We often associate radiation with dangerous atomic bombs and nuclear power plant disasters. It has the potential to damage tissues, mutate cells, affect our fertility, and even lead to long-term conditions like cancer.
Given its high potential for harmful effects on the human body, it's no wonder that many worry about sources of everyday radiation like microwaves, phones, or X-rays.
But are such low-dose sources of radiation really as harmful as we think?
The answer to this depends on the type of radiation and how much of it you're exposed to. Before we go into how radiation affects our body, let's first clarify what it actually is.
Radiation is energy that moves in the form of waves and particles through space or other materials. Different types of radiation are described along the electromagnetic spectrum and are distinguished from each other in terms of their wavelength.
On one end of the spectrum, you have things like radio waves which are longer in wavelength. While on the other end of the spectrum, you have gamma rays which are shorter in wavelength.
To understand the effect of radiation on humans, we also need to know how it's measured.
The amount of absorbed radiation is measured in units of Gray (Gy). However, this unit by itself is not very useful in understanding how it impacts health. This is because 1Gy of X-ray versus alpha radiation could have very different effects on human cells.
To better reflect how different doses of radiation impact health, we now use the unit sievert (Sv) and millisievert (mSv). With the Sv or mSv, it's no longer strictly a measure of how much radiation there is. It also represents the amount of health risk it poses to humans. Therefore, 1Sv could have the same effect for different Grays of X-ray or alpha radiation.
Another important way to distinguish between the different types of electromagnetic radiation is in terms of what it can do.
Ionizing radiation (shorter wavelengths and more dangerous) has enough energy to remove electrons from atoms to create ions — atoms that have a net positive or negative electrical charge. This is the more harmful kind of radiation, and long exposure to it in high concentrations may cause cell alterations or cancer. An example would be gamma rays from nuclear reactors.
Non-ionizing radiation (longer wavelengths and less dangerous) does not have enough energy to remove electrons from atoms and is considered safer. An example would be the radiation from radio waves on the longer end of the spectrum. However, as wavelengths get shorter, it still has the potential to heat up substances and cause damage (think microwaves). WiFi also falls under non-ionizing radiation, and there is little evidence to suggest that it increases cancer risk.
The point at which non-ionizing radiation becomes ionizing radiation occurs around the ultraviolet range of the spectrum.
While the potential health effects of any kind of radiation may sound scary, the truth is, we're actually exposed to radiation all the time. And a big part of our exposure comes from natural sources like the sun, food, and radon (a radioactive gas produced by the decay of uranium in the soil).
There are also naturally occurring geographical differences in the level of background radiation in different places around the world — with some even being 200 times higher than the average. A similar effect can be found with cosmic radiation (which comes from space). Places closer to space (on a mountain or in a flying aeroplane) will see greater levels of this radiation coming from space than somewhere closer to sea level.
Generally, this kind of background radiation is not harmful to health. And on average, we're exposed to about 3 millisieverts (mSv) of radiation a year because of this constant exposure. In fact, it has pretty much been the same since the 1980s. However, a cause of worry for some people is our exposure to man-made sources of ionizing radiation — which has nearly doubled during this period.
Part of the increase comes from sources like industrial nuclear power stations, consumer products, and household items. But the greatest source of this increase can be attributed to medical imaging technology like X-rays and CT scans, which has grown from 15% in the 1980s to 50% of our total radiation exposure today. In fact, we're currently exposed to 1.5 mSv of radiation from CT scans on average each year.
If we start at the top of the exposure spectrum, we have radiation treatment (radiotherapy) for cancer which is estimated to be about 50,000 mSv (directed at the tumour). At this higher radiation dose range, there is an increased risk for individuals to develop second cancers. But in these situations, the benefits of receiving the treatment for the existing cancer could far outweigh the risks of the development of a second cancer.
In terms of understanding the effects of high doses of radiation on healthy individuals, clinical trials are limited. And what we know about it comes from the 1945 Japanese atomic bomb survivors or nuclear power plant disasters. It's important to bear in mind though that such studies have their limitations as these individuals received large doses of radiation at one go, while medical imaging takes place in small doses spread out over time.
If we look specifically at the Hiroshima and Nagasaki bombings in Japan, the immediate damage done was devastating as it caused a loss of around 200,000 lives. Longer-term effects included the development of cancers like leukemia which took several years to appear after the incident.
But new follow-up studies are also suggesting that our common perceptions of the atomic bomb health impact may be exaggerated. While cancer rates were higher in survivors compared to those that had been away during that time, most survivors did not develop cancer. And the average reduction in lifespan for this group (taking into account all causes of death) was 1.5 years.
So what does this data about extreme radiation exposure mean for us practically when it comes to lower-dose medical imaging technology like X-rays or CT scans? Afterall, the radiation dose in such cases are much lower than an atomic bomb. Should we have no concerns whenever a health professional orders medical imaging or treatment to be done? Not necessarily either.
The biggest takeaway from such reports is to understand that we shouldn't be too quick to be swayed by sensationalized media reports of the latest health scares. Instead, we should look at what statistics has to say to balance our evaluations.
