Category: Health Effects

27 Mar 2024
Airplane flight crew character design. Pilot and stewardess flat vector illustration
Background Radiation, Health Effects, Ionizing Radiation, Radiation Safety Versant Physics 0 comment

Flight Crews and Radiation Exposure

Flight crews are among the occupational groups most exposed to ionizing radiation, with an average annual effective dose surpassing that of other radiation-exposed workers in the United States, excluding astronauts.1 This elevated exposure is primarily due to the high levels of cosmic radiation encountered at flight altitudes, which can pose significant health risks to pilots and cabin crew members.2 In this blog post, we’ll explore the nature of cosmic radiation, its potential health effects, current exposure levels for aircrews, as well as the guidelines and regulations in place to ensure their safety.

What Is Cosmic Ionizing Radiation?

As we’ve touched on in a previous blog, cosmic ionizing radiation–or simply cosmic radiation–originates from beyond Earth’s atmosphere. Additionally, it consists of two main components: galactic cosmic radiation (GCR) and solar particle events (SPEs).3,4

Galactic Cosmic Radiation

GCR is a constant background radiation that permeates interstellar space, originating from distant stars and galaxies. It is composed primarily of high-energy protons (85%) and alpha particles (14%). There is also a small fraction of heavier nuclei (1%) ranging from lithium to iron and beyond. These particles span a wide energy range, and as a result some reach extremely high energies capable of penetrating deep into the Earth’s atmosphere and passing through aircraft shielding.5

Solar Particle Events (Solar Flares)

Solar particle events, on the other hand, are sporadic bursts of intense radiation associated with solar flares and coronal mass ejections. During an SPE, the Sun ejects a large number of high-energy protons and other particles that can reach Earth within hours to days. While less frequent than GCR, SPEs can dramatically increase radiation exposure for flight crews, particularly those on polar routes where the Earth’s magnetic field provides less protection.6,7

At higher altitudes, such as those typically encountered during air travel, the Earth’s atmosphere provides less shielding against cosmic radiation, resulting in increased exposure for flight crews and passengers.

Several studies that have investigated the difference in cosmic ray levels at various altitudes versus ground level found that the dose rate of cosmic radiation at a cruising altitude of 30,000 feet was approximately 10 times higher than at sea level.

The specific increase in cosmic ray exposure at higher altitudes is influenced by several factors, including the solar cycle (solar maximum vs. solar minimum), geomagnetic field strength, and also the path of the flight (polar routes are exposed to higher levels of cosmic rays). For example, during periods of high solar activity (solar maximum), the increased solar wind can actually shield the Earth from some cosmic rays, slightly reducing the exposure at high altitudes. Conversely, during a solar minimum, the cosmic ray intensity can be higher.

Estimates of the number of hours that have to be flown in order to receive an effective dose of 1 mSv at 30,000 feet are 510 hours at a latitude of 30o South and 1,330 hours at the equator.8

Health Effects and Uncertainties

The health risks associated with radiation exposure are generally well-documented. Prolonged exposure to high levels of radiation can increase the risk of cancer, cataracts, as well as other adverse health effects.  However, quantifying the specific risks associated with the chronic low-dose radiation experienced by flight crews remains a challenge.

The World Health Organization’s International Agency for Research on Cancer (IARC) acknowledges that ionizing radiation causes cancer in humans and is also associated with reproductive problems. However, when it comes to cosmic ionizing radiation, several uncertainties remain:

  1. Cancer Risk: Most radiation health studies have focused on groups exposed to much higher doses from different types of radiation (such as atomic bomb survivors or patients receiving radiation therapy).9 Due to this, the specific link between cosmic ionizing radiation and cancer risk is not yet fully understood.
  2. Reproductive Health: Miscarriages and birth defects related to cosmic radiation exposure are still not definitively established.10

Despite the limitations of current research, several studies have suggested that flight crews may have a higher incidence of certain cancers compared to the general population. These include breast cancer, melanoma, as well as non-melanoma skin cancers.11,12 However, the causal link between cosmic radiation exposure and these increased risks has not been definitively established. Other factors, such as lifestyle and genetic predisposition, may also play a role.13

Exposure Levels for Flight Crews

Recent dose and risk assessments by a wide variety of investigators have demonstrated the need to dedicate further attempts to quantify potential radiation exposure.14 The National Council on Radiation Protection and Measurements (NCRP) reports an average annual effective dose of 3.07 mSv for flight crews; most of this exposure comes from natural radiation:

  • Estimates of annual aircrew cosmic radiation exposure range from 0.2 to 5 millisieverts (mSv) per year depending on factors such as flight routes, altitude, and solar activity.
  • Solar particle events occur less frequently, but during events, exposure levels can increase substantially and potentially lead to higher doses over short periods.

