Radiation

Existing everywhere and used for weapons and health care

The radiation from nuclear weapons wreaks enormous damage on the human body. Even after a long time has passed, it can induce diseases such as cancer. On the other hand, radiation can also be useful to our lives.

For this issue, we studied the topic of "radiation" and explored the mechanism by which radiation does damage to the human body.

Victims of radiation, whose genes have been damaged, include not only atomic bomb survivors from Hiroshima and Nagasaki. Even today, patients who have reportedly been harmed by the radiation of depleted uranium are on the rise in Iraq and other countries.

Radiation itself isn't evil. It can be beneficial when used in the treatment of cancer and for modifying plant species. However, when radiation is an element of weapons, it can cause tremendous harm. The damage done by radiation is another reason that nuclear weapons must be eliminated.

Radiation is emitted from atomic nuclei The amount of radiation we are exposed to in daily life (sievert) A stomach X-ray 0.6 A roundtrip flight from Tokyo to New York 0.2 Natural radiation per person (per year) (content) From the universe From the earth From food By inhalation 2.4 0.39 0.48 0.29 1.26 A CT scan 6.9 The soil of Guarapari, Brazil (an area with a high level of natural radiation, per year) 10 A spot 1 km from the hypocenter of the Hiroshima bomb (with no objects to provide shielding) 4000-5000 What exactly is radiation? We posed this question to Hirohiko Sawamura, 56, a former junior high school teacher who led a "peace club" for junior high and high school students. Matter consists of elements, aggregates of atoms, or a compound of elements. Some atoms transform into other types of atomic nuclei to be more stable. In this process, radiation is produced. The power to emit radiation is called radioactivity and all matter composed of elements which emit radiation, such as uranium, thorium, and radium, is considered radioactive material. Radiation is found all around us. A very small amount of radiation is emitted from the earth and from food. We are generally exposed to about 2.4 sieverts a year of this naturally-occurring radiation. At the same time, there is also artificial radiation, such as radiation used in X-rays. Radiation is absorbed by the human body in two ways. One way is by direct exposure and the other is when particles of radiation are taken into the body. Alpha radiation can't reach cells of the human body from exposure alone, but when taken into the body, the cells are exposed to a strong dose of radiation. (Chisa Nishida, 14)

A girl suffered hair loss as a result of the atomic bomb's radiation. (Photo by Shunkichi Kikuchi, courtesy of Hiroshima Peace Memorial Museum)

In addition to the destruction caused by the blast and heat rays, the atomic bomb dropped on Hiroshima brought terrible radiation damage. According to Nori Nakamura, 62, a researcher of the Radiation Effects Research Foundation and an expert in radiation biology, the amount of radiation released by the bomb at a distance of 1 km from the hypocenter was roughly 2,000 times as much as the radiation found in nature. Even at a point 2 km from the hypocenter, the amount is estimated at 100-200 times greater than naturally-occurring radiation.

Radiation damage is classified into two types: the first involves acute symptoms while the other symptoms develop after some time has passed.

An example of the acute symptoms includes an interruption in the body's ability to manufacture new cells, such as blood cells. As a consequence, the number of white blood cells declines and can lead to infection. Another example is hair loss, which victims of radiation poisoning often suffer.

Over time, other symptoms may appear because radiation can harm DNA and this damage can induce such diseases as cancer. A-bomb survivors develop leukemia at twice the rate of ordinary people. The incidence of other types of cancer, too, is high for A-bomb survivors.

Radiation is also destructive to cells which are usually in the process of actively dividing. As a result, those who were in their mothers' wombs at the time of the bombing may suffer from microcephaly.

The Radiation Effects Research Foundation is engaged in researching the causes of death of people exposed to the atomic bombings and the chromosome mutations of their blood. They are also investigating the effects on the children of A-bomb survivors. The results of this research are used to establish safety standards for radiation levels, particularly for those who work with radiation. (Miyu Sakata, 13)

A mother holding her child with leukemia at a hospital in Basra, southern Iraq. The child's stomach has become bloated due to abdominal dropsy. (Photo by Haruko Moritaki, July 2003)

Weapons which use depleted uranium (DU), a byproduct of enriching the uranium needed for nuclear power and nuclear weapons, cause terrible harm to the human body.

DU weapons were originally produced in order to help dispose of radioactive waste. DU is 2.4 times as heavy as iron and can penetrate an iron sheet 10 cm thick. When DU explodes, it burns at a temperature of 3,000-4,000 Celsius. Particles of uranium are dispersed in the form of mist. When one of these particles is absorbed into a cell, it continues to emit radiation. Additionally, the chemical toxicity of uranium makes DU's impact on the human body even more serious.

