The Church Rock Uranium Mill Spill occurred in New Mexico, USA, in 1979 when United Nuclear Corporation‘s Church Rock uranium mill tailings disposal pond breached its dam. Over 1,000 tons of radioactive mill waste and millions of gallons of mine effluent flowed into the Puerco River. Local residents used river water for irrigation and livestock and were not immediately aware of the toxic danger. In terms of the amount of radiation released the accident was comparable in magnitude to the Three Mile Island accident of the same year and has been reported as the largest radioactive accident in U.S. History.
On July 16, 1979, United Nuclear Corporation’s Church Rock uranium mill tailings disposal pond breached its dam and 1100 tons of radioactive mill waste and approximately 93 million gallons of mine effluent flowed into the Puerco River. The contaminated water from the Church Rock spill traveled 80 miles downstream, traveling through Gallup, New Mexico and reaching as far as Navajo County, Arizona. The flood backed up sewers, affected nearby aquifers and left stagnating pools on the riverside.
The 50 ft. earthen dam was recognized as built on geologically unsound land by the corporation’s consultant and federal agencies. By 1977 cracks had appeared in the dam and went unreported to authorities. According to Paul Robinson, research director at the Southwest Research and Information Center, the spill resulted from “poor oversight, poor siting and poor construction” and is an example of the problems that can occur at uranium mines and mills.
In terms of the amount of radiation released the accident was comparable in magnitude to the Three Mile Island accident of the same year and has been reported as “the largest radioactive accident in U.S. History”. Shortly after the breach below the dam radiation levels of river water were 7000 times that of the allowable level of drinking water. In all, 46 curies of transuranic elements and heavy metals were released.
Although steps were taken at the time of the accident to notify the public in accordance with a state contingency plan, local residents were not immediately aware of the toxic danger and were accustomed to using the riverside for recreation and herb gathering. Residents wading in the water went to the hospital complaining of burning feet and were diagnosed with heat stroke. Livestock were also found dying. Prior to the accident local residents used river water for irrigation and livestock. The eventual assistance of trucked in water ended in 1981 and farmers were then left with little choice other than to resume use of the river.
For some types of cancers Navajo have a significantly higher rate than the national average. Yet, no ongoing epidemiological studies have been done at Church Rock. A peer reviewed article in the American Journal of Public Health in 2007 proposed that the stark lack of peer-reviewed studies of health effects of the accident when compared to well studied events such as Three Mile Island may be related to both the “early stage in the nuclear cycle” (mining, milling and processing) dependent on a large numbered labor-force and “low-income rural American Indian communities”.
Clean up was performed by state and federal criteria. About 3,500 barrels of waste materials were retrieved (estimated at only 1%). However, according Robinson, only a “very little of the spilled liquid was pumped out of the water supply”. The uranium mill site closed in 1982 related to a declining uranium market. In 1983 the site entered the National Priorities List of the Environmental Protection Agency‘s Superfund investigations and clean up efforts because radionuclides and chemical constituents were recognized as entering local ground water. In 1994 the EPA extended its efforts with a study of all known uranium mines on the Navajo Nation.
Soon after the dam break, two West German radiation biologists, Bernd Franke and Barbara Steinhilber-Schwab, sharply criticized the issued CDC report that downplayed the potential dangers of the accident and for sampling too few of the local livestock. They urged chromosome checks on area residents and called for the establishment of cancer and birth registries as well as intense ongoing radiation monitoring in the area. They also warned that thorium and other isotopes from the spill could enter the human body not only through eating contaminated animals, but also when radioactive dust settled on vegetables. Dr. Carl Johnson, director of Colorado’s Jefferson County Health Department, further warned that detectable radiation levels in the tissues of children might only surface “over a period of many years.”
Potential pathways of contamination are: inhalation, ingestion, injection, and absorption. At present, there is an elevated health risk for people who frequent the site from inhaling radium contaminated dust particles and/or radon gas, contact with contaminated rainwater and runoff that has pooled in ponds, and ingesting livestock that have drank and fed from contaminated water and grass.
Different radio-nuclides emit gamma rays of varying strength, but gamma rays can travel long distances and are able to penetrate entirely through the body. Both thorium 230 and radium 226 are alpha-emitters; extremely dangerous if ingested or inhaled. Therefore, any skin contact with contaminated surfaces poses a health risk. Thorium 230, for example, has a half-life of eighty thousand years and is believed by some to be as toxic as plutonium. Thorium, a silver-white metal, tends to deposit in the liver, bone marrow, and lymphatic tissue, where even minute quantities can cause cancer and leukemia. If inhaled as dust it can cause lung cancer. According to a study by Winterer, under some circumstances thorium can become “trapped” in the body, making it “a permanent source of radiation” there, and thus doing untold damage to the human organism.
Elevated concentrations of Radium-226 have been detected throughout the 125-acre mine permit boundary and contiguous surface areas. Exposure to high levels of Radium-226 over a long period of time may result in harmful effects including anemia, cataracts, fractured teeth, cancer (especially bone cancer), and death. Exposure to high levels of uranium can cause kidney disease.
In 1983, the privately owned site, owned by UNC, was designated a Superfund site by the U.S. Environmental Protection Agency, who detected elevated radium and uranium contamination in 14 areas on and off-site, and beyond the permit boundary. The CDC warned locals not to drink water from the river, and to avoid its banks during windstorms, when radioactive particles might be more easily inhaled. The CDC emphasized that while radiation levels detected in local animals did not exceed New Mexico standards, caution should be exercised as “the health risks of low doses of radiation” were “not completely understood.” Contamination had exceeded low dosage levels in local animals. One veterinarian told a documentary crew from Eleventh Hour Films that abnormal radiation levels had been found in the tissues of goats and sheep that were drinking Rio Puerco water.