Lead Bullet Risks for Wildlife & Humans

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Understanding the Role of Hunting

Viable, thriving ecosystems include checks and balances. Hunting has been part of natural balances for thousands of years, depending upon grazing and browsing animals just like the coyote and mountain lion. Scavengers like condors can benefit from eating the scraps that hunters or predators leave on the land. Hunters that use non-lead ammunition carry on the proud tradition of wildlife conservation by preventing condors and other animals from being exposed to lead, a toxic substance.

California condors feed on a carcass.
California condors feed on a carcass.

NPS Photo

Impacts of Lead Bullets on Condors and Other Wildlife

Most lead-core rifle bullets fragment into hundreds of tiny pieces when they strike animal tissue. Lead-tainted meat may become part of scavengers' food supplies when any of the following occur: a wounded animal escapes a hunting attempt, an animal shot as a pest is not retrieved from the field, or when gutpiles remain on the landscape after a hunt. Over the past 3 decades, California condor recovery efforts have brought to light how this lead pathway in the ecosystem can threaten even the very survival of a species. But as you will see, impacts extend to many other wildlife species also.

X-Ray of condor 318 with lead fragments in the digestive tract. This bird died from lead poisoning in 2012.


Lead Poisoning is the Biggest Threat to California Condors

Numerous scientific studies have reached a consensus: lead poisoning is the biggest threat facing the successful recovery of the California condor. Semi-annual test results show that the majority of free-flying condors at Pinnacles National Park have blood lead levels that exceed 10 ug/dL, which is the same threshold used by the Center for Disease Control as an initial warning sign that a human child is at risk. Some condors have been measured with blood lead levels as high as 570 ug/dL, a value that would potentially kill a human. By the time condors at Pinnacles reach breeding age of 7 years old, almost all of them have received emergency, life-saving chelation treatment at least once. Numerous condors in the flock have now required multiple chelation cycles.

Scientific studies have documented that the primary source of this lead is from spent ammunition that remains in carcasses after they are shot. When a lead rifle bullet traveling at almost 3 times the speed of sound strikes animal tissue, it quickly begins to expand and loses hundreds of tiny pieces as it continues its journey. The organs and other bloodshot areas that are trimmed away and left behind are usually contaminated with these lead fragments. Because condors feed on dead animals and are group feeders, even small amounts of lead can sicken or kill many condors. Also, since all of their meals come from dead animals, condors are more frequently exposed to lead bullet hazards than most wildlife.

Two golden eagles on a large mammal carcass
Golden eagles feed on a carcass in San Benito County, CA

However, lead poisoning through ingestion of spent lead bullets and shell shot has been demonstrated as being a serious factor for many other wildlife species too, including our national symbol the bald eagle. Other scavengers that have documented as being affected include golden eagles, hawks, ravens, turkey vultures, and grizzly bears.

More than 500 scientific studies published since 1898 have documented that worldwide, 134 species of wildlife are negatively affected by lead ammunition.

An X-ray of meat wrapped in butcher paper shwith white areas circled in red
In this X-ray of a package of processed meat, lead fragments are circled in red.

Human Health Concerns

Studies are increasingly showing that lead fragments can also be found in wild game meat processed for human consumption, even though best attempts are made in the field to remove sections that are within the bullet wound channel.

A recently published scientific study examined the prevalence of lead bullet fragments in packaged venison. Thirty different white-tail deer were harvested using lead rifle bullets and then given to 30 different game meat processors. Researchers randomly selected 324 packages of ground venison and whole cuts from the processors and x-rayed them to document how many contained lead bullet fragments. Of the 324 randomly selected packages of ground venison, 34% contained metal fragments; some packages contained as many a 168 separate pieces. Further analysis positively identified the metal as 93% lead and 7 % copper. Also, when these tainted packages were fed to domestic pigs, blood levels became elevated with 2 days of ingestion. This demonstrates that while the results are preliminary and much further study needs to be done to better assess risks to humans, it appears that the if lead bullets are used, odds are high that you will ingest lead particles in ground game meat.

CT-scan showing meat packages with bright white dots scattered throughout

Another study was conducted in North Dakota that examined ground venison packages that had been donated by hunters to food pantries. It found that 59% of the packages had lead fragments.


Lead Bullet Fragmentation

The reason lead bullets represent such a problem for anything that ingests them is that they fragment into hundreds of tiny pieces when they strike an animal being shot. The following photos demonstrate various aspects of lead bullet performance and are contrasted with non-lead bullets, which are effective and humane, but much less toxic to both wildlife and humans.