Guidelines and Regulations

While there are no official dose limits specifically for aircrew in the United States, national and international guidelines provide context:

  • International Commission on Radiological Protection (ICRP): Recognizes aircrew as radiation-exposed workers. They also recommend an effective dose limit of 20 mSv per year averaged over 5 years (totaling 100 mSv in 5 years) for radiation workers. However, for the general public, the recommended limit is 1 mSv per year.15
  • Pregnant Aircrew: The ICRP recommends a dose limit of 1 mSv throughout pregnancy.16

Current regulations aim to limit radiation exposure for flight crews, but there is room for improvement. The International Commission on Radiological Protection (ICRP) sets guidelines for radiation protection and also includes dose limits for occupational exposure. However, these guidelines may not adequately address the unique challenges faced by flight crews. To improve current radiation safety regulations for aircrews, a multi-faceted approach is necessary. This should include:

Improved Monitoring and Data Collection

Implementing advanced radiation monitoring systems on aircraft in addition to encouraging the use of personal dosimeters by flight crews can provide more accurate and comprehensive data on exposure levels17. This information can help refine risk assessments as well as guide the development of more effective protection strategies.

Aircraft Shielding and Design

Continued research into advanced shielding materials in addition to aircraft design modifications can help reduce the radiation dose received by flight crews and passengers18. This may also involve the use of novel composite materials or the incorporation of additional shielding in critical areas of the aircraft.

Route Optimization and Flight Planning

By carefully planning flight routes and altitudes, airlines can minimize exposure to cosmic radiation, particularly during solar particle events19. This may also involve rerouting flights to lower latitudes or reducing flight time at higher altitudes when necessary.

Education and Awareness Programs

Providing flight crews with comprehensive information about the risks of cosmic radiation exposure in addition to the importance of proper protection measures can empower them to make informed decisions about their health and safety20. This should include training on the use of personal protective equipment, such as dosimeters, as well as guidelines for managing exposure during pregnancy.

Regulatory Harmonization and Enforcement

Strengthening international collaboration to harmonize radiation protection standards for flight crews in addition to ensuring consistent implementation and enforcement of these standards across the aviation industry can help create a safer working environment for all aircrews2121.

Conclusion

Although no regulations officially set dose limits, radiation exposure is still a concern to be evaluated for airplane flight crews due to their occupational exposure to cosmic radiation. While the specific health risks associated with this chronic low-dose exposure remain uncertain, continued efforts are essential ensure a safe working environment. By implementing measures such as personal dosimetry devices, increased monitoring, staff training, and encouraging airplane manufacturers to consider shielding and design modifications, airlines can better protect their flight crews. Ensuring a safer career for every radiation worker will require time, dedication, and collaboration. However, the benefits for the health and safety of all industries, including aircrews, make it a worthwhile endeavor.

Versant Physics is a full-service medical physics and radiation safety consulting company based in Kalamazoo, MI. Contact us for all of your regulatory, radiation safety, and personnel dosimetry needs.

Sources

  1. Friedberg, W., & Copeland, K. (2003). What aircrews should know about their occupational exposure to ionizing radiation. Oklahoma City, OK: Civil Aerospace Medical Institute, Federal Aviation Administration. ↩︎
  2. United Nations Scientific Committee on the Effects of Atomic Radiation. (2008). Sources and effects of ionizing radiation: UNSCEAR 2008 report to the General Assembly, with scientific annexes. New York: United Nations. ↩︎
  3. Validation of modelling the radiation exposure due to solar particle events at aircraft altitudes. Radiation Protection Dosimetry, Volume 131, Issue 1, August 2008, Pages 51–58. https://doi.org/10.1093/rpd/ncn238 ↩︎
  4. Wilson, J. W., Townsend, L. W., Schimmerling, W., Khandelwal, G. S., Khan, F., Nealy, J. E.,  & Norbury, J. W. (1991). Transport methods and interactions for space radiations. NASA Reference Publication, 1257 ↩︎
  5. O’Sullivan, D. Exposure to galactic cosmic radiation and solar energetic particles. Radiat Prot Dosimetry. 2007;125(1-4):407-11. https://pubmed.ncbi.nlm.nih.gov/17846031/ ↩︎
  6. Turner, R. E. (2007). Solar particle events from a risk management perspective. Radiation Protection Dosimetry, 127(1-4), 534-538. ↩︎
  7. Lantos, P., & Fuller, N. (2003). History of the solar particle event radiation doses on-board aeroplanes using a semi-empirical model and Concorde measurements. Radiation Protection Dosimetry, 104(3), 199-210. ↩︎
  8. Cosmic Radiation Exposure for Casual Flyers and Aircrew, https://www.arpansa.gov.au/understanding-radiation/radiation-sources/more-radiation-sources/flying-and-health ↩︎
  9. National Research Council. (2006). Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2 (Vol. 7). National Academies Press. ↩︎
  10. CDC – Aircrew Safety and Health – Cosmic Ionizing Radiation – NIOSH Workplace Safety & Health Topics. Centers for Disease Control and Prevention. Published 2019. https://www.cdc.gov/niosh/topics/aircrew/cosmicionizingradiation.html ↩︎
  11. Pukkala, E., Aspholm, R., Auvinen, A., Eliasch, H., Gundestrup, M., Haldorsen, T., & Tveten, U. (2003). Cancer incidence among 10,211 airline pilots: a Nordic study. Aviation, Space, and Environmental Medicine, 74(7), 699-706. ↩︎
  12. Rafnsson, V., Hrafnkelsson, J., & Tulinius, H. (2000). Incidence of cancer among commercial airline pilots. Occupational and Environmental Medicine, 57(3), 175-179. ↩︎
  13. Hammer, G. P., Blettner, M., & Zeeb, H. (2009). Epidemiological studies of cancer in aircrew. Radiation Protection Dosimetry, 136(4), 232-239. ↩︎
  14. Olumuyiwa A. Occupational Radiation Exposures in Aviation: Air Traffic Safety Systems Considerations. International Journal of Aviation, Aeronautics, and Aerospace. Published online 2020. doi:https://doi.org/10.15394/ijaaa.2020.1476 ↩︎
  15. International Commission on Radiological Protection. (2007). The 2007 recommendations of the International Commission on Radiological Protection. Annals of the ICRP, 37(2-4), 1-332. ↩︎
  16. International Commission on Radiological Protection. (2000). Pregnancy and medical radiation. Annals of the ICRP, 30(1), iii-viii, 1-43. ↩︎
  17. Bartlett, D. T. (2004). Radiation protection aspects of the cosmic radiation exposure of aircraft crew. Radiation Protection Dosimetry, 109(4), 349-355. ↩︎
  18. Wilson, J. W., Miller, J., Konradi, A., & Cucinotta, F. A. (1997). Shielding strategies for human space exploration. NASA Conference Publication, 3360. ↩︎
  19. Copeland, K. (2014). Cosmic radiation and commercial air travel. Radiation Protection Dosimetry, 162(3), 351-357. ↩︎
  20. International Civil Aviation Organization. (2012). Manual of Civil Aviation Medicine. https://www.icao.int/publications/Documents/8984_cons_en.pdf ↩︎
  21. International Atomic Energy Agency: Cosmic radiation exposure of aircrew and space crew. https://www.iaea.org/sites/default/files/20/11/rasa-cosmic.pdf ↩︎
29 Jul 2022
Female dial painter at the US Radium Corporation
Health Effects, Radiation Safety, Radium, Radium Girls, Women in Science Versant Physics 0 comment

