Measure Radiation Exposure in Bananas?


We would like to share with you a short educational movie made by the team at Veritasium, a science video blog. The video titled “The Most Radioactive Places on Earth” can be used as an easy-to-digest summary of many subject matters we have touched on already.

Watch it to refresh your memory or use as a primer for such topics as ionizing radiation, sources of radiation and units of measure. If the term sievert has not yet become a staple in your vocabulary, this video is for you. Or, forget the confusing lingo and let’s measure exposure in Bananas! Seems a lot less intimidating, does it not?

“The Most Radioactive Places on Earth” is an 11 minute video with an opening scene set in an abandoned hospital in Pripyat near Chernobyl. Piles of contaminated clothing, tools and rubbish are scattered over the floors of the deserted rooms. The building is no longer supplied electricity. The light is scarce. A person in a protective suit moves quickly from room to room, the hollow spaces amplify Geiger counter clicks as they get faster and faster.

The first 34 seconds of the video build an immediate suspense. The scientific staff at the Institute gave it thumbs up. I hope you enjoy it too.

Are you ready to do “banana math”? One of the movie viewers has done exactly that and came to  the conclusion that 20 million bananas consumed at once have enough radiation to kill a human being. While we applaud the math, we are in full agreement with the team at Veritasium – if you have your heart set on eating 20 million bananas, radiation is not your most immediate problem.


Worried about your cell phone? Consider these four simple steps.

If you have not read our posts Cell Phones and Cancer and Non-ionizing Radiation. A Word on EMF let us summarize the main thought: presently there is no conclusive evidence that radiofrequency (RF) waves from cell phones cause any harmful health effects.  More studies are underway and we shall be looking forward to their outcomes. If all the available to date findings are not putting your mind at ease consider the advice from the American Cancer Society and follow these four simple steps:


Use the speaker mode on the phone or a hands-free device such as a corded or cordless earpiece. This moves the antenna away from your head, which decreases the amount of RF waves that reach the head. Corded earpieces emit virtually no RF waves (although the phone itself still emits small amounts of RF waves that can reach parts of the body if close enough, such as on the waist or in a pocket). Bluetooth® earpieces have an SAR value of around 0.001 watts/kg (less than one thousandth the SAR limit for cell phones as set by the FDA and FCC).


Texting instead of talking on the phone may be another option to reduce your exposure. But it may not be a good option in some situations, especially if you are driving. For safety reasons, it is especially important to limit or avoid the use of cell phones while driving.


Limit your (and your children’s) cell phone use. This is one of the most obvious ways to limit your exposure to RF waves from cell phones. You may want to use your cell phone only for shorter conversations, or use it only when a conventional phone is not available. Parents who are concerned about their children’s exposure can limit how much time they spend on the phone.


Some people might consider choosing a phone with a low SAR value. Different models of phones can give off different levels of RF waves. But as noted above, according to the FCC the SAR value is not always a good indicator of a person’s exposure to RF waves during normal cell phone use. One way to get information on the SAR level for a specific phone model is to visit the phone maker’s website. The FCC has links to some of these sites If you know the FCC identification (ID) number for a phone model (which can often be found somewhere on the phone or in the user manual), you can also go to the following web address: On this page, you will see instructions for entering the FCC ID number.

Public EMF Exposure at Wi-Fi Access Points

There are many advantages to having Wi-Fi access points in businesses, public and private institutions, and other public spaces, since Wi-Fi allows almost instantaneous access to information. However, there has been considerable public concern over the effects of exposure to Wi-Fi frequencies, particularly in areas frequented by children, such as schools.

Industry Canada has recently performed measurements to determine the level of exposure to the public from electromagnetic frequencies (EMF) emitted at Wi-Fi access points. To perform these measurements, Industry Canada simulated a typical Wi-Fi environment by installing 24 Wi-Fi enabled laptops, all simultaneously uploading and/or downloading data using a Wi-Fi connection, in a closed room with 2 Wi-Fi access points. Multiple configurations were considered.

The maximum instantaneous exposure level, measured at 20 cm from the Wi-Fi access point, was 10.59% of the Health Canada Safety Code 6 guideline for public exposure to Wi-Fi frequencies. In more typical scenarios, in which people are located several meters from the access point, Industry Canada determined that the exposure levels would be thousands of times below the Safety Code 6 limits.

