Airport Body Scanners: Cancer Risk Or Safe Passage?

Airport body scanners have been a topic of concern for travellers, with many worrying about their radiation exposure. While the issue of privacy has been a major concern, some experts have also debated whether or not these scanners expose travellers to potentially harmful amounts of radiation, and if so, whether this could increase the risk of cancer.

There are two types of full-body scanners used in airports: millimeter-wave scanners and backscatter X-ray scanners. The former uses radio waves to search for hidden weapons or devices, while the latter uses X-rays to create a detailed image of the body, which can reveal items hidden under clothing.

While the use of backscatter X-ray scanners has raised concerns about potential cancer risks, the consensus among experts is that the amount of radiation exposure from these scanners is extremely low and does not pose a significant risk to human health.

The two types of body scanners: millimeter wave and backscatter X-ray

The two types of body scanners used in airports are millimeter wave scanners and backscatter X-ray scanners.

Millimeter wave scanners use electromagnetic radiation to detect objects concealed underneath a person's clothing. Millimeter wave scanners come in two varieties: active and passive. Active scanners direct millimeter wave energy at the subject and interpret the reflected energy, while passive systems create images using only ambient radiation and radiation emitted from the human body or objects. Millimeter wave scanners are considered non-ionizing and are, therefore, incapable of causing cancers by radiolytic DNA bond cleavage.

Backscatter X-ray scanners are an advanced X-ray imaging technology that detects the radiation that reflects from the target. This technology is based on the Compton scattering effect of X-rays, a form of ionizing radiation. Backscatter X-ray scanners detect the radiation that reflects off the person being imaged and form an image.

Both types of scanners can produce detailed and revealing images of those screened, including genitalia, breasts, buttocks, and prosthetics. To address privacy concerns, the U.S. Congress prohibited the display of detailed images and required that metal and other objects be displayed on a generic body outline. Automated Target Recognition (ATR) software has also been implemented to further protect the privacy of those being scanned.

In terms of safety, millimeter wave scanners are considered safer than backscatter X-ray scanners as they do not use ionizing radiation. Backscatter X-ray scanners have raised concerns about possible mutagenic potential and their ability to cause cancer. However, the radiation doses emitted by these scanners are exceedingly low, and the risk of causing harm is considered trivial. The Transportation Security Administration (TSA) in the United States has taken steps to ensure the privacy and safety of passengers when using these scanners.

The amount of radiation emitted by each type of scanner

There are two types of full-body scanners: millimeter wave scanners and backscatter X-ray scanners. Millimeter wave scanners emit extremely low-energy waves, similar to those emitted by cell phones, and do not generate ionizing radiation. The dosage of radiation received from this type of scanner is usually between 0.05 and 0.1 μSv. On the other hand, the more common backscatter X-ray scanners, which are used in the US, utilize very low-dose X-rays, similar to those used in medical imaging. The dosage of radiation received from backscatter X-ray scanners is 0.03-0.1 μSv per scan, which is equivalent to 3-9 minutes of radiation received from naturally occurring sources.

To put this into context, an individual would have to undergo more than 50 airport scans to equal the exposure of a single dental X-ray, and 200,000 scans to equal the exposure of a single abdominal and pelvic CT scan. Thus, the doses of radiation emitted by airport scanners are relatively small and are considered safe by several health authorities.

However, critics argue that the radiation emitted by some full-body scanners is as much as 20 times stronger than officially reported and poses a risk to children and at-risk populations. There are also concerns about the potential for defects in the machines or software errors to focus an intense dose of radiation on one spot of the body.

In response to these concerns, the US Transportation Security Administration (TSA) has implemented several measures, including independent safety assessments of the scanners and the use of Automated Target Recognition software, which replaces the image of a nude body with a cartoon-like representation.

The potential health risks of each type of scanner

There are two types of full-body scanners used in airports: millimeter wave scanners and backscatter X-ray scanners.

Millimeter wave scanners use non-ionizing electromagnetic radiation in the form of extremely high-frequency radio waves to create an image of the body. The health risks posed by these machines are still being studied, and the evidence is mixed. While millimeter wave scanners do not generate ionizing radiation, no long-term studies have been conducted to assess their safety. However, the energy waves emitted by these scanners are extremely low, delivering only a small fraction of the energy of a cell phone.

Backscatter X-ray scanners, on the other hand, utilize very low-dose X-rays, similar to those used in medical imaging. Unlike millimeter wave scanners, backscatter X-ray scanners use ionizing radiation, which has the potential to cause damage depending on the dose. At low doses, radiation causes biological damage that cells can repair rapidly. Moderate doses can permanently change cells, leading to cancer or abnormalities like birth defects. Higher doses, such as those used in cancer treatment, can result in serious health problems as cells cannot be replaced quickly enough.