What the Radium Girls Taught Us About Radiation Safety

The plight of the Radium Girls in the 1920s would teach us a great deal about the radioactive element radium and its effect on the human body. It brought to light the dangers of working with radium and created a universal understanding of the need for occupational and radiation safety measures.

What is radium?

Radium is a naturally occurring radioactive metal formed when uranium and thorium decay. In the environment, radium is present at low levels in groundwater, soil, rocks, and plants.

There are four radium isotopes, all of which are radioactive and have drastically different half-lives.

As radium decays it releases ionizing radiation in the form of alpha, beta, and gamma radiation. This radiation excites certain fluorescent chemicals in the metal and results in radioluminescence. It can also form other elements, such as radon.

Radium was discovered by Marie Sklodowska Curie and her husband Pierre Curie in 1898, although it would be more than a decade before the pair had isolated a sample large enough to work with.

Early Misinformation About Radium

Soon after the Curies discovered radium, medical professionals began using the radioactive substance as a cancer treatment. Before it could be properly studied, this initial use led to an explosion of interest from the American public and a host of false medical claims that radium was “healthful rather than medicinal.” 

Radium was initially considered a cure-all for a variety of health conditions, including arthritis, tuberculosis, rheumatism, gout, and high blood pressure. It was also thought to improve vitality in the elderly, treat skin conditions like eczema, and cure insomnia.

Because of its seemingly magical healing properties, major corporations began putting radium into their products and heavily promoting its use. Radium-infused toothpaste, pillows, facial creams, and tonic water were popular amongst the public, as were radium spas and clinics.

Radium-based cosmetics were trendy among women. They used these products to combat signs of aging in the form of wrinkles, crows-feet, and even unwanted body or facial hair.

The radium cosmetics gave the women’s skin a warm and cheerful glow and came to be known as “liquid sunshine.” This further cemented the idea that the products contained restorative properties that would revitalize the body and improve its overall health.

Who Were the Radium Girls?

In 1917, the United States entered World War I. There was a sudden demand for instruments and watches that could be read in the dark by U.S. soldiers. Thanks to a high-tech, glow-in-the-dark paint called UnDark, which was made with radium, this became possible.

With most of the country’s men on foreign battlefields, the United States Radium Corporation (USRC) in New Jersey began hiring young women to paint a variety of radium-lit instruments for use in the trenches. These women were called dial painters.

The dial painters would mix the radium-based paint in a crucible at their workstations and used fine, camel hair paint brushes to paint on the tiny, delicate numbers. The brushes quickly lost their shape after a couple of strokes. Management encouraged the women to use their lips to bring the brushes to a fine point for better precision. They were told repeatedly that radium was safe to ingest, and so continued with the “lip, dip, paint” process while they worked.