Health Canada’s Safety Code 6 limits are based on an in-depth evaluation of available scientific literature on thermal and possible non-thermal effects of radio-frequencies on biological systems. For Wi-Fi frequencies, the limits are based on tissue-heating effects. Safety Code 6 has set the public exposure limit to be 50 times below any exposure that may lead to significant tissue heating. In other words, exposures in public areas below the Safety Code 6 limits will result in no adverse health effects.

To learn more, read Industry Canada’s Case Study: Measurements of Radiofrequency Exposure from Wi-Fi Devices.

Cell Phones and Cancer Risk

Concerns about the potential relationship between cell phone use and brain cancer risk continue to arise. The worry is that radiofrequency energy from cell phones may affect the brain and other tissues. The only known biological effect of radiofrequency energy is heating and exposure from cell phone use does cause heating; however, it is not sufficient to measurably increase body temperature.

In the words of the National Cancer Institute: “it is generally accepted that damage to DNA is necessary for cancer to develop. However, radiofrequency energy, unlike ionizing radiation, does not cause DNA damage in cells, and it has not been found to cause cancer in animals or to enhance the cancer-causing effects of known chemical carcinogens in animals (3–5).”

At this point in time there is no conclusive scientific evidence from studies of  cells, animals, or humans to suggest that cell phone use causes cancer. The debate in the scientific and public domains continues. Have you ever had a conversation on a controversial subject that started with “The research shows(…)”?

get the factsIt is true, the research is there. Researchers have carried out several types of epidemiologic studies to investigate the possibility of a relationship between cell phone use and cancer risk. Some of the more talked about studies are: The INTERPHONE study; The Danish cohort study; The Million Women Study. The problem with the all the studies done so far is that each has its own limitiations. So before we can start drawing our own conclusions from any study it is important to understand what theese limitations are.

Scientific methodolody, if you are not a die hard researcher, could be a boring subject. So lets switch gears and go straight to the visual. Here is a another great video from the team at Veritasium that talks about cell phone use and related studies. If all this will leave you with more questions, remember you can always call us at 1-800-263-5803, reach out to us on twitter @RSICanada or on our Facebook page.

Need Help Navigating Regulations? Look no Further!

Have you ever wondered who is charge of your safety when it comes to the use of radiation? Canada has a stringent and complex radiation safety regulatory framework. One and the same workplace may fall under the jurisdiction of several regulatory bodies. For example, a large hospital in Ontario, one that runs imaging and nuclear medicine programs, needs to comply with:  X-Ray Safety Regulations under the Occupational Health and Safety Act enforced by the Ontario Ministry of Labour; with the Healing Arts Radiation Protection Act under the Ontario Ministry of  Health and Long-Term Care and Nuclear Safety and Control Act and Regulations enforced by the Canadian Nuclear Safety Commission.

Confusing already, right? Our Free Inquiry and Information Service 1-800-263-5803 daily receives questions regarding the correct interpretation and application of the Canadian federal and provincial radiation safety regulatory standards. Based on the nature of inquiries received by our Service it is fair to say that in many cases workers are not well aware of the regulations that govern their particular sector or find the regulations difficult to understand, particularly in the circumstances where the workplace falls under multiple regulatory jurisdictions.

Proper understanding and implementation of regulatory standards is paramount to workplace safety in and prevention of radiation induced occupational disease (e.g. cancers and cataracts) and injures (e.g. radiation burns). We are happy to answer any and all questions that come in, so connect with us any time! But thinking of how we can be more helpful to you, we came up with the Interactive Regulatory Search Tool idea.

We wanted to develop a web based Tool that would allow the “non expert” to input details about their specific application of a radiation device and get answers about the applicable legislation and  brief explanation of those requirements.

The Tool is now finished.  We made it with all your questions in mind. It gives answers to work related questions  and valuable advice to the members of general public who want to know more about radiation safety in Canada.  For example, the Tool will can help navigate the requirements that pertain to registration of an x-ray machine used for a specific purpose or that apply to transportation or disposal of a radioactive source. The Tool can also provide regulatory guidance for specific user functions related to the particular application of radiation (e.g. medical, industrial, dental, veterinary).

