The U.S. medical industry generates more than 2 million tons of waste per year, and some of that waste makes its way to incinerators. When burned, the waste releases dioxin, mercury and other toxins. In recent years, however, some providers have begun to think greener. Most efforts focus on reducing toxic waste, cutting back on water, and energy conservation. But some doctors and health workers are also considering changes in their practices that could enhance environmental and patient health.