By Don Lincoln, Ph.D., Fermi National Accelerator Laboratory (Fermilab)
Radiation is considered dangerous to human lives with high doses resulting in irreversible damage. However, small doses can be ignored in everyday life, and radiation is beneficial to people in medical treatments, be it CT scans, dentistry, or X-rays. With proper knowledge about its benefits and harms, moderate use can save people from any predictable harm.
Explaining Q Factors
Q factors for the various types of radiation like beta, gamma, and X-ray radiation all have a Q factor of 1, and all have the same ability to damage. In contrast, slow neutrons do five times as much damage for the same amount of deposited energy, and fast neutrons do 10 times. The very damaging alpha particles do 20 times as much damage as the betas and gammas, making it dangerous to inhale alpha-emitting substances.
Radiation in Everyday Life
Knowing about radiation in the real world and how much radiation is encountered on a daily basis—which is dangerous or which can be ignored—is important. Suppose a healthy person, living in the woods, encounters almost 3 millisieverts per year. But that may not be true for people living in cities and towns, visiting a dentist twice a year and maybe having an X-ray, who may get about 6 millisieverts, which is double the radiation of the person living closer to nature.
Radiation is not all that much of a concern for people, meaning, a few millisieverts are fine. As to being personally radioactive, the radioactive elements inside a human body decay over the course of a year and irradiate the body at about 0.4 millisieverts each year. Flying across the Atlantic Ocean will incur about 0.025 millisieverts because flying is above most of the Earth’s atmosphere, which protects people from radiation from space. A whole-body CT scan turns out to be 100 millisieverts, about 15 years of ordinary background radiation, which slightly increases the cancer risk.
Learn more about the history of cancer and what has transpired in its war.
Results of Increased Doses of Radiation
People working in nuclear facilities encounter about 50 millisieverts or about eight times what a regular person gets each year. 100 millisieverts results in a small, but not-zero, increase in cancer risk. Getting 400 millisieverts in a small amount of time can give someone radiation sickness, but they will usually recover. If someone gets five times, coming in at 2,000 millisieverts, it will result in severe radiation poisoning that can sometimes kill, although some do recover.
Four thousand millisieverts usually kills a person, although with top medical care and good genes, survival chances are better. But getting 8,000 millisieverts results almost certainly in death. Receiving a radiation dose of about 2,700 times that of a person living in the woods will also result in death. That is ballpark 1,300 times the radiation that a person encounters each year.
This is a transcript from the video series Understanding the Misconceptions of Science. Watch it now, on Wondrium.
Real Understanding of Radiation
Radiation is like fire. There is an enormous difference between a match and a bonfire where one is small, and the other could be very injurious. What makes radiation sound dangerous is that humans do not have any senses that can detect it, and with no visceral experience this makes people apprehensive. Radiation can be a real danger but it is not necessarily a danger. It depends on the amount, the half-life, and the radiation type.
Several nuclear incidents have happened over the years and the dangers are known in a credible way. In 1986, the Chernobyl nuclear disaster occurred due to bad design and operational mistakes leading to an explosion and a fire that went on for nine days. Standing near the bare Chernobyl reactor core within 10 minutes, someone would have encountered a radiation dose 8,000 times what is normally encountered over an entire year, resulting in a quick death.
Learn more about the discovery of the neutron in 1932.
Fukushima Disaster and Its Aftermath
Another more modern example is the Fukushima disaster. The Japanese Nuclear Regulatory Agency sent in robots that were built to work in a radioactive environment, but the radiation destroyed the robots in short order.
Going into the towns near the destroyed reactor can be dangerous, depending on the exact location. But the number that is usually quoted is that living in one of those towns for a year would result in an additional 30 millisievert dose. That is about five times what is usually received and about a quarter or a third the dose that gives a measurable increase in cancer risk.
Radioactivity in Coastal California
There is another concern about the danger of eating fish off the coast of California. Scientists have detected evidence of radioactivity from the Fukushima disaster in coastal California waters but detecting does not really give any context. Scientists have sensitive detectors that can monitor even tiny doses. The real way to understand the danger is to pick a particularly susceptible fish species and test it, probably a tuna, an apex predator, who eats fish that have eaten other fish. Each fish concentrates the radioactivity and, consequently, tuna should be one of the most radioactive fish. If tuna that live off the California coast are tested, it is indeed found that they contain radioactivity which came from Fukushima. But the levels are less than the radioactivity of bananas.
Learn more about the process of radioactive decay.
Getting to the Facts About Radiation
There is so much disinformation about radiation; while there are responsible environmental groups, government agencies, and corporate entities, there is also a lot of partisan hyperbole, ranging from the hyperventilation of some ultra-green partisans to corporations trying to avoid legal responsibility. Thus, hearing about a radiation incident, it is necessary to dig deeper and find out.
Radon and Cosmic Rays
Radon from homes is where most naturally occurring radiation comes from with cosmic rays from space the second largest source. The way to avoid cosmic ray radiation is to live at sea level where the atmosphere can be a shield. The bigger danger is radon, which occurs in the northern latitudes of the US.
Common Questions About Understanding Various Aspects of Radiation
Examples of radiation in everyday life are cell phones, microwaves, CT scans, and X-rays.
The Chernobyl nuclear disaster occurred and went on for nine days. Standing near the bare Chernobyl reactor core, within 10 minutes, someone would have encountered a radiation dose 8,000 times that normally encountered over an entire year, resulting in a quick death. On the other hand at the Fukushima disaster, the Japanese Nuclear Regulatory Agency sent in robots that were built to work in a radioactive environment, but the radiation destroyed the robots in short order. Thus Fukushima is considered worse than Chernobyl.
Scientists have detected evidence of radioactivity from the Fukushima disaster in coastal California waters. Scientists have sensitive detectors that can monitor even tiny doses. Tuna that live on the California coast, contain radioactivity which came from Fukushima but the levels are less than the radioactivity of bananas.
