The National Rifle Association has asked to intervene in a lawsuit seeking to force the agency to ban the use of lead in ammunition.

The NRA, joined by Safari Club International, claims its members "who use lead-based ammunition in their hunting and shooting sports activities will be impaired if they are no longer able" to do so.

The lawsuit against the EPA was filed by the Trumpeter Swan Society and the Center for Biological Diversity -- the group that has pursued the lead ban issue relentlessly in recent years.

Each time, however, the Environmental Protection Agency has turned aside CBD's request at the administrative level.

The group has asked EPA to ban the use of lead in ammunition and initially requested a ban on the use of lead in fishing sinkers.

The fishing sinker request prompted a crush of public comments submitted to the EPA even though most of them had to do with using lead in ammunition.

The EPA has consistently rejected the request to ban lead even though it has done so in other uses.

In its lawsuit, filed in federal court in Washington, D.C., the Center for Biological Diversity contends wildlife suffers secondary effects from lead poisoning as a result of picking up and ingesting lead shotgun pellets.

The group specifically points to avian scavengers such as bald and golden eagles and the California condor as especially susceptible as they pick up lead from animals killed with lead.

The group also points out that waterfowl received some protection in 1991 with a federal requirement of using nontoxic shot.

And, the lawsuit states, ammunition manufacturers market a wide variety of non-lead, nontoxic bullets and shotgun shot.

"There is no technological or commercial reason why nontoxic bullets and shot with comparable effectiveness should not be substituted in ammunition for their lead counterparts," the lawsuit states.

The NRA claims an outright ban ignores "the fact that ban on a lead-based ammunition would significantly undermine recreational hunting, shooting and wildlife conservation."

Alternatives to lead-based ammo, NRA said, are more difficult to obtain, less effective and "generally more expensive."

"Additionally, the inability to choose lead-based products will make0 some types of hunting and shooting activities more difficult, if not impossible and much more expensive," the NRA request to intervene states.

They went on to say the taxes paid on the sale of lead ammunition "are an invaluable source of funding for wildlife and habitat conservation. That funding would diminish significantly if lead-based ammunition was removed from the market."

No hearings have been set in the case.