To date, DU weapons have been used in the Gulf War, the war in Afghanistan, the Iraq War, and in Somalia and the former Yugoslavia. The military forces of the U.S., U.K. and NATO have been responsible for their use and the U.S. has officially denied that DU weapons cause harm to the human body.

Haruko Moritaki, 70, a leader of the "NO DU Hiroshima Project," which has been pursuing a ban on the use of DU weapons, told us that the number of people in Iraq with cancer, including leukemia, is increasing. DU has also been detected in the urine of American soldiers stationed in Iraq.

No international treaty banning DU weapons currently exists, but in Belgium, a law forbidding the use of DU weapons came into effect in June 2009. A similar bill is now being considered by Costa Rica's national assembly. "To establish a treaty banning DU weapons, it's urgent that public awareness of the damage from these weapons be widely raised," said Ms. Moritaki. (Masanori Mikoshi,16)

Medical uses for radiation Patients being exposed to high density radon. (From a brochure of the Misasa Medical Center at Okayama University) Radiation is made use of medically. For example, hot springs, with their natural radiation, can have a positive effect on people's health. We asked Kiyonori Yamaoka, 53, a professor at Okayama University and an expert on the science of radiation for supporting health, about how radiation can be of benefit to human beings. X-rays used for medical diagnosis are a weak dose of radiation. They help locate diseases while still in an early stage. Strong radiation, to combat cancer cells, is used in cancer treatment. And research is being done on weak radiation to determine its positive effects on curing cancer and lifestyle-related illnesses such as hardening of the arteries. A hot spring in Tottori Prefecture called Misasa Radon, promotes the body's immunity through a small amount of radiation. This can alleviate the pain of lifestyle-related illnesses, too. Cancer treatment involving radiation causes little pain. When cancer strikes the pharynx, for example, radiation can help avoid removal of the organ so patients preserve their voice. However, such treatment also brings side effects by harming healthy cells, too, like fatigue and skin damage. (Shiori Kosaka, 13)

Radiation enhances plant species Flowers enhanced with radiation. The yellow flower (above left) changed to pink (above right), then orange (below left), then white (below right). The experiment was part of research conducted by Takasaki Advanced Radiation Research Institute and Gunma Prefecture. Radiation is also used to enhance plant species and sterilize food. A survey conducted by the Food and Agriculture Organization (FAO) and the International Atomic Energy Agency (IAEA) confirmed that 2,570 kinds of plant species have been enhanced with radiation. We spoke with Atsushi Tanaka, chief of the Radiation-Applied Biology Division of Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency. He said that the artificial enhancement of plant species using radiation began in the United States in 1928. Applying radiation to plants causes mutations and rewrites their genetic code. In second or third generation plants the new genetic code becomes fixed, which can produce new colors in flowers. Radiation introduced directly into the DNA of food products prevents the cells from multiplying, halting further germination and sterilizing the food. In Japan, applying radiation to food is banned, except for potatoes, due to safety concerns. "Mutations from radiation can occur in nature, so increasing this incidence won't endanger the human body," Mr. Tanaka said. "Applying radiation to food has been approved as safe by the World Health Organization (WHO) and other organizations." (Akane Murashige, 16)

Nuclear power generation using nuclear fission accounts for 26% of all power generation in Japan. The Chugoku Electric Power Company, based in Hiroshima City, runs two nuclear power stations in Shimane Prefecture which generate about 10% of all nuclear power in the nation.

Pellets of processed natural uranium are needed for nuclear power generation. Neutrons collide with the pellets in the fuel pipes and produce nuclear fission, which then heats the pipes. When the water in the nuclear reactor boils, steam from the water turns the turbines.

Hiroshi Ogawa, 53, a company spokesperson, told us that one of the advantages of nuclear power generation is the fact that it emits no carbon dioxide through this process, in contrast to thermal power generation. It can also generate an enormous amount of energy from a small quantity of fuel. However, the disadvantage is that, if radiation should leak out, the impact on the surrounding environment could be devastating.

For safety,there are five measures in place,including the cover on the fuel rods, the walls of the building housing the nuclear reactor, (shown in the illustration) and, if an earthquake should strike, a device will automatically stop the plant's operations.

After being used to generate power, the uranium fuel becomes waste that contains radioactive material. By reprocessing the nuclear waste, power plants try to produce mixed oxide, another type of fuel for reactors. The Chugoku Electric Power Company makes mixed oxide fuel at their Shimane station.

According to Hitoshi Yoshioka, a professor at Kyushu University and an expert on the history of science, the advantage of mixed oxide is that it reduces the amount of plutonium, which can be used to produce nuclear weapons. On the other hand, plutonium is highly toxic and its nuclear fission is more difficult to control as compared to uranium. The high cost of reprocessing is another problem. (Daishi Kobayashi,16 and Rika Shirakawa,12)