CONCORD - Calling attention to an issue that they say has both international and local impact, about 70 peace activists used yesterday's Martin Luther King Jr. holiday to protest the manufacture and use of depleted uranium munitions by the military. ''Dr. King would have supported this kind of caring, the kind that brings us together out of our small little groups,'' said An Sokolovska of Cambridge, a retired sociologist and longtime activist. About 70 protesters stood in thick snowfall yesterday in the middle of a traffic circle in Concord Center to make their point, holding signs saying ''Depleted Uranium is Forever'' and ''What Would Dr. King Say?'' Depleted uranium, a heavy metal, has been used for two decades on the tip of various munitions, not because of its radioactivity - which military officials say is negligible - but because its high density allows it to penetrate even hardened steel armor.

A growing chorus of critics, particularly in Europe, has begun to question whether the material has caused cancer.

Some protesters, members of the groups Grassroots Action for Peace and Veterans for Peace, were protesting the use of depleted uranium weapons by US-led forces during the Gulf War and the conflicts in Bosnia and Kosovo.

''How can we say that getting our way in Iraq is more important than the lives of ... Iraqi children? There is something really uncivilized about that,'' said Carol Dwyer of Concord, a member of the steering committee for Grassroots Action for Peace.  Other activists, meanwhile, focused on the problems associated with manufacturing the weapons, problems that Concord and its neighbors are still dealing with even though a defense contractor here stopped manufacturing depleted uranium weapons in 1999. The Starmet Corp. plant in West Concord has been proposed as a federal Superfund hazardous waste site because of the tons of heavy metals dumped there in the 1980s and 1990s.

Protesters said they fear the contamination may leach into the Assabet River and into the water supply of nearby towns. ''The half-life of depleted uranium is 4 billion years,'' activist and Billerica resident Kevin Gilligan said. ''This problem is not going away.''