However, the dial painters didn’t just ingest the radium at their workstations. Due to its many reported health claims, workers would often paint their teeth or nails with radium-based paint before going out for the evening to impress their dates or amaze party guests. The dust from the hand-mixed paint coated the women’s hair and dresses, giving them a ghost-like glow that earned the women the nickname “ghost girls.”

For many dial painters, who were mostly between the ages of 14 and 20, this work was as desirable as it was glamorous. Radium’s luminous, sparkling appearance gave them a unique status. Furthermore, America’s obsession with its magical healing properties combined with the available compensation for the work had entire families flocking to the factory for a position.

Radiation Sickness

By the early 1920s, medical professionals throughout the area were noticing a frightening increase in the young worker’s health complaints. Many of their female patients complained of stiff and cracking joints, painful toothaches, oozing mouth sores, and listlessness, while others had broken out or developed severe anemia.

Dentists began pulling multiple teeth from young dial painters at a time. There were several instances where, during the tooth extraction, pieces of the woman’s decaying jawbone would come out with the tooth. In many cases, the tooth extractions wouldn’t heal.

Other symptoms of radium poisoning in the dial painters, which would later become understood as radiation sickness, were sterility, cataracts, leukopenia, eosinophilia, leukemia, anemia, and menstruation issues.

Mollie Maggia was the first dial painter to fall ill and die. She first developed increasingly painful toothaches that traveled from tooth to tooth. Severe pain in her limbs also prohibited her from walking.

Although dentists didn’t know it at the time, Mollie had developed “radium jaw.” This occupational disease involved necrosis of the upper and lower jawbones, bleeding gums, ulcers, and bone tumors. At the end of her life, Mollie’s dentists merely lifted her jaw from her mouth to remove it. Mollie died in 1922 just days before her 25th birthday.

Another 12 women who worked for the U.S. Radium Corporation as dial painters died the following year, with an additional 50 women falling severely ill.

Radium’s Effect on the Human Body

Radium has similar effects on the human body as calcium and strontium when inhaled or ingested. Once it enters the bloodstream, radium concentrates in the bones in high quantities. It emits alpha particles as it decays, which irradiates the cells on the bone’s surface. Over time radium will settle into the bone where it wreaks havoc on bone marrow and blood cell production.

If radium is ingested with food or water, over 80% of the element is excreted through urine or feces. The other 20% will travel throughout the body, settling in the bones and remaining there throughout the person’s life.

Historical Impact & Worker’s Rights

The surviving dial painters sued the U.S. Radium Corporation, although the road to doing so was not easy. The case was eventually settled out of court in 1928. The women were awarded $15,000 plus $600 per year for future medical expenses because of radium poisoning.

This landmark case was one of the first instances of workers receiving compensation for a disease developed because of their occupation. However, most of the women who received the money died within two years of the settlement.

At the time of the dial painters, there were no radiation safety measures put into place to prevent direct contact with the radioactive substance from occurring. The case of the Radium Girls opened people’s eyes to the dangers of radium and other radioactive substances. They were seen as an example of what could go wrong in an occupational setting and completely changed the course of occupational disease labor laws and regulations.

Their case had a direct impact on scientists’ approach to radiation safety during The Manhattan Project. It was also a leading cause for the creation of the Occupational Safety and Health Administration in 1970.

Radium would continue to be used as a luminescent paint until the early 1960s when its toxicity and danger to human life could no longer be ignored.

29 Jun 2022
Straw hat, bright red glasses and orange bottle of sunscreen for sun protection
Health Effects, Non-ionizing radiation, Radiation Safety Versant Physics 0 comment

Ultraviolet Radiation: How to Protect Yourself

Summer is in full swing. As a result, many Michiganders are spending more time in the great outdoors taking advantage of the warmth and sunshine.

However, the more time a person spends outdoors the more their body is exposed to Ultraviolet (UV) radiation. UV radiation, a form of non-ionizing radiation, is invisible to the human eye and cannot be felt. It can cause severe skin damage and lead to the development of skin cancer.

Here at Versant Physics, our focus is primarily on radiation safety in relation to ionizing radiation sources used in medical procedures and cancer treatments. However, it is just as important that you protect yourself from naturally occurring UV radiation and understand the potential health risks.  

In honor of UV Safety Month, we’ll explain what UV radiation is, the most common types of skin cancer and other health risks associated with UV radiation, and important protective measures you should take when out in the sun.

What is UV Radiation?

Ultraviolet (UV) radiation is a non-ionizing form of electromagnetic radiation that has both natural and artificial sources. Most of the UV radiation from sunlight gets absorbed by Earth’s atmosphere. What doesn’t get absorbed makes its way to the surface and interacts with our skin. UV rays are present even on cloudy days and also reflect off surfaces like snow, sand, and water.

There are three types of UV radiation rays:

  • Ultraviolet A (UVA)
  • Ultraviolet B (UVB)
  • Ultraviolet C (UVC)

UVA rays have the lowest wavelength of the different types of UV radiation; however, they make up over 95% of the rays that reach the Earth’s surface. These rays penetrate through the layers of skin, damaging the elastin and collagen. This results in tanned skin and skin aging, often in the form of wrinkles or age spots.  

