The plutonium separation process resulted in the release of radioactive isotopes into the air, which were carried by the wind throughout southeastern Washington and into parts of Idaho, Montana, Oregon, and British Columbia. Downwinders were exposed to radionuclides, particularly iodine-131, with the heaviest releases during the period from 1945 to 1951. These radionuclides entered the food chain via dairy cows grazing on contaminated fields; hazardous fallout was ingested by communities who consumed radioactive food and milk. Most of these airborne releases were a part of Hanford's routine operations, while a few of the larger releases occurred in isolated incidents. In 1949, an intentional release known as the "Green Run" released 8,000 Curies (296 Tbq) of iodine-131 over two days. Another source of contaminated food came from Columbia River fish, an impact felt disproportionately by Native American communities who depended on the river for their customary diets. A U.S. government report released in 1992 estimated that 685,000 curies (25.4 PBq) of radioactive iodine-131 had been released into the river and air from the Hanford site between 1944 and 1947.