Year: 2025

30 Jul 2025
Ionizing Radiation, Irradiation, Radiation Safety, Uncategorized Versant Physics 0 comment

The Banana Equivalent Dose: Demystifying Radiation

The idea that radiation exposure is inescapable through everyday life might cause a feeling of concern or even trepidation. To make it more palatable to the public, a somewhat quirky unit of measurement was born for absorbed radiation dose. This is the “Banana Equivalent Dose”, or BED (not to be confused with the other well-known BED, the Biologically Effective Dose). Bananas, a fruit found in many homes, all contain a very small but measurable dose of ionizing radiation. The BED provides an opportunity to bring an unusual yet helpful perspective towards discussions on radiation exposure so that the science behind radiation feels more accessible and less mysterious. Let’s explore the BED, why radiation in food exists, and what it teaches us about daily radiation encounters.

What is the Banana Equivalent Dose?

The Banana Equivalent Dose (BED) is an informal unit of measurement that expresses a radiation dose in terms of the amount one person would receive from eating a single banana.1 Instead of the knowledge that radiation can exist in our food being a cause for concern, it provides a chance for better understanding of a difficult topic. The idea of the BED offers a way for the public to frame seemingly large or unfamiliar numbers relating to ionizing radiation into a more meaningful context. Although it isn’t an official unit endorsed by regulatory agencies or scientific organizations, the BED has shown to be an easier baseline for regular citizens to comprehend than attempting to explain rems or sieverts.

The average BED is about 0.1 microsieverts (μSv) per banana (1 μSv = 0.000001 sieverts, a recognized unit for measuring ionizing radiation dose).1 For some context, an average person will receive roughly 2,000 to 3,000 μSv per year due to natural background radiation like cosmic rays, radon gas, and terrestrial sources. This is equivalent to 20,000 to 30,000 bananas. When someone consumes a single banana, a minuscule addition to this background radiation occurs.

Why Are Bananas Radioactive?

Bananas are well-known for being rich in potassium, which is an essential mineral for human nutrition. They gain most of this potassium through the uptake of the mineral via the roots of their trees. There is also deposition, which is when the fruit absorbs radioactive particles in the air that settle on it.2 Naturally occurring potassium will normally be comprised of the mostly stable isotope potassium-30, but close to 0.012% of the potassium is the radioactive isotope, potassium-40. Potassium-40 decays with a half-life that equals about 1.3 billion years which means it releases radiation at a very slow rate.3

After eating a banana, both radioactive and non-radioactive potassium isotopes enter your body, becoming part of the natural chemical makeup. The human body strictly regulates potassium levels, so any excess is excreted fairly quickly. After some time to digest and excrete, your body is able to return your internal dose of potassium-40—including its radiation—to its equilibrium, regardless of whether you might eat one banana or even a dozen.3

How the Banana Equivalent Dose Came to Be

The true origin of the Banana Equivalent Dose is not clearly recorded in any sources. However, it is reasonable to surmise that the unit was suggested during research on radiation found in foods. The earliest known mention of the BED is from 1995 on a recorded email chain from Gary Mansfield. An employee at Lawrence Livermore National Laboratory at the time, Gary suggests that he found the BED to be “very useful in attempting to explain infinitesimal doses (and corresponding infinitesimal risks) to members of the public”.4

By comparing common procedures like a typical chest X-Ray (about 1000 BEDs) or actions like flying from New York to London (about 400 BEDs) to the dose from a banana, experts can create an easier connection of these common, low-level exposures to the overall idea of radiation safety. Even large organizations like the United States Environmental Protection Agency (EPA) reference the BED in public educational articles.2

The BED has remained a popular option for comparison in scientific forums and educational websites due to familiarity and relatability. Radiation is given a more understandable setting within bananas. The common household snack serves as a reminder that sometimes exposure is not as disastrous as previously believed.

