Initial Publication Date: December 13, 2012

Radiation and Cancer

Author: Laura Gilstrap

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

This web page provides information about the different types of radiation, where they come from, how they can impact your health, and what you can do to lower your chances of radiation exposure.

Introduction

Energy that comes from a source and travels through material or space is called radiation. Radiation occurs in atoms when the unstable nuclei decay and release particles. Ionized radiation occurs when an atom loses an electron and becomes unstable. Unstable atoms have either excess energy or mass. The emissions of the excess energy or mass give off radiation. Radiation is measured in rem (roentgen equivalent in man) unit doses. Radiation can cause burns, cancers, and death when it comes into contact with organic material. Types of radiation include electromagnetic, particulate, and ionizing radiation. We also experience radiation from cosmic rays and naturally occurring radioactive materials, this is called natural background radiation exposure. The dose of radiation you receive is depended on your altitude; the higher you are the higher the cosmic radiation dose.

Sources of Radiation

Natural radiation sources include radon, cosmic radiation, and elements in the ground. Radon is the leading source of radiation exposure and the second leading cause of lung cancer. It is found many places, but most prominently in the soil. The ground all around us has varying levels of naturally occurring radioactive elements that can turn into a radon gas. Cosmic Radiation comes from various types of radiation from outer space, for example, gamma rays and heavily charged particles. Our atmosphere can absorb and filter some cosmic radiation however, some still makes it through so we receive small doses. The following chart from the National Council on Radiation Protection and Measurement (NCRP) show's our annual dose of each natural radiation source. Natural Radiation Sources (Acrobat (PDF) 2.6MB Dec7 12)

Along with natural radiation sources there are man-made radiation sources. The most significant man-made source of radiation comes from medical sources. Man-made radiation also comes from consumer products such as construction materials, televisions, fluorescent lamp starters, smoke detectors, tobacco, and lantern mantles.

How Radiation Enters The Body

The way iodizing radiation enters the body is dependent on the source. Radiation can pass directly through the body when exposed to X-rays and gamma rays. Alpha, beta, and gamma rays can be taken into the body by contaminated materials such as dust in the air, dissolved in water, and by eating contaminated plants and animals. The mouth, nose, around the eyes and breaks and cuts in the skin are the main entry pathways for contaminated materials.

Radiation in your Food

Despite contrary belief, radiation from things like microwaves does not make food radioactive. However, food can be radioactive if the plant you are eating was grown in radioactive soil. You can also be exposed to radiation in animals that have eaten these plants, or, in some cases animals that have been exposed to high doses of radiation.

Impacts on Human Health

Since the dosage of rems of radiation represents the amount of tissue damage, the higher the radiation dosage of rems you are exposed to, the more harmful the effects. We are exposed to low doses of radiation that don't have much of an effect on us, however levels as low as 25 rems can cause changes in the blood. The first radiation sickness symptoms start appearing when a person reaches doses above 100 rems. Symptoms of radiation sickness include headache, nausea, vomiting, and some loss of white blood cells. Radiation doses over 300 rems are very harmful. It causes hair loss and significant internal damage. Because mutated cells are emitting excess energy and mass, it is being transferred to the healthy cells in the body; therefore, mutating them. This dosage causes a severe loss of white blood cells, weakening the immune system and making victims susceptible to disease. Another side effect that can appear is blood clotting and hemorrhaging due to the reduced production of blood platelets. A person exposed to 450 rems only has a 50% chance of survival. Once exposed to 800 rems, there is no chance of survival.

Because ionizing radiation has the ability to break chemical bonds and change the charge of atoms, you are at a high risk for various cancers and DNA mutations. There are two categories for the health effects of radiation exposure based on the amount of radiation you were exposed to and how long you were exposed to it; stochastic and non-stochastic. Long-term, low-level exposure to radiation are stochastic effects. The primary health concern for people exposed to radiation is cancer, due to the uncontrolled growth of cells caused by damage, disrupting the body's natural cell growth processes. It also causes damages in DNA called mutations. There are also non-stochastic health effects which occur when a person is exposed to high levels of radiation, the health effects become more severe as the duration of exposure increases. If the person is only exposed to a high dosage for a short period of time it is called 'acute' exposure. Health effects present themselves much sooner in people with this type of exposure. People that have experienced 'acute exposure' may suffer from burns or radiation sickness.

The areas most vulnerable to radiation's negative effects are bone marrow and the thyroid gland. Because of bone marrow's sensitivity to radiation, the most common radiation induced cancer is Leukemia. Radiation can cause cancer in any part of the body, but it is most commonly linked to lung cancer, skin cancer, thyroid cancer, multiple myeloma, breast cancer, and stomach cancer.

Prevention or Mitigation

There is no way to completely avoid radiation exposure however; there are measures you can take to minimize the amount of radiation you are exposed to. Before choosing a house you should have the house and surrounding soil tested for levels of radon and other radioactive gasses. You can buy inexpensive testing kits to test for radon levels. If you find that you do have high levels of radon at your home and aren't planning to move you can have an active soil depressurization (ASD) system installed. This reduction technique uses a fan and vent pipe to vent radiation from beneath the house.