The doses of ionizing radiation emitted by backscatter X-ray scanners are considered exceedingly low, and the potential harm is trivial. However, with 750 million passenger enplanements annually, even a small risk per person could potentially lead to a significant number of cancers. The exposure from these scans is equivalent to 3-9 minutes of radiation from natural sources or 1-3 minutes of radiation exposure during a flight.

To put this in context, an individual would need to undergo 50 airport scans to equal the exposure of a single dental X-ray, 1,000 scans for a chest X-ray, 4,000 scans for a mammogram, and 200,000 scans for an abdominal and pelvic CT scan. Thus, the doses from airport scans are extremely low compared to medical procedures.

While the risks associated with backscatter X-ray scanners are minimal, the controversy surrounding their use in airports has led to their ban in multiple countries.

The use of body scanners in other countries

Europe

The European Union (EU) has prohibited the use of X-ray body scanners in airports across its 27 member countries. This decision was made by the European Commission, which enforces common policies across the EU. The Commission adopted the rule "in order not to risk jeopardizing citizens' health and safety." Instead, European countries are allowed to use alternative body scanners that rely on radio frequency waves, known as millimeter-wave scanners, which have not been linked to cancer.

The United Kingdom, for example, uses X-ray scanners but only for secondary screening when a passenger triggers the metal detector or raises suspicion. Under the new European Commission policy, the UK will be allowed to complete a trial of X-ray scanners but will not be able to deploy them permanently.

Australia

In Australia, the government has implemented a no-opt-out policy for body scanners at eight of its international airports: Adelaide, Brisbane, Cairns, Darwin, Gold Coast, Melbourne, Perth, and Sydney. Only passengers on international flights are currently affected. Domestic and international passengers departing from the Newcastle Port Stephens airport have also been subject to body scanning since October 2019.

Canada

In Canada, 24 airports currently use body scanners, specifically employing millimeter-wave technology. Transport Canada notes that passengers selected for a secondary search can choose between a full-body scan or a physical search.

Asia-Pacific

The Asia-Pacific region is projected to experience high market growth in the body scanner market during the 2020-2025 forecast period, particularly due to significant airport investments and improvements in prison systems. China and India are heavily investing in greenfield airport construction. In January 2020, the Indian government decided to equip 84 airports with full-body scanners, contributing to the region's high growth rate.

Netherlands

Schiphol Airport in the Netherlands was the first airport in the world to implement SafeView's millimeter-wave body scanner on a large scale. On May 15, 2007, two of the 17 purchased security scans were installed.

Italy

The Italian government had initially planned to install full-body scanners at all airports and train stations but later announced in September 2010 that it would remove the scanners from airports, deeming them "slow and ineffective."

To summarize, the use of body scanners varies across countries and regions, with some adopting different types of scanners, implementing opt-out policies, or even banning certain types of scanners due to health and safety concerns.

The privacy concerns of body scanners

The use of body scanners in airports has raised several privacy concerns. The scanners generate highly detailed and revealing images of those screened, displaying intimate body parts, prosthetics, catheters, and piercings. This has led to protests and legal challenges by various groups, including religious organisations, the American Civil Liberties Union, and the Electronic Privacy and Information Center (EPIC).

To address these concerns, the Transportation Security Administration (TSA) has implemented several measures. They have introduced technology that blurs faces, installed software to make the images less suggestive, and used software that displays a chalk outline of the scanned individual. Additionally, the TSA has separated the security personnel viewing the images from direct interaction with passengers. They have also asserted that the scanners deployed in airports cannot store or export images, although there have been reports of improper saving and dissemination of scanner images, raising doubts about the effectiveness of these safeguards.

The privacy issues with body scanners are not limited to the revealing nature of the images. The potential for unauthorised storage and dissemination of scanned images is a significant concern. There have been reports of tens of thousands of scanner images being improperly saved and distributed, which has led to worries about whether the TSA's assurances regarding image storage are accurate. Additionally, there is a question of whether employees can manipulate the scanner settings to remove the privacy safeguards put in place.

The EPIC, a public interest research centre, has filed a lawsuit against the Department of Homeland Security, alleging that the body scans violate the Fourth Amendment, the Privacy Act, the Religious Freedom Restoration Act, and the Video Voyeurism Prevention Act. The TSA's removal of some body scanners from US airports in 2013 due to unresolved privacy issues further highlights the ongoing challenges in balancing security measures and privacy rights.

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