead 

“sinkers” that can be lost; the amount of lead for this is not included in Table 1 but estimated from 

purchases by the supervisor of the program. Table 1 gives a breakdown of the animals taken with 

the different methods. 

Table 1. The annual average number of target and nontarget animals taken with the variety of firearms 

used by WS during WDM from FY11 thru FY15. 

ANNUAL AVERAGE SPECIES TAKEN WITH FIREARMS

TARGET NONTARGET 

Method Killed Dispersed Killed

Firearm Was Method of Take or Harassment1

Shotgun from Ground (12 gauge shot) 317,303 4,338,717 0

Shotgun from Air (12 gauge shot)1 41,747 0 0

Rifle (large caliber bullets) 29,189 1,490 0.2

Rifle (.22 caliber bullets) 35,026 8,329 0.4

Pneumatic Rifle (pellets) 29,287 124,729 0

Method of Take Was Traps or Snares, and Animals Possibly Euthanized with Firearms2

Large Animal (large caliber rifle/pistol) 15,083 - 127

Small Animal (.22 caliber rifle/pistol) 51,234 - 1,186

TOTAL 522,955 4,473,265 1,314

1=Addressed in Use of Firearms, Aircraft, and Dogs Risk Assessments; 2=Addressed in Use of Cage Traps, Foothold Traps, and 

Cable Restraints Risk Assessments, but does not include animals euthanized with euthanasia drugs. 

WS has no way to determine the exact amount of lead that was used conducting WDM due to 

how that type of information is collected, but it can be estimated. All of the WS State Programs 

were asked the composition of ammunition used for various WDM activities in their state. It was 

determined that most shotgun use from the ground used lead-free shot, whereas most was leadbased for aerial hunting (safety factor – ricochet is a problem for aircraft); rifle and pistol 

ammunition, including pellets from air rifles, varied, but more was lead-based. It was assumed 

that 2 shots were fired for each animal taken with ground-based shooting and 3 shots for those 

taken with shooting from aircraft, regardless of the firearm type used. It was assumed that only 

one shot was taken to euthanize an animal caught with another method such as a foothold trap.

For dispersal, it was assumed that one shot was fired for every 100 flocking birds hazed, 10 for 

loosely flocking birds and herding mammals, and 1 shot for solitary mammals and birds, and all 

reptiles. These are inherently conservative as these assumptions likely overestimate the number 

of shots fired (e.g., shooting small flocking birds with shotguns often results in many being taken 

with a single shot, most animals on the ground are taken with a single shot, and many animals 

caught in some WDM devices such as neck snares are taken lethally and are not euthanized with 

a firearm). Weights of ammunition varies, but a standard weight of 1.2 ounces of lead for each 

shotgun shell, 0.3 ounces for each large caliber rifle bullet, 0.1 ounce for each .22 caliber bullet, 

and 0.03 ounces for each pellet. It was assumed that most birds were taken with shotguns, large 

mammals (average adults 20 pounds or more) were taken with large caliber rifles, small 

mammals, reptiles, amphibians, and birds at night (with spotlights/night vision) were taken with 

2

 FY11 equals the federal Fiscal Year 2011 which is October 1, 2010-September 30, 2011 (the year is denoted by FY11, FY12, and so on and is 

the federal Fiscal Year for 2011, 2012, and so on. 3 The MIS does not separate the types of firearms used (i.e., shotgun, large or small caliber rifle) and whether or not an animal is subsequently 

euthanized with a firearm such as a small caliber pistol if taken with another method such as a cage or foothold trap. 
3 

.22 caliber rifles. Animals in traps were taken with .22 caliber pistols or rifles, except large 

mammals (40 pounds or greater) were assumed to be shot with large caliber rifles or pistols. For 

the sake of the estimate, it was assumed that all carcasses were left in the field, thus the lead 

would be available in the environment. These estimate parameters provided weights for all WDM 

activities and an estimate of the lead used.

Based on the above assumptions, WS used an estimated average of 11,080 lb. (5.6 tons4) of lead 

annually from FY11 to FY15 (Table 2). This average is minimal when compared to the U.S. use 

of lead from ammunition, shot and bullets (0.002% of other use in U.S.), based on USGS (2011) 

data. Conservative WS lead use in each individual state varied (Table 2) with most use in Texas 

(2,743 lbs.), Oklahoma (1,881 lbs.), and Wyoming (996 lbs.) and least in Washington, D.C. (0 

lbs.), Delaware (0 lbs.), and New Hampshire (0.2 lbs.). 

Table 2. The estimated average annual use of lead by WS in wildlife damage management from FY11 to 

FY15.

State Total lb. State Total lb. State Total lb. State Total lb.

AK 3.5 ID 89.4 NC 68.3 RI 49.7

AL 274.9 IL 106.4 ND 361.3 SC 24.8

AR 2.8 IN 1.9 NE 25.4 SD 1.0

AZ 10.7 KS 277.1 NH 0.2 TN 97.4

CA 229.1 KY 73.5 NJ 2.2 TX 2743.0

CO 462.8 LA 310.6 NM 384.3 UT 461.3

CT 31.6 MA 46.1 NV 21.1 VA 208.0

DC DE 0 MD 4.0 NY 11.8 VI 7.3

FL 43.2 ME 3.7 OH 51.3 VT 1.2

GA 40.2 MI 6.1 OK 1,881.1 WA* 221.5

GB 4.1 MN 21.1 OR 321.7 WI 7.0

GU 6.5 MO 28.9 PA 39.2 WV 5.2

HI 61.9 MS 14.6 PR 33.5 WY 996.3

IA 11.1 MT 889.3 WS Total 11,080.2 lb.

*Includes 150 lbs. of lead sinkers conservatively estimated to be used annually in a fish removal program on the Columbia River 

since this was an unknown but tracked more precisely in FY16 with 118 pounds lead sinkers used. 

To put this into perspective at the landscape scale, WS worked on an average of 18.7 million 

acres annually in Texas for FY11 to FY15 (31.7 million acres for the cumulative time period from 

FY11 through FY155). Thus, WS added an estimated average of 67 mg lead/acre for WDM

activities annually; WS worked on an average of 11.1% of the land area in Texas (18.9% of the 

state was worked from FY11 to FY15 cumulatively or 196 mg/acre for the 5-year period). In 

Oklahoma from FY11 to FY15, WS worked on an average of 7.0% of the land area and averaged 

282 mg/acre for WDM activities annually (19.7% of the state was worked cumulatively from FY11 

to FY15 or 501 mg/acre for a 5-year period). 

2 PROBLEM FORMULATION

WS uses firearms in WDM activities and uses the best ammunition available for a specific firearm, 

especially since WDM activities require accuracy and precise shot placement, especially in certain 

locations and areas such as suburban and airport settings, rocky terrain where aerial shooting is 

involved, or when shooting from greater distances and in relatively populous or otherwise 

sensitive settings. Lighter non-lead bullets can reduce accuracy when discharged through rifle 

4 The actual amount of pure lead used would be estimated to be 5.5 tons since shot, bullets, and pellets are actually alloys with shot and pellets 

about 97% lead and rifle bullets about 90% lead. 5 During this time, WS conducted WDM on many of the same properties, thus the cumulative total is a fraction of the total if added for 5 years.
4

barrels that have twist rates designed for conventional lead-based bullets. Non-lead rifle 

ammunition can also result in "non-frangible bullet pass-through," resulting in failure of the bullet 

to convey its full energy to the target animal. In addition to the increased risk of hitting an 

unintended target, non-frangible bullet pass-through also increases the likelihood that the target 

animal will not be fatally wounded and, thus, would not be as humane as conventional bullets

(APHIS 2012, Caudell et al. 2009, 2012). As new lead-free ammunition becomes commercially 

available, WS personnel assess the effectiveness of the ammunition as applicable; the WS 

Firearms Committee sends out memoranda regarding new information on lead substitutes as it 

becomes available.

WS uses non-lead ammunition to mitigate or minimize the effects of lead ammunition on the 

environment, wildlife, and public health in compliance with Federal and State regulations. Most 

often, WS uses steel or other non-lead shot to remove birds since most Migratory Bird Treaty Act 

permitted activities typically require its use, especially on waterfowl production and wintering 

areas, wetlands, U.S. Fish and Wildlife Service refuges, and National Park Service lands. Nonlead shot, bullets, and pellets may also be required in some areas to prevent ingestion by 

threatened and endangered species such as the California condors (Gymnogyps californianus) 

during carcass consumption. WS, however, uses non-lead shot for a variety of WDM activities. 

WS observations of non-lead ammunition for WDM in terms of safety and performance suggest 

that lead ammunition likely remains the best alternative under certain circumstances, but not 

always (APHIS 2012). For example, while shooting from an aircraft, steel shot is more likely to 

ricochet off hard surfaces, and WS aircraft, personnel, or other unintended targets can be struck, 

thus, presenting unacceptable risk to human safety (APHIS 2012); ricochets have damaged WS 

aircraft. However, further research is called for in order to take advantage of non-lead types to 

the greatest extent possible (APHIS 2012, Caudell et al. 2012), as many seem to perform as well 

as lead for many applications (Knott et al. 2009, McCann et al. 2016). 

2.1 Chemical Description and Product Use

Lead ammunition includes lead shot, bullets, and pellets. An average lead shot contains 97% 

metallic lead, 2.5% antimony, and 0.5% arsenic, a lead pellet contains up to 97% metallic lead, 

2% antimony, 0.5% arsenic, 0.5% nickel, and jacketed bullets contain up to 90% metallic lead, 

9% copper, and 1% zinc (Tanskanen et al. 1991, Scheuhammer and Norris 1995, Scheetz and 

Rimstidt 2009). The amount of lead varies in ammunition based on the type of firearm and size of 

the shell, shot, bullet, or pellet. More specifically, the amount of lead for shotguns varies with the 

gauge, the length of the shell used, and the shot size, and for rifles, pistols, and air guns, the 

caliber, the type of bullet or pellet, and the grains (weight) of the bullet or pellet used.

WS uses ground and aerial shooting in various WDM activities throughout the United States and 

these typically occur over a wide geographic area; for example, in Texas from FY11 to FY15, WS 

worked on an annual average of almost 19 million acres and cumulatively in the five-year period 

on 32 million acres. Shooting may include the use of various caliber and gauges in rifles, pistols, 

air guns and shotguns, depending on the target animal and other site-specific conditions. In all 

situations, WS aims to use the fewest number of shots on targeted animals for humaneness 

reasons and to limit environmental lead and non-lead ammunition. Lead ammunition use by WS 

in WDM activities is minimal compared to lead use at firing ranges and in recreational hunting and 

fishing.
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2.2 Physical and Chemical Properties 

Lead, CAS Number 7439-92-1, is an odorless, bluish-white, silvery, or gray naturally occurring 

metal. The molecular weight is 207.2 (National Institutes of Health 2016). Melting point is 327.4oC.

The boiling point is 1740oC. Vapor pressure is 1.77 mm Hg at 1000oC. Lead is very resistant to 

corrosion and copper adds more resistance to corrosive properties. It is insoluble in water but 

dissolves slowly in water containing a weak acid (National Institutes of Health 2016).

2.3 Environmental Fate

The environmental fate of lead is the process by which lead shot, bullets, or pellets move or are 

transformed in the environment. The environmental fate processes include: 1) mobility, 

persistence, and degradation in soil, 2) movement to air, 3) migration potential to groundwater 

and surface water, and 4) plant uptake.

