Lead, for centuries the core ingredient of ammunition, is now coming under attack itself.

As the U.S. military begins to embrace "green bullets," environmental groups are pushing state and federal officials to ban the use of lead in hunters’ guns and fishermen’s tackle.

Their goal is to protect both the animals that scavenge the carcasses of hunted prey and the people who consume meat from hunting expeditions.

On Tuesday, the Center for Biological Diversityand the American Bird Conservancyplan to file a petition with the Environmental Protection Agency seeking a comprehensive nationwide ban on lead-based sporting ammunition and fishing tackle.

The petitioners argue that "it is now incontrovertible fact" that lead fragments in the bodies of animals shot with lead bullets or lead pellets are "a serious source of lead exposure to scavenging animals" and a health risk to humans who eat hunters’ kills.

Scientists have found that chronic lead poisoning in birds leads to "appetite loss, anemia, anorexia, reproductive or neurological impairment, immune suppression, weakness, and susceptibility to predation and starvation," the petition said.

Lead’s toxicity has long been known, and most of the uses that led to human exposure, like the manufacture of lead paint, have been banned for decades. Lead ammunition consumed only about 3 percent of the 6.4 million tons of lead used worldwide in 2000, according to a 2003 report by the Nordic Council of Ministers.

Michael Fry, a wildlife toxicologist who directs conservation advocacy for the American Bird Conservancy, said that even sub-lethal levels of lead in condors, bald eagles and other raptors can be debilitating, affecting their ability to fly and avoid collisions.

But hunting organizations dispute the dimensions of the problem. Larry Keane, the vice president and general counsel of the National Shooting Sports Foundation, said the petition was "fundamentally flawed as a matter of science."

"You don’t manage harm to individual animals," he said in an interview. "Wildlife biologists manage wildlife populations."

Populations of eagles, one of the raptors cited by the petition as being at risk, are soaring, Keane added.

Jeff Miller, a conservation advocate at the Center for Biological Diversity, said several regional bird populations were indeed affected by ingesting lead ammunition or fishing tackle, including the endangered Mississippi sandhilll crane; eiders in Alaska, which are listed as threatened by the Interior Department; and trumpeter swans, considered species of concern in the Rocky Mountain West.

"If we had to show major population-level effects on many species to evaluate anything that caused ecological harm, we’d never ban anything," he said. "There is compelling evidence of harm to many species, and there are alternatives. It doesn’t make sense to continue with it."

Ammunition manufacturers have long experimented with alternatives to traditional bullets. Bullets made from copper, bismuth and various alloys have been under development for 20 years or more. In June, the Army announcedthat it was shipping 1 million rounds of a new 5.56-mm lead-free cartridge that had been in development for a decade to its troops in Afghanistan.

But most sporting ammunition still comes in the form of copper-jacketed lead, which is dense, the better to carry the energy of the shot downrange, and malleable, the better to expand on impact, increasing the bullet’s lethality.

Nationally, the chief existing regulation on the domestic use of lead ammunition is a 19-year-old Interior Department ban on the use of lead shot to hunt waterfowl in wetlands, according to the groups’ petition. California has banned the use of lead ammunition in the range of the endangered California condor.

Richard Patterson, the managing director of the Sporting Arms and Ammunition Manufacturers’ Institute, an industry-supported technical organization, dismissed the arguments made in the environmental groups’ petition as "inflammatory, throw-it-against-the-wall material."

The petitioners counter that hunters and fishermen should not cause lead poisoning in animals they are not even seeking to kill.

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