Understanding Radiation Dose with the BED

An issue with radiation being an enigma for many is the misconception that all radiation is harmful, regardless of dose. There are many circumstances where that is not the case. The BED assists with putting radiation exposure into a new light:

  • Dental X-ray: Roughly equivalent to 50 BEDs
  • Yearly dose from living near a nuclear power plant: 1 – 100 BEDs
  • Chest CT scan: 70,000 BEDs
  • Typical targeted dose used in radiotherapy (one session): 20,000,000 BEDs1

Although it may be hard to fully imagine a stack of twenty million bananas, it proves to be a more tangible idea to promote informed understanding of the amount of radiation exposure in a procedure than the more abstract measurements of sievert values for the public.

What Other Foods with Radiation Exist?

Many foods naturally absorb radioisotopes from the soil and water in which they grow, putting bananas into some popular company for regular consumption. Here are some of the most recognizable foods with radioactive elements:

  • Brazil nuts are well-known for having high levels of radium-226 and radium-228, with doses that can, at times, be even higher than bananas. This is because Brazil nut trees have deep roots that access radium-rich soil and lead to these concentrations.
  • Potatoes are another potassium-rich food and contain potassium-40. Unlike bananas, however, they also absorb small amounts of uranium and thorium.
  • Carrots and red meat can accumulate some minor amounts of radioisotopes, particularly potassium-40. However, their doses are minimal compared to annual background radiation.
  • Some beer has trace amounts of potassium-40—not unlike other plant-derived foods.5

Of course, it is important to note that, despite the radioactivity in these foods, they pose no health risks when considering consumption in a normal diet. As previously mentioned, the human body is capable of handling low doses of naturally occurring radiation. Regulatory agencies also take care to monitor food safety to safeguard public health.  

Conclusion: The Public Value of the BED

When it comes to encouraging better understanding of a complex subject like radiation exposure, there’s value in linking it to a familiar concept in a person’s life. Not only does the BED provide a light-hearted opportunity to understand your day-to-day exposure but it also helps show that consuming food with absorbed radioactive elements does not normally pose a risk to one’s health or make a person radioactive—far from it, even. The Banana Dose Equivalent gives the public a dose measurement that “peels” back the layers of uncertainty to see that radiation is a natural part of the world that’s findable in the food we eat and even ourselves.

Sources

  1. P2 Nuclear and Par-Cle Physics –Dan Protopopescu. https://www.ppe.gla.ac.uk/~protopop/teaching/NPP/P2-NPP.pdf
  2. ‌Natural Radioactivity in Food. US EPA. Published November 27, 2018. https://www.epa.gov/radtown/natural-radioactivity-food
  3. ‌Schwarcz J. McGill University. Office for Science and Society. Published December 30, 2018. https://www.mcgill.ca/oss/article/you-asked/it-true-banana-radioactive
  4. Banana Equivalent Dose. Iit.edu. Published 2025. http://health.phys.iit.edu/extended_archive/9503/msg00074.html
  5. Helmenstine A. These 10 Common Foods Are Radioactive. ThoughtCo. Published 2014. https://www.thoughtco.com/common-naturally-radioactive-foods-607456
31 Jan 2025
Background Radiation, Cancer Treatment, Irradiation, Radiation Therapy Versant Physics 0 comment

What Really Happens? The Impact of Radiation Inside the Body

What is Radiation?

Radiation is a fundamental phenomenon that exists as a natural part of the world and universe. It is the emission and propagation of energy in the form of waves or particles through space or a material medium. At its most basic level, radiation occurs when unstable atomic nuclei release energy by emitting particles (such as alpha particles, beta particles, or neutrons) and/or electromagnetic waves (such as gamma rays). Electromagnetic radiation is also produced through several other processes: X-rays are generated when electrons transition between inner atomic energy levels or when fast-moving electrons are decelerated (bremsstrahlung), while UV radiation primarily comes from electron transitions in excited gases and thermal emission from very hot objects such as the sun. The impact of radiation has the potential to be either beneficial or destructive to biological systems.

