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| Fig. 1: The United Nuclear Corporation's Church Rock Uranium Mill (Source: Wikimedia Commons) |
In July of 1979, as the US still swirled with stories about the Three Mile Island nuclear disaster, the largest radioactive spill in US history began and ended in span of just a few hours. [1] After an earthen dam burst at the Church Rock Uranium Mill, a significant amount of radiation was released directly into local water systems, yet it garnered only a small fraction of the media attention of Three Mile. [1] The people most directly impacted where the Navajo Nation, whose critical source of water for livestock and personal drinking, the Puerco River, was suddenly contaminated with 94 million gallons of radioactive (3.56 × 108 liters) and acidic nuclear wastewater. This radioactive waste contained an estimated 46 Ci of gross α activity, corresponding to 1.3 × 105 pCi per liter. [2,3,4]
However, while the volume of contaminant is large, it is difficult to determine direct links to physiological impacts. Many government documents in the decades following the spill noted that the measured levels of radioactivity in the Puerco and nearby water wells are only dangerous if consumed regularly or if the meat of animals who drank that water are consumed as a major part of a person's diet. [2,3] While many of the Navajo people were drinking this water and eating this meat every day, the lack of a longitudinal study leaves us unable to conclude if there were any causal effects as a result of this persistent consumption. [3] And while it has been stated before that Church Rock released more radiation than Three Mile Island, it is important to consider the difficulty in comparing these two events. Church Rock was mostly solid and liquid waste, measured in gross α activity, where the Three Mile Island disaster released mostly gaseous and many of the reported values of radiation consider all isotopes, unlike measurements of gross α activity.
The record of largest radioactive spill in US history allows the Church Rock Spill to float to the top of some Google searches and is recalled by the occasional local news outlet remarking on the anniversary of the spill. The extent of the impact on the Navajo community is difficult to determine, in part because quantifying the spread of the leak is geophysically challenging, but also in part because the spill did not contribute all that much radiation in comparison to the overall amount leaked over the decades. During the peak years of mining in the region, there was over 2 billion gallons of mine water released in the region annually, amounting to about 5 million gallons of uranium contaminated water per day. [3] In total, there was 260 Ci of gross α activity dispersed through regular wastewater into the Puerco River over the 22 years of operation. [3] Putting the 94 million released from the Church Rock Spill into perspective, it's apparent that the spill itself is only one small part of the overall pollution from Church Rock.
While the amount of uranium and overall radiation released into the Puerco and ultimately exposed to and consumed by the Navajo people is significant, some early reports suggest the physiological impacts may not have been so severe. Six individuals likely exposed to spill contaminants were tested by CDC and found to have normal amounts of radioactive material present in the human body. [2] The majority (80%) of wells within 700 meters of the Puerco river were found to have met drinking-water standards of radioactive elements set by the Federal government. [3] While the imagery of the spill and the catastrophic nature of the burst may imply a serious gravitas, the more measurable health impacts on the Navajo people come from the long term mining operations themselves.
From 1944 to 1986, there were extensive uranium mining operations on the Navajo Nation (see Fig. 1). Navajo men worked across these mines, to deleterious outcomes. They suffered elevated rates of mortality from lung cancer, tuberculosis, and other rates of respiratory diseases. In particular, a comprehensive study of uranium miners among the Navajo showed that duration of exposure to underground uranium mining was statistically significant as a predictor of increased mortality risk for such diseases. [4] The local uranium mines did not only affect the men working in them. A subsequent study showed that Navajo children born to women living near the mines were nearly twice as likely to suffer a birth defect. [5] Beyond the pure statistics, the families of miners have provided strong anecdotal evidence and painful stories of the physiological damage wrought upon the community members. [6]
It took the federal government decades to enact sufficient policies to protect uranium miners after science had thoroughly demonstrated the health risks, not just for the Navajo but for all uranium miners. This history, as well as the lack of health risk information provided to the Navajo miners in particular, is well-documented. [7]
Within months of the spill, members of the Navajo Nation were brought before Congress and were able to share their stories, not just of the spill, but of the decades of uranium mining. [8] While the US government is finally enacting plans to clean the area, there are still a majority of the 523 abandoned uranium mines still un-assessed and un-cleaned. [9]
© Ky Friedman. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] D. Brugge, J. L. deLemos and C. Bui, "The Sequoyah Corporation Fuels Release and the Church Rock Spill: Unpublicized Nuclear Releases in American Indian Communities," Am. J. Public Health 97, 1595 (2007).
[2] J. Millard et al., "The Church Rock Uranium Mill Tailings Spill: A Health and Environmental Assessment," New Mexico Health and Environmental Department, September 1983.
[3] L. Wirt, "Radioactivity in the Environment A Case Study of the Puerco and Little Colorado River Basins, Arizona and New Mexico," US Geological Survey, Report 94-4192, 1994.
[4] H. Nguyen, "Church Rock: The Forgotten Nuclear Disaster," Physics 241, Stanford University, Winter 2019.
[4] R. J. Roscoe et al., "Mortality Among Navajo Uranium Miners," Am. J. Public Health 85, 535 (1995).
[5] C. Arnold, "Once Upon a Mine: The Legacy of Uranium on the Navajo Nation," Environ. Health Perspect. 122, A44 (2014).
[6] D. Brugge et al., "Memories Come To Us In the Rain and the Wind," Navajo Uranium Miner Oral History and Photography Project, 2000.
[7] D. Brugge and R. Goble, "The History of Uranium Mining and the Navajo People," Am. J. Public Health 92, 9(2002).
[8] U.S. House, Committee on Interior and Insular Affairs, "Mill Tailings Dam Break at Church Rock, New Mexico," House Report 96-25, 1980.
[9] "Abandoned Uranium Mine Settlements On or Near the Navajo Nation," U.S. Environmental Protection Agency, November 2022.
