Joshua Lott for The New York Times

As I reported last weekend in The Times, a cattle rancher stumbled upon an abandoned uranium mine in the summer of 2010 on his grazing land, about 60 miles east of the Grand Canyon on the Navajo reservation, and notified federal officials. They came in with Geiger counters and found levels of radioactivity that were alarmingly high.

A year and a half later, the former mine in Cameron, Ariz., is not fenced off to either humans or animals, and cattle continue to roam through the site and eat grass that might be tainted with uranium and other toxic substances.

“Those cattle go to auction in Sun Valley and are sold on the open market,” said Ronald Tohannie, a project manager with the Navajo advocacy group Forgotten People. “Then people eat the meat.”

The owner of Valley Livestock Auction in Sun Valley, Ariz., Derrek Wagoner, has confirmed that he buys cattle from the Navajo reservation and is aware that cattle graze near uranium mines there. He adds that cattle come to him from all over the Southwest, where there are plenty of former uranium mines.

There is no dispute that beef and milk from those cattle make their way into the food chain. What is not precisely known is how much radioactive material plants absorb through the soil, how much the cattle ingest by grazing on the plants and what the effect might be on humans.



Livestock grazing around the abandoned mines is common throughout the Southwest, according to many environmentalists, scientists, government officials and people in the cattle business. The Colorado Plateau is particularly rich in minerals and in the former mines, which for 40 years supplied crucial materials for the nation’s cold-war nuclear weapons program.

But the effect of the radioactivity on the food chain remains an open question. “There’s just not a lot of data,” said Chris Shuey, an environmental health specialist with the Southwest Research and Information Center. “That’s because mining ended 25 years ago, and the studies ended then, too.”

Yet a resurgence in corporate interest in mining uranium has brought a new wave of studies. In a 2010 report, the Department of the Interior said proposals for uranium mining at sites adjacent to the Grand Canyon National Park in Arizona had prompted the agency “to investigate physical, chemical and biological issues potentially affected by mining.”

In January, Interior Secretary Ken Salazar signed a 20-year moratorium on new uranium and other hard-rock mining claims on a million acres of federal land around the Grand Canyon, saying it was needed to preserve the mile-deep canyon and the river that runs through it. The mining industry is challenging that decision in court.

The Interior report summarizes the available findings, saying that although conclusive data is lacking, studies have indicated that toxic substances like uranium and its decay products — including radium and radon — “can affect the survival, growth and reproduction of plants and animals.” It cited reptiles, birds and “mammalian wildlife that represent essential components of the food web.”

David Shafer, a manager in Colorado for the Energy Department, one of several federal agencies involved in cleaning up the legacy of cold-war uranium mining on the Navajo reservation, said the department was studying how much uranium was absorbed by plants but that its research remained incomplete. “We don’t know what the uptake is,” he said.

“Milk is very stringently tested,” possibly because it is a staple of children’s diets, Mr. Shafer said. “Beef is less so.”

After cattle are auctioned off, they go to various processing facilities where they are butchered and tested for contaminants under U.S.D.A. standards, Mr. Wagoner of the livestock auction company said.

Federal standards, however, do not include routine screening for toxic chemicals like uranium and its decay products. Standard testing includes biological contaminants like E. coli and salmonella and physical substances like bits of metal that might fall inside a meat grinder. But beef is only spot-checked for chemical contaminants, said Janet McGinn, a senior officer with the U.S.D.A.’s Food Safety and Inspection Service.

When an animal is spot-checked for such substances, it is either because it is part of a random sampling of the entire population or because it is suspected to be ill.

The lack of data makes some experts uneasy. “We still can’t answer fundamental questions — are there wide population health effects due to uranium mining?” said Mr. Shuey, the environmental health specialist.

“Immune function, kidney disease, high blood pressure — all these things contribute to the burden of ill health” and could be affected by uranium, he said, “but we don’t know for sure.”

“Now there are companies that want to mine uranium again,” he said, “and we’re still a couple of generations away from dealing with the totality of that legacy.”

“We still can’t answer fundamental questions — are there wide population health effects due to uranium mining?” — Chris Shuey,

Southwest Research

and Information Center

For people who make a living off the land, a topic of endless speculation is tainted cattle.

“They get it in multiple pathways,” said Larry Gordy, the rancher who found the mine on his property and alerted federal officials two years ago. “Cattle eat plants covered with radioactive dust, they breathe in radon, and they drink contaminated water.”

In the arid Southwestern region, water is a precious commodity, and it is collected through various systems throughout the Navajo reservation. Dan Canyon, a former rancher, said that irrigation dams collected water from runoff and some of it came from former uranium mines, where it could be contaminated by ore tailings.

Standing atop one such dam in Cameron, Ariz., a slope of earth dotted by sagebrush and scored by rivets, Mr. Canyon gestured toward the former mine directly above it. For years, his cattle grazed here.

“I sold my cattle,” he said. “I didn’t want to be responsible for contaminated meat on the market.”