The U.S Geological Survey has confirmed that radioactive fallout from the Fukushima nuclear power plant in Japan was measured in minimal amounts in precipitation in the U.S. in approximately 20 percent of 167 sites sampled in a nationwide study released earlier this week.
The USGS led the study as part of the National Atmospheric Deposition Program (NADP).
Levels measured were similar to measurements made by the U.S. Environmental Protection Agency in the days and weeks after the devastating March 2011 earthquake and tsunami in Japan. Those levels were determined to be “well below” dangerous levels.
“Japan’s unfortunate nuclear nightmare provides a rare opportunity for U.S. scientists to test an infrequently needed national capability for detecting and monitoring nuclear fallout over a wide network,” explained USGS director Marcia McNutt. “Had this been a national incident, NADP would have revealed the spatial and temporal patterns of radioactive contamination in order to help protect people and the environment.”
After the earthquake, precipitation was collected at monitoring sites within the NADP network. USGS scientists detected low levels of Iodine -131, Cesium-134, and Cesium-137, the primary radioactive elements released during an incident such as this one.
These elements were most frequently found along the West Coast of the United States, in the central and northern Rocky Mountain States, and the eastern United States where precipitation fell most heavily in the weeks after the Fukushima disaster.
The EPA, meanwhile, had used the rapid-response RadNet to keep track of network fallout from Fukushima immediately after the incident. RadNet sites provide information about levels of radiation in the Nation’s air, drinking water, precipitation, and pasteurized milk. The levels of radioactive fallout measured at RadNet and NADP sites were similar, and while the USGS does not assess human health risks, the EPA RadNet monitoring confirms that radiation levels were far below any level of concern for human health in the United States.
This represents the second time samples from the NADP network have been utilized to measure radioactive fallout in the U.S. The first time was after the Chernobyl disaster in 1986. The NADP network allows scientists to sample fallout at a wide range of sites, including rural and isolated areas.
“This analysis provides scientifically valid measurements of radioactive fallout in precipitation over North America, which helps add more details to the picture of fallout in the U.S in the weeks following the Fukushima incident,” said Greg Wetherbee, USGS chemist who led the study. “NADP and USGS demonstrated that this network enhances national capabilities to monitor radionuclides in precipitation following releases to the atmosphere.”
A USGS report and article published in the journal Environmental Science and Technology, as well as a map of NADP sites with observed fallout can be viewed here.
- New Study Confirms Low Levels of Fallout from Fukushima (junkscience.com)
- New study confirms low levels of fallout from Fukushima (physorg.com)
- U.S. Experienced Low Levels Of Radioactive Material From Fukushima (cen.acs.org)