Although well-trained and tested for proficiency, WS personnel at times contribute to the release 

of intact lead ammunition into the environment when shots are missed, if a shot passes through 

a target animal, or when a target animal decomposes in the field. Environmental lead ammunition

is insoluble under some conditions, but minor amounts of weathering occurs when lead 

ammunition comes into contact with soil (USEPA 2005).

In the environment, intact lead shots oxidize to form a crust containing lead carbonates 

(hydrocerussite (Pb3(CO3)2(OH)2), cerussite (Pb CO3), and lead sulfates (e.g., anglesite (Pb

SO4)). The oxidation rate depends on oxidation/reduction potential, ionic strength, pH, oxygen 

content of the soil, and the presence of compounds (e.g., phosphate) that may inhibit oxidation.

The dissolution of lead compounds in the crust material releases lead to the environment (USEPA 

2003). The bioavailability of lead sulfates and lead carbonates in soil varies from less than 25% 

(lead sulfates) to more than 75% (lead carbonates). The relative amount of these compounds in 

soil determines the overall bioavailability of lead. The speciation of lead in soil is dependent upon 

the equilibrium of the redox potential (eH), soil pH, and the amount of carbonate and sulfate 

present in soil. Lead sulfate is the dominant form of lead at a low pH (<5.3), carbonates are the 

dominant form at a pH between 5.3 and 8.5, and lead hydroxides are dominant at a high pH (>8.5)

(USEPA 2003).

In the absence of other environmental factors, lead released to soil usually binds to soil particles

and remains immobile in the top 6 inches of the surface soil (Cullen et al. 1996, Hue 2002). Wind 

and rain influence the transport of lead in surface soil. Lead in dry surface soil can move to air by 

wind through dust and particulates. Rainfall increases the mobility of lead in soil through 

dissolution or erosive transport. The smaller particles are more susceptible to transport by erosion 

and runoff to surface water, and the higher surface area of smaller particles increases the rate of 

dissolution and leaching into the surrounding soil and surface water (Massachusetts Department 

of Environmental Protection 2009).

Other environmental factors that affect the solubility of lead compounds from lead shots into the 

soil and within the soil matrix itself include pH, the presence of carbonate, sulfate, sulfide, 

phosphate, and chloride, content of organic matter, and soil type. Lead mobility under neutral and 

basic conditions is low. At a low pH (4-6), lead becomes more soluble and leaching from soil to 

groundwater can occur. The presence of carbonate, sulfate, sulfide, phosphate, and chloride in 

soil form lead compounds with varying solubility in water. High organic carbon content in the soil 

can reduce conditions favorable to the formation of lead sulfides, which are relatively insoluble 

and immobile. High clay and organic carbon soil reduce the transport of dissolved lead through 
6

absorptive process, which inhibits lead’s transport from soil to surface water and groundwater

(Agency for Toxic Substances and Disease Registry (ATSDR) 2007). Lead may also migrate 

down the soil profile in alkaline soils containing high amounts of organic matter (Cao 2003).

Phosphate sources [NaH2(PO4)3, commercial superphosphate and phosphate rock] were 

determined to be effective at mitigating lead in the soil and human population near mining and 

smelting areas by reducing solubility by 92% (Sergio et al. 2008).

Water pH, hardness, and oxidation reduction conditions affect the solubility of lead. Dissolved 

lead concentrations increase when water pH decreases. Dissolved lead precipitates out of 

solution when raising the water pH, particularly between pH 7.5 and 9.5. However, lead solubility 

increases at a pH above 9.5 (ATSDR 2007).

The bioavailability of lead in soil for plant uptake generally is limited because of the strong 

adsorption of lead to soil particles especially in the presence of high organic matter. A significant 

soil-metal fraction renders lead insoluble and largely unavailable for phytoremediation or plant 

uptake (Miller et al. 2008). Consequently, the uptake of lead by plants is not a significant fate 

pathway (Pourrut et al. 2011).

2.4 Hazard Identification 

Lead can cause a variety of adverse health effects in humans, including death, and can potentially 

affect any system or organ in the body depending upon the level and duration of exposure

(ATSDR 2007). Lead affects the neurological, cardiovascular, renal, immune, hematological, 

reproductive, and developmental systems. Lead can also affect other systems including hepatic, 

gastrointestinal, musculoskeletal, respiratory, and endocrine systems (USEPA 2017a). These 

effects are the focus of this section and are discussed separately in the subsections below.

Exposure to lead, even low concentrations, can be seriously damaging to the health of children 

because the child’s body absorbs lead more efficiently (Rosen and Sorell 1978 cited in Scheetz 

and Rimstidt 2009). In addition, children typically have higher intake rates (per unit body weight) 

for environmental media (such as soil, dust, food, water, air, and paint) than adults, since they are 

more likely to play in dirt and put their hands and other objects in their mouths. Children tend to 

absorb a higher fraction of ingested lead from the gastrointestinal tract than adults and are more 

susceptible to the adverse neurological and developmental effects of lead. Nutritional deficiencies 

of iron or calcium, which are common in children, may facilitate lead absorption and exacerbate 

its toxic effects (ATSDR 2007).

2.4.1 Toxicokinetics

Humans can absorb inorganic lead from environmental exposure into the bloodstream via 

inhalation (30% to 50% of the inhaled dose), oral (8% to 15% of the ingested dose), and dermal 

(very limited) exposure routes. The dermal route is much less efficient than the inhalation and oral 

routes for inorganic lead. Small submicron size lead particles can be almost completely absorbed 

through the respiratory tract, whereas larger particles may be swallowed. The extent and rate of 

absorption of lead through the gastrointestinal tract varies among individuals and the 

physiochemical characteristics of the medium ingested. Children can absorb 40–50% of an oral 

dose of water-soluble lead compared to 3–10% for adults. After gastrointestinal absorption 

approximately 94% of the total body burden of lead distributes into the bones in adults, but only 

approximately 73% in children. Once adsorbed into the human body, lead in blood is primarily 

taken into the red blood cells. Lead distributed to blood plasma, the nervous system, and soft 

tissues can be redistributed and bioaccumulate in bones (National Toxicology Program 2016, 
7

USEPA 2017a, U.S. National Library of Medicine 2017). Metabolism of inorganic lead occurs

through formation of complexes with a variety of protein and non-protein ligands. Lead can be 

transferred from the mother to the fetus and from the mother to infants via maternal milk. Lead 

excretion is primarily through urine and feces with minor routes from other sources such as sweat, 

saliva, hair, nails, and breast milk. The elimination half-lives for inorganic lead in blood and bone 

are approximately 30 days and 27 years, respectively (ATSDR 2007).

2.4.2 General Lead Poisoning Effects

Lead poisoning has no unique symptoms. Lead can affect numerous organs and systems in the 

human body with children, especially those six years and younger being the most susceptible. 

Early symptoms from lead exposure may include persistent fatigue, irritability, loss of appetite, 

stomach discomfort or constipation, reduced attention span, and insomnia. Prolonged lead 

poisoning in adults may cause poor muscle coordination, nerve damage to the sensory organs 

and nerves controlling the body, increased blood pressure, decreased kidney function, hearing 

and vision impairment, reproductive problems (e.g., decreased sperm count), and adversely affect

fetal development (such as reduced growth of the fetus and premature birth) at relatively low 

exposure levels. Prolonged lead poisoning in children may cause damage to the brain and 

nervous system, behavioral and learning problems, anemia, liver and kidney damage, hearing 

loss, lower IQ and hyperactivity, developmental delays, and seizures, coma, and death in extreme 

cases (USEPA 2013, 2017a, b).

Due to public health and environmental concerns regarding lead, a substantial amount of

published information is available on its toxicity including several reviews (ATSDR 2007, National 

Institutes of Health 2016, USEPA 2017a, b, U.S. National Library of Medicine 2017). USEPA

(2013) published an integrated science assessment for lead, providing a comprehensive review 

on the health effects of lead. The assessment evaluated the available epidemiological and 

toxicological studies and made causal determinations for the relationship between exposure to 

lead and health effects. The information below summarizes the major health effects of lead on 

neurological, cardiovascular, renal, immune, hematological, reproductive and developmental 

systems and the effects of lead on them, based on the USEPA (2013) integrated science 

assessment. Other metals in ammunition pellets and shot (antimony (being replaced by calcium), 

arsenic, and nickel) and bullets (copper and zinc) are not evaluated in this risk assessment 

because the impacts from the small amounts (0.5%-9%, see Section 2.1) of these naturally

occurring metals are expected to be minimal.

2.4.3 Lead Effects on Neurological Systems

Lead exposure can cause a range of nervous system effects. In children, extensive

epidemiological and toxicology studies show that lead exposure can impair cognitive, auditory, 

motor, and visual functions as well as alter externalizing and internalizing behaviors. Children 

ages 4 to 11 years with mean blood lead levels between 2 and 8 micrograms/deciliter (μg/dL) had

lower full-scale intelligence quotient (FSIQ), executive function, and academic performance and 

achievement. Children ages 2 to 17 years experienced reduced neurocognitive levels in FSIQ, 

infant mental development, memory, learning, and executive function at blood lead levels of 5-10 

μg/dL. In juvenile animals, dietary exposure resulting in blood lead levels of 10-25 μg/dL caused 

a decrease in learning, memory, and executive functions.

Effects on externalizing behaviors in children include two groups: 1) attention decreases, 

impulsivity, hyperactivity, and attention-deficit hyperactivity disorder (ADHD); and 2) conduct 

disorders that included aggression, delinquency, and criminal offenses. Children between the 
8

ages of 3 and 13 years of age had observable externalizing behavioral changes at mean blood 

lead levels of 7 to 14 μg/dL (and greater) including conduct disorders leading to a higher likelihood 

of criminal offenses later in their early adulthood (ages 19-24 years old). Animal studies also show 

increases in impulsivity or impaired response inhibition with relevant post-weaning and lifetime 

lead exposures that resulted in blood lead levels of 11 to 30 μg/dL. Effects on internalizing 

behaviors include withdrawn behavior and symptoms of depression, fearfulness, and anxiety.

Parent and teacher ratings of internalizing behaviors in children ages 8-13 years were reported 

to be higher in children with a higher lifetime average blood (mean: ~14 μg/dL) or childhood tooth 

(from ages 6-8) lead levels.

Other nervous system effects in children include a decrease in auditory and motor, and possibly 

visual function. Increased hearing thresholds were reported at ages 4-19 years with median blood 

lead levels of 8 μg/dL. Decreases in fine and gross motor function were reported in children ages 

4-17 years with lifetime average blood lead levels ranging from 4.8 to 12 μg/dL. In addition, some 

studies indicate negative effect on visual function; however, the available epidemiologic and 

toxicological studies are insufficient or inconsistent.

In adults, lead exposure impairs cognitive function and can cause psychopathological effects.

Declines in cognitive function (executive function, visuospatial skills, learning and memory) were 

reported in adults over the age of 50 years who, over a two-year period, had higher baseline bone 

lead levels. In lead-exposed workers with blood lead levels in the range of 14 to 89 μg/dL, 

epidemiologic studies showed reductions in memory, attention, reaction time, and reasoning.

Non-occupational exposed studies with adults (examining bone lead levels and concurrent blood 

lead levels) suggested there is an influence of past or cumulative lead exposures on current 

cognitive function, indicating a long-term impact.

