Lead Bullet Risks for Wildlife & Humans

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Bald eagle scavenging on deer carcass
A bald eagle scavenges on a deer carcass.

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Understanding the Role of Hunting

Viable, thriving ecosystems include checks and balances. Hunting has been part of the natural balance for thousands of years, depending upon grazing and browsing animals. 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.

 

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.

 
Radiograph of condor with lead fragments in digestive tract
Radiograph of condor 318 with lead fragments in the digestive tract, with a pullout photo of the actual lead fragment removed from the bird. This bird died from lead poisoning in 2012.

NPS

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 (micrograms per deciliter), 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 higher than 800 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.

However, lead poisoning through ingestion of spent lead bullets and shell shot is a serious threat for many other wildlife species too, including our national symbol- the bald eagle. Other scavengers that are affected by eating spent lead ammunition 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.

 
Comparison of a lead and nonlead bullet fired into gelatin.
Figure 1: Comparison of lead bullet (top) vs. nonlead bullet (bottom) when fired into gelatin.

Peregrine Fund

Lead Bullet Fragmentation

Lead bullets are so dangerous for anything that ingests them because they fragment into hundreds of tiny pieces when they strike an animal that was shot. The fragments can spread beyond the wound channel, the main path of the bullet through the animal. Even if a hunter attempts to remove the largest remaining piece of the bullet from the animal, the tiny fragments of lead will still remain in the meat and gut piles that are left behind in the field. These fragments can be enough to poison both humans and wildlife.

 
Lead fragments in deer carcass
Figure 2: Lead fragments in a deer carcass

Figure 1 compares a lead bullet (top) with a non-lead bullet (bottom) when fired into gelatin. The lead bullet fragments into many pieces that would spread throughout the wound channel in an animal, while the non-lead bullet remains intact.

The x-ray image in Figure 2 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.

 
pig skull shot with copper
Figure 3: Pig skull shot with non-lead bullets.

Figure 3 shows a radiograph of a wild pig skull that was shot twice with 9mm Barnes non-lead bullets. As you can see, the bullets remained intact and didn't fragment throughout the animal.

In Figure 4, the photo compares two different .270 caliber bullets that have been discharged and retrieved. Notice how the non-lead bullet shown on the right mushroomed out upon impact, but remained in one piece. The lead bullet on the left, however, disintegrated into hundreds of lead fragments that are toxic not only to condors, but also to other humans and wildlife that ingest it.

 
Fragments of 270 cal lead bullet
Figure 4: Comparison of discharged lead (left) and non-lead (right) bullets

Further Reading:

To further understand the effects of lead bullet fragmentation on condors and other species, explore these informative websites.

Ventana Wildlife Society: Condors and Lead
California Department of Fish & Game: Get the Lead Out
USGS: Lead Poisoning In Wild Birds
Hunting With Nonlead: Information For Hunters

 

Learn and Explore

Extensive scientific studies on lead and its effects on humans and wildlife

Lead has been studied extensively for over 100 years because of its negative impacts to life on earth. Lead causes widespread damage to cells and organs when it is ingested, inhaled, or absorbed in surprisingly small quantities. Explore the links to the right to read though numerous scientific papers about the proven harmful effects of lead for both hunters and scavenging wildlife.

Last updated: September 24, 2019

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