Negotiators for 122 nations have agreed on a global ban on the so-called “dirty dozen” pollutants, including PCBs and dioxins, that have been linked to cancer, birth defects and other adverse health effects.

The treaty, more than two years in the works, calls for releases of dioxins to be minimized and ultimately eliminated where feasible. Continued use of electrical equipment containing PCBs will be permitted until 2025 as long as the equipment does not leak. Use of the industrial pesticide DDT to combat malaria will be permitted until alternatives are available.

Fifty nations, including the United States, must ratify the treaty before it can take effect. Negotiations have been organized by the United Nations Environment Program.