Adults with higher concurrent blood or tibia lead levels self-reported symptoms of depression and 

anxiety. Epidemiologic studies also indicate that decreases in auditory function is associated with 

higher tibia lead level. Amyotrophic lateral sclerosis, Parkinson's disease, and essential tremors

were also reported to be associated with lead exposure. In addition, some studies indicate effects 

on visual function decreases; however, the available epidemiologic and toxicological studies are 

insufficient or inconsistent.

2.4.4 Lead Effects on Cardiovascular System

Both epidemiologic and animal toxicological studies show that increased lead exposure is 

associated with increased cardiovascular effects, in particular, blood pressure and incidence of 

arterial hypertension. Other effects of lead on the cardiovascular system include altered vascular 

reactivity and cardiac function, atherosclerosis, and increased cardiovascular mortality.

Experimental animal studies show mean blood lead levels of 10 μg/dL or greater caused an 

increase in blood pressure. Epidemiologic studies also demonstrated associations of blood and 

bone lead levels with other cardiovascular diseases (CVD), such as ischemic heart, 

cerebrovascular, and peripheral vascular diseases, and CVD-related mortality in adults. In 

addition, cardiovascular effects can arise secondarily to lead-induced renal injury as the 

cardiovascular and renal systems are intimately connected.

2.4.5 Lead Effects on Renal System

Epidemiologic and toxicological studies indicate that lead exposure is associated with reduced 

kidney function and chronic kidney disease among adults (with mean blood lead levels between 
9

20 and 30 μg/dL) through mechanisms such as reduced glomerular filtration rate and creatinine 

clearance, and increased serum creatinine. Long-term lead exposure is associated with 

pathological changes in the renal system such as proximal tubule cytomegaly, renal cell death, 

mitochondrial dysfunction, aminoaciduria, increased electrolyte excretion, adenosinetriphosphase dysfunction, oxidant redox imbalance, and altered nitric oxide homeostasis with 

ensuing elevated blood pressure are known as well. Longitudinal studies show lead-related 

reductions of renal function in populations with mean blood lead levels between 7 and 9 μg/dL.

Animal toxicological studies provide clear evidence for lead-induced kidney dysfunction at blood 

lead levels 30 μg/dL and greater. Kidney dysfunction evidence in animals at blood lead levels less 

than 20 μg/dL is not available.

2.4.6 Lead Effects on Immune System

Epidemiologic and toxicological studies show an increase in allergic and inflammatory conditions 

and decreased immune resistance resulting from lead exposure. Prospective studies in children 

(ages 1-5 years) indicate associations of asthma and allergy with prenatal cord and childhood 

blood lead levels. Epidemiologic studies show children with concurrent blood lead levels 10 μg/dL

and above had an increased level of immunoglobulin E (IgE) antibody, which plays a crucial role 

in the allergic response, and increased asthma prevalence. Evidence of lead-induced increases 

in T helper cells (Th2) cytokine production and inflammation in animals also support leadassociated increases in asthma, allergies, and IgE antibodies. Although toxicological or

epidemiologic evidence does not clearly identify a critical life stage or duration of lead exposure 

associated with allergic and inflammatory conditions, the evidence points to an influence of 

gestational and cumulative lead exposures.

Evidence for lead-induced decreased immune resistance is mainly from animal toxicological 

studies. Dietary lead exposure (blood lead levels of 7-25 μg/dL) in rodents resulted in increased 

susceptibility to bacterial infection and suppressed delayed type hypersensitivity. Evidence of

suppressed production of T helper cells (Th1) cytokines and decreased macrophage function in 

animals also provides support to lead-induced decreased immune resistance.

2.4.7 Lead Effects on Hematological System

Animal toxicological and epidemiologic studies show effects including decreased red blood cell

(RBC) survival and function and altered heme synthesis resulting from lead exposure. Human 

exposure resulting in blood lead levels between 2 and 7 μg/dL resulted in altered hematological 

parameters; oxidative stress; increased cytotoxicity in RBC precursor cells; and changes to the 

mode of action endpoints such as decreased intracellular calcium concentrations, decreased 

adenosine-triphosphate activity, and increased phosphatidylserine expression. Effects related to 

altered heme synthesis from relevant lead exposures (e.g., blood lead levels of 6.5 μg/dL) include 

decreased activities of delta-aminolevulinic acid dehydratase (ALAD) and ferrochelatase, and 

decreased levels of hemoglobin.

2.4.8 Lead Effects on Reproductive and Developmental System

Epidemiologic and toxicological studies show lead’s negative effects on male and female 

development and reproductive function. Developmental effects include delayed pubertal onset in 

cross-sectional epidemiologic studies of girls (ages 6-18 years) and boys (ages 8-15 years) with 

concurrent blood lead levels from 1.2-9.5 μg/dL. Experimental animal studies indicate delayed 
10

pubertal onset in female pups with blood lead levels of 1.3-13 μg/dL and delayed male sexual 

maturity at blood lead levels of 34 μg/dL. In addition, studies suggest that lead may affect birth 

outcomes (e.g., low birth weight/fetal growth, and spontaneous abortion) and female reproductive 

function (e.g., hormone level, and placental pathology). However, the overall evidence is 

inconsistent.

2.4.9 Carcinogenicity and Mutagenicity of Lead

Concerns have been expressed that lead and lead compounds are likely or potential human 

carcinogens (National Toxicology Program 2003, 2016, International Agency for Research on 

Cancer 1998, 2006, 2017, USEPA 2013). The International Agency for Research on Cancer 

(1998, 2006, 2017) classified inorganic lead compounds as probable human carcinogens (Group 

2A of the International Agency for Research on Cancer classification) based on limited human 

evidence and sufficient animal evidence. USEPA (2013) classified lead as a “probable human 

carcinogen” (B2 of the USEPA classification) based on sufficient cancer evidence from cancer 

studies in experimental animals (rodents) but inadequate cancer evidence from epidemiologic 

studies in humans. Chronic human epidemiologic studies showed limited evidence of increased 

risks of lung and stomach cancers, although concerns about confounding from arsenic exposure 

was raised (ATSDR 2007). In addition, weak evidence for an association with kidney cancer and 

gliomas has been noted (Steenland and Boffetta 2000 as cited in ATSDR 2007).

Lead is a clastogen (causing disruption or breakage of chromosomes). Studies conducted on 

workers exposed to lead showed an increase in chromosomal aberrations, and micronuclei and 

sister chromatid exchanges in peripheral blood cells (Minozzo et al. 2004, ATSDR 2007).

However, studies on sister chromatid exchange and genetic studies on humans environmentally 

exposed to lead, together with in vitro mutagenicity studies in microorganisms, do not show the 

same results (National Toxicology Program 2016). Thus, workers in enclosed areas appear to be 

exposed to lead differently than those exposed to lead environmentally.

3 DOSE-RESPONSE ASSESSMENT

3.1 Human Health Dose-Response Assessment

Dose-response assessments evaluate the dose levels (toxicity criteria) for potential human health 

effects from exposure to potentially harmful substances.

USEPA (2013) concluded it was inappropriate to develop an oral reference dose for inorganic 

lead given that the impacts to children can occur at blood lead levels too low for a threshold6.

Adverse effects in adults associated with bone lead concentrations exceeding 10 μg/g include 

cardiovascular, renal, and neurobehavioral effects. Adverse effects at a blood lead concentration 

less than 10 μg/dL include delayed and impaired development of the nervous system, delayed 

sexual maturation, neurobehavioral effects, increased blood pressure, depressed renal 

glomerular filtration rate, and inhibition of pathways in heme synthesis. Delay or impairment of 

neurological and sexual development occurred in children during pre- and post-natal 

development; and cognitive deficits, hypertension, and depressed glomerular filtration rate 

occurred in adults older than 60 years or postmenopausal (ATSDR 2007). USEPA (2013) uses 

blood lead concentration as a biomarker to regulate lead exposure. The Centers for Disease 

6 The maximum level set for children in USEPA (2013) was based on data from Lanphear et al. (2005), with some data points being erroneous. 

USEPA (2014) reanalyzed the conclusions of USEPA (2013) for children and determined they were still valid.
11

Control and Prevention (2012, 2017) uses a reference level of 5 μg/dL for lead exposure in 

children. 

USEPA (2013) has established a hazard standard of 400 ppm lead in residential soil in children’s 

play areas or an average of 1,200 ppm lead in soil in the rest of a residential yard. Lead present 

at or above these levels is considered to be a hazard in the areas described. The sources for lead 

in residential soil are either naturally occurring or man-made sources such as automobile or 

industrial emissions.

3.2 Ecological Effects Analysis

This section of the risk assessment discusses available ecological lead effects data for terrestrial 

and aquatic biota from ammunition but should not be considered an exhaustive review. 

3.2.1 Aquatic Effects Analysis

The toxicity of lead to aquatic resources such as invertebrates and vertebrates is dependent upon 

the species tested, endpoint and threshold evaluated, and water chemistry. Lead can occur in 

various forms in aquatic systems based on water and sediment chemistry parameters that can 

significantly alter the toxicity to nontarget species. Water hardness, pH, and temperature are just 

a few of the water quality parameters that can impact the toxicity of lead to aquatic biota. Lead 

will also partition to sediment where sediment chemistry parameters such as acid-volatile sulfide 

levels, organic matter and redox potential all impact the bioavailability and toxicity of lead to 

aquatic invertebrates and vertebrates. Lead can bioconcentrate in aquatic organisms, especially

filter feeders and algae, but has not been reported to bioaccumulate (Eisler 1988).7

3.2.1.1 Aquatic Vertebrates and Invertebrates

Lethal and sublethal lead effects have been noted in aquatic invertebrates, including physiological 

and biochemical functions that can lead to reduced reproduction and growth, and the inability to 

avoid predators and forage for prey items (Eisler 1988, Rattner et al. 2008). Freshwater 

cladocerans and amphipods appear to be the more sensitive group of aquatic invertebrates to the 

effects of lead based on available literature (Eisler 1988, USEPA 2006, 2013). Adverse effects to 

fish occur at concentrations ranging from 3.5 to 29,000 micrograms per liter (μg/L), with cold water 

species such as the rainbow trout being one of the more sensitive species to the effects of lead 

(Eisler 1988, USEPA 2006, 2017a). The range of toxicity values for fish are within the range of 

toxicity values that have been reported for amphibians (Eisler 1988, USEPA 2006, 2017a). 

Median lethality for amphibians range in the low part per million to greater than 12,500 μg/L in 

pore water, or interstitial sediment water, for the northern leopard frog (Lithobates pipiens) with

no observable effect concentrations reported as low as 10.0 μg/L (Eisler 1988, Chen et al. 2006). 

3.2.1.2 Aquatic Plants

The reported median effect concentrations for duckweed (Lemna minor) during a seven-day

exposure was 5,500 μg/L and several wetland plants have been shown to have impacts on growth 

at dissolved lead concentrations of 20,000 μg/L. Aquatic macrophytes are less sensitive to the 

impacts of lead compared to freshwater and marine algae, and algae and diatoms showed that 

7

 Bioconcentration is the accumulation of a chemical such as lead in or on an organism solely in water or the concentration of a chemical exceeding 

that of water as a result of exposure in water whereas bioaccumulation is the accumulation of substances such as lead in an organism and is not lost 

at a rate faster than via catabolism and excretion. Biomagnification is the accumulation of a chemical in an organism as a result of feeding on plants 

and animals that have taken up the chemical already and retain the chemical, thus the concentration is taken in at even a greater rate. 
12

growth was impacted at lead concentrations as low as 5.1 μg/L, and up to and greater than 1,000 

μg/L (Eisler 1988, USEPA 2017a). 

