Contamination from decades of uranium mining lingers on Navajo land


Three researchers look over an abandoned mine on the Navajo Nation land near Cameron, Arizona on Oct. 19, 2013. Uranium mining from the mid-1900s left over 500 unregulated mines scattered once mining stopped in 1986.
Photo by David Begay

On Navajo Nation land, the ghost of the mining industry’s past still haunts the native people who live there.

It began in the 1940s when the Navajo land was — and still is — a hotbed for uranium.  The new weapon-manufacturing industry brought a new opportunity for jobs among the natives living on the land, but it came at a cost.

Now, government agencies and researchers from across the country work toward cleaning the hundreds of abandoned mines left after four decades of mining ended in 1986. A goal is to understand the effects that decades-long uranium contamination has on the Navajo people.

The contamination effects over half of the tribe’s population. With 300,000 people, the Navajo tribe is the second largest Native American group in the U.S., according to recent U.S. Census data. Of those 300,000, some 156,000 Navajo live on the Navajo Nation land, which spans 27,000 square miles across Arizona, Utah, Colorado and New México.

In an effort to alleviate environmental and health impacts, the Environmental Protection Agency and the Navajo Nation EPA began the long process to clean up contaminated areas that pose a health risk to the population.

Clancy Tenley, assistant director of the EPA Superfund Division, is one of the leaders heading the projects to clean up contaminated areas not only on Navajo land but across the U.S. Tenley said the EPA began the process in the 1990s but still has a long way to go.

After the EPA mapped all of the abandoned mines the area, the first five-year plan began in 2008. The EPA identified 46 mines considered high priority. All of the mines emit at least 10 times the radiation level set by the EPA.

The goal for the current five-year plan is to finish risk evaluations in the area and select a cleanup process. But, every clean up isn’t the same. Tenley said that depending on the mine and the severity of the contamination the cleanup process can be different.

William McCray, 4, overlooks a clean up operation of radium and uranium contaminated soils near his home on Oct. 9, 2009. Uranium mining from the mid-1900s left over 500 unregulated mines scattered once mining stopped in 1986. Photo by Teddy Nez

“The first step is to conduct a very detailed evaluation and a detailed process of how to clean it up. It involves going out to the field and taking samples from the ground surface level,” Tenley said. Once the team evaluates the options they have for cleanup they choose an efficient safe method depending on the area.

“Our goal for this current five-year plan that goes between 2011 to 2018 is for all of those high priority mines is to complete detailed evaluations that will be necessary in order for us to determine how to clean them up,” Tenley said.

Elena Neibaur, communication lead for the Navajo program in the Superfund Division, said the EPA still works to keep companies accountable for the abandoned mines they left. Just last year, the EPA made an agreement with 11 private companies to ensure that each participates in cleaning abandoned uranium mines.

“With some of our federal partners, we’ve had invested in more than $1.7 billion to assess the risk to the Navajo people. We replaced 48 contaminated homes and cleaned up groundwater contamination,” Neibaur said.

Since the end of the mining industry, Navajo working in and around the mines suffered serious illnesses from uranium contamination.

Chris Shuey and Debra MacKenzie are lead researchers for the Navajo Birth Cohort Study team, which is investigating the legacy exposure of uranium contamination on young tribal children. The team, still in the first few stages of research, is mainly focusing on the reproductive outcomes of heavy metal uranium exposure.

“We are not just looking at uranium in terms of radiation but we are looking at uranium as a heavy metal contaminant,” MacKenzie said.

She said the whole purpose of the study is to see if there are any health impacts from this type of exposure.  

One of the most common health effects from uranium exposure is kidney damage. When uranium is introduced to the body, it can enter the bloodstream and have a serious effect on kidney function. A recent study conducted by Shuey and MacKenzie’s team found that around a quarter of the population living on Navajo land exceed accepted EPA levels for uranium in the body.

The team is in the last stages of enrollment in the cohort study, which MacKenzie said has 1,630 participants altogether — 753 mothers, 656 young children and 221 voluntary fathers. The team also is measuring the uranium levels in and around families’ homes.

They have looked at almost 600 homes and found that the 86 percent had some level of uranium in the dust particles. But the study has yet to determine if that uranium is natural or from mine waste, which is the case with much of the research that the groups have done.

Most of their findings are considered preliminary and cannot determine any causes or strong correlations when it comes to illness and uranium contamination in homes.

“It’s going to be another year before we get around to trying to put all the data into a massive database,” Shuey said.

Lauren Renteria is a reporter for the Arizona Sonora News, a service from the School of Journalism with the University of Arizona. Contact her at

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