In 2016, the Department of Defense (DOD) began soliciting designs for biodegradable, seed-stuffed artillery to replace traditional grenades, mortars, and bullets used in training. It's not the first time the military has tried to manufacture a greener bullet, but it might be the DOD's most ambitious attempt yet to stop contaminating millions of acres of training ground across the United States and abroad.
The U.S. military has long been one of the nation's largest polluters; more than two-thirds of the Environmental Protection Agency's toxic Superfund sites are associated with military operations. But only after toxic chemicals from decades of live-fire training with lead-based munitions began to spread from bases to nearby civilian communities did the military become subject to environmental oversight.
Lead has long been favored for bullet cores because its weight helps pack a destructive punch, but, over time, old bullets buried in the ground leach the heavy metal—a known neurotoxin—into the soil and groundwater. In the 1990s, the EPA began shutting down training ranges at military bases that violated state environmental regulations, effectively forcing the services to develop lead-free ammunition.
The Army began manufacturing training rounds with tungsten, another dense metal that leadership believed to be "non-toxic" and "non-mobile"—in other words, it wouldn't dissolve into the groundwater and poison nearby communities. They were wrong on both counts.
But the DOD's latest solicitation for biodegradable bullet designs suggests that the military doesn't need heavy metals at all—at least not for training rounds. The Army Corps of Engineers has already bioengineered seeds that won't germinate until they've been underground for several months. The next step is to find the right material to insert them into, which the DOD says could come from biodegradable plastics reinforced with bamboo fibers or soy-based matrices.
Of course, going green doesn't mean sacrificing military readiness: In 2010, the Army's green ammunition program introduced a bullet made of copper and steel that was not just more environmentally friendly than its predecessors, but more lethal as well.