Body Scanners: Are They Safe To Use?

Airport body scanners are used to ensure passengers' safety by detecting any prohibited items, such as weapons or explosives, that they might be carrying. There are two types of full-body scanners: one uses millimetre-wave technology, and the other uses backscatter x-ray technology. The former is currently used in Canada and emits non-ionizing radiation, which, according to Health Canada, is safe. The latter was previously used in the US and emits ionizing radiation, which can be harmful to human health in high doses. However, experts are divided on whether backscatter x-ray scanners expose travellers to dangerous amounts of radiation. While some argue that the dose is too low to cause harm, others claim that there is a small cancer risk associated with this technology.

Do airport body scanners expose travellers to dangerous levels of radiation?

Airport body scanners use two different technologies to ensure passengers are not carrying prohibited items: millimeter-wave technology and X-ray technology. The former is currently used in Canadian airports, while the latter is not.

Millimeter-wave scanners use electromagnetic waves to generate high-resolution images of unusual objects that might be concealed by a passenger's clothing. These anomalies are then superimposed on the image of a mannequin to protect privacy. The radiation emitted by these scanners is considered non-ionizing and high-frequency—the kind that heats up molecules. According to the International Commission on Non-Ionizing Radiation Protection (ICNIRP), millimeter-wave scanners emit only a tenth of the radiation limit for the general public.

X-ray scanners, on the other hand, emit low levels of X-rays, a form of electromagnetic ionizing radiation. These scanners were introduced in 2009 and were deemed controversial due to privacy and health concerns. They produced revealing full-body images of passengers, and some experts argued that they exposed travellers to potentially dangerous amounts of radiation. According to John Sedat, a professor of biophysics at the University of California, San Francisco, the exposure from these machines was about 10% of what one would get during a chest X-ray. David Brenner, a professor of radiation biophysics at Columbia University Medical Center, agreed that there were likely some small cancer risks associated with the X-ray machines. As a result of these concerns, European authorities banned the use of X-ray scanners in 2011, and the Transportation Security Administration (TSA) followed suit in 2013.

In conclusion, while X-ray scanners may have exposed travellers to low levels of radiation, millimeter-wave scanners, which are now widely used, are considered safe and non-invasive. According to Andrew Maidment, an associate professor of radiology at the University of Pennsylvania Health System, millimeter-wave scanners are "not a concern" in terms of health risks. The radiation emitted by these scanners is believed to cause harm only when powerful enough to cause molecular changes, and the dose is too low to do so. Therefore, while X-ray scanners may have posed a slight risk, the currently used millimeter-wave scanners do not expose travellers to dangerous levels of radiation.

What are the differences between backscatter x-ray scanners and millimetre wave body scanners?

Backscatter X-ray scanners and millimetre wave body scanners are both used to detect weapons, explosives, or other threats concealed on passengers. However, there are several differences between the two technologies.

Firstly, backscatter X-ray scanners use low-energy X-rays to bounce off a passenger's body and create a 2D image, while millimetre wave scanners use ultrahigh-frequency millimetre wave radiation (a form of electromagnetic radiation) to generate 3D images. The waves emitted by millimetre wave scanners are much larger than those of backscatter scanners, which means they have less impact on small structures in the human body, such as proteins and nucleic acids.

In terms of construction, backscatter machines consist of two rectangular radiation sources that face each other, with a gap in between for the person being scanned to stand in. On the other hand, millimetre wave scanners resemble oversized, hexagonal telephone booths, with two open panels for entrance and exit, and four transparent panels.

Another difference is the time required for scanning. Backscatter machines take around 30 seconds to complete a scan, while millimetre wave scanners take only about 10 seconds.

One of the most significant distinctions between the two technologies is the type of radiation they use. Backscatter X-ray scanners use ionizing radiation, which has enough energy to remove electrons from atoms and can alter biological molecules. In contrast, millimetre wave scanners use non-ionizing radiation, which does not carry the same risks as it cannot break chemical bonds.

While backscatter machines have raised concerns about potential health risks due to their use of ionizing radiation, millimetre wave scanners are generally considered safer. However, millimetre wave scanners have been found to have higher false-positive rates, as they can be fooled by folds in clothing, buttons, and even sweat.

In terms of privacy, both types of scanners can reveal intimate details about passengers. However, backscatter machines have been particularly controversial as they produce graphic images. To address this, software has been implemented to blur sensitive areas or replace them with generic outlines. Millimetre wave scanners typically use automated target recognition software, which superimposes anomalies onto a mannequin-like outline, protecting privacy.

