Mammography Risks Part 1

That old nagging question keeps raising its head. Does the radiation exposure from the mammography x-rays contribute to the development of breast cancer?

If it does, should I have a mammogram every year to check for breast cancer?

Those are tough but important questions.

So let’s take an in-depth look at the scientific considerations. Then you must decide your course of action for yourself.

John D Boyce, Jr, DSC, Scientific Director, International Epidemiology Institute, Rockville, MD 20850 wrote a comprehensive article titled Ionizing Radiation and Breast Cancer Risk. You may access the full article on the Cornell University web site at:

http://envirocancer.cornell.edu/factsheet/physical/fs52.radiation.cfm#mammog

Over the next few newsletters we will look at the highlights from that article and some newly released research findings.

We will also look at the question:

Is there a reliable alternative for early detection of breast cancer that does not use ionizing radiation?

Dr. Boyce points out the difference between ionizing radiation and non-ionizing radiation, an important distinction when considering the effects of exposure to radiation.

“What is ionizing radiation?

Radiation is the emission of energy in the form of waves or particles. Radiation that is so powerful that it can remove electrons from atoms is called ionizing. Examples of types of ionizing radiation are x-rays from medical machines and gamma rays from radioactive substances.

How does exposure to “non-ionizing” radiation, such as from microwave ovens, affect breast cancer risk?

Non-ionizing radiations do not possess enough energy to remove electrons from atoms. Examples of non-ionizing radiation are the electromagnetic fields from electrical power lines, radio and television waves, radar, cellular telephones and microwave ovens. The mode of interaction of non-ionizing radiation with the body is much different from the way ionizing radiation interacts. Most importantly, ionizing radiation can directly damage DNA and cellular molecules whereas non-ionizing radiation cannot.

The concern over non-ionizing radiation is related to the heating effects of this type of radiation. Exposure standards are set to keep exposures well below the level that might shock or heat tissue to an unacceptable level. They are thus set to reduce the occurrence of rapidly occurring effects and not effects which require long periods of time to develop such as cancer. While there is overwhelming evidence from human investigations, animal experiments and cellular studies proving that ionizing radiation is a cause of cancer, there is no such evidence for the non-ionizing radiations. There is a world of difference between the radiation from an x-ray machine and the non-ionizing electromagnetic fields from say an electric blanket, and care should be taken not to confuse the two.

How do people get exposed to radiation?

We live in a sea of low-level radiation from natural sources. These natural sources include radioactive radon gas that we breathe, radioactive elements such as potassium-40 that is found in many foods (including salt), uranium and thorium which are found in soils and building materials, and cosmic rays that continually bombard us from outer space.

However, there are other sources of manmade ionizing radiation. These sources include medical x-rays which are used to both diagnose disease and to treat cancer; occupational radiation which is experienced during employment in certain industries and professions; radioactive fallout from nuclear weapons testing or reactor accidents; and radioactive emissions from the normal operation of nuclear facilities such as those used to produce electrical power.

In terms of exposure to the entire population, natural sources contribute by far the largest radiation dose to people, with medical radiation contributing the next largest amount. For individual women the amount of radiation experienced throughout life is influenced by her access to medical care, illnesses requiring diagnosis or treatment, residence that is related to levels of background radiation, and occupation in a profession with possible radiation exposure.

As you read through this series of articles over the next few weeks keep in mind this distinction between ionizing and non-ionizing radiation.

Now don’t start worrying your head off about whether or not to have mammograms done. Be patient and review all of the information in the subsequent articles, then make an informed decision.

Blessings,

Dr. Jo