By KRISTI EATON
VIEW ON HEALTH
The threats in Japan following the explosion of nuclear reactors caused by the 9.0-magnitude earthquake and subsequent tsunami that rocked the country on March 11 have many Americans worried about radiation contamination.
Watching television images of Japanese people stock up on food and supplies as employees at the Fukushima Dai-ichi complex work around the clock to control the devastation has caused even the most level-headed to wonder about safe radiation levels. Possible contamination of food shipped out of Japan has further heightened safety concerns.
But safety experts and government officials here and abroad have repeatedly said Americans are not currently in any danger.
“The events are still unfolding, but as of now it appears as if emergency procedures are effective and releases of radioactive materials to the environment are manageable,” said William E. Kennedy, Jr., executive vice president of Dade Moeller, a U.S. health physics company that consults with federal, state and commercial clients on radiation operations and safety
Trace amounts of radioactive material have been identified in the western United States. But officials have said the amounts are so small that the public should not be concerned.
Three monitors in California and Washington captured radiation samples of radioactive iodine, cesium, and tellurium stemming from the Japanese nuclear incident. Tests conducted by the U.S. Environmental Protection Agency show the samples “are hundreds of thousands to millions of times below levels of concern,” the agency said in a statement.
Miniscule levels of an isotope found at a monitoring site in Hawaii are also far below any level detrimental to human health.
So it looks like the United States is safe for now, but could radiation be a threat in the future? What should people know to be prepared?
WHAT IS RADIATION?
Radiation is the release of energy from an unstable atom, said Jack Glass, principal consultant for New Jersey-based J Tyler Scientific Company.
“This energy can be absorbed by molecules of the body. When this occurs, the molecule may split irregularly. This is a random event and cannot be predicted. The more radiation you are exposed to, the higher the probability of getting cancer,” he said.
There are different types of radiation, Kennedy said, but the type associated with radioactive decay is called ionizing radiation, which is simply a special kind of energy.
“Unlike other forms of energy, such as sunlight, ionizing radiation has the capability to produce ions in matter,” Kennedy said.
Ions are atoms or molecules with an electric charge — either positive or negative. The charge causes it to interact with other molecules, he said.
“It is this property, producing ions, that causes damage to cells or organs in the human body, because ions produced in the body sometimes interact with cells in a damaging way,” said Kennedy.
Humans are constantly exposed to external sources of ionizing radiation, called natural background radiation.
“External sources include cosmic rays and natural radioactive materials in the soil and rocks around us,” he said.
Kennedy said people can also be exposed to internal sources by inhaling airborne radioactive materials, such as radon, or when the materials are found in food and water consumed.
The Food and Drug Administration has announced that it is detaining all milk and milk products and vegetables and fruits produced or manufactured from the four Japanese prefectures of Fukushima, Ibaraki, Tochigi and Gunma upon entry into the United States. This will stop the food from entering the U.S. food supply.
A major source of radiation exposure could be through X-ray imaging or therapeutic purposes, like treatment for cancer, Kennedy said.
He noted that The National Council on Radiation Protection and Measurements recently published a report finding medical applications were the largest source of ionizing radiation exposure, on average, to the population of the United States.
But, he added, for a typical healthy person, the largest source of ionizing radiation exposure is from the natural background.
RADIATION’S EFFECTS ON HEALTH
Dr. Aaron A. Ambrad, a radiation oncologist at Ironwood Cancer & Research Centers in Mesa, Ariz., said too much exposure causes acute changes to the body, while chronic changes are also possible.
“Depending on the level of exposure and how much of the body is affected, acutely people develop radiation sickness, which can be manifested as colitis, pneumonitis, encephalitis, and organ failure [or] death in extreme cases,” he said.
In chronic cases, people can develop hypofunction in organs like the thyroid or kidneys, and ultimately, cancer in the affected organ, he said.
Glass said the skin can burn and blister if exceedingly high levels of radiation are present.
“Radiation sickness is a devastating disease and includes the failure of multiple body organs and a painful death,” he added.
The amount of radiation exposure considered safe is based on three levels: time, distance and shielding, said Glass.
“Decreasing the time you are exposed, or increasing the distance or shielding will reduce the amount of radiation you can absorb,” he said.
Members of the public, Kennedy said, are currently limited to 100 millirem, or 0.1 rem, of exposure per year. Rem stands for Roentgen Equivalent Man, a unit of radiation exposure.
