Lead Bullet Risks for Wildlife & Humans
Understand the Role of Hunting
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.
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.
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.
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.
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.
Pig shot with non-lead ammo
Links to more information about lead and wildlifeList of Scientific Studies
California Department of Fish & Game: Get the Lead Out
Arizona Game and Fish: Condors and Lead
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
Hunting With Nonlead.org
Local and online non-lead ammo retailers
Hog Blog - Lead Ban Chronicles
Center for Disease Control Main Lead Page
Examination of Presence of Lead Bullet Fragments in Commercially Processed Ground Venison
Did You Know?
Pinnacles National Park has the greatest number of bee species per unit area of any place ever studied. The roughly 400 bee species are mostly solitary; they don't live in hives.