In a multimillion dollar project, the US Army has come up with a new bullet said to be just as deadly as the old lead-based one but cleaner for the Earth. "We want to be good stewards of the environment," said Army spokeswoman Karen Baker. The military says using "green ammunition" cuts soil contamination caused by the millions of slugs fired year after year at its practice ranges, Associated Press reports. In the new bullet, a less toxic tungsten composite replaces the lead. It's just one of the Pentagon's efforts to keep troops trained for combat while protecting the environment on military land. Critics say the armed forces have a long way to go on that score. In a program it says has cost about $12 million so far, the Army in 1994 started researching ways to make a more environmentally friendly 5.56 mm bullet. It's used in the M-16 rifle, a weapon issued to every Army infantry soldier, and an estimated 200 million rounds are shot a year. Researchers studied different combinations of metal to design a slug that would perform the same as the old one, have the same density, ballistic quality and so on, said Michael Dette of the Army Environmental Center at Aberdeen Proving Ground, Maryland. They settled on a tungsten composite slug and kept the old copper casing to produce a bullet Dette says actually turned out to be more accurate and causes less barrel erosion. Soldiers won't notice a difference, he said. The Army, which produces ammunition for all the services, started limited use of the new version in 1999 and is producing 50 million rounds this year for practice at a new range in Alaska and an old contaminated one in Massachusetts. Officials hope the switch to lead-free slugs will be complete in 2005. The new bullets cost about 8 cents each compared with a half cent for the old ones. Dette said they'll cost less in full production and when officials consider the savings of millions of dollars that would otherwise go for cleaning contaminated ranges. The 5.56 mm bullet accounts for half the small caliber ammunition used annually -- troops shoot another 200 million rounds of 7.62 mm and 9 mm bullets, not to mention mortars, artillery and other large ammunition. The lead slug is not the only noxious part of the bullet. Chemicals used for sealing, waterproofing and painting the bullet as well as for propelling the slug also are being studied -- and some of their ingredients have been changed, too. But officials don't know when ammunition might be completely green. In 1997, the U.S. Environmental Protection Agency ordered the Army's Massachusetts Military Reservation to stop all live-fire training after a study showed lead and other toxins seeping into Cape Cod's underground water supply. Troops started using the new ammunition there in October 1999. But critics recently urged an end to training in small weapons at the reservation's Camp Edwards after a new National Guard study said soil had illegally high amounts of an ingredient from the ammunition's propellant. American army was the first military in the world to conclude that bullets can do harm to the environment. However service-men have not raised up a question, whether bullets can do harm to the human being.