抖阴ap

NAIROBI, Kenya — The Obama administration reversed years of U.S. policy Monday by calling for a treaty to cut mercury pollution, which it described as the world’s gravest chemical problem.

Some 6,000 tons of mercury enter the environment each year, about a third generated by power stations and coal fires. Much settles into the oceans, where it enters the food chain and is concentrated in predatory fish such as tuna.

Daniel Reifsnyder, the deputy assistant secretary of state for environment and sustainable development, told a global gathering of environmental ministers in Nairobi, Kenya, that the U.S. wants negotiations on limiting mercury to begin this year and conclude within three.