UVB radiation is made up of high-energy UV rays that interact with the top layers of skin. UVB rays interact with skin cells and damage them, causing DNA mutations that show up later in the form of sunburns, skin cancer, or cataracts.

UVC rays are the strongest of the UV rays. Almost all of this UV radiation is absorbed by Earth’s atmosphere.

Unprotected, prolonged exposure to UV radiation from the sun is connected to a variety of health risks, including:

  • Premature aging
  • Skin damage
  • Cataracts
  • Immune system suppression
  • Skin cancer

UV Radiation Exposure and Skin Cancer

UV radiation causes melanoma and nonmelanoma skin cancers called basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).

Melanoma

Melanoma is a type of skin cancer that forms in the melanocytes. These cells are located beneath the squamous and basal cells and are what produce melanin, the pigment that gives hair, eyes, and skin its color.   

Melanoma is less common than other types of skin cancer, however, it is more dangerous. This is because melanoma it more likely to spread to other parts of the body if left untreated. Melanoma often presents as a highly pigmented black or brown tumor on the torso, chest, neck, or face.

The “ABCDE” rule can help patients identify if their existing mole or new skin growth is a warning sign of melanoma:

  • Asymmetry. The two halves of the mole do not match.
  • Border. Normal moles have a clean, even border. Melanoma will present with uneven or ragged edges.
  • Color. Melanoma tumors can be black, brown, pink, red, or white.
  • Diameter. Melanoma is usually a growth larger than a pencil eraser, or ¼ inch in diameter.
  • Evolving. The existing mole or new growth is changing in size, shape, texture, or color. It also may begin to itch, bleed, or ooze.

People with light skin, eyes, and hair are considered more at risk of developing melanoma than people with darker skin. Age, gender, occupation, family history, and lifestyle choices also play a role in the level of risk associated with developing melanoma.

Nonmelanoma Skin Cancers

Basal cell carcinoma is the most common type of skin cancer that begins in the basal cells. It shows up on areas of the body that are frequently exposed to UV radiation from sunlight, such as the head, face, or neck. It normally presents in the form of a skin lesion or shiny, skin-colored bump.

Squamous cell carcinoma is less common but just as serious. It presents as open sores, thick or wart-like skin, raised growths, or scaly red patches that may itch or bleed. SCC can show up anywhere on the body, although they are most often found on areas of the body that are frequently exposed to the sun.

Both BCC and SCC grow relatively slowly and are highly treatable. The sooner a new or strange-looking growth is looked at by a dermatologist and diagnosed, the better the odds are of treating the skin cancer. However, if left untreated, these skin cancers can spread to other areas of the body and become more dangerous.

UV Radiation Protection

There are many simple protective measures the average person can implement to help lessen the risks associated with UV radiation and its negative side effects.

  • Seek shade
  • Avoid prolonged sun exposure from 10 a.m. to 4 p.m. when the sun is strongest
  • Wear long sleeves or pants
  • Wear a hat and/or UV-blocking sunglasses
  • Wear a broad-spectrum sunscreen

Sunscreen is a major protector against UV radiation. Broad-spectrum sunscreens protect the skin from both UVA and UVB rays. Wearing a minimum of SPF 15 can reduce the risk of developing melanoma by 50% and SCC by 40%. Wearing a protective sunscreen daily can also help prevent premature skin aging.

Are There Any Health Benefits to UV Radiation?

Exposure to natural UV radiation from the sun has an important health benefit for the human body. UV radiation helps our bodies produce vitamin D, which is an essential vitamin that absorbs calcium in our stomachs, reduces inflammation, and is needed for healthy bone growth. Some food products contain vitamin D however most people get a portion of their vitamin D needs through sunlight.

There are no hard and fast numbers detailing how much sunlight exposure is needed for optimal vitamin D synthesis. The World Health Organization recommends no more than 15 minutes of direct sun exposure at least 3 times a week.

However, this does not negate the need for sun protection measures such as sunscreen and wearing protective clothing.

The Takeaway

It is important to protect yourself from UV radiation any time of the year. Although this non-ionizing source of radiation can help our bodies create vitamin D, it also interacts with our skin in a way that can lead to skin cancer. To prevent this, you should wear and apply sunscreen as directed, invest in UV-blocking glasses and clothes, and try to stay out of the sun as much as possible.

Learn more about UV and sun safety here.

20 Apr 2022
nurse guiding patient entering mri scanner
ALARA, Health Effects, Radiation Safety, Radiation Shielding, Regulatory Versant Physics 0 comment

The Basics of Radiation Shielding in Medicine

Basic radiation protection guidelines can be summed up in three simple concepts: time, distance, and shielding. While both limiting the time spent and increasing the proximity to an ionizing radiation source is something that lies within the power of the individual, shielding and X-ray room design require careful planning and execution by the facility or Radiation Safety Officer.

What is radiation shielding?

Radiation shielding is simply a barrier placed between a source of radiation and the area or person that needs to be protected. The purpose of radiation shielding is to limit, control, or modify the radiation exposure rate at a set point.

