Last week, we examined the negative effects radiation can have on the body and discussed the recent scare in Fukushima Prefecture, Japan. Again, our thoughts and prayers are with the people of Japan, and there are still many ways you can help, such as by donating to the American Red Cross. As a continuation of this discussion, I thought I would further investigate the radiation exposure we encounter daily and if this leaves us at risk of any negative effects. Moreover, I will dispute many of our radiation myths. So, let us begin with some of the main sources of radiation around us.
According to the United States Nuclear Regulatory Commission (USNRC), the main sources of radiation in our daily lives result from medical procedures, naturally occurring radiation in the soil and atmosphere, and radioactivity in our food. However, scientific discussion also points to exposure sources like security devices, household products and industrial buildings. The key to understanding these risks is to realize the amount of radiation emitted from each of these sources, as well as by understanding how much radiation we can tolerate safely.
The USNRC notes that medical procedures account for nearly 96 percent of human exposure to man-made radiation. Of these offending procedures, x-rays, mammography, CT use and nuclear medicine account for the majority of this radiation. A chart on the USNRC website reveals that a typical x-ray gives a dose of about 0.01rem, a mammogram gives 0.072rem, a full body CT scan gives 1rem and nuclear medicine emits about 0.4rem. What do these units mean? They indicate that about two x-rays can lead to genetically-modified Glowing Green Monster Syndrome or can make you climb walls and shoot spider webs out of your palms; Spiderman and The Hulk can attest. Of course, I’m just kidding. According to the Britannica Encyclopedia, rem is a unit of radiation dosage that is equivalent to the dosage of radiation in rads that will cause bodily damage of gamma rays. As a baseline for effects of the amount of rem received in a short period, 1 rem is safe, 10 rem is safe but may slightly increase risk of cancer, 100 rem may cause health effects that are recoverable and may slightly increase risk of cancer and 1,000 rem will cause immediate detrimental health effects and can likely cause death. Comparing this to your average x-ray, the risk of experiencing effects caused directly by radiation seems fairly minimal and unrealistic. If you are having many radioactive medical procedures, the amount of radiation to which you are exposed can increase quickly in a short space of time, so it is always important to ask your doctor if the prescribed test is necessary and your best option.
One resource I stumbled upon is the website www.xrayrisk.com, which calculates your risk of radioactive effects by having you input your gender, age, number and type of exams, which it then compares to data about your estimated lifetime risk of death. I really like this because it not only estimates your overall lifetime risk of developing an invasive cancer based on known averages, but it puts into perspective the little risk of actual effects from medical procedures.
Looking at another type of radioactive source—our food—I was similarly unconvinced that we are truly at biological risk for radioactive exposure. Again the USNRC discusses that all organic matter contains small amounts of radiation from radioactive potassium and isotopes, as well as from water, which contains tiny amounts of uranium and thorium. Another chart on their website reveals that the average person receives about 0.03 rem a year from foods like bananas, Brazilian nuts and white potatoes; these three are the top offenders. A process called food irradiation uses high doses of radiation to kill bacteria and parasites in processed and packaged foods; however, this does not leave us at significant risk of radiation exposure. So you can consume with ease, as it’s proved unlikely that any significant exposure will stem from your banana split.
Looking at the overall picture, the NRC says average Americans receive a radiation dose of around 0.62 rem a year, half of which comes from natural background radiation. Naturally occurring radiation comes mostly from soil, space and radon in the air we breath, and 0.31rem of the 0.62 comes from manmade sources of radiation. This yearly dose has proven to not cause any harm in humans, so you can put away your lead jacket.
One recent study concerns the question of whether cell phones produce a significant amount of radiation. According to the National Cancer Institute, this concern stems from the kind of ewnergy that is emitted by the radio frequency waves of cell phones; this is called radiofrequency (RF) energy, a form of non-ionizing electromagnetic radiation. X-rays produce ionizing radiation, so there is yet to be strong conclusive evidence that indicates that non-ionizing electromagnetic radiation poses a cancer risk.
There have been suggestions from a few studies that it can slightly increase the risk of certain types of brain tumors, but this has yet to be adequately proven. There is, however, the notion that many of these studies are inconclusive due to variations in how and when people talk on their phone. This is complicated by the relatively short existence of cell phones, the possibility of carcinogenic exposure from other sources and the lack of information about RF energy exposure over a long period of time. Whether or not using your cell phone is actually dangerous, people are exposed to radiation via the antennae on their phones; to reduce risk, one could use speakerphone rather than holding it up to your head.
With all the hype concerning radiation in the news recently, it’s easy to get caught up in the media and begin fearing contracting radiation poisoning. As proven by my research, our actual risk is very low and quite unlikely to result from biological effects. As always, tune in for more health tips and send me an e-mail at gkatz10@brandeis.edu with any health-related questions you may have.