3.2.2 Terrestrial Effects Analysis

3.2.2.1 Mammals

The effect of lead on wild and domestic mammals is similar to the types of impacts discussed in 

the hazard characterization section of this risk assessment (Section 2.4). An extensive amount of 

literature exists regarding impacts to standard laboratory test mammals and livestock with less 

data available for wild mammals. Wild mammal studies focus on body burdens of lead for 

mammals that forage in areas contaminated by lead from industrial practices. These studies have 

revealed lead body burdens that have the potential for adverse effects to a variety of small and 

large mammal species (Rattner et al. 2008). The potential for effects to wild and domestic 

mammals from WS activities would be the greatest for mammals that scavenge carcasses 

containing lead ammunition.

3.2.2.2 Birds 

Bird sensitivity to lead from exposure to ammunition such as lead shot, bullets or bullet fragments, 

and lead tackle is well documented. Clinical signs of lead poisoning in birds are observed when 

blood lead concentrations reach 20 to 50 μg/dL while severe clinical signs are observed at 

concentrations exceeding 100 μg/dL. Clinical signs of lead poisoning include wing droop, anemia 

and weakness in affected birds (Rattner et al. 2008). The effects of the ingestion of lead shot have 

been noted in various avian species. Pain et al. (2009) documented impacts to 33 raptor species 

and 30 other species including ground nesting birds, cranes, and upland game birds. In fact, as 

few as 10 pellets can result in lethal and sublethal impacts to large raptor species such as the 

bald eagle (Eisler 1988). Lead impacts from spent ammunition have also been noted in numerous 

waterfowl species (Tranel and Kimmel 2009). Lethal and sublethal effects can occur at relatively 

small doses of lead from ammunition. An individual lead pellet has been shown to result in lead 

toxicosis in waterfowl and ground nesting birds. It should be noted that lead fishing tackle is also 

a risk factor for 75 bird species (USEPA 1994); it is the leading cause of mortality for common 

loons (Grade et al. 2018). 

Sublethal impacts to birds are similar to those observed in mammals and other vertebrates.

Depending on the dose and exposure time lead can exert deleterious effects on a range of 

physiological and biochemical functions. Reproductive impacts include effects to the testes, 

sperm count, eggshell thickness, reduced hatching as well as numerous embryo-related impacts 

in various avian test species. Other physiological impacts include ALAD inhibition, immune 

suppression, and impacts to the central nervous system among other effects. Behavioral effects 

including depressed locomotion, impaired ability to thermoregulate, diminished migratory 

movement, and reduced ability to avoid predation were also noted in a variety of test species 

(Burger 1995).

3.2.2.3 Reptiles and Amphibians (Terrestrial) 

Effects from lead shot have been observed in reptiles, especially from chronic exposures. Lance 

et al. (2006) reported reproductive impacts to captive American alligator that were fed nutria 

containing lead shot. This supports previous work regarding the detection of lead in captive 

alligators that were related to ingestion of nutria containing lead shot (Camus 1998). Lead blood 

levels of 280 μg/dL with no apparent lead toxicosis suggests that reptiles may be less sensitive 
13

to the effects of lead than other vertebrates. Hammerton et al. (2003) made similar observations 

with estuarine crocodiles (Crocodylus porosus) that had high lead blood levels from consuming 

prey contaminated with lead ammunition. 

3.2.2.4 Terrestrial Invertebrates and Microorganisms

A majority of the published literature regarding lead and terrestrial invertebrates focuses on the 

potential residues that could occur in these organisms in areas that are adjacent to industries 

related to lead use or production. USEPA (2005) established ecological soil screening levels (EcoSSL) that can be used as an effect threshold based on the available toxicity data. The Eco-SSL 

in this case was based on the geometric mean of the maximum allowable toxicant concentration

(MATC) using the collembolan (Folsomia candida) and reproduction as the endpoint. The value 

estimated from these studies was 1,700 mg/kg dry weight (dw). Soil pH ranged from 4.5 to 6.0 

with an organic matter content of 10% in all studies 

Other toxicity studies assessing lead effects to nematodes and earthworms did not meet the 

criteria for estimating the Eco-SSL but still provided information regarding lead sensitivity for other 

soil borne terrestrial invertebrates. In these studies, median lethality values for the nematode

(Caenorhabditis elegans) ranged from 11.6 to 1,434 mg/kg dw with higher toxicity at lower pH 

and organic matter values. Median lethality for the earthworm (Eisenia fetida) was reported at 

3,716 mg/kg dw with reproductive effects noted between 1,629 and 1,940 mg/kg dw.

3.2.2.5 Terrestrial Plants

Lead has been shown to inhibit photosynthesis, impact water adsorption and affect various 

metabolic processes in various monocot and dicot species (Sharma and Dubey 2005). USEPA 

(2005) has established an Eco-SSL of 120 mg/kg dw based on the geometric mean of the MATC 

for growth in studies using loblolly pine (Pinus taeda) red maple (Acer rubrum), berseem clover

(Trifolium alexandrium) and ryegrass (Lolium rigidum). The Eco-SSL was based on impacts to 

growth in each terrestrial plant species with ryegrass being the most sensitive (MATC = 22 mg/kg 

dw) and berseem clover the least sensitive (MATC = 316 mg/kg dw). NOEC and LOEC values for 

various other terrestrial plants including other crops and tree species have values at, or 

exceeding, the Eco-SSL established for terrestrial plants (Demayo et al. 1982, USEPA 2005).

4 EXPOSURE ASSESSMENT

4.1 Human Health Exposure Assessment

This exposure assessment estimates the potential for human lead exposure from WS activities. 

Identified lead exposure pathways are reported to include inhalation from shooting-related 

activities, and exposure from consuming meat from animals killed with lead ammunition. 

Handling and firing bullets are sources of lead exposure mainly through inhalation of airborne 

particles. The National Research Council (2012) evaluated the potential health risks to United 

States Department of Defense firing-range personnel from recurrent lead exposure. This 

evaluation indicated that airborne particulates and re-suspension of settled lead dust during range 

maintenance and cleaning are major sources of exposure for firing ranges. In WS programs, lead

exposure from inhalation of lead fumes and dust during firing is commensurate with normal 

shooting practices (mostly outdoors plus indoor calibration activities). Exposure to lead from 

accidental exposure such as shooting oneself or cleaning firearms is not expected due to rigorous 

training requirements (WS Directive 2.165, WS Firearm Use and Safety) and the use of protective 
14

equipment such as gloves. Shooting glasses and hearing protection are also required during 

shooting to prevent eye injury from debris and hot gas, and to prevent permanent hearing damage 

from noise.

The potential for the public to come into direct contact with lead such as shot, bullets, and pellets 

that remain intact after discharge will be low because bullets and shots fired will remain in the 

targeted animal. APHIS WS expects a minimal occurrence that WS personnel would miss the 

target animal or that a shot would pass through the target animal.

Regular consumption of game meat harvested with lead ammunition, especially those harvested 

with highly fragmented bullets such as high-powered, soft-point or rapid expanding ballistic tip 

lead bullets, may cause increases in blood lead levels compared to background levels, particularly 

in children (Johansen 2004, Kosnett 2009, Tranel and Kimmel 2009). Rapid expanding ballistic 

tip bullets had the highest fragmentation rate compared with the shotgun slug and muzzleloader 

bullet, with an average of 141 lead fragments per carcass and an average maximum distance of 

11 inches from the wound channel (Cornicelli and Grund 2009). Other studies show that humans

can be exposed to bioavailable lead from bullet fragments through consumption of deer killed with 

standard lead-based rifle bullets and processed under normal procedures (Hunt et al. 2009, Pain 

et al. 2010). When lead shot is used in WS programs, potential dietary exposure among the public 

is unlikely as most carcasses are disposed of properly. WS participates in meat donation 

programs such as “Sportsmen Against Hunger” whereby meat is donated under WS Policy 2.510 

(Fur, Other Animal Parts, and Edible Meat, 10/08/2003). However, only meat that is processed 

professionally or by the recipient is donated. Hematomas tend to be cut out to avoid lead 

fragments and foul-tasting meat. Donated meat such as deer is almost always from head or neck 

shots, thereby, reducing the chance of contaminating meat with lead. Feral swine are not donated 

due to FDA rules and regulations. Recreational hunters tend to aim behind the shoulder of an 

animal, where bullets that fragment often deposit lead into muscle tissue. In contrast, WS deer 

removals using firearms ideally involve fatal shots to the head or upper neck to incapacitate and 

kill an animal immediately unless long-ranges are involved, reducing the risk of lead introduction 

to parts of the animal used for edible meat.

A complete exposure pathway is not identified for soil, groundwater, and surface water media or 

plant uptake because the amount of lead from ammunition directly released onto soil is minimal.

The small amount of lead released to soil tends to stay in soil based on the environmental fate of 

lead. A standard measurement for soil weight per acre is an “acre furrow slice” which is 2 million 

pounds of soil in the top 6.7 inches of an acre of land (actually 2,024,458 lb. or 918,279 kg), and 

the soil where released lead would be immobilized (Cullen et al. 1996, Hue 2002). Thus, for 

Texas, it was determined that WS distributed 67 mg per acre of lead using the annual average 

for FY11 to FY15 or 196 mg per acre for FY11 to FY15 for the cumulative area worked from FY11 

to FY15 and the total pounds used during this time. To be conservative, it is assumed that all the 

lead would remain in the top inch of soil where the lead would be deposited. The weight of one 

inch of soil over an acre is estimated at 302,158 lb. (137,056 kg). Thus, in the top inch of soil, WS 

added 0.0005 mg/kg (= ppm) lead for the annual average from FY11 to FY15 or 0.0014 ppm for 

the cumulative total from FY11 to FY15. In 100 years, WS would add 0.05 ppm at the annual 

average in Texas. In Oklahoma, where calculations were higher, it was determined that WS 

distributed 282 mg per acre of lead for an annual average for FY11 to FY15 or 501 mg per acre 

for the cumulative total lead used from FY11 to FY15. WS added 0.0021 ppm using the annual 

average or .0037 for the five-year cumulative total. The estimated lead distribution conservatively 

represents the potential lead concentration released to soil from WS activities. The natural 

background levels of lead in soil range between 50 parts per million (ppm) to 400 ppm (USEPA 

2017a). The estimated lead use by APHIS WS contributes a small amount yearly (24,000 times 
15

less) to the lowest natural background concentration of 50 ppm in Oklahoma. USEPA (2017a) set 

the lead hazard standard for residential soil in children play areas at 400 ppm, thus WS adds an 

insignificant amount of lead to the soil. In fact, the amount of lead distributed by WS is likely six 

times less than that estimated or 144,000 times less than the natural background level of lead.

4.2 Ecological Exposure Assessment

4.2.1 Aquatic Exposure Assessment

Lead shot or bullets, or fragments may be transported to aquatic ecosystems via runoff from soil,

from an animal being fatally wounded in an aquatic environment, or directly from ammunition 

being discharged into aquatic areas. These circumstances are expected to result in minimal 

loading of lead in aquatic environments since large numbers of shot, bullets, and fragments would 

not be expected for most WS programs. In addition, bioavailability would be very low under these 

conditions.