Shielding is based on attenuation or the gradual reduction in the intensity of energy through a specific medium. X-ray radiation that passes through certain materials decrease and are absorbed, thereby reducing the exposure to the other side of the barrier.

Without shielding, the public, radiation workers (including dentists and veterinarians), and even nearby office workers could be exposed to levels of radiation outside regulated exposure limits, which can potentially lead to negative health effects. Although it is impossible to completely avoid exposure to radiation, shielding is a critical consideration in any medical facility that greatly reduces unnecessary exposure.

Shielding Materials

There are several different materials that provide protection from penetrating radiation. Concrete, water, special plastic shields, air stops, and lead are all barriers that stop different types of rays and particles, reducing the overall dose a person receives.

In medical environments, the most common shielding materials used include lead, lead-free shielding, and lead composites.

Lead

Lead is one of the most used and most effective shielding materials. It is a highly dense material with a high atomic number and a high number of electrons which make it ideal for shielding in most medical radiation environments. This is because the type and energy of radiation in a medical environment that passes through lead are absorbed or scattered by the electrons present in the material.

Vet team wearing shielding garments during exam

Lead is also cheap and easy to process. It can be mixed with other materials like glass, or binders like vinyl, which allows it to be used as construction materials in X-ray rooms or worn as shielding garments.

Lead-Free Shielding

Technological advances have allowed for the creation of non-toxic, lead-free shielding materials as well. Other attenuating materials such as antimony (Sb), tungsten (W), and tin (Sn) are used in place of lead and combined with additives and binders to create wearable protective garments or materials. They offer equal protection from scatter radiation.

Lead-free shielding has several benefits, including being both recyclable and non-toxic. Lead-free shielding materials can also be lighter which makes them easier for personnel to wear during longer procedures.  

Lead Composite

Lead composite shielding is a long-lasting mixture of lead and lighter materials that attenuate radiation just as successfully as traditional lead shielding barriers.

Because of lead’s weight, it can be cumbersome to use and wear for long periods of time, limiting the efficacy of a radiation worker. Lead composites solve this problem. They are made with blends of tin, vinyl, and rubber and create a shielding barrier that can be up to 25% lighter than traditional shielding without sacrificing their ability to block penetrating radiation.

Shielding and Scatter Radiation

In some diagnostic X-ray procedures, medical personnel such as operators, radiologists, and technologists are required to remain in the room with the patient. This proximity frequently exposes them to something called scatter radiation or radiation that bounces off a patient’s body during a procedure.

To limit this exposure, some medical personnel are required to wear frontal or full wrap-around style lead aprons, thyroid shields, and lead glasses/gloves. These protective garments can attenuate roughly 93% of photons at typically scattered energies.

Lead apron and thyroid collar on hangar

Shielding Products and Design

There are several different ways radiation shielding can be applied or designed to protect healthcare workers.

Room Shielding

Shielding may be required in the floor, ceiling, doors, or any wall of any X-ray or radioactive material use room.  Shielding is used to protect workers, patients, or the public that may be in the adjacent areas/rooms.

During a room’s construction, special shielding materials are installed where their need has been determined. These materials can include lead-lined windows and doors, lead-lined drywall or plywood, lead sheets for floors and ceilings, pipe shielding, and more.

X-ray room shielding requirements vary from state to state. It is important to consult with a qualified expert familiar with these regulations as well as work with an architect experienced in constructing X-ray suites before building a new room.

Leaded Glass and Curtains

In some cases, it isn’t possible for a facility to build shielding into the physical structure of a building.

Leaded glass barriers are a barrier used by techs and doctors which allow them to safely view a patient during an imaging procedure. This type of glass is ideal for radiation-producing equipment in the 80-300 kV range thanks to its high lead content.

Lead curtains are also used to shield radiation workers, particularly in large animal hospitals or operating rooms. These curtains are leaded rubber or vinyl sheets that are ideal for protection against low-level or secondary radiation. They make for room-saving partitions that can be open or closed as needed and typically offer protection from 0.5mm to 2.00mm lead equivalency.

Mobile Shielding Barriers

In some cases, additional barriers are needed to protect doctors and techs during radiology, nuclear medicine, cath lab, or diagnostic imaging procedure. These barriers are lead-lined partitions on wheels, often with a protected window to allow for patient observation.

Mobile radiation barriers come in a variety of shapes, sizes, and lead equivalencies. They are ideal for maintaining flexibility and ease of movement in a procedure room while successfully minimizing the scattered radiation dose to workers in the room.

Versant Physics Shielding Services

Understanding the detailed shielding requirements for your state or facility can be a time-consuming challenge. If executed incorrectly, there can be serious consequences to the health and safety of radiation workers, patients, and building staff as well as potential regulatory compliance fines.

That’s why it is important to have a radiation safety consultant like Versant Physics on your side. Whether you’re constructing a new X-ray room, remodeling or repairing an existing shielding setup, or looking to upgrade your current shielding equipment, our team of expert health and medical physicists can assist.