Here are the numbers put forward in a comprehensive review by the Biological Effects of Ionising Radiation VII report from the US National Academy of Sciences (BEIR VII). The report estimates that for every 1 mSv of radiation that we're exposed to, it increases our risk of solid cancer (non-leukemia) by about 1 in 10,000. For leukemia, it's 1 in 100,000. And for any cancer death, it's 1 in 17,500.
Here's another way to look at it. If we take an X-ray as an example, you're likely to be exposed to about 0.1mSv through the process. Your risk of death from cancer in this radiation dose range (from 0.1 to 1.0 mSv) is comparable to the risk of dying from flying 4500 miles.
For higher exposure tests like CT scans which have a dose of about 10mSv, your risk of dying from cancer is about the same as dying from 40,000 miles of driving.
The main point is, everything that we do is not without risk whether it's standing outside in the sun or doing an x-ray. But as with any risk that we take in life, there may also be benefits.
Medical imaging helps more than 20 million people a year in the US by helping to prevent and treat a wide variety of diseases. If you really want to decrease your exposure to radiation in everyday settings, you can keep your phone away from sleeping areas or get a microwave shield. However, medical imaging or treatment may not be one of the wisest things to forego.
Looking at the advice of major government medical bodies, it's clear that the risk of refusing essential medical tests is largely greater than the level of radiation it exposes us to.
However, where we may want to apply more caution about radiation, is in relation to the amount of exposure that children receive. The risks we've mentioned so far are applicable to the adult population, and these statistics change when it comes to children.
Considering that younger people have smaller bodies and are less protected by outer layers of tissue, internal organs will receive a higher dosage of radiation when exposed to external sources. Furthermore, cell division occurs more rapidly in children and fetuses. This gives radiation energy a lot more chances to interrupt the process and cause mutations or damage.
Studies have indicated that youth under 20 years old may be two times as likely as adults to develop leukaemia after receiving the same dose of radiation exposure. For infants (under 1 years old), the cancer risk from radiation can be up to three to four times higher compared to adults.
Radiation risks increase even further when it comes to embryos or fetuses as they're in an even more precarious stage of development. It can cause brain damage in foetuses if exposed to an acute dose of more than 100 mSv between weeks 8-15 of pregnancy. Fetal exposure to radiation also has a similar risk of cancer risk as exposure during early childhood.
If we take it a step even further, radiation effects may be passed on from one generation to another when the genetic material within parental reproductive cells (like the sperm or ovum) is altered through radiation. This may lead to genetic defects in offspring. But the issue is that such genetic disorders from radiation are difficult to study as they are hard to isolate and the effects may only show up several generations down the line.
In summary, children and fetuses are particularly sensitive to radiation exposure as they're more biologically vulnerable to radiation. And factoring in age is crucial in the development of radiation precautions.
Unfortunately, due to a mixture of sensationalized news stories and political agendas, our attitudes towards radiation have become skewed.
Take this example cited by Mr. Madhava Bhat in an article for Australasian Physical & Engineering Sciences in Medicine. He explains that few will be able to recall an industrial pesticide plant accident that took place in Bhopal, India in the 1980s which killed over 10,000 people in a single night. However, the Chernobyl nuclear power plant accident (which occurred 2 years later) killed 31 individuals from the immediate blast and caused approximately 5,000 cases of cancer. Articles still get written about the Chernobyl disaster to this day and a Netflix film has even been produced about it.
He cautions that we must have a clearer understanding of the risks involved with radiation. "If our perception of the risk is not balanced, we are predisposed to making incorrect judgments. Such decisions are invariably costly and often lead to exposure to the unknown and perhaps more significant risk elements," writes Bhat.
Unfortunately, this fear of radiation may be costing us our health. 69% of hyperthyroidism patients in the US refuse the recommended radioactive iodine treatment and opt for a less effective treatment. While practitioners across various health professions like GPs, dentists, and chiropractors are often met with refusals to take x-rays from patients.
One dentist has even illustrated that performing dental examinations without x-ray data would be as good as doing the check with a blindfold on. By refusing medical imaging or treatment, we're restricting ourselves from accessing the best available technology for understanding and managing a host of conditions.
So is radiation dangerous? Most certainly in extreme doses as we have seen from past atomic bombing and nuclear power plant catastrophes.
But how about nuclear medicine (our greatest yearly additional source of man-made ionizing radiation exposure)? The short answer is that there are risks involved, but the same can be said of driving a car or taking a plane. For some reason, we seem more comfortable accepting the risks of the latter scenarios to harness their benefits. But the same cannot be said of situations involving radiation exposure.
Nuclear medicine has been essential in a host of medical fields — including the treatment of cancer. And it even extends to other industries like agriculture and renewable energy.
Conversations surrounding radiation at the state and media level need to start being more balanced and reflect the statistical evaluations put forth by researchers. This way, the general public can be more educated about the actual risks and benefits involved instead of making decisions purely based on emotive rhetoric from the latest news headlines.
The author, Dawn Teh, is a health writer and former psychologist who enjoys exploring topics about the mind, body, and what helps humans thrive.