Due to the health and privacy concerns associated with backscatter X-ray scanners, they have been banned in the European Union and phased out by the TSA in the United States, with millimetre wave scanners being favoured as a safer alternative.

Are there any health risks associated with millimetre wave body scanners?

Millimetre wave body scanners are a common technology used for full-body imaging and detecting objects concealed underneath clothing. They use electromagnetic radiation to scan the body and create a three-dimensional image, which is then displayed on a monitor for analysis. This technology is often used at airport security checkpoints, government buildings, and commercial buildings. While millimetre wave body scanners have raised concerns about potential health risks, there is ongoing debate about the level of risk they pose.

Non-ionizing Radiation

Millimetre wave scanners emit non-ionizing radiation, which has insufficient energy to remove electrons from atoms. In other words, it cannot alter the structure of biological molecules such as proteins and nucleic acids. This type of radiation is present in everyday life and is emitted by cell phones, microwave ovens, and even the sun. The amount of radiation produced by millimetre wave scanners is far less than that of a cell phone and is within safe limits set by international organisations.

Health Effects

The primary health concern with millimetre wave radiation is its potential thermal impact on the body. The localized heating caused by the radiation can lead to chemical changes in the epidermal and dermal layers of the skin. However, the energy density required to produce thermal injury is much higher than what is typically delivered by these scanners. Additionally, a 2009 study found that terahertz range radiation, which includes millimetre waves, can interfere with DNA function by affecting its breathing dynamics.

Safety Precautions

To address privacy and health concerns, several precautions have been implemented. For example, the U.S. Congress prohibited the display of detailed images, requiring scanners to show a generic body outline instead. Automated target recognition (ATR) software further enhances privacy by masking specific body parts and creating generic outlines for all individuals. These measures ensure that the detailed images captured by the machines are not stored or viewed by unauthorised individuals.

While millimetre wave body scanners have been the subject of health concerns, the current consensus is that they pose little to no risk to individuals. The radiation emitted by these scanners is non-ionizing and within safe limits. Additionally, the short scan duration and low penetration depth of the millimetre waves further reduce any potential health risks. However, ongoing research is being conducted to thoroughly understand the biological effects of this technology.

How do airport body scanners work?

Airport body scanners use a technology called Advanced Imaging Technology (AIT) for full-body scans at airport checkpoints. One of the two types of AIT scanners is the millimetre-wave scanner, which uses electromagnetic waves to generate images of unusual objects that might be concealed by a passenger's clothing. The millimetre-wave scanner projects low-level millimetre-wave, radio-frequency (RF) energy above and around the passenger's body. The RF energy is reflected back from the body and from objects concealed on the body to produce a generic image indicating areas requiring additional search.

The other type of AIT scanner is the backscatter X-ray scanner, which uses low doses of radiation to generate a computerized image of the entire body. These scanners were criticized by several groups, including physicians and experts in the field of radiological research, due to their use of ionizing radiation—the kind that can break apart molecules and knock electrons away from atoms, creating free radicals that can damage DNA and increase the risk of cancer.

In response to these concerns, the Transportation Security Administration (TSA) in the United States began phasing out the use of backscatter X-ray scanners in 2012 and shifted to millimetre-wave scanners, which are considered safer. Today, millimetre-wave scanners are the standard full-body scanners used in U.S. airports. These scanners emit far less energy than a cell phone and are important for airport security because they can show hidden threats such as guns and knives.

Are airport body scanners effective?

The effectiveness of airport body scanners is a highly debated topic. While some experts claim that body scanners are effective at spotting weapons, others argue that they are expensive and inaccurate.

Body scanners have been proven to detect metallic and non-metallic items, including weapons made from ceramics. They use advanced imaging technology (AIT) and are said to be highly confident in their detection capability. The technology is also said to be a proven alternative to full-body pat-downs.

However, critics argue that body scanners are not infallible and can malfunction, resulting in false alarms. Additionally, the high cost of the machines, which are significantly more expensive than metal detectors, has been questioned.

One of the two primary types of body scanners, the backscatter X-ray scanner, was banned in Europe and phased out in the US due to health and privacy concerns. The other type, the millimeter-wave scanner, is still in use and is considered safe by health authorities. However, there have been concerns about the potential health risks associated with this technology, and some countries, such as France and Germany, have banned them.

In conclusion, while airport body scanners have been shown to be effective in detecting certain items, there are also limitations and controversies surrounding their use. The debate about their effectiveness and safety is ongoing, and further research and long-term studies are needed to fully understand their impact.

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