Understanding The Risks Of Radiation On Human Health

2011-03-17 Wellescent |

It situations involving radiation such as the disaster unfolding in Japan following the massive earthquake and tsunami, our collective lack of understanding regarding radiation and its effects on the body becomes quite clear. The thought of any problems at a nuclear power plant quickly brings our minds to the Chernobyl disaster and the decades of contamination that follow such an event. With respect to human health, such events invoke fear because they remind us of the dramatically higher risks of illness and cancer experienced by those exposed.

Indeed, such situations are possible, but they represent more extreme events and a serious systemic failure on the part of any governments in power. While it is understandable that we are not completely knowledgeable about radiation given that most people are neither doctors nor physicists, the use of radiation in modern medical science means that a basic understanding is important as we strive to be informed patients and prepared citizens.

In simplistic terms, there are two types of radiation, ionizing and non-ionizing. The most important difference between the two in terms of health is the amount of energy that the radiation carries. The least energetic form of ionizing radiation is the very familiar ultraviolet light. When we are exposed to this radiation, we get burns after some duration of exposure. Over the long-term, regular exposure to ultraviolet light can raise our risks of skin cancer.

While ultraviolet light represents the lowest energy form of ionizing radiation, the more energetic forms are x-rays and gamma rays. These forms of radiation carry far more energy and have increased ability to penetrate our body tissues. This is why x-rays are valuable in medical imaging as compared to visible light or ultraviolet light that can barely pass a few layers of skin before losing all of its energy. Likewise, this is why gamma rays represent a valuable cancer treatment for penetrating the tissues to destroy tumor cells.

Why ionizing radiation is dangerous is because such radiation has enough energy to break chemical bonds. This means that our body chemistry can be altered by exposure to such radiation. Changes to our body chemistry from significant doses can prevent the body from functioning properly. Normal chemical reactions fail to occur and unexpected reactions do occur. These effects are felt particularly during the complex process of cell division.

What this means is that the effects of radiation on the body are felt most rapidly amongst cells with a short lifespan that must be replaced most regularly. Many of the different white blood cells that form an important part of the immune system live only for a day to 5 days. This means that radiation significantly reduces the effectiveness of the immune system making those exposed to radiation at increased risk of infection. Amongst those who receive radiation therapy for cancer treatment, the reduced immune function experienced is for the same reason.

In addition to the white blood cells, the cells of the stomach and intestines also have very short life spans and a need to be replaced through cell division with days. With radiation exposure, a common symptom is nausea and diarrhoea because the stomach and intestines can no longer function properly with an absence of the cells that would normally line the digestive system.

Longer term, the effects of radiation exposure are due to the ionizing radiation damaging the DNA within our cells. Such damage can ultimately lead to cancers in the same way that ultraviolet light exposure contributes to skin cancer risk. Higher risks are also seen amongst those with medical conditions that require frequent x-rays for disease monitoring.

In the event of a partial nuclear plant failure such as the one that occurred in Japan, the risks are primarily for those in the vicinity of the reactor. They risk direct exposure from the ionizing radiation coming out of the damaged plant as well as exposure to radioactive material that escapes the containment that a working plant would normally provide. As the distance from the nuclear plant increases, the risks of exposure to radiation or contamination decrease exponentially. This means that the risks of exposure across the Pacific in North America or even south of Japan in Australia are extremely low.

For those close to the nuclear plant, however, the contamination risk is the greater one because contaminated material can enter the air as well as food and water supplies. In contrast to external radiation exposure which can be minimized through shielding, exposure within the body from consumed or inhaled materials is much more difficult to treat. The contaminated radioactive material within the body continues to give off ionizing radiation that continues to damage the cells and alter body chemistry.

Treatments for radiation contamination do not reverse the effects of the radiation, but rather work to limit absorption or remove any radioactive material that has been absorbed. Potassium Iodide pills, for example, only work to limit the absorption of radioactive iodine. Another example is Prussian Blue that helps to get radioactive cesium and thallium out of the system faster by preventing it from being absorbed by the intestines. Contamination with different radioactive particles requires specific treatments to minimize the time that these particles are within the body.

When nuclear incidents occur, we too often react with a knee-jerk reaction with regard to the personal health dangers involved. Certainly the dangers for those in the area of the nuclear plant failure are quite real, but for those of us a quarter planet away, fears of radiation poisoning and contamination are generally unfounded. That is not to say that we should avoid keeping a careful eye on the deployment and use of nuclear energy. Nor should we allow anyone to reduce the handling restrictions for nuclear waste. It is not an attempt to promote nuclear energy instead of safer alternative forms of energy. What is important is being aware of the actual risks of radiation and responding rationally when incidents occur.

Related Links

http://www.epa.gov/rpdweb00/understand/ionize_nonionize.html
http://www.merckmanuals.com/professional/sec21/ch317/ch317a.html
http://theoncologist.alphamedpress.org/cgi/content/full/7/6/492
http://bloodjournal.hematologylibrary.org/cgi/content/abstract/116/4/625
http://pubs.acs.org/doi/abs/10.1021/cen-v055n044.p017

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