More than 140 nations have adopted the first legally-binding international treaty aimed at reducing mercury emissions, UN officials have said.
The UN Environment Programme said the treaty was adopted after all-night negotiations that capped a week of talks in Geneva, Switzerland.
A signing ceremony will be held later this year, and then nations must begin formally ratifying the treaty before it comes into force several years from now.
"To agree on global targets is not easy to do," UNEP executive director Achim Steiner said. "There was no delegation here that wished to leave Geneva without drafting a treaty."
The agreement will for the first time set enforceable limits on emissions of mercury, a highly toxic metal that is widely used in chemical production and small-scale mining, and exclude, phase out or restrict some products that contain mercury.
But some supporters of the treaty said they were not satisfied with the agreement.
Joe DiGangi, a science adviser with advocacy group IPEN, which works for the elimination of persistent organic pollutants, said that while the treaty is "a first step," it is not tough enough to achieve its aim of reducing overall emissions.
For example, DiGangi said, there is no requirement that each country create a national plan for how it will reduce mercury emissions.
The draft agreement that was issued before the meeting committed countries to phase out mercury thermometers, some kinds of light bulbs and small "button" batteries, with 2018 the earliest possible deadline.