WS uses a variety of ammunition in its various programs so the amount of lead that could be 

discharged from a specific firearm is variable. As a conservative estimate of lead loading into 

aquatic environments a large caliber rifle (.30-06) was assumed to be used with a 220-grain bullet 

which is considered a heavier grain bullet for that type of rifle for the majority of species taken 

(these are typically used for very large animals and predators). Generally, 150-160 grain bullets 

are used for large animals such as black bears and 110-125 grain bullets for coyotes and deer.

Assuming a shallow water body of one foot deep by one acre and all of the lead from a bullet 

being discharged into the water body, this would result in a lead concentration of approximately 

10 μg/L. The assumptions are that the shot or bullet is 90% lead, all of the lead would become 

soluble, and instantaneously dissolve equally throughout the body of water. In reality aquatic 

residues would be orders of magnitude less since the bullet would erode slowly over time in 

aquatic environments and be subject to binding in sediment and organic matter in the water 

column. The estimated residue is not meant to serve as a benchmark concentration, but to 

illustrate that lead residues in aquatic environments from WS activities would be expected to be 

very low. Lead from spent ammunition that would occur in runoff from soil would also be extremely 

low. Degradation rates for lead pellets and bullets to more soluble or bioavailable forms in soil is 

variable depending on soil type and other site-specific factors, but half-lives for pellets ranged

from 40 to 70 years (Jorgensen and Willems 1987). In addition, the amount of lead that becomes 

soluble in soil is usually very small (0.1-2.0%) (USEPA 2005).

4.2.2 Terrestrial Exposure Assessment

Exposure to terrestrial vertebrates, primarily birds and mammals, could occur from dietary 

exposure through the ingestion of soil or carcasses that contain spent lead ammunition. Dietary 

exposure from the consumption of water is not expected to be a significant pathway of exposure 

since lead pellets and bullets degrade slowly over time and the amount of lead that would be 

available is negligible compared to ingestion from soil or sediment used as grit in some bird 

species or scavenging of carcasses killed with firearms by vertebrates. Dietary lead exposure to 

terrestrial vertebrates from the consumption of plants or prey would also not be considered a 

potential exposure pathway. Lead uptake in plants and various prey items have been shown to 

occur; however, the low amounts of lead ammunition that are being used by WS and the lack of 

bioavailability to plants and other prey items suggest this exposure pathway to terrestrial 

vertebrates is negligible.
16

Terrestrial plants and soil-borne invertebrates could potentially be exposed to lead directly.

Potential soil-lead levels (0.0021 mg/kg) are anticipated to be very low based on historical use 

estimated for the WS Oklahoma program, a program with the highest lead use per acre. This 

amount would actually be less since only a small fraction of the lead would be bioavailable and 

lead that is released would bind in the top 6 inches of soil. Only a small fraction of lead is water 

soluble in soil due to slow degradation and, therefore, the quantities available for uptake into 

plants or that could impact soil invertebrates would be negligible to nonexistent.

5 RISK CHARACTERIZATION

This section qualitatively characterizes risks associated with adverse human health and fish and 

wildlife. Under the anticipated uses, lead from bullets, shot, or pellets should pose minimal risk to 

human health and most nontarget organisms. Risk is further reduced in WS operations that are 

able to use non-lead ammunition. The use of non-lead ammunition is expected to increase over 

time further reducing risk to human health and the environment.

5.1 Human Health

WS uses lead shot, bullets, or pellets in aerial or ground-based shooting over relatively wide areas 

in mostly remote locations. Although potentially toxic to humans, it is highly unlikely that adverse 

health effects as a result of WS activities involving lead will occur. Approximately 5.5 tons (5.0

metric tons) of lead are released to the environment per year in all states during WS activities.

Over the landscape, this is minor.

Lead exposure and risk to human health from WS activities is not expected to result in significant 

risk to any subgroups of human populations (such as WS personnel, and the public including 

children, and hunters). There is potential for exposure and risk to WS personnel who handle lead 

ammunition. However, exposure and risk are expected to be low since firing occurs almost always 

outdoors reducing inhalation exposure from lead fumes and dust that may occur during firing. In 

addition, APHIS policies and practices for WS personnel handling firearms reduce the potential 

for lead exposure as well as from injuries related to the discharging of firearms (WS Directive 

2.165). Subgroups of the public that could be exposed to lead ammunition from WS activities are 

people who may consume some of the animals that are donated or have been wounded or shot 

by WS personnel. Carcasses from ground or aerial shooting will be collected, when feasible, and

then disposed of and not available for human consumption.

Small numbers of game animals that are mortally wounded but are not collected by WS personnel 

may be available for human consumption. However, this is not expected to be a significant risk to 

people for several reasons, including: (1) The goal of WS personnel conducting direct lethal 

control is to kill target animals with minimal wounding; (2) WS personnel typically make lethal 

shots to the head and neck region of an animal during WS WDM activities, which is generally not 

the part of a game animal (e.g. deer) that is harvested for meat and reduces the potential for lead 

exposure from meat; (3) WS employees and meat processor remove hematomas caused by 

bullets, shot, pellets, or fragments and remove them during preparation, if meat is to be donated 

for consumption; (4) carcasses found in the field are not fit for human consumption in a relatively 

short time, dependent on temperature; and (5) the potential for lead exposure is null in cases 

where WS uses non-lead ammunition. Therefore, the low potential for lead exposure from 

activities related to WS activities is expected to result in negligible risk to human health. 
17

5.2 Ecological Risks

5.2.1 Aquatic

Risk to aquatic ecosystems is expected to be minimal based on the available toxicity data for 

lead, the potential exposure pathways, and environmental fate for lead. Risk to aquatic 

ecosystems including fish, amphibians, invertebrates and plants may occur primarily as lead 

ammunition either degrades in soil and is transported via runoff or is directly deposited. Lead 

levels estimated from WS activities based on conservative assumptions of exposure would not 

exceed toxicity levels for aquatic nontarget organisms. In addition, lead levels would not exceed 

acute or chronic aquatic life criteria under the Clean Water Act that vary based on water hardness 

(USEPA 1985). Ingestion of lead shot, bullets or associated fragments is not considered a 

significant risk to fish and amphibians (Rattner et al. 2008). In addition, risk to aquatic ecosystems 

is further reduced as WS transitions to non-lead shot and bullets. The current use of non-lead 

ammunition varies between states within WS, but approximately 64% of the state WS programs 

use less than 20% lead ammunition. Lead use in WS is expected to continue to decline.

5.2.2 Terrestrial

Exposure and risk to nontarget mammals and birds will be greatest for those that consume animal

carcasses killed with lead ammunition. However, the potential for lead exposure and risk to these 

types of scavengers will be reduced in instances where carcasses are removed by WS. There is 

also the potential for lead exposure and risk to nontarget mammals and birds that may consume 

soil that could contain lead fragments or pellets. Risk would be greatest for birds that consume 

soil for grit to aid in digestion. The use of non-lead ammunition and pellets within the WS program 

will remove the risk of lead exposure through these two exposure pathways. 

Risk to terrestrial plants and soil-borne invertebrates is expected to be negligible based on the 

use pattern for lead by WS, the environmental fate of lead ammunition and pellets, and the effects 

data for these two nontarget groups. The potential concentration of lead in soil from the use of 

lead ammunition by WS in its Texas program (see section 4.1), is 6.7 x 10-5 mg/kg. The Eco-SSLs 

for terrestrial plants and invertebrates were 120 and 1700 mg/kg dw. Effect values for terrestrial 

plants and invertebrates were seven to eight orders of magnitude above the soil residue value 

estimated in Texas suggesting wide margins of safety. Lead concentrations could be higher within 

a given acre since lead ammunition and pellets are not evenly distributed within an acre; however,

even in concentrated areas the levels would still be well below effect thresholds. In addition, these 

values assumed that all of the lead in the acre is available for uptake by plants and invertebrates 

which would not be the case due to the slow degradation and environmental fate of lead in soil.

6 UNCERTAINTIES AND CUMULATIVE IMPACTS

This section qualitatively discusses the potential uncertainties with this risk evaluation and the 

cumulative effects associated with additional lead exposures from other sources to human health 

and environment, and potential cumulative effects from exposure to other stressors. The 

uncertainties associated with this risk evaluation arise primarily from various parameters (see 

Section 2.3) associated with the weathering rate of lead shot and potential lead leaching from soil 

to groundwater, which is qualitatively discussed in this section. These parameters include 

precipitation, chloride ion concentration, organic matter cover, and pH. However, the transition by 

WS from lead to non-lead ammunition, which is proactively occurring in many WS State Offices,

where feasible, and the low concentrations of lead released by WS into the environment suggest 

that significant adverse impacts to human health or the environment are unlikely.
18

WS uses aerial and ground shooting for a range of animal control activities on an annual basis.

Minimal repeated exposure of WS personnel to lead during the loading and firing of guns is 

expected. Lead accumulation in the human body will not occur from repeated use of lead 

ammunition due to the small amount of lead released to the environment from WS activities. We 

estimate that it will take approximately 750,000 years of activity of the type and magnitude that 

WS conducts to release the amount of lead that is equal to the low end of the background lead 

soil level of 50 mg/kg (Section 4). Risk from lead ammunition use is also extremely low for the 

general public from WS activities. Sources of lead from firearms, hunting, and shooting activities 

that are not part of WS activities as well as airborne emissions from metals industries (such as 

lead smelters and iron and steel production), manufacturing industries, and waste incineration are 

large sources of lead. The reported lead accumulation rates on individual shooting ranges are 

between 1.4 to greater than 15 metric tons per year (Rattner et al. 2008). Annual shot deposition 

in upland fields from hunting may be as much as one million shots per hectare (Schulz et al. 

2002). Data shows that U.S. use of lead from ammunition, shot and bullets, was 69,200 metric 

tons (USGS 2008, 2011). An approximated 3,977 metric tons of lead fishing sinkers are sold in 

the United States annually (Rattner et al. 2008). Average lead use in WS programs is 

approximately 5.0 metric tons per year. The amount of lead released into the environment from 

WS activities is less than 0.01% than just the estimates for lead in ammunition and fishing sinkers, 

and not including industrial activities. The contribution of lead to the environment from WS is 

negligible and, therefore, an incrementally negligible addition to the cumulative effects from all 

sources of lead in the environment. 

Cumulative impacts to human health and the environment from WS lead ammunition use will be 

negligible when considering potential impacts from exposures to other anthropogenic and natural 

stressors. Lead has wide-ranging effects on most biological systems in humans and nontarget 

animals, therefore current effects to any biological systems from other contaminants or stressors 

would be expected to have a cumulative effect when considering lead use in WS programs.

Spatial and temporal variability in exposure to different contaminants and stressors, as well as a 

lack of knowledge about the impacts of multiple stressors, make it difficult to state what types of 

cumulative impacts could be expected. However, the potential risk to human health and the 

environment from lead ammunition exposure as a result of WS activities is so low that cumulative 

impacts to any effects would be incrementally minor when considering exposure to other 

stressors.

7 SUMMARY

Lead has a variety of industrial and manufacturing usages including uses in ammunition (shot, 

bullets, or pellets) and fishing sinkers. The WS Program uses lead ammunition for aerial and 

ground shooting for a variety of programs and minimal amounts of fishing sinkers, but use of lead 

has declined as non-lead substitutes have become available, researched, and determined to be 

effective. Lead ammunition use as a percentage of total ammunition used by WS varies from state 

to state, but the total lead ammunition use in WS operational activities as a percentage of total 

lead use from ammunition in the United States is very low (~0.002%), and even magnitudes less 

considering all uses of lead, especially in mining and smelting areas (USEPA 2017a). The use of 

lead ammunition and weights in WS is expected to continue to decline.

