Seth Ellingsworth of West Richland, Washington, says he got sick in an instant last year, when he briefly inhaled a strange odor at his job at the nearby Hanford Nuclear Site. Seventy years ago, the Hanford Site produced plutonium for America's nuclear arsenal. Today, it's run by the Department of Energy through its contractor, Washington River Protection Solutions. The contractor is managing a $110 billion cleanup of 56 million gallons of chemical and nuclear waste, stored in 177 underground tanks. But the tanks are leaking, and the vapors they emit contain toxic and radioactive chemicals. Some nuclear experts have called Hanford the most toxic place in America" and "an underground Chernobyl waiting to happen." The DOE has acknowledged in nearly 20 studies conducted over the past 24 years that there is a safety risk to workers at Hanford. But critics say the DOE ... continues to put workers at risk. Neuropsychologist Brian Campbell says he has evaluated 29 people at Hanford with both respiratory and cognitive symptoms, including "some of the worst cases of dementia that I've seen in young people." Dr. Campbell said the DOE doesn't want to acknowledge the injuries. Workers told us that "over and over," the Department of Energy and the contractor on site told them the readings for harmful materials were safe. Former workers also said that in the past they were almost never allowed to opt for protective gear, like the supplied air tanks recommended by many experts.