Whether you are employer, employee or member of public, to find answers simply click on the Tool link, select the criterion that best applies to your particular situation and browse to explore. We hope it l will be useful and informative. If on your exploratory journey you will come up with more questions than the Tool answers, you can always follow up with us or other experts whose contact details are included. Give it a go and let us know what you think!


Non-ionizing Radiation. A Word on EMF.

So far we have given ionizing radiation most of our attention, now lets talk about its the non-ionizing type. Remember, we have looked at both in our earlier What is Radiation post?

emf-awarenessThough the term EMF stands for Electromagnetic Field, it is typically used colloquially to refer to low energy electromagnetic fields, more specifically Radio Frequencies. We are continuously surrounded by EMF through power lines and cell phones, which has led many to wonder if these fields may cause adverse health effects to humans, and particularly to children.

We have compiled information for you on this topic from the World Health Organization, Health Canada, and the Health Physics Society. As you will see, these experts all agree that if there are adverse health effects to be expected from EMF, they are very small.

Quotes from the World Health Organization

  • Conclusions from scientific research In the area of biological effects and medical applications of non-ionizing radiation approximately 25,000 articles have been published over the past 30 years. Despite the feeling of some people that more research needs to be done, scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields. However, some gaps in knowledge about biological effects exist and need further research
  • Effects on general health Some members of the public have attributed a diffuse collection of symptoms to low levels of exposure to electromagnetic fields at home. Reported symptoms include headaches, anxiety, suicide and depression, nausea, fatigue and loss of libido. To date, scientific evidence does not support a link between these symptoms and exposure to electromagnetic fields. At least some of these health problems may be caused by noise or other factors in the environment, or by anxiety related to the presence of new technologies.
  • Electromagnetic fields and cancer Despite many studies, the evidence for any effect remains highly controversial. However, it is clear that if electromagnetic fields do have an effect on cancer, then any increase in risk will be extremely small. The results to date contain many inconsistencies, but no large increases in risk have been found for any cancer in children or adults. A number of epidemiological studies suggest small increases in risk of childhood leukemia with exposure to low frequency magnetic fields in the home. However, scientists have not generally concluded that these results indicate a cause-effect relation between exposure to the fields and disease (as opposed to artifacts in the study or effects unrelated to field exposure). In part, this conclusion has been reached because animal and laboratory studies fail to demonstrate any reproducible effects that are consistent with the hypothesis that fields cause or promote cancer. Large-scale studies are currently underway in several countries and may help resolve these issues. While an increased risk of brain tumors is not established from INTERPHONE data, the increasing use of mobile phones and the lack of data for mobile phone use over time periods longer than 15 years warrant further research of mobile phone use and brain cancer risk. In particular, with the recent popularity of mobile phone use among younger people, and therefore a potentially longer lifetime of exposure, WHO has promoted further research on this group. Several studies investigating potential health effects in children and adolescents are underway.

Quotes from Health Canada

  • Exposures in Canadian Homes, Schools and Offices Present No Known Health Risks Research has shown that EMFs from electrical devices and power lines can cause weak electric currents to flow through the human body. However, these currents are much smaller than those produced naturally by your brain, nerves and heart, and are not associated with any known health risks. There have been many studies about the effects of exposure to electric and magnetic fields at extremely low frequencies. Scientists at Health Canada are aware that some studies have suggested a possible link between exposure to ELF fields and certain types of childhood cancer. The International Agency for Research on Cancer (IARC) has evaluated the scientific data and has classified ELF magnetic fields as being “possibly carcinogenic” to humans. IARC based this classification on the following:
    • human health population studies showing weak evidence of an association with childhood leukemia; and
    • a large database of laboratory study results showing inadequate evidence of an association with cancer in animals.
  • To put this into context, it is important to understand that the “possibly carcinogenic” classification is also applied to coffee, gasoline engine exhaust and pickled vegetables, and is often used for agents that require further study. In summary, when all of the studies are evaluated together, the evidence suggesting that EMFs may contribute to an increased risk of cancer is very weak.