Risk to human health and the environment from lead has been documented in this report. Risk of 

lead related maladies from ammunition (e.g., through consumption of carcasses) is minimized by 

training WS personnel (e.g., shot placement) and the WS carcass disposal policy. In addition, 

most WDM conducted for animals such as deer, swine, rabbits, or migratory game birds (e.g., 
19

ducks and native doves) that have the highest likelihood of being consumed are conducted mostly 

on private or secured public lands (e.g., airports), where public access is restricted. Overall, the 

risk of lead poisoning from WS use is minimal. WS expects that the potential of lead toxicity from 

WS use to humans, especially children who are the most sensitive to the effects of lead, and the 

environment will be negligible. WS anticipates that this risk will continue to decline

Ecological impacts to aquatic resources are also expected to be minimal based on the low 

potential for exposure to most aquatic biota. In terrestrial systems the greatest potential for 

exposure and risk is to nontarget vertebrates that consume lead ammunition fragments 

inadvertently from the ground or from scavenging carcasses. Risks to nontarget animals are 

reduced when carcasses are removed and when non-lead ammunition can be used. Lead 

ammunition degrades slowly in terrestrial and aquatic environments. Its environmental fate once 

it degrades suggests that the small amounts of lead that may be present in the environment as a 

result of WS activities would not have an adverse impact to soil, air or water quality. Regardless, 

WS is increasing the use of non-lead ammunition and fishing sinkers in WDM and remains 

committed to working with the U.S. Fish Wildlife Service, other federal agencies, and state 

agencies to proactively manage lead exposure to fish and wildlife.

8 LITERATURE CITED

Animal and Plant Health Inspection Service (APHIS). 2012. Re: Use of lead ammunition in wildlife damage 

management (WDM) activities. USDA, APHIS letter to Natural Resources Defense Council, Land and 

Wildlife Program, Director.

Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological profile for lead. U.S. 

Dept. Health and Human Services, Public Health Service, ATSDR. Aug. 528 pp. @ 

http://www.atsdr.cdc.gov/toxprofiles/tp13.pdf. Accessed 11/18/2017.

Burger, J. 1995. A risk assessment for lead in birds. J. Toxicol. Environ. Health: Current Issues. 45(4): 369-

396.

Camus, A.C., M.M. Mitchell, J.E. Williams and P.L.H. Jowett. 1998. Elevated lead levels in farmed American 

alligators, Alligator mississippiensis consuming nutria, Myocastor coypus, meat contaminated by lead 

bullets. J. World Aqua. Soc. 29(3): 370-376.

Cao, X., L.Q. Ma, M. Chen, D.W. Hardison, Jr., W.G. Harris. 2003. Weathering of lead bullets and their 

environmental effects at outdoor shooting ranges. J. Environ. Qual. 32:526-534.

Caudell, J.N., B.C. West, B. Griffin, and K. Davis. 2009. Fostering greater professionalism with firearms in 

the wildlife arena. Proc. Wildl. Damage Manage. Conf. 13: 95-99.

Caudell, J. N., S. R. Stopak, and P. C. Wolf. 2012. Lead-free, high-powered rifle bullets and their 

applicability in wildlife management. Human–Wildlife Interactions 6:105–111.

Cornicelli, L., and M. Grund. 2009. Examining variability associated with bullet fragmentation and deposition 

in white-tailed deer and domestic sheep: Preliminary results. Minn. Dept. Nat. Res. 13 pp. @

http://files.dnr.state.mn.us/fish_wildlife/lead/bulletstudy/resources/publicsummary.pdf. Accessed 

10/18/2017.

Centers for Disease Control and Prevention. 2012. Low level lead exposure harms children: A renewed call 

for primary prevention. CDC Advisory Comm. On Childhood Lead Poisoning Report. Jan. 4. 54 pp. 
20

Centers for Disease Control and Prevention. 2017. Blood Lead Levels in Children. CDC, Div. Emergency 

and Environ. Health. @ http://www.cdc.gov/nceh/lead/acclpp/blood_lead_levels.htm. Accessed 

10/19/2017. 

Chen, T.H., J.A. Gross and W.H. Karasov. 2006. Sublethal effects of lead on northern leopard frog (Rana 

pipiens) tadpoles. Environ Toxicol Chem. 25: 1383-1389.

Cullen, G., A. Dines, and S. Kolev. 1996. Lead. Monograph for United Kingdom Poison Information. Int’l 

Programme Chem. Safety INCHEM. @ http://www.inchem.org/documents/ukpids/ukpids/ukpid25.htm. 

Accessed 1019/2017. 

Demayo, A., M.C. Taylor, K.W. Taylor, P.V. Hodson, and P.B. Hammond. 1982. Toxic effects of lead and 

lead compounds on human health, aquatic life, wildlife plants, and livestock. CRC Critical Reviews in 

Environ. Control. 12(4):257-305.

Eisler, R. 1988. Lead hazards to fish, wildlife, and invertebrates: A synoptic review. U.S. Fish Wildl. Serv. 

Biol. Rep. 85(1.14). 94 pp.

Grade, T.J., M.A. Pokras, E.M. LaFlamme, and H.S. Vogel. 2018. Population-level effects of lead fishing 

tackle on common loons. J. Wildlife Management 82(1):155-164. DOI: 10.1002/jwmg.21348.

Hammerton, K.M., N. Jayasinghe, R.A. Jeffree and R.P. Lim. 2003. Experimental study of blood lead 

kinetics in estuarine crocodiles (Crocodylus porosus) exposed to ingested lead shot. Arch. Environ. 

Contam. Toxicol. 45:390–398.

Hue, C. A. 2002. Lead distribution throughout soil, flora, and an invertebrate at a wetland skeet range. J. 

Toxicol. Environ. Health 65(15):1093-1107

Hunt, W. G., R. T. Watson, J. L. Oaks, C.N. Parish, K. K. Burnham, R. L. Tucker, J. R. Belthoff, and G. 

Hart. 2009. Lead bullet fragments in venison from rifle-killed deer: Potential for human dietary exposure. 

PLoS ONE 4(4):e5330. @ http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0005330.

Accessed 11/18/2017. 

International Agency for Research on Cancer. 1998. Lead and lead compounds: Lead and inorganic lead 

compounds (group 2B) and organolead compounds (group 3). IPCS INCHEM Home, IARC Summaries 

and Evaluations. Updated March 3 @ http://www.inchem.org/documents/iarc/suppl7/

leadandleadcompounds.html. Accessed 11/20/2017. 

International Agency for Research on Cancer. 2006. Inorganic and organic lead compounds. World Health 

Org., IARC. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Vol. 87. 468 pp. @ 

http://monographs.iarc.fr/ENG/Monographs/vol87/index.php. Accessed 11/20/2017. 

International Agency for Research on Cancer. 2017. Agents classified by the IARC monographs, volumes 

1-120. IARC. Last update October 27. 36 pp. @ http://monographs.iarc.fr/ENG/Classification/

ClassificationsAlphaOrder.pdf. Accessed 11/20/2017. 

Johansen, P., G. Asmund, and F. Riget. 2004. High human exposure to lead through consumption of birds 

hunted with lead shot. Environmental Pollution 127:125–129. 

Jorgensen, S. and M. Willems. 1987. The fate of lead in soils: the transformation of lead pellets in shootingrange soils. Ambio 16(1):11-15.

Knott, J., J. Gilbert, R. E. Green, and D. G. Hoccom. 2009. Comparison of the lethality of lead and copper 

bullets in deer control operations to reduce incidental lead poisoning; field trials in England and 

Scotland. Conservation Evidence 6:71–78.
21

Kosnett, M. J. 2009. Health effects of low dose lead exposure in adults and children, and preventable risk

posed by the consumption of game meat harvested with lead ammunition. In R. T. Watson, M. Fuller, 

M. Pokras, and W. G. Hunt (eds.). Ingestion of Lead from Spent Ammunition: Implications for Wildlife 

and Humans. The Peregrine Fund, Boise, Idaho, USA. DOI 10.4080/ilsa.2009.0103

Lance, V.A., T.R. Horn, R.M. Elsey and A. de Peyster. 2006. Chronic incidental lead ingestion in a group 

of captive-reared alligators (Alligator mississippiensis): Possible contribution to reproductive failure.

Comparative Biochemistry and Physiology, Part C 142: 30-35.

Lanphear, B.P.; R. Hornung, J. Khoury, K. Yolton, P. Baghurst, D.C. Bellinger, R.L. Canfield, K.N. Dietrich, 

R. Bornschein, T. Greene, S.J. Rothenberg, H.L. Needleman, L. Schnaas, G. Wasserman, J. Graziano, 

R. Roberts. 2005. Low-level environmental lead exposure and children's intellectual function: An 

international pooled analysis. Environ. Health Perspect. 113: 894-899.

McCann, B. E., W. Whitworth, and R. A. Newman. 2016. Efficacy of non-lead ammunition for culling elk at 

Theodore Roosevelt National Park. Human-Wildlife Interactions 10:268–282.

Massachusetts Department of Environmental Protection. 2009. Assessment of ecological risk associated 

with lead shot at trap, skeet and sporting clays ranges. MDEP, Office of Research and Standards. May 

11. 35 pp.

Miller, G., G. Begonia, M Begonia, and J. Ntoni. 2008. Bioavailability and uptake of lead by coffeeweed 

(Sesbania exaltata Raf.). Int J Environ Res Public Health. 5(5):436-40.

Minozzo R, L.I. Deimling, L.P. Gigante, and R. Santos-Mello. 2004. Micronuclei in peripheral blood 

lymphocytes of workers exposed to lead. Mutat Res. 565:53-60. @ 

http://www.sciencedirect.com/science/article/pii/S1383571804002347?via%3Dihub. Accessed 

10/17/2017.

National Institutes of Health. 2016. Elemental lead: CASRN: 7439-92-1. NIH, U.S. Libr. Med., Toxic. Data 

Network (TOXNET). Last Revision Oct. 25. @ https://toxnet.nlm.nih.gov/cgibin/sis/search2/f?./temp/~x5n254:1. Accessed 10/19/2017.

National Research Council. 1983. Risk Assessment in the Federal Government: Managing the Process.

NRC, Committee on the Institutional Means for Assessment of Risks to Public Health. Washington, DC. 

National Academies Press, Washington, DC. 190 pp.

National Research Council. 2012. Potential Health Risks to DOD Firing-Range Personnel from Recurrent 

Lead Exposure. NRC, Div. on Earth and Life Sciences. Washington, DC: National Academies 

Press.173 pp. @ https://www.ncbi.nlm.nih.gov/pubmed/24901199. Accessed 11/20/2017.

National Toxicology Program. 2003. Report on carcinogens background document for lead and lead 

compounds. Prepared by Techn. Planning & Manage. Corp., Durham, NC for US Dept. Health and 

Human Serv., Publ. Health Serv., NTP. No. N01-ES-85421. May 8. 198 pp. @ 

https://ntp.niehs.nih.gov/ntp/newhomeroc/roc11/lead-public_508.pdf. Accessed 10/19/2017.

National Toxicology Program. 2016. 14th Report on Carcinogens: Lead and Lead Compounds. US Dept. 