We provide radiation shielding calculations, evaluation, and design for facilities of all kinds, including hospitals, clinics, dentist offices, chiropractor offices, and veterinary clinics. Our range of expertise includes:

  • Radiography
  • Fluoroscopy
  • Computed Tomography (CT)
  • Nuclear Medicine/PET
  • Mammography
  • Dental/Veterinary X-ray

Not sure what materials or type of shielding is right for your facility? Contact our regulatory experts for a free 30-minute consultation.

05 Jan 2022
Consumer Products, Health Effects, Non-ionizing radiation, NORM Versant Physics 0 comment

Top 3 Consumer Products that Contain Radioactive Materials

Radioactive materials are present in our natural environment and in man-made products we use every day. Such consumer products are defined as “a device or manufactured item into which radionuclides have deliberately been incorporated or produced by activation, or which generates ionizing radiation, and which can be sold or made available to members of the public without special surveillance or regulatory control after sale.”

Many devices that use WiFi or Bluetooth technology or connect to cell phone towers emit radio waves, also known as electromagnetic radiation (EMF).

This may concern consumers who are worried about the negative health effects associated with “radioactive materials” and “radiation.” However, in most cases, these materials we interact with are safe and pose no danger to our health.

Below we guide you through three common consumer products the average person uses or engages with regularly, discuss how the radioactive materials they contain work, and determine the health risk they pose to you and your family.

Cell Phones

Cell phones have become an integral part of daily modern life. We depend on them for communication, connection, and as a source of entertainment. However, their permanent presence and increased usage have raised concerns over the years that cell phones can cause negative health effects to humans, including brain tumors and hearing loss.

pile of cell phones

Do cell phones emit radiation?

Cell phones are not consumer products that contain radioactive materials. However, they communicate by transmitting EMF, a type of non-ionizing radiation at the low-energy end of the electromagnetic spectrum in the 100kHz to 300GHz frequency range.

RFs are widely used in communication technologies such as cell phones, Wi-Fi, radio, and TV. They are also found in MRI equipment, from natural sources like outer space, and in the microwave oven sitting on your kitchen counter.

Are there health risks?

Decades of research on RF radiation have concluded that exposure to this frequency has minimal health effects. Due to their frequency, RF radiation can be absorbed by the human body. In large amounts, this can produce heat, which has the potential to cause burns or tissue damage.

Numerous short-term studies have taken place on the link between cancer rates and cell phone usage. Small, individual studies have found slight associations between cell phones and cancer of the salivary glands, as well as a possible increase in the risk of gliomas. In 2011, the International Agency for Research on Cancer evaluated these studies and concluded that there is limited or inadequate evidence of carcinogenicity. Longer-term studies may need to be conducted to accurately determine the level of cancer risk associated with cell phones.

Those uncomfortable with incurring any level of risk can take steps to limit their cell phone usage by purchasing a hands-free headset or utilizing the speakerphone function when making calls.

Smoke Detectors

Most smoke detectors in the United States are ionization smoke alarms, which contain a small amount of the man-made radioactive element called americium-241.

how smoke alarms work

Why is radioactive material present?

Ionization smoke alarms are more responsive to flaming fires. The radioactive material present in the smoke alarm rests between two electrically charged plates which ionize the air and causes a current between them. Smoke entering the chamber disrupts the flow of ions, reducing the current and thereby activating the alarm.

Are there health risks?

Smoke detectors pose little to no health risk to human beings. The amount of americium-241 present is minimal, wrapped in gold foil, and shielded by the plastic case and stainless steel. These protective measures prevent easy tampering rather than limiting radiation exposure. However, there is no risk of significant exposure as long as these sources are contained in the detector housing.

Granite Countertops

Like many natural materials found on Earth, granite, a type of durable stone used in construction and home décor, contains small amounts of radioactivity.

Granite is a consumer product that contains a small amount of natural radioactive material.

Does granite emit radiation?

Trace elements of uranium, thorium, and radium can show up in slabs of granite. When these elements are present, they decay into radon. According to the EPA, radon released from granite materials can be released over the lifetime of its use but is typically diluted by ventilation.

Are there health risks?

It is extremely unlikely that the radiation emitted from granite countertops in your home would increase radiation doses above normal background levels. The radon released from granite is a significantly lower concern when compared with radon which originates in the soil and can build up inside the home. This type of radon is the second leading cause of lung cancer in the United States and should be tested for on a regular basis.

Conclusion: Are Consumer Products That Contain Radioactive Materials or Emit Radition Unsafe?

It is true that some common consumer products contain trace amounts of naturally occurring radioactive materials or emit non-ionizing radiation. However, this does not mean they are dangerous or pose a health risk to humans. In fact, in products like ionizing smoke detectors, the presence of radioactive material is crucial for keeping humans safe.

Further Reading:

Radiation Safety for Consumer Products, Specific Safety Guide No. SSG-36

15 Jun 2021
Background Radiation, Health Effects Versant Physics 0 comment

The Truth About Background Radiation

Background radiation is all around us, and always has been. That idea can be a frightening concept at face value, but the truth is background radiation is natural, normal, and expected.