Quotes from the Health Physics Society

  • Potential health concerns about power lines were first raised in a 1979 study which associated increased risk of childhood leukemia with residential proximity to power lines. Since that initial study, numerous other investigations have attempted but failed to clarify whether observed associations between electromagnetic fields (EMFs) and various health effects were causal or coincidental. Some scientists have argued the physical impossibility of any health effect due to weak ambient levels of EMFs, while others maintain that the potential health risks should not be dismissed even though the evidence remains equivocal and contradictory. There are no known health risks that have been conclusively demonstrated in relation to living near high-voltage power lines. But science is unable to conclusively prove that anything, including low-level EMFs, is completely risk free. Most scientists believe that exposure to the low-level EMFs near power lines is safe, but some scientists continue research to look for possible health risks associated with these fields. If there are any risks such as cancer associated with living near power lines, then it is clear that those risks are small.

CT-Scan and Radiation Dose

As we mentioned in a previous post “What is a CT-Scan?” CT-scans are essentially a large set of X-rays, taken at many angles around the body, in order to create a 3-D anatomical image.  To put the dose received by a CT-scan into context, remember that on average, Canadians receive 2-4 mSv of radiation dose per year from natural background radiation, which has not been shown to lead to adverse health effects, and that an accumulated exposure of 1000 mSv over a lifetime leads to an estimated 4% increased risk of developing cancer.

We know a single X-ray does not deliver much radiation dose: a typical chest X-ray delivers about 0.1 mSv of radiation, about the same radiation dose you receive from background radiation in about 12 days.  However, CT-scans are a series of many X-rays, and deliver much more radiation dose than a regular x-ray.  A typical chest CT, for example, delivers 6 mSv of radiation dose.  Though this may triple your annual radiation dose for that year, this still represents a very small risk   You would need about 40 CT-scans in your life to increase your chance of getting a fatal cancer by 1%.

Scans over larger areas, like the pelvis, abdomen and chest, can give about 10 mSv of dose, whereas a typical head CT may only give 1.5 mSv.  A screening mammogram delivers about 3 mSv of radiation dose.

Still unsure about what it all means? Take a listen at our Staff Scientist, Claire Cohalan, summarize it all for you in brief 1 minute video.

What is a CT-Scan?

Have you ever had a CT-scan done? If you have you probably have noticed warning signs on the imaging room doors, staff around you wearing dosimeters and taking safety measures to avoid exposure. Does it make you wonder: What about me? How much radiation am I getting? Is it safe? What are the risks involved?

We will split the answer between two posts. Before we start talking about exposures and doses, let’s focus a bit on theoretical fundamentals and look at how CT-Scans work.  Because CT-scans produce electromagnetic radiation we will start with a short re-fresher on that particular subject.

 What are photons and electromagnetic radiation?

Photons are bundles of energy which travel through space at the speed of light.  Lower energy photons include radiowaves, microwaves, and infrared light, medium energy photons include visible light, and higher energy photons make up UV light, X-rays, and gamma rays.

Photons travel through space as waves.  They are made up of two components: an electric field and a magnetic field, which oscillate perpendicular to each other.  This is why photons are referred to as electromagnetic radiation

How do CT scans and Medical X-rays work?

X-rays are high energy electromagnetic radiation.  In other words, they are made of the same “stuff” as radiowaves, microwaves, infrared light, visible light, and UV rays, but are higher in energy.  Because of their high energy, some X-rays can go right through the less dense parts of our bodies, such as skin and muscle, untouched, like visible light through a pane of glass.

These X-rays then reach a film, or detector, placed behind the patient and darken the image.  However, the more dense parts of our body, our bones for example, absorb X-rays, preventing them from reaching the film or detector.

As we can see in the X-ray image to the right, all of the x-rays which traveled through the air around the hand reached the film and darkened it.  However, very few of the x-rays which had to travel through the thick layer of bone in the wrist reached the film, leaving a very light region in the image.

There is a clear contrast between bone and muscle tissue.  The muscle tissue is less dense than bone, and so appears darker on the image.