Health and Human Serv., Publ. Health Serv., NTP. 5 pp. @ 

https://ntp.niehs.nih.gov/ntp/roc/content/profiles/lead.pdf. Accessed 10/19/2017.

Pain, D. J., I. J. Fisher, and V. G. Thomas. 2009. A global update of lead poisoning in terrestrial birds from 

ammunition sources. In R. T. Watson, M. Fuller, M. Pokras, and W. G. Hunt, eds. Ingestion of Lead 

from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. 

DOI 10.4080/ilsa.2009.0108
22

Pain, D.J., R.L. Cromie, J. Newth, M.J. Brown, E. Crutcher, P. Hardman, L. Hurst, R. Mateo, A.A. Meharg, 

A.C. Moran, A. Raab, M.A. Taggart, and R.E. Green. 2010. Potential Hazard to Human Health from 

Exposure to Fragments of Lead Bullets and Shot in the Tissues of Game Animals. PLoS One 

5(4):e10315. 17 pp. @ http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010315. 

Accessed 10/17/2017. 

Pourrut, B., M. Shahid, C. Dumat, P. Winterton, and E. Pinelli. 2011. Lead uptake, toxicity, and detoxification 

in plants. Rev. Environ. Contam. Toxicol. 213:113-36. 

Rattner, B.A., J.C. Franson, S.R. Sheffield, C.I. Goddard, N.J. Leonard, D. Stang, and P.J. Wingate. 2008. 

Sources and Implications of Lead Ammunition and Fishing Tackle on Natural Resources. Wildl. Soc. 

Techn. Review. The Wildlife Society, Bethesda, MD. 62 pp.

Scheetz and Rimstidt. 2009. Dissolution, transport, and fate of lead on a shooting range in the Jefferson 

National Forest near Blacksburg, VA, USA. Environ. Geol. 58:655-665. @ http://www.deepdyve.com/lp/ 

springer-journals/dissolution-transport-and-fate-of-lead-on-a-shooting-range-in-the-7olE1eHECM. 

Accessed 11/20/2017.

Scheuhammer, A.M., and S.L. Norris. 1995. A review of the environmental impacts of lead shotshell 

ammunition and lead fishing weights in Canada. Canadian Wildl. Service Occ. Paper No. 88. 48 pp. @ 

ghttp://www.biologicaldiversity.org/campaigns/get_the_lead_out/pdfs/health/Scheuhammer_and_Norr

is_1995.pdf. Accessed 11/20/2017. 

Schulz, J.H., X. Gao, J.J. Millspaugh, and A.J. Bermudez. 2009. Acute lead toxicosis and experimental lead 

pellet ingestion in Mourning Doves. Extended Abstract pp. 187-189. In R.T. Watson, M. Fuller, M. 

Pokras, and W.G. Hunt, eds. Ingestion of Lead from Spent Ammunition: Implications for Wildlife and 

Humans. The Peregrine Fund, Boise, Idaho. DOI 10.4080/ilsa.2009.0203

Sergio, T. B., J. Enzweiler, R.S. Angelica. 2008. Lead bioaccessibility in soil and mine wastes after 

immobilization with phosphate. Water, Air and Soil Pollution 195:257-273. @ https://link.springer.com/

article/10.1007/s11270-008-9744-6. Accessed 10/17/2017.

Sharma, P. and R.S. Dubey. 2005. Lead toxicity in plants. Braz. J. Plant Physiol. 17(1): 35-52.

Tanskanen, H., I. Kukkonen, and J. Kaija. 1991. Heavy metal pollution in the environment of a shooting 

range. Finland Geol. Surv. Special Paper 12:187-193.

Tranel, M. A., and R. O. Kimmel. 2009. Impacts of lead ammunition on wildlife, the environment, and human 

health—A literature review and implications for Minnesota. In R. T. Watson, M. Fuller, M. Pokras, and 

W. G. Hunt, eds. Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The 

Peregrine Fund, Boise, Idaho, USA. DOI: 10.4080/ilsa.2009.0307

U.S. Environmental Protection Agency (USEPA). 1985. Ambient water quality criteria for lead. USEPA, 

Office Water Regs. & Stds. EPA440/5-84-027. Jan. @ https://www3.epa.gov/npdes/pubs/owm586.pdf. 

Accessed 11/22/2017.

_____ USEPA. 1989. Risk assessment guidance for Superfund volume I, human health evaluation manual 

(Part A). Interim Final. Office of Emergency and Remedial Response, Washington, DC. EPA/540/1-

89/002 December. 

_____ USEPA. 1994. Lead fishing sinkers: Response to citizen’s petition and proposed ban. USEPA, 40 

CFR Part 745, Federal Register Notice 59:11121-11143.

_____ USEPA. 2003. TRW Recommendations for performing human health risk analysis on small arms 

shooting ranges. USEPA, Office of Solid Waste and Emergency Response, Wash., DC. OSWER 

#9285.7-37. March. 52pp.
23

_____ USEPA. 2005. Ecological soil screening levels for lead – Interim final. USEPA, Office of Solid Waste 

and Emergency Response. Wash., DC. OSWER #9285.7-70. March. 242 pp.

_____ USEPA. 2006. Air quality criteria for lead. USEPA, Office of Research and Development, Nat’l Cen. 

Environ. Assessment, Research Triangle Park, NC. EPA/600/R-05/144aF-bF. @ 

https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=158823. Accessed 11/22/2017.

_____ USEPA. 2013. Integrated science assessment for lead. USEPA, Office of Research and 

Development, Research Triangle Park, NC. EPA/600/R-10/075F. June.

_____ USEPA. 2014. Memorandum: Re: Identification and consideration of errors in Lanphear et al. (2005), 

“Low-Level Environmental Lead Exposure and Children’s Intellectual Function: An International Pooled 

Analysis” Integrated science assessment for lead. To: Integrated Science Assessment for Lead Docket 

(EPA-HQ-ORD-2011-0051). USEPA, Office of Research and Development, Research Triangle Park, 

NC. EPA/600/R-10/075F. May 9.

_____ USEPA. 2017a. Lead. USEPA, Oct. 20. @ https://www.epa.gov/lead. Accessed 11/22/2017. 

_____ USEPA. 2017b. Lead at superfund sites. USEPA, Wash., DC. @ 

https://www.epa.gov/superfund/lead-superfund-sites. Accessed 11/22/2017.

_____ USEPA. 2017c. Pesticide science and assessing pesticide risks. USEPA, Office of Pesticide 

Programs @ https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks. Accessed 

8/14/2017.

U.S. Geological Survey (USGS). 2008. Lead Shot and Sinkers: Weighty Implications for Fish and Wildlife 

Health. Science Daily. 16 July 2008. @ www.sciencedaily.com/releases/2008/07/080711125733.htm.

Accessed 11/23/2017.

U.S. Geological Survey (USGS). 2013. 2011 Minerals Yearbook: Lead. USGS, Chapt. 42. 18 pp. @ 

http://minerals.usgs.gov/minerals/pubs/commodity/lead/myb1-2011-lead.pdf. Accessed 11/23/2017.

U.S. National Library of Medicine. 2017. Lead. Toxnet Toxicology Data Network. ChemIDplus: a toxnet 

database. @ https://chem.nlm.nih.gov/chemidplus/rn/7439-92-1. Accessed 11/23/2017.

9 PREPARERS

9.1 APHIS WS Methods Risk Assessment Committee

Writers for “Use of Lead in Wildlife Damage Management Risk Assessment”:

Primary Writer: Fan Wang-Cahill 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Environmental Health Specialist

Riverdale, MD

Education: B.S. Biology and M.S. Hydrobiology - Jinan University, Guangzhou, China; Ph.D. Botany 

(Ultrastructure/Cell Biology) – Miami University

Experience: Joined APHIS in 2012, preparing human health risk assessments and providing assistance 

on environmental compliance. Prior experience before joining APHIS includes 18 years 

environmental consulting experience specializing in human health risk assessments for 

environmental contaminants at Superfund, Resource Conservation and Recovery Act (RCRA), and 

state-regulated contaminated facilities.
24

Primary Writer: Jim Warren 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Environmental Toxicologist, Little Rock, AR 

Education: B.S. Forest Ecology and M.S. Entomology – University of Missouri; Ph.D. Environmental 

Toxicology – Clemson University

Experience: Sixteen years of experience working for APHIS preparing ecological risk assessments and 

providing assistance on environmental compliance. Prior experience before joining APHIS includes 

other government and private sector work regarding ecological risk assessments related to various 

environmental regulations.

Writer: Thomas C. Hall

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Fort Collins, CO

Education: BS Biology (Natural History) and BA Psychology – Fort Lewis College; MS Wildlife Ecology –

Oklahoma State University

Experience: Special expertise in wildlife biology, identification, ecology, and damage management.

Thirty-one years of service in APHIS Wildlife Services including operations and research in CO for 

research and OR, GU, CA, OK, and NV for operations conducting a wide variety of programs 

including bird damage research and management, livestock protection (predators and birds), invasive 

species management, wildlife hazard management at airports, property and natural resource 

protection including waterfowl, brown tree snake, feral swine, rodent, and beaver damage 

management. Applied and supervised the use firearms, and thus, the use of lead. 

Editors/Contributors for “Use of Lead in Wildlife Damage Management Risk Assessment”:

Editor/Contributor: Timothy Algeo

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Concord, NH

Education: BS Biology – Johnson State College; MS Wildlife Conservation – University of Massachusetts; 

Ph.D. Natural Resources and Environmental Studies – University of New Hampshire

Experience: Special expertise in wildlife biology, ecology, wildlife disease, and wildlife damage 

management. Nineteen years of service with APHIS Wildlife Services 

Editor/Contributor: Michael Green 

Position: USDA-APHIS-Wildlife Services (WS), Environmental Coordinator, Fredrick, MD

Education: BS Wildlife and Fisheries Sciences, University of Tennessee

Experience: Special expertise in wildlife biology, ecology, and damage management. Eleven years of work 

experience with WS in MD and VA. Experienced in a wide range of program activities including nutria 

eradication, airport wildlife management, and wildlife damage management to protect livestock, 

aquaculture, public safety, and natural resources. Served as staff biologist in WS Headquarters for 2 

years.

Editor/Contributor: Andrea Lemay 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis 

Services (ERAS), Biological Scientist, Raleigh, NC

Education: BS Plant and Soil Science (Biotechnology) - University of Massachusetts; MS Plant 

Pathology -North Carolina State University 

Experience: Thirteen years of service in APHIS conducting risk analysis. Four years of experience in 

preparing environmental analyses in compliance with the National Environmental Policy Act.

Editor/Contributor: Jeanette O’Hare 

Position: USDA-APHIS-Wildlife Services (WS), National Wildlife Research Center (NWRC), Registration 

manger, Fort Collins, CO 

Education: B.S. Biology – College of Saint Mary; M.A. Biology – University of Nebraska - Omaha

Experience: 13 years of experience working for WS NWRC providing regulatory compliance support for 

the development of wildlife damage management tools. Prior experience before joining APHIS includes 

assessing the environmental fate of pesticides and providing the agency guidance on water quality 
25

issues at the state government level, and laboratory experience in the fields of pharmacology and 

toxicology, and immunology. 

