Putting radiation in perspective

The images of the destruction in Japan from last week’s major earthquake and tsunami have been horrifying. But as wrenching as they are, at least we can see them. Not so with radiation that may be leaking from a quake-damaged nuclear power reactor.

Radiation is like a stealth warrior. You can’t see, hear or feel it. Those with the highest and most immediate exposure, such as nuclear power plant workers, tend to show the effects within hours, days or weeks. But for most of the population, the health effects from lower-level exposure might not manifest themselves until 20 or 30 years later.

Rather scary? Well, yes. Here are a few facts, however, to help put things in perspective: The radiation risk to the Japanese public is low, at least for now. People can limit their exposure further simply by staying indoors. The health risk from radiation exposure depends on the type of radiation, the amount and length of exposure, as well as one’s cumulative lifetime dose.

From a New York Times article explaining the potential effects of radiation exposure from the disaster in Japan:

The more likely risk for the public is that of low-level exposures, which can increase the risk of cancer many years later. Again, the danger depends on the length of exposure and what types of radioactive materials to which one is exposed.

Some radioactive materials are readily absorbed by the body and linger there. Iodine, for example, goes to the thyroid gland, and strontium to the bone, and they emit radiation inside the body that over time can lead to cancer or leukemia. Other radioactive materials, like tritium, pass quickly through the body.

The article also notes that one of the main long-term risks isn’t from direct exposure per se. It’s from radioactive fallout that can enter the food chain, contaminating streams and offshore ocean water, for instance, or orchards, vegetable gardens and pastures.

Although many people are frightened of radiation, there’s an important point to keep in mind: We’re all exposed to radiation every day, primarily from natural and background sources. And for the average American, the single biggest source of exposure isn’t from nuclear power plants or clouds of radioactive fallout; it’s from medical imaging. Experts have calculated that CT scans and nuclear medicine account for more than one-third of the total radiation exposure and three-fourths of the medical imaging radiation exposure among the U.S. population.

How much radiation do you think you absorb on a daily basis? Here’s an online calculator from the EPA that helps you estimate your risk. (You’ll need to know the local altitude; Willmar is about 1,100 feet above sea level.) You can also keep track of your lifetime dose of medical-related radiation with this calculator from Xrayrisk.com, a site sponsored by the American Society of Radiologic Technologists. It includes the basics such as chest X-rays and dental X-rays, along with CT scans, nuclear medicine and interventional procedures. For more information on therapeutic radiation involved in cancer treatment, click here.

Photo: Associated Press