Ionizing and Non-ionizing Radiation

Radiation is categorizable into two groups: ionizing radiation and non-ionizing radiation. Ionizing radiation has enough energy to remove tightly bound electrons from atoms, creating charged particles (ions). This group includes alpha particles, beta particles, gamma rays, X-rays, and neutrons. Ionizing radiation is commonly associated with medical applications, such as X-rays and radiotherapy, but it also occurs naturally, as in the form of cosmic rays or radon decay.

In contrast, non-ionizing radiation does not have sufficient energy to ionize atoms or molecules. This group includes ultraviolet (UV) radiation, visible light, infrared radiation, microwaves, and radio waves. However, ultraviolet (UV) radiation exists on the boundary: lower-energy UV radiation is typically non-ionizing, while higher-energy UV radiation, such as extreme UV, can ionize atoms and molecules. Non-ionizing radiation is generally less harmful and technologies such as communication devices and heating systems use it. On the beneficial side, the visible light radiation coming from the sun enables photosynthesis in plants and infrared radiation provides warmth. As is also common knowledge, the use of X-Rays in medicine is very popular in current times.

Regardless of whether radiation is produced naturally through something such as UV rays, or the high-energy radiation created by humans for radiotherapy and other medical procedures, there are biological impacts for any living creature that encounters it. Today, we will explore the impact of radiation on a cellular level and why, despite these potentially harmful effects, the risk is worth the reward when it comes to continued radiation use.

How Does it Affect the Body Overall?

Ionizing radiation can cause damage to one’s cells in different ways:

Cellular Impact of Radiation

Although any cell within the body exposed to ionizing radiation can have a reaction to it, the impact of this radiation depends heavily on which types of cells are exposed and the intensity of the radiation. Cells, by default, have mechanisms to repair DNA damage. Should the repair be successful, then the cell can continue to function as normal.

Some of the human body’s cells, especially those that have rapidly dividing tissues such as bone marrow and the gastrointestinal system, are more vulnerable to radiation damage.3

Animal Cells and Irradiation Effects

  1. DNA Damage and Mutations: Damage to DNA is probably the most significant consequence of radiation exposure. Radiation can cause single-strand or double-strand breaks in the DNA, which may lead to mutations or chromosomal abnormalities as a result of errors in the repair process. Any such DNA mutation can alter how genes normally function and may result in cancerous growths or even developmental abnormalities, should the cell replicate with damaged DNA.4
  2. Cell Death: Most commonly, cell death from radiation is mitotic death. During the process of cell division, damage to the chromosomes cause cells to fail to complete their replication and die. This occurs most often when radiation damage is severe enough, as happens with double strand breaks, causing failed or incorrect repair. A secondary type of cell death that may occur is apoptosis. Apoptosis, known as programmed cell death, is normally a natural process to aid in getting rid of dysfunctional or no longer needed cells. For example, apoptosis is what allows the tadpole to lose its tail. Radiation damage may also cause a cell to enter into the apoptosis cycle leading to cell death and impaired organ function.5 Radiation induced apoptosis, however, is highly dependent on the type of cell being most common blood cells and cells associated with the immune system.
  3. Genetic Instability and Cancer: One of the most concerning effects of radiation on cells is the potential to cause cancer. The DNA mutations mentioned earlier can lead to the development of oncogenes (genes that promote cancer) or the inactivation of tumor suppressor genes. When these changes happen in critical genes that control the cell cycle and cell division, it can result in uncontrolled cell growth. This, more often than not, leads to cancer.5

Plant cells also may suffer radiation damage. Due to differences of structure and metabolism between animal and plant cell types, plant cells have a higher resistance to the effects of radiation making them more tolerant to ionizing radiation than animals.6 For plants, radiation has a less significant impact and can sometimes produce beneficial effects.