Computed Tomography (CT), also referred to as Computed Axial Tomography (CAT),  produces a three-dimensional (3D) X-ray image.  Through a series of 2D X-ray images, taken along a ring perpendicular to the subject’s body, a 3D image of the inside of the subject is reconstructed using a computer.

CT scans are very helpful to doctors, as they give a complete picture of what is going on inside the body in three dimensions. This allows a doctor to find internal bleeding, or assess exactly where in the body a tumour is while also getting a detailed picture of the size and shape of it. Because CT scans require a series of X-ray images to produce a complete picture, they emit much more ionizing radiation than a typical X-ray does.  A CT scan of the chest can give 100 times more radiation dose than a typical X-ray of the same region. However, this radiation dose still results in minimal risk to a patient.

We hope this gives you a nice background to move on and explore putting the issue of dose received from a CT-Scan procedure into perspective in CT-Scans and Radiation Dose.

5 Things you Need to Know About Radon Testing

Now that we have covered the “Why” of radon testing  in the post “Why Radon Gas is Not to be Ignored?”,  lets take a look at the “How”?

Testing for radon is very simple. You can either purchase a do-it-yourself test kit or contact a certified Radon Measurement Professional to come and do it for you.

Do-it-yourself kits are user-friendly and  inexpensive. So, unless you have specific constraints or reasons for engaging a third-party  e.g., for the purpose of independent assessment, do-it-yourself route is a reasonable option.

Test-kits can be purchased online or through a department store , e.g.  Home Depot .

If you Google “radon-test” you will get a long list of potential suppliers. How do you choose? There are not set rules, but here are some points that you might find helpful to consider:

1.  Service Provider Qualifications

Check if your supplier of choice is a Registered Measurement Professional or a C-NRPP certified Radon Analytical Laboratory. C-NRPP stands for Canadian – National Radon Proficiency Program. It establishes guidelines for training professionals in radon services in Canada. If you supplier is certified, it means that he or she has gone through the training, passed the exam and is continuously updating  their education;  if it is a laboratory, it also adheres  to very specific quality control standards.

For  a list of certified professionals please click here: Find a Professional

2.  Price

Prices may vary  from $13 per device for a department store charcoal kit, on the low end, to $250 for a continuous monitoring device , on the high end. Generally, you will find yourself somewhere in the range of $30 to $65 dollars, depending on the device.

When evaluating your options we encourage you consider the following:

  • are laboratory fees included in the price (with $13 option it would normally be an add-on)
  • what part (if any) of shipping and handling costs are included in the price

3.  Service Scope and Quality

Because prices for  the same type of testing device may differ only marginally, when  choosing your supplier you might want to consider the  following;

  • experience supplier has had with radon testing
  • access to live support throughout testing process (what is your preferred communication mode? Would you like a live person you can call to discuss your test results or will E-mail suffice?)
  • Where is the laboratory analysis performed? ( the latter is of no particular consequence  other than personal preference.  If you  wish to have your results analysed by a Canadian company, look for a certified radon analytical laboratory. If it is not a local lab, your test will go to the US for analysis, which is not a negative by any means, just a longer supply chain)

4.  Where, When and for How Long to Test?

Health Canada recommends that home owners do a long-term radon test, for a minimum of three months, during the fall or winter months.  In choosing where to place the detector we suggest you consider the  lowest lived in level of the home (typically any place where homeowners spend a minimum of 4 hours per day).  When positioning the detector, try to choose a location which best represents the air you breathe. For example, if you do not spend all your time in the bathroom (and we do not judge if you do) this may not be the optimal testing location.

5.  Choice of the Device

We recommend that you choose a technology that has been approved by the C-NRPP.

Your two likely choices are : Alpha Track Detector and Electret Ion Chamber (known as E-Perm) . Descriptions that follow are the courtesy of Take Action on Radon Campaign resources:

Alpha Track Detector

These detectors use a small piece of special plastic enclosed in a container. The detector is exposed to the air in a home for a specified time. When the radon in the air enters the chamber, the alpha particles produced by decay leave marks on the plastic. At the end of the test the detector is returned to a laboratory for analysis, and the average radon concentration is calculated.

