In the United States, monitoring for radiation contamination is an ongoing task. In the wake of recent radiation releases from Japan's damaged nuclear reactors, this effort has taken on a special significance. Several established monitoring sites throughout the U.S. reported trace levels of isotopes from Japan in various environmental sources in the weeks following the incident, but they were far below levels that cause harm. The constant vigilance from these monitoring sites can be key to a timely response with this type of potential public health threat. Likewise, testing to detect whether an individual has absorbed radiation and what ill effects, if any, may result is of public health importance.
What is radiation?
Radiation is energy that moves through space in the form of particles or waves. The type that can be especially harmful is ionizing radiation, which includes X-rays and gamma rays and alpha and beta particles. This type is capable of damaging the molecular components of cells, tissues, and organs of the human body. It can be a health concern because it may, depending on the source, dose, and length of exposure, cause varying degrees of cell damage, burns, and/or damage to genes (cause mutations).
A person can be injured by ionizing radiation either through excessive exposure or contamination.
- A person is said to be exposed when radiation waves or particles in the air penetrate their body. There is no contact with radioactive material, but energy can be absorbed within the body. If the exposure is beyond safe limits, it can result in damage to cells and tissues.
- Contamination occurs when radioactive material is deposited on the skin (external contamination), ingested (as from food or water), or inhaled (internal contamination). Though the radioactive material may be removed by washing the skin, for example, injury results from contact with the radioactive material.
If it is suspected that someone was exposed or contaminated, testing can be done to confirm that and to establish the extent of the exposure. A scan of the air around a person using a device that measures ("counts") the ionizing radiation can estimate the radiation energy absorbed by that person.
Laboratory testing may also be performed to determine if radioactive materials have been absorbed, ingested, or inhaled. This typically involves collecting samples of urine (and sometimes blood); it can determine the presence of a particular radioisotope, the unstable, radioactive form of an element such as iodine-131, and can be helpful in making treatment decisions. In addition, laboratories can perform tests that would detect any biological effects from exposure, such as a drop in the number of blood cells (red blood cells, white blood cells, platelets) or abnormalities in chromosomes, which would be useful in assessing short- or long-term damage from radiation.
Currently, few laboratories are certified to test human samples for radioactive atoms or nuclides (radionuclides); they include the Centers for Disease Control and Prevention (CDC), a few public health laboratories, and one reference laboratory. In addition, only a few types of radionuclides can be identified with current testing methods. However, the CDC is in the process of developing a new urine test to determine whether a person has radionuclides in their body and, if so, what type and how much is present. Results from the test would help to identify those exposed, evaluate their risk of complications from the exposure, and help make treatment decisions. The goal of CDC's program, called Urine Radionuclide Screen (URS), is to have the capability to detect and measure at least 20 different radio-nuclides that are considered to be high-priority and to provide results in 24 hours rather than the current 2-3 days.
Environmental and food testing, in contrast, is often performed to detect radiation contamination in sources such as crops, animals, water, and air. Though the samples are different than those used for clinical testing, the methods employed are the same. The purpose is to detect contaminated material, minimize its spread, and decrease the likelihood that it reaches humans. This requires sampling and testing at regular intervals at various sites throughout the country, and such monitoring can be ramped up as needed in response to a particular radiation hazard.
Radiation emergency response
When substances like food or water become contaminated with radioactive material, as happened in Fukushima, Japan, it is an international public health and safety concern. Worldwide, various agencies have been performing tests to determine the extent to which the radiation released by the damaged reactors has disseminated and/or contaminated environmental sources. Soon after the incident, radioisotopes released by the Japanese reactors into the environment were detected in various countries, including the United States, but in amounts far below safety limits.
In the United States, radiation testing and monitoring and the response to any potential radiation hazards such as the Fukushima incident is a multi-agency effort. Here are a few examples:
- In response to the threat from Japan, the Environmental Protection Agency (EPA) stepped up monitoring of rain water (precipitation), milk, drinking water, and air filters. The agency continuously monitors these through a national system called RadNet.
- The U.S. Food and Drug Administration (FDA) continues to screen items imported into the country and has placed restrictions on some items from Japan. Currently, the FDA has determined that there is no threat to the U.S. food supply.
- Customs and Border Protection scans cargo containers, ships, and persons entering the US.
- The CDC sent urine collection cups to state radiation control program directors along with guidance for steps to take if Customs and Border Protection finds contamination on a traveler/passenger. (For details, see the CDC web page on Laboratory Information for Radiation Emergencies.)
- The Nuclear Regulatory Commission (NRC), responsible for the oversight of a nuclear facility's emergency preparedness, issued a Temporary Instruction to all operating nuclear facilities to perform inspections that would assess a nuclear facility’s readiness to respond to an event similar to the one experienced at the Fukushima nuclear plant.
- At the state and local level, some public health laboratories are responsible for testing for radiation. Though not needed in this recent case, they have the capability to test environmental or food samples; a few are certified by federal regulations (Clinical Laboratory Improvement Act, CLIA) to test human samples.
- During the Japan Fukushima incident, the White House headed the coordination of efforts across the federal government. Although not activated in this incident, the Integrated Consortium of Laboratory Networks (ICLN) is able to help organize the activities of various laboratory networks, such as EPA's Environmental Response Laboratory Network, FDA's Food Emergency Response Network, and CDC's Laboratory Response Network. (For more on these, see the ICLN web site).
Plans for increased readiness
Even before the March incident in Japan, there were plans in place to enhance coordination between local, state, and federal agencies in the U.S. A new coalition, the National Alliance for Radiation Readiness, was formed in 2010 and brought together several public health agencies with federal partners in an effort to improve readiness. As it happened, this group met for the first time in March of this year, just as disaster struck in Japan. Participants in the conference, in conjunction with the CDC, NRC, and Customs and Border Protection, were able to provide information on radiation, testing, and readiness to the federal government, which was then disseminated to the state level, during the height of the crisis.
Additionally, the CDC has recently proposed adding another aspect to the existing Laboratory Response Network that would deal with radiological emergencies (LRN-R.) The proposal envisions five state public health laboratories that would provide a greater capacity to test for radiation in the event of a disaster resulting in a dramatic increase in the number of samples to be tested. The goal would be to provide emergency responders at every level with much needed information to be able to react appropriately to a radiological emergency, accident, or attack.
The incident with Japan's nuclear reactors has placed a focus on radiation health concerns and has revealed some potential gaps and the need for improvement in the response to such incidents. In the U.S., emergency response planning is a continual effort and as officials study and learn from past emergencies, the preparation advances and improves.
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
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Mehrhoff, Marinea, BS, CLS, Supervisor, Radiochemistry section, State Hygienic Laboratory at the University of Iowa.