Plant Cells and Irradiation Effects

  1. DNA Damage and Mutations: As with animal cells, the nucleus of plant cells is the area of highest injury from ionizing radiation. The amount of damage that may occur to the DNA is dependent on chromosome volume. This volume changes between plants and is also affected by the different stages of the plant life cycle. Mutations (DNA deletions, base substitutions, and chromosomal alterations) can vary from non-lethal to lethal depending on the dosage of radiation exposure. 6
  2. Phenotypical Responses: As a consequence of the genetic mutations plant cells may develop after radiation exposure, the plant itself can go through a phenotypical response such as reduced growth, altered leaf morphology, and impaired development. High doses of irradiation (several Gy) can likely cause structural modifications during the plant’s growth, but chronic low levels of radiation may also introduce changes in plant traits. These studies are normally done with plant seeds that are irradiated and then observed as they develop. However, if the exposed cells have greater radioresistance, this resistance will prevent them from producing a more pronounced phenotypical response as the seed matures.6
  3. Photosynthesis: High doses of gamma radiation exposure to plants can result in a decrease of photosynthesis by disrupting the photosynthetic pigment–chlorophyll–and the photosynthetic electron transfer rate in some plants. As with the potential for DNA damage or mutations however, the impact to photosynthesis can be influenced by the plant’s developmental stage with younger or actively growing plants potentially experiencing a more significant impact compared to mature plants.6

How Radiation can Beneficially Impact the Body

Despite the tendency to associate the aforementioned biological effects with harm, radiation can have positive applications. These are mostly within the medical field but are recognizable throughout other industries as well. Here are a few ways that humans have turned the potency of radiation into a benefit:

Cancer Treatment (Radiotherapy):

Cancer treatment is, unsurprisingly, one of the most significant uses of radiation for good. High-energy radiation is usable for targeting and destroying cancerous cells by decreasing the rate of tumor cell proliferation through cell cycle arrest stimulated by DNA damage. By preferentially focusing radiation on solid tumors and limiting the dose to normal critical structure, cancer cells may be either killed or shrunk sufficiently to prevent cancer from spreading or to make it easier to remove through other means. Cancer cells divide rapidly, which makes them more sensitive to radiation than normal cells making them an ideal target for radiation therapy.7

  • Radiation in Chemotherapy: Radiation therapy is usable in conjunction with chemotherapy drugs, which increases the effectiveness of an overall treatment plan and can prevent tumor growth.8
  • Precision Medicine: This method was designed to help healthcare providers deliver more personalized treatments. In cancer care, it considers how variations in specific genes or proteins in a patient’s cancer cells may influence treatment choices. Radiation can benefit cancer treatment specifically through precision medicine when using targeted therapy that includes radiopharmaceuticals.9 An example of a targeted therapy is one that uses antibodies to which a radioactive atom has been attached. The antibody recognizes particular antigens expressed by tumor cells and bind to the cell thereby delivering its radioactive package.

Medical Imaging and Diagnostics

Diagnostic work and medical imaging benefit from radiation as well, as we’ve covered in previous blogs. Whether they are imaging options such as X-rays and CT scans, or nuclear medicine diagnostics using injected radioactive tracers, these techniques allow doctors to visualize internal structures of the body. This helps with diagnosis and monitoring of various health conditions and provides detailed anatomical information needed for planning radiation therapy. Although these procedures do involve exposure to low doses of radiation, the reward of accurate diagnosis and treatment planning to manage radiation treatment in the long run is worth the small but inherent risk.

Sterilization and Disinfection

Somewhat within and outside of the medical field, sterilizing medical equipment and food products is possible with ionizing radiation. This helps to reduce the risk of foodborne illnesses and infections. This is a process known as radiation sterilization. Through it, controlled doses of radiation can help to destroy bacteria, viruses, and other pathogens.

Balancing the Positive and Negative Aspects

The impact that radiation has at the cellular level and on the overall body is a double-edged sword: the potential to heal can also be potential for harm. When using radiation for things like treatment or imaging, the difficulty lies in ensuring as small a risk as possible while maximizing the benefit. Precise and controlled radiation doses in these procedures require careful planning and monitoring that have been developed over the years.