Editor/Contributor: Emily Ruell 

Position: USDA-APHIS-WS, NWRC, Registration Specialist, Fort Collins, CO

Education: B.S. Zoology and Biological Aspects of Conservation – University of Wisconsin - Madison; 

M.S. Ecology – Colorado State University (CSU); M.A. Political Science – CSU

Experience: Three years of experience with WS NWRC preparing and reviewing vertebrate pesticide 

registration data submissions and other registration materials, and providing pesticide regulatory 

guidance to WS, WS NWRC, and collaborators. Prior experience before joining APHIS includes 

seven years of conducting field and laboratory wildlife research at CSU, and environmental policy 

research for the U.S. Geological Survey.

Editor/Contributor: Ryan Wimberly 

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Madison, TN

Education: BS Wildlife Management and Ecology – Northwest Missouri State University

Experience: Special expertise in wildlife biology, ecology, and damage management. Seventeen years of 

service with APHIS Wildlife Services, including operations and research, conducting a wide variety of 

programs, including bird damage research and management, livestock protection, invasive species 

management, wildlife hazard management at airports, property, and natural resource protection.

Expert in preparing environmental documents for WS programs to comply with the National 

Environmental Policy Act and the Endangered Species Act.

Data Contributor: Joey Millison

Position: USDA-APHIS-WS Information and Technology (IT), Junior Applications Developer

Education: Information and Technology coursework from various sources

Experience: Eleven years of experience in APHIS, WS Management Information System (MIS) Group.

Retrieves WS field data from the MIS for writers, reviewers, and editors.

9.2 Internal Reviewers

USDA APHIS Wildlife Services

Reviewer: Kevin Grant (retired)

Position: USDA-APHIS-WS, State Director/Supervisory Wildlife Biologist, Oklahoma City, OK

Education: BS in Plant and Soil Science, Tarleton State University, Texas, Graduate Wildlife Biology, 

University of Texas, Tyler.

Experience: Twenty-eight years of service in APHIS, Wildlife Services in Oklahoma and Arizona, with 

seven years as a Wildlife Damage Management Field Specialist with Texas A&M Cooperative 

Extension Service. Special expertise in the application and supervision of Integrated Wildlife Damage 

Management techniques for the prevention of damages to resources from predators, rodents, and 

feral swine. 

Reviewer: John Steuber

Position: USDA-APHIS-WS, State Director/Supervisory Wildlife Biologist, Billings, MT

Education: BS Biology, BS Wildlife Management Texas A&M University

Experience: Special expertise in wildlife biology, wildlife damage management, and aviation program 

management. Thirty years of service in APHIS Wildlife Services including a wide variety of programs 

such as endangered species protection (avian and mammalian predators), livestock protection (avian 

and mammalian predators), and property and resource protection (aquatic rodent and feral hog damage 

management). Expert in managing statewide aviation programs (CA, OK, and MT). Seventeen years 

of experience as a State Director (OK and MT) managing a statewide APHIS Wildlife Services program.

Reviewer: Michael Yeary

Position: USDA-APHIS-WS, State Director/Supervisory Wildlife Biologist, Lakewood, CO

Education: BS in Wildlife Ecology, Texas A&M University
26

Experience: Special expertise in wildlife damage management including applying and supervising M-44s 

and their use. Thirty-eight years of service in APHIS Wildlife Services in TX, KS, CO, and WS 

Regional Office with experience in a wide variety of programs (livestock, aquaculture, dairy, property, 

natural resources, and human health and safety protection) including predator, bird, beaver, feral 

swine, and rodent damage management activities.

9.3 Peer Review

The Office of Management and Budget requires agencies to have peer review guidelines for 

scientific documents. The APHIS guidelines were followed to have “Use of Lead in Wildlife 

Damage Management” peer reviewed. WS worked with the Association of Fish and Wildlife 

Agencies to have experts review the documents.

9.3.1 Peer Reviewers Selected by the Association of Fish and Wildlife Agencies

Alabama Department of Conservation and Natural Resources

Michigan Department of Natural Resources

New York State Department of Environmental Conservation

9.3.2 Comments

Peer reviewers provided editorial comments on the manuscript. These were appreciated and 

incorporated into the final document. Following are the comments regarding concerns with the 

risk assessment and a response:

1. Comment: The risk assessment for lead fluctuates between statements that lead use by the 

agency is of such small volume that adverse effects will be negligible, and reiteration of protocols 

undertaken to mitigate these adverse effects. This could be portrayed as WS being proactive, but 

several seemingly conflicting and controversial statements jeopardize this effort.

Response: The risk assessment demonstrates the minimal use of lead by WS but attempts to

reduce the use of lead as safe and effective alternatives become available. Thus, while this 

dichotomy exists, we believe that WS use of lead poses minimal risks, but WS will continue to take 

measures that reduce the risks associated with lead ammunition use. 

2. Comment: One significant area of omission in the lead risk assessment is any mention of lead 

toxicosis and loons. The absence of this particular species was notable because of the abundance 

of data regarding adverse effects related to lead ingestion, likely from the use of lead sinkers. There 

was a singular statement that ‘an individual lead pellet has been shown to result in lead toxicosis 

in waterfowl and ground nesting birds’ (Section 3.2.2.2); this statement seemingly contradicts other 

assertions that ‘lead from bullets, shot, or pellets should pose minimal risk to most nontarget 

organisms.

Response: The risk assessment notes the high toxicity of lead to birds, especially waterfowl.

However, a sentence was added specifically for birds in Section 3.2.2.2 regarding lead sinkers 

which can pose a serious threat to birds. Overall, WS expects that the risks are low to this group of 

birds because most WS activities involving waterfowl damage management require the use of nontoxic shot. The transport of bullets and pellets to aquatic systems would be negligible based on 

how WS uses these forms of ammunition and the environmental fate of any lead that may end in 

the soil or water. On the other hand, sinkers could pose a problem if used in areas frequented by 

waterbirds where fishing damage management is occurring. Since common loons and other birds 

are affected by fishing tackle, more information was added in Section 3.2.2.2. It is not anticipated 

that WS will have much of an effect on them because of the minimal amount of lead weight used 

annually and the location of such activities. WS has a fishing program for overabundant 
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pikeminnows on the Columbia River in deep waters downstream of dams to protect threatened and 

endangered salmonids. WS loses an estimated 150 lbs. of sinkers annually in these deep waters

that likely become snagged on the bottom of the river. The lead sinkers would be at the bottom of 

rivers where they will not likely be consumed by birds.

3. Comment: The lead risk assessment does a good job of highlighting the uncertainty in lead usage 

across the agency. However, the document repeatedly mentions a ‘conservative estimate’ of lead 

use that likely overestimates the actual amount of lead being used (and judging from the context 

this is accurate), but the phrase by definition usually refers to a lower than true amount. This may 

be somewhat confusing to readers.

Response: We agree with this assertion and attempted to provide an explanation for this use and 

maybe a better word would be careful or cautious. No matter the word, it is attempting to provide 

the “worst-case-scenario” to ensure that environmental risks and impacts are addressed. Thus, in 

this risk assessment, it is conservative to provide an overestimate of the use of lead given 

4. Comment: In my opinion this document heavily overestimates the amount of lead deposited by 

WS and available for environmental uptake. Estimates provided are very conservative. 

Response: We provide conservative estimates, using exaggerated numbers of more lead than 

likely used to ensure WS use is under that threshold and to evaluate a worst-case scenario. We 

see minimal effects from the overestimates, so we know that impacts are even less than those 

given.

5. Comment: The lead risk assessment would better achieve its intended goals of completeness if it 

improved its focus on the procedures and protocols employed by WS to mitigate any adverse 

effects of lead usage, rather than rely on questionable mathematical extrapolations or comparisons 

with other sources of lead to argue the activities pose little to no risk.

Response: The risk assessment cites and summarizes the relevant procedures and protocols WS

has developed related to the use of lead in WDM. The risk assessment also estimated conservative 

estimates of use as a screening tool to characterize the risk to human health and the environment. 

The risk assessment cites the applicable protocols throughout the risk assessment. WS recognizes

that the estimates are highly conservative and may overestimate actual exposure and risk to human 

health and the environment; however, this was the intent of this screening level risk assessment.

 

6. Comment: As rightfully described in the lead risk assessment, the use of lead may be necessary 

in specific situations to ensure humane killing and protect the safety of staff/public. These 

objectives are of paramount importance and warrant more attention within the document. 

Response: We believe your assessment of the necessity for the use of firearms to humanely 

euthanize wildlife and protect public safety is correct and a goal of WDM. A discussion of the 

humaneness was given in the risk assessment introductory chapter for the risk assessments as 

this is an issue that arises for most methods used in WDM. We also addressed this in the risk 

assessment “The Use of Firearms in Wildlife Damage Management by WS.”: This risk assessment 

tried to focus on just the issue of lead impacts on people and the environment and did not want to 

dilute this assessment with additional information that have already been addressed. We 

appreciate the comment.

7. Comment Section 1.1 extrapolates lead contamination on a broad geographic scale to argue the 

amount of lead deposition is minimal. However, it is unclear if this is an appropriate method of 

estimation because the activities of the Program are typically clustered on the landscape (as is later 

pointed out in the document), and focal areas of WDM activities will certainly have higher risks of 

lead deposition than others. 
28

Response: WS conducts WDM over the landscape by many employees in a state. While WDM 

may be clustered in some areas, such as at an airport, the general area where WDM is conducted 

is still of considerable size. The greatest amounts of lead come from aerial work for feral swine 

and coyotes and activities are conducted much more so over the landscape where animals are 

found. It is unlikely that animals at this level are found at the same location on a property. Thus, we 

believe that while we estimated the amount of lead used conservatively (overestimate in this 

sense), we would have few, if any, areas where the amount of lead used was clustered to the extent 

that lead deposition would rise to a level of high risk.

8. Comment: There were multiple statements that seemingly portrayed the lead use by the agency 

as not a risk because it is at a smaller scale than other activities, notably that of recreational hunting 

and fishing (Section 2.1). This could be viewed as an inflammatory redirect or negative 

commentary on those activities. 

Response: The use of the comparison between recreational activities and WDM activities was 

meant to give the reader an idea of the extent of lead used by WS in WDM. We did not draw these 

comparisons to be negative on recreational activities. To the contrary, we believe that it gives 

readers an idea of the potential extent of risks and we believe it to be minimal.

9. Comment: This document contends WS adds an insignificant amount of lead to the soil because

the amount distributed is less than ‘the lead hazard standard for residential soil in children play 

areas at 400 ppm’ (Section 4.1), but also reminds the reader the USEPA contends ‘the impacts to 

children can occur at blood lead levels too low for a threshold’ (Section 3.1).

Response: We agree with your assessment that acceptable levels of lead for children are likely 

very low and that we would not want to surpass that level anywhere. USEPA continually modifies 

acceptable levels of lead in the soil for people, especially children, as the science continually 

improves our understanding of lead toxicity and safe levels of lead for people. We have evaluated 

this risk and the potential to add to the lead level to the soil. Even over 100 years, WS would not 

add 1 ppm lead to the soil. For comparison, the background level, lead already in the soil, is 50 

ppm. Thus, we believe that using these levels helps illustrate the risk of WDM activities and the 

amount of lead that is added to the environment from WDM. We believe that this is a very low level 

and the risk would be considered minimal. Additionally, many areas where WS conducts WDM are 

off-limits to the public and, therefore, we believe risks are likely even lower. 

Comments received not requiring a response. We appreciate these comments.

1. Comment: This review adequately describes the use of lead and techniques that use lead for 

wildlife damage management.

2. Comment: Overall the method risk assessment was complete and thorough in describing methods, 

consequences and successes.

3. Comment: I appreciated the opportunity to review the risk assessment!