When shopping for alpha track devices, try to choose a technology which has a filter installed over the air entry port.  This removes the airborne  decay products and ensures the devices is measuring the radon gas concentration only.  In technical jargon – it makes the device less sensitive to the radon “equilibrium ratio” inside the home.

Electret Ion Chamber

This detector contains a disk called an “electret,” which has an electrostatic charge housed in a container. When the detector is exposed to the air in a home for a specified time, the radon in the air enters the container and the ionization produced by decay reduce the electret charge. The difference in the charge is measured by a specialized voltmeter, and from that the average radon concentration is calculated.

Both devices will do the job. For our own purpose at the Institute  have decided to use E-Perm for home testing to stay environmentally friendly (the chambers and electrets can be re-used and have no waste).

 Understanding Your Results

We will talk more about the different action levels later on, for now we would like you to keep in mind just one figure 200 Bq/m³. Should your test come back with the result higher than 200 Bq/m³ – Health Canada recommends that remedial measures should be taken.

Why Radon Gas is Not to be Ignored

There isn’t a year that passes without our learning about some newly discovered hazard. As the number of natural and man-made agents, that are potentially harmful, grows so does our “hazard fatigue”.  Radon is one of the hazards to garner recent public attention.  Is the trend here to stay or shall this too pass?

As a public safety topic, it may only now be reaching the news, but it is not a “new” hazard.  Radon is found where uranium is and, in some concentration, uranium is present in the soil most everywhere. Radon is a naturally occurring radioactive gas that has been there long before it made its news debut in the public domain.

It is a colourless, tasteless and odourless radioactive gas that may seep through foundational cracks or other openings into a home.  Long-term exposure, especially for smokers, to elevated radon levels increases the risk of developing lung cancer.

Based on statistical data, the Canadian Cancer Society identifies cancer as the leading cause of deaths in Canada, with lung cancer being the most common type of the disease.

Did you know that radon is the 2nd leading cause of the lung cancer after smoking?  According to Health Canada an estimated 16% of lung cancer deaths among Canadians are attributable to indoor radon exposure.  Its potential threat is not always well understood and indeed, the  debate on the health risks posed by radon gas continues.

What we know, beyond all doubt, is what we have learned firsthand through our experience with radon induced cancers contracted by hundreds of Ontario workers on the job. This is the story of Elliot Lake.

Uranium was discovered in Ontario in 1953 and mining became an important industry for the province. Between 1955 and 1990 Elliot Lake mines produced most of the world’s uranium.  As far as workers’ safety was concerned, the 50s, 60s, and 70s were a different world from today. An alarming trend started to emerge: cases of lung cancers and silicosis were on the rise. The workers were looking for answers. In 1974 this led to a wildcat strike, lead by the United Steelworkers Union, and the appointment of a Royal Commission to investigate the matter. The work conditions are best described in the words of the Commission findings. 

“The potential hazards in the enclosed spaces underground are many. (…) The regular processes of drilling, blasting, mucking, and crushing generate fine respirable mineral dusts which are potential causative agents in pneumoconiosis (literally ‘lung-dust disease’). (…) The radioactive gases radon and thoron emanate from rock faces and arise from the elements uranium and thorium which are present in many rock formations, especially in uranium mines”.

The Workers Safety Insurance Board of Ontario (WSIB) has allowed the claims of 220 miners who lost their lives due to working condition in the Elliot Lake mines.

Today we know the answers to the miners’ questions about lung cancers. Radon gas, produced by the breakdown of uranium, is radioactive. When breathed in, especially mixed with dust particles, it has a long-term impact on the lungs, continuously damaging lung tissue from within.

It is of course unlikely that the modern home or work conditions will compare to the uranium underground mines of the past.  The story, however, highlights how dangerous radon hazard can be when unchecked.   We encourage all home owners and workplaces to test for radon. Testing is easy and affordable.   We hope to see the number of home radon tests to increase regardless of whether you get a test kit from our National Laboratory  or another supplier. To help you choose, in the post “5 Things you Need to Know about Radon Testing” we list the main criteria for you to consider. If you find that radon levels in your home are above Health Canada action levels there are steps you can take to mitigate “Radon – Reduction Guides for Canadians“.

If you have questions, remember – you can always call us at 1 800 263 5803 or email We love to hear from you!