One of the arguments for the benefits of radiation exists in a hypothesis for how radiation can impact the body depending on dosage. Despite the harmful effects of radiation that we detailed earlier, scientists have seen evidence for some beneficial effects in an area known as radiation hormesis.

The radiation hormesis model supports the idea that low-dose radiation can stimulate adaptive or protective mechanisms within cells (both plant and mammalian) when exposed. This low-dose radiation can aid with prevention of both spontaneous and toxicant-related cancers, along with other adverse health effects. Through this stimulation, the adaptive protection developed by the cells would thereby improve health.10 The radiation hormesis model, though well known by professionals in the field, requires more research, time, and development. There are no accredited organizations in the medical physics world that recognize radiation hormesis as a usable model and the LNT (Linear-No-Threshold) model maintains as the worldwide safety standard.

Conclusion

Even if human-made radiation had never come to exist, natural radiation makes it an intrinsic part of our lives. Knowing the biological impact that radiation can have down to the cellular level allows us to harness its potential in the safest ways possible for the greatest benefits and smallest risk. Although radiation can damage cells in a way that leads to mutations, cancer, or even organ failure, it is vital in treating diseases, making diagnoses, and sterilizing necessary items like food or medical equipment. As with many sources in the world, humans must strike a balance with its use. Through understanding the full effects of radiation, good and bad, we pave the way to using radiation in an effective and responsible manner.

Sources

  1. Ionizing Radiation and Non-Ionizing Radiation – Frequently Asked Questions a RESOURCE for VETERANS, SERVICE MEMBERS, and THEIR FAMILIES. https://www.warrelatedillness.va.gov/WARRELATEDILLNESS/education/factsheets/Radiation.pdf
  2. Di Meo S, Venditti P. Evolution of the Knowledge of Free Radicals and Other Oxidants. Oxidative Medicine and Cellular Longevity. 2020;2020:1-32. doi:https://doi.org/10.1155/2020/9829176
  3. Nuclear Regulatory Commission. Reactor Concepts Manual Biological Effects of Radiation Biological Effects of Radiation.; 2023. https://www.nrc.gov/reading-rm/basic-ref/students/for-educators/09.pdf
  4. Baskar R, Dai J, Wenlong N, Yeo R, Yeoh KW. Biological response of cancer cells to radiation treatment. Frontiers in Molecular Biosciences. 2014;1(24). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4429645/
  5. Little JB. Principal Cellular and Tissue Effects of Radiation. Nih.gov. Published 2014. https://www.ncbi.nlm.nih.gov/books/NBK12344/
  6. Arena C, De Micco V, Macaeva E, Quintens R. Space radiation effects on plant and mammalian cells. Acta Astronautica. 2014;104(1):419-431. doi:https://doi.org/10.1016/j.actaastro.2014.05.005
  7. ‌ American Cancer Society. How Radiation Therapy Is Used to Treat Cancer. www.cancer.org. Published December 27, 2019. https://www.cancer.org/cancer/managing-cancer/treatment-types/radiation/basics.html
  8. Rallis KS, Yau THL, Sideris M. Chemoradiotherapy in Cancer Treatment: Rationale and Clinical Applications. Anticancer Research. 2021;41(1):1-7. doi:https://doi.org/10.21873/anticanres.14746
  9. Xiong Y, Jian H, Han X, Li L, Zhou L. A decade of incremental advances in radiopharmaceuticals: a promising future ahead. Journal of Translational Medicine. 2024;22(1). doi:https://doi.org/10.1186/s12967-024-05891-4
  10. Vaiserman AM. Radiation hormesis: historical perspective and implications for low-dose cancer risk assessment. Dose Response. 2010;8(2):172-191. Published 2010 Jan 18. doi:10.2203/dose-response.09-037.Vaiserman

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