One hundred millirem is about one-third the dose an average person receives from natural background sources of radiation in a year, said Kennedy.
Glass said any additional exposure to radiation than what is necessary is too much.
“If you believe you may have a broken bone, then it is appropriate to have an X-ray,” he said. “If you do not suspect a broken bone, this level of exposure would be unacceptable.”
WHEN YOU HAVE TOO MUCH EXPOSURE
Kennedy said large amounts of acute or immediate exposure to ionizing radiation can cause an immediate impact to an individual.
“As the acute exposure increases, more severe effects can occur,” he added.
Below 25 rem, or about 80 times annual background, acute effects have not been observed, he said. But studies show that increasing the amount of dosage, up to between 25 and 100 rem received at once, or about 80 to 300 times annual background, can cause acute observable effects, including reduced red and white blood cell counts.
As the doses increase, up to 100 to 300 rem, or from 300 to 1,000 times annual background, people can experience nausea, vomiting, and suppression of the immune system. From 300 to 600 rem, more severe effects like hemorrhaging, diarrhea, burns, loss of hair and sterility are possible, Kenney said.
Reaching a rate of 450 rem can be deadly. About half of those exposed to that dosage would die within 30 days, he said. Acute doses greater than 600 rem, or over 2,000 times annual background delivered at once, will result in death in 30 days.
He said the probability of developing cancer from ionizing radiation increases with higher doses.
“This means that at low levels the risks of cancer caused by radiation are quite low,” Kennedy said. “The definition of low is open to some interpretation, but in our opinion a dose less than the annual dose limit of 0.1 rem, or 100 millirem – even for multiple years of exposure at this level – would certainly be considered low with essentially no additional risk of cancer.”
THE IMPACT OF JAPAN’S NUCLEAR CRISIS ON THE UNITED STATES
It’s important to note, Glass said, that a nuclear reaction is not occurring in Japan. Rather, it is radioactive material being released into cooling water. This is turning to steam and rising into the atmosphere.
“The level of radiation will reduce as you increase the distance,” he said. “In addition, as the radiation rises into the upper atmosphere, it will become indistinguishable from normal upper atmospheric radiation.”
Only potassium iodide is FDA-approved to treat radioactive iodine contamination. However, the FDA said the U.S. government has not recommended any of its citizens take potassium iodide, even as a precaution.
Only trace levels of radiation released from the Fukushima Daiichi facility have been detected at a handful of locations in the United States. Even if the releases increase, Kennedy said, the Pacific Ocean’s vast distance will help dilute it before it arrives in America.
“The Pacific Ocean provides about 5,000 miles to allow dilution and dispersion of the material by the prevailing winds,” he said. “Deposition of particulate radioactive material would also occur by rainfall. These forces will significantly reduce the concentrations that could arrive on our west coast.”
Still, there is concern about contaminated food.
“A more significant concern will be realized from ingestion of food that has residual radiation. This will include produce that is grown in contaminated soil, meat from cattle that has fed on the contaminated food, and fish that swim in contaminated water,” said Glass.
Realizing the growing safety concerns, the FDA announced on March 22 that it would be taking additional measures regarding the importation of food into the United States from Japan.
In addition to milk and milk products, fruits and vegetables produced in the four prefectures — Fukushima, Ibaraki, Tochigi and Gunma — the agency is also testing other food products from the area, including seafood, although they are not subject to the Import Alert issued.
“Because of the heavy damage caused by the earthquake and tsunami to the region, there are little or no products are currently being exported from the affected area. Products generally travel by vessel, and the typical transit time for products to reach the U.S. is about 8 days,” the FDA said.
IS A SIMILAR INCIDENT IN THE UNITED STATES POSSIBLE?
The safety regulations currently in the place in the United States exceed those that were in place in Japan when the nuclear site was constructed, Glass said. “This is not to say that a catastrophic event could not create the same type of release, but it is less likely,” he added.
He said he believes any response would be immediate and significant, noting that the United States has in place a National Response Plan, a National Incident Management System and has the Federal Emergency Management Agency to help with disasters.
“While there is certain to be panic, and chaos, the resources and communication that is required to reduce the impact are well established,” he said.
Dr. Lissa Rankin said she has friends who are fleeing the West Coast because they fear the effects of exposure.
This, the doctor said, is cause more by irrational fear than common sense.
She noted that emotional stress is more likely to kill an individual in the United States than a radioactive cloud.