These photos show examples of fragmentation in lead bullets.

Bullet paths for lead and non-lead bullets through ballistic gel
This photo shoes a lead bullet that has been shot into a ballistic gelatin block. This technique allows you to see the tissue disruption caused by a bullet, and in the case of lead bullets, gives you a good idea of the scattering of fragments as the bullet passes through the gel block. The density of these gel blocks is designed to approximate what muscle tissue is like.
X-ray of ballistic gel showing white fragments along the lead bullet path, while the non-lead bullet path is clear
This x-ray shows the same block of ballistic gel. As you can see, the non-lead bullets at the top and bottom of the screen gave a good wound channel, but didn’t exhibit any fragmentation. By contrast, the lead-core bullet in the middle shows a huge amount of fragmentation as the bullet passed through the gel block. The same thing happens in animals, but can be even worse when the bullet strikes bones and keeps on travelling. Even lead bullets that exit an animal leave a toxic trail of lead fragments behind.
X-ray of deer neck showing dark fragments along spine
This x-ray image shows more than 450 lead bullet fragments that were spread through the neck of a mule deer after it was shot with a lead rifle bullet. The lead fragments appear as dark spots, while any bone chips would be light gray in color due to their much lower density. Just a few of these fragments contain enough lead to sicken or kill a bald eagle or California condor.
X-ray of deer carcass showing non-lead bullet in single piece
This x-ray shows the broken ribs in the chest of a deer after it was shot with a Barnes-Triple Shock non-lead rifle bullet. Note that the mushroomed bullet is intact, unlike the lead bullet in the deer neck x-ray above.
pig skull shot with copper
X-ray of wild pig skull; shot twice with 9mm Barnes non-lead bullets

Pig shot with non-lead ammo

Hundreds of fragments from a spent lead bullet are shown
This photo compares two different .270 caliber bullets that have been discharged and retrieved.  Notice how the nonlead bullet shown on the right upon impact has mushroomed out, but remained in one piece. The lead bullets on the left however, disintegrated into hundreds of lead fragments that are toxic not only to condors, but also to other wildlife.  Ingested lead bullet fragments may also pose a risk to human health.
Hundreds of lead fragments are shown.
This photo shows a Remington Core-Lokt lead-core rifle bullet that has been discharged and retrieved. Notice the numerous lead fragments that resulted from the bullet expanding and that the bullet only retained 70% of the original mass.


Further Reading:

Ventana Wildlife Society: Condors and Lead
List of Scientific Studies
California Department of Fish & Game: Get the Lead Out
USGS: National Wildlife Health Center
USGS: Lead Poisoning In Wild Birds
University of Minnesota Raptor Center
Ingestion of Spent Lead Ammunition: Implications for Wildlife and Humans - Proceedings of the Conference
Peregrine Fund's Bullet Fragmentation Study: Supplementary Data and Images
Saving Our Avian Resources
Project Gutpile

Information about non-lead ammunition and hunting:

Hunting With Nonlead.org

Links to web sites concerning lead and human health:

Center for Disease Control Main Lead Page
Center for Disease Control ATSDR Page
CDC Childhood Lead Poisoning Prevention Program
Oregon Department of Human Services Lead Page
Ingestion of Spent Lead Ammunition: Implications for Wildlife and Humans -- Proceedings of the Conference

Examination of Presence of Lead Bullet Fragments in Commercially Processed Ground Venison
Health Effects of Low Dose-Levels of Lead Exposure in Adults and Children
Elevated Levels of Lead Documented in Canadian Hunters
Reductions of Blood Lead Levels in Canadian Hunters Following Cessation of Using Lead Shot
Lead Exposure in Humans in Greenland Consuming Game Meat
Use of Lead Isotopes to Analyze Blood Lead Levels in Canadian Hunters
September 2009 Description of Methods Used in North Dakota Study To Examine Prevalence of Lead Fragments in Game Meat
Guidance From North Dakota Department of Game & Fish Concerning CDC Study on Blood Lead Levels in Humans
Final Report from CDC on North Dakota Study Assessing Risk to Humans Who Eat Game Meat
Description of Various Techniques to Examine Presence of Lead Fragments in Ground Venison Sampled From Food Pantries in North Dakota
Wisconsin Health Department Examination of the Potential for Ingestion of Lead Fragments in Ground Venison

Last updated: June 13, 2019

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