Just 35 municipal waste incinerators, cement kilns, and steel plants in the eastern and central U.S. accounted for one-third of the dioxin reaching the Canadian Arctic in one year, according to a study released yesterday by the North American Commission for Environmental Cooperation. The study represented the first time that dioxin pollution in the Arctic has been traced back to its sources. Dioxin has been linked to cancer and developmental and reproductive abnormalities in animals and increasingly in humans. Led by well-known ecologist Barry Commoner of New York City’s Queens College, the study team looked at emissions from 44,000 dioxin sources in North America from July 1996 through June 1997 and tracked their impact on the Nunavut Territory in the Arctic. The study was completed in preparation for international negotiations in December on a treaty to limit emissions of persistent organic pollutants such as dioxin.