Lead bullets may harm humans and golden eagles

Local golden eagle migration research may indicate dangers associated with the use of lead bullets, especially health risks to human consumers of big game meat, researchers say.
The high levels of lead found in the eagles is a result of the birds feeding on the carcasses of animals that were shot by hunters using lead bullets, meaning the meat could be unfit for people to eat.
“A lot of these eagles are coming in with lead levels that could be fatal to human beings,” said Tyler Veto, a wildlife biologist for the Missoula-based Raptor View Research Institute.
Rob Domenech, executive director and founder of the institute, said more than 50 percent of the eagles they tested in 2007 have a greater-than-background level of lead in their blood.
“And that’s cause for concern,” he said.

According to Veto, the institute defines background levels as ten micrograms of lead per deciliter of blood. He said the background level is “basically the point where we should start to worry.”
“Any amount of lead is bad, so it’s really hard to call it background level,” he said.
Two main concerns are exposed by the research done by the institute, said Heiko Langner, research assistant professor and director of the Environmental Biogeochemical Laboratory in the Geosciences Department at the University of Montana. Langner, who manages the laboratory testing of the blood for the institute, said there is a health risk for humans who eat venison that was shot using lead bullets.
Veto said that when a bullet penetrates the body of an animal, the lead could fragment up to two feet from the entry wound, spreading poison throughout.
“A lot of people think they’re doing themselves a favor by avoiding beef and going out and shooting their own venison, when some may be bringing home lead to their wives and children,” Veto said.
Langner said there is also an environmental health concern associated with the use of lead bullets.
There are more common animals — like bears, mice, coyotes and ravens — that feed from carcasses left by hunters, he said.
Domenech said they aren’t able to pinpoint the source of the lead found in golden eagles but one possible explanation could be that the eagles are feeding on carcasses that were killed with lead-based bullets.
He said the institute is currently researching a host of potentially poisonous heavy metals with an emphasis on lead and mercury.
“We’re not trying to ban bullets,” Domenech said of the research-based organization that monitors Montana raptor migration and researches the factors, both human and not, that affect migration.
Langner said this year’s results haven’t been analyzed in the lab yet, but that tests done with a field kit show similar results to last year’s tests.
He said there is no other major source of lead that eagles would come in contact with other than gut piles left by hunters.
“This is the big factor,” he said.
Several organizations and state departments have recently sought restraint on the use of lead bullets used for hunting.
The Wisconsin Department of Natural Resources issued a warning in a recent newsletter against deer harvested with lead bullets. According to the newsletter, tiny lead fragments may be too small to be seen and can disperse far from the wound.
The Ridley-Tree Condor Preservation Act has effectively banned the use of lead bullets when hunting in range of the condor since July 1, 2008.
Washington state’s Department of Ecology is also targeting lead ammunition as part of a proposed “Lead Chemical Action Plan.”
Langner said the chief reason for the continued use of lead bullets is their thrift. He said lead bullets are cheaper but copper bullets may perform as well or better.
The National Rifle Association is an outspoken advocate for the maintained legalization of lead ammunition.
In response to the Lead Chemical Action Plan, the NRA has organized an effort aimed at Washington Gov. Chris Gregoire, urging the public to speak out in favor of lead ammunition supported by claims that their affect on humans and wildlife do not justify a ban.
“It’s a big health concern for humans and it’s a big health concern for the environment, too,” Langner said, “and it’s really something that’s so easy to get rid of.”
jeff.osteen@umontana.edu