Scientists cannot explain exactly why the levels were so high. DOE officials stated it was not a health concern. Scientists, Hanford cleanup contractors, and other officials at the site claim there are no health risks from the newly detected plutonium even though officials admit they can't say exactly where the most recently discovered radioactive dust came from, how long it's been there, or how it moves around. Strontium-90 is chemically similar to calcium, and will accumulate in milk, in the body, or can be taken up by trees. It is a beta-emitter of particles that can last more than 300 years.
Beta rays can pass through paper and travel a few feet.
At Hanford, strontium-90 is commonly found in Russian thistle. Here in New Mexico, chamisa has been found with high levels of strontium-90. It can become a vapor if it gets hot enough, then cool, condense and fall to the ground. It also mimics potassium, and can be taken up by plants. Plutonium-239, which is a byproduct of nuclear weapons production, remains in the environment for 240,000 years, and once it's trapped in dust or dirt, it stays there, becoming resuspended by the winds.