Most natural background sources of radiation fall into one of three categories:

Cosmic Radiation

Think of this as steady waves of external radiation being sent from the sun and stars in space to Earth. This type of radiation occurs naturally and introduces extremely low levels of radiation to the average person. The amount (or dose) of cosmic radiation one receives can depend on weather and atmospheric conditions, the Earth’s magnetic field, and differences in elevation. For example, people who live at higher altitudes like Denver, Colorado are exposed to slightly more cosmic radiation than people who live in lower altitudes, such as New Orleans, Louisiana or Miami, Florida. Furthermore, the farther north or south one is from the equator results in a higher dose of cosmic radiation due to the way the Earth’s magnetic field deflects cosmic radiation toward the North and South poles.

silver airplane flying above orange clouds

Air travel can also expose individuals to low levels of cosmic radiation. The received dose is similarly dependent on altitude, latitude, and the duration of the flight. A coast-to-coast flight in the United States would expose an individual to approximately 3.5 mrem. For comparison, a typical medical procedure involving radiation, such as a chest X-ray, exposes an individual to 10 mrem, and the average American receives a total radiation dose of 540 mrem each year.

In general, a person’s average dose from cosmic radiation in the United States is small, making up only 6% of their total annual dose.

Terrestrial Radiation

Terrestrial radiation is the portion of natural background radiation that is emitted by naturally occurring radioactive materials on earth, and it is responsible for approximately 3% of the average person’s annual received dose. The physical earth, including soil and sedimentary and igneous rock, contains common elements like uranium, thorium, and radium. These naturally occurring radioactive materials, which have existed as part of the earth’s crust since the earth was formed, are released into the water, vegetation, and the atmosphere as they breakdown at different rates. People are largely exposed to the resulting emitted radiation through their skin.

Radon:

diagram of radon gas infiltrating a house

Perhaps the most significant form of terrestrial radiation is that which is inhaled. When the naturally occurring radioactive element uranium (found in the earth’s crust, underwater caves, and seawater) decays it can change into a scentless, invisible gas called radon. All the air we breathe contains trace amounts of radon, and it is responsible for the largest portion of background radiation dose that the average American receives in a year. Outdoors, this radioactive gas disperses rapidly and does not pose any health risk to human beings. A build-up of radon gas indoors, however, can potentially increase the risk of lung cancer over time, which is why it is important to test homes and workplaces for radon on a regular basis. Smoking, especially near or inside the home, can amplify the risk of cancer when coupled with radon exposure.

The average person can expect to receive 42% of their annual radiation dose from radon.

Internal Radiation

Background radiation can also be received through ingestion. Some common foods contain small amounts of radioactive elements that do not pose a radiation risk to the person ingesting them. The most common example is the banana. This delicious, nutritious fruit contains naturally high levels of potassium which helps muscles contract, keeps your heartbeat regular, and offsets the harmful effects of sodium on blood pressure. A tiny portion of potassium is also naturally radioactive. A single banana emits 0.01 mrem, which is received internally by the person eating it. According to the EPA, a person would have to eat 100 bananas to receive the same amount of radiation exposure naturally received each day from the environment. (It should be noted that this naturally occurring radiation is not the same thing as food irradiation, which is a process used by humans to kill bacteria, molds, and pests to prevent foodborne illnesses and spoilage.) Overall, the levels of natural radionuclides found in our food and water are low and considered safe for human consumption by regulatory bodies.

Most surprisingly for some is the fact that other humans are also a source of exposure to one another. From birth, people have internal radiation in the form of radioactive potassium-40, lead-210, and carbon-14. These elements reside in our blood and bones. As previously noted, humans also ingest traces of naturally occurring radioactive material found in our food and water. When our bodies metabolize the non-radioactive and radioactive forms of potassium and other elements, they then contain small amounts of radiation which can act as exposures to others.

Man-Made Radiation Exposure

A more familiar source of radiation exposure to many is man-made radiation, such as procedures using X-Rays and radiation therapy to treat cancer. According to the Health Physics Society, approximately 42% of annual dose comes from man-made radiation. This percentage includes medical procedures, household products like smoke detectors, and small quantities of normal discharges from nuclear and coal power plants.

Learn more about the health effects of man-made ionizing radiation in our blog post here.

Conclusion

Natural background radiation has always been a part of life on earth, and it always will be. It is important to understand that this is not something to be feared. Low levels of ionizing radiation from naturally occurring sources such as space, the ground beneath our feet, and even some of the food we eat are not dangerous and do not pose a direct health risk to ourselves or our loved ones.

For more information, visit the Health Physics Society webpage, epa.gov, or the International Atomic Energy Agency.

Note: Visit our regulatory page to learn how Versant Physics’ board-certified Internal Dose Specialists, Medical Physicists, and Health Physicists, can assist with your radiation safety program needs.

Additional Sources:

https://www.nrc.gov/about-nrc/radiation/around-us/sources/nat-bg-sources.html

https://www.cdc.gov/nceh/radiation/air_travel.html

NCRP Report 160

NCRP Report 184

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