Dr. Carafano: That would depend on how much material, what kind of material, the altitude of the debris cloud, wind currents, etc.
Even if material was widely dispersed it is not clear what the long-term health affects might be. Many of the projected causalities resulting from possible terrorist attacks employing radiological devices are estimates of increased cancer deaths based on low-dose (i.e. very small amounts) exposure to radiation. Frankly, the science in this area is less than clear. The danger of low dose exposure from a radiological weapon may be far less than is commonly assumed. The long-term effect of low-dose radiation is determined by the capacity of irradiated tissue to repair DNA damage within individual cells. This is governed by a number of exposure, health, and genetic factors. There is some scientific evidence that current models may overestimate risks.
On the whole, I think it is unlikely that terrorist groups could employ a radiological dispersal device that could result in long-term health risks over large sections of the country.
FOX Fan Question: How long would we have to stay inside after a dirty bomb attack?
Dr. Carafano: The distance from the radioactive source, the manner of dispersal, weather conditions (which will affect how far contaminated particles mixed in a debris cloud or aerosol attack will disperse), the degree of protection (e.g., buildings, overhead cover) and the type of radiation will significantly affect the manner of the threat. Alpha particles, for example, travel a short distance and most will not penetrate beyond the dead layer of epidermal skin. They are harmful, however, if inhaled or swallowed. Beta particles can penetrate the skin and inflict cellular damage, but common materials like plastic, concrete, and aluminum can block them. In contrast, gamma rays and neutrons are far more powerful and do not lose energy as quickly as alpha and beta particles when they pass through an absorber like clothing or walls. Heavy lead shielding, great amounts of other shielding with absorbent or scattering material (e.g. several feet of earth or concrete), or significant distance (perhaps in kilometers) may be required to avoid high-dose exposure. In an urban attack, buildings might absorb or shield significant amounts of radiation significantly reducing the initial prospects for casualties, though the clean up of contaminated buildings would have substantial economic consequences.
The key precaution is to avoid ingesting or inhaling the debris cloud after any fire or explosion. This just makes good sense regardless of the kind of natural or manmade disaster that generates smoke, ash, and dust. They could contain toxic material such as asbestos. The best thing to do is stay inside, close doors, windows, and vents and wait for public safety announcements. Having a battery-operated radio is always a good idea.
FOX Fan Question: Would the radioactive material affect our water or agriculture?
Dr. Carafano: It would depend on a number of factors including the type of radiation, extent of contamination. In the immediate, aftermath of any fire or explosion where there is a debris cloud, fire, smoke, dust, etc. you want to be careful not to ingest debris particles, which might well contain toxic materials. It is doubtful that a radiological device would have widespread, long-term affects on the food or water supply.
On the other hand, an attack that suggested contamination of agricultural products might have a cascading impact on suppliers, transporters, distributors, restaurants, and foreign trade causing serious economic disruption as well as physical and psychological casualties. The amount of material required for significant contamination makes this form of agricultural terrorism unlikely, but even small amounts of contamination could have a dramatic effect by causing product scares that drive consumers away from possibly tainted commodities
FOX Fan Question: How will we know if a dirty bomb goes off? If we see it on the news is it too late?
Dr. Carafano: The only way to know if a radiological device is present is with a detector that can measure radiation. You don't necessarily need immediate warning to prevent serious sickness or injury. First, you can always protect yourself by remaining in doors, in a basement or interior room. This will help you avoid contaminated particles that might be part of a debris cloud. Also, dirt and concrete will absorb and disperse radiation like neutrons and gamma rays.
In addition, sickness and death resulting from radiological exposure is often not the result of "radiation sickness" but from injuries or infection received during after the event. Radiation exposure depresses the human immune system leaving sick or injured more vulnerable. Thus, prompt medical treatment is perhaps the most important factor.
FOX Fan Question: Is it that easy for terrorists to gain access to radioactive material?
Dr. Carafano: Unlike nuclear weapons, a radiological dispersal device does not require plutonium or enriched uranium. All that is needed is some form of radioactive material. Any nuclear reactor is capable of producing material for a radiological weapon. Worldwide, the International Atomic Energy Association (IAEA) lists 438 nuclear power reactors, 651 research reactors (284 in operation), and 250 fuel cycle plants. Highly radioactive material, such as spent fuel rods or other waste material is subject to export controls. It is, however, far more easily bought or stolen than weapons-grade material. Security worldwide is uneven and trafficking in these materials is not unprecedented. Since 1993 the IAEA has recorded 531 cases of illegal transactions in radioactive material.
Additionally, there are tens of thousands of radiation sources in medical, industrial, agricultural, and research facilities. Illicitly obtaining these materials is well within the realm of the possible. According to the IAEA over 100 countries have inadequate regulatory systems for controlling radioactive material. Even the United States has significant gaps in its export rules covering highly radioactive substances. Current regulations permit unlimited export of high-risk materials to any country other than Iran, Iraq, Libya, North Korea, and Sudan without government review.
James Jay Carafano, Ph.D., is a Senior Research Fellow for National Security and Homeland Security in the Kathryn and Shelby Cullom Davis Institute for International Studies at The Heritage Foundation.