Category Archives: Brain Cancer

Biden’s ‘Cancer Moonshot’ Turns Toward Pollution

Ariel Wittenberg and Nico Portundo, E&E News: February 3, 2022


President Biden made an emotional pledge yesterday to “end cancer as we know it” by reinvigorating the Cancer Moonshot initiative he first launched in 2016, just one year after his son Beau succumbed to the disease.

“I committed to this fight when I was vice president. It’s one of the reasons, quite frankly, why I ran for president,” Biden told a room of cancer patients, survivors, caregivers, researchers and advocates.

A lot has changed since Biden first launched the program. This moonshot doesn’t come with any new funding, for example, but the White House says recent progress in cancer therapeutics, diagnostics and patient-driven care, as well as public health lessons learned during the Covid-19 pandemic, mean the initiative can be successful.

Another change in the renewed moonshot: an acknowledgment that environmental exposures can cause cancer.

While the previous Cancer Moonshot largely focused on funding research for treatments and cures for cancer, the renewed effort—whose goal is to reduce cancer death rates by 50 percent in the next 25 years — includes multiple initiatives to prevent cancer.

That includes addressing pollution.

“President Biden described seven areas of focus in which to make progress to end cancer as we know it today,” White House Cancer Moonshot Coordinator Danielle Carnival told E&E News in a statement. “Cancer prevention is one of those pillars and limiting exposure to carcinogens is an important part of preventing cancer.”

[….]

Though many in the environmental health field have long understood that chemical exposures can cause cancer and change peoples’ cancer outcomes, that fact hasn’t always been acknowledged by the broader medical community, which has focused more on genetic causes (Greenwire, May 4, 2021).

Linda Birnbaum, who formerly lead the National Institute of Environmental Health Sciences, told E&E News that she “tried really hard” to get the agency involved in the first moonshot initiative but was met with resistance from the National Cancer Institute.

“Environment is just not something they think about,” she said. “I’m glad to see it is at least mentioned this time.”

[….]

‘Just one sentence’

Indeed, cleaning up pollution is just one part of one of the new moonshot’s goals, which also include diagnosing cancer sooner, preventing cancer, addressing inequities, targeting the right treatment for each patient, and ramping up progress against rare and childhood cancers, among other things.

Environmental health experts were quick to note that merely acknowledging chemicals’ impact on cancers is only a first step, and say that the administration would have to do a better job at curbing pollution in order to truly “end cancer as we know it.”

In all of the pomp and circumstance surrounding the new moonshot’s launch, the experts note that environmental factors were mentioned just once in a fact sheet, and not at all in remarks from the president, vice president or first lady. Rather, much of the White House material on cancer prevention focuses on whether the mRNA technology used in Covid-19 vaccines to teach the immune system to respond to the virus could also teach bodies to stop cancer cells when they first appear.

“mRNA technology, yes, let’s spend as much money as we can to try and develop that vaccine, and maybe it will work,” said Diana Zuckerman, president of the National Center for Health Research. “But if you really wanted bang for your buck, you would want to look at environmental issues where prevention will really improve peoples’ health and reduce cancers, and that’s just one sentence here.”

Julie Brody, executive director of the Silent Spring Institute, said she wanted the moonshot to “take a bigger approach to prevention and environmental chemicals in particular,” citing a “revolution in how we think about causes of cancer” since the previous moonshot was launched.

[….]

But when White House officials discussed cancer prevention in a call with reporters earlier this week, environmental issues didn’t come up at all.

“We know cancer is a disease where we have too few effective ways to prevent it,” said one senior administration official. “There are some: don’t smoke, for example. But we don’t have lots of effective ways right now to prevent cancer.”

American Lung Association Senior Vice President for Public Policy Paul Billings agrees that there’s not one chemical like tobacco that could be the focus of prevention efforts. But, he said, “If you really want to end cancer as we know it, we do need to deal with things like environmental exposures.”

[….]

To read the entire article, click here.

Children and Cell Phones: Is Phone Radiation Risky for Kids?

Hannah Kalvin

Children use cell phones to watch TV, play games, make phone calls, and send text
messages.  Many older kids and teens have their own cell phones, which they are attached to kid texting24/7. But are there risks to such frequent use by children, and if so is that different than the risks for adults?

Cell phones emit a type of radiation that is known as Radio Frequency-Electromagnetic Radiation (RF-EMR), also referred to as microwave radiation. There have been concerns from the scientific community about whether or not cell phones are safe. Cancer is a particular concern, but since cancers take 10-20 years to develop and children’s frequent cell phone use is a relatively recent development, there are more questions than answers.  To read more about whether we should be worried about cell phone radiation in general, read our article here.

There are several studies of the impact of cell phone radiation on children. Here are some of the conclusions so far:

  • A 2010 study of cell phone radiation noted that, “in general and on average, children suffer a higher exposure of their brain regions than adults.”  This is because children have proportionally smaller heads and brains, yet receive the same levels of cell phone radiation as adults.1 The American Academy of Pediatrics agrees, saying that “when used by children, the average RF energy deposition is two times higher in the brain and 10 times higher in the bone marrow of the skull, compared with mobile phone use by adults.”2
  • Another study found that people who begin using cell phones (and cordless landline phones) before the age of 20 are at an even higher risk of developing brain tumors than people who begin using these wireless phones as adults.3,4 This is because of the closer proximity of the source of radiation to the brain of kids (they have thinner tissues and bones than adults).
  • Research also suggests that cell phone exposure could affect children’s behavior.5 The children in the study who were hyperactive or had emotional or behavioral problems, including trouble getting along with other kids, were much more likely to have mothers who used cell phones during pregnancy. After accounting for other factors that could affect behavior, the children of these mothers were 80% more likely to have behavioral problems than children whose mothers rarely or didn’t use cell phones. However, this is difficult to study because mothers who use cell phones frequently during pregnancy or after the baby is born, may pay less attention to their children, resulting in the children’s bad behavior. More research is needed to understand the link between mother’s cell phone use and children’s behavior.
  • Children that used cell phones more were more likely to have ADHD. Although the link to ADHD was only for children who also had high levels of lead in their blood, when researchers adjusted for blood lead level, they still found that ADHD was more likely for children who made more phone calls and spent a longer amount of time on the phone.6 This study was conducted in Korea, so it would be important to do similar research on children living in other countries.
  • A 2014 article reviewing studies on children and their cell phone use found that the younger the child, the greater the risk of brain cancer and brain tumors. The same article also points to studies concluding that cell phones are associated with an increased risk of breast cancer (due to adolescents putting cell phones in their bras), parotid (salivary) gland tumors, and sperm damage for adolescents and adults.7

Reactions To Research About Cell Phone Radiation

In 2012, the American Academy of Pediatrics wrote a letter to the Federal Communications Commission, which sets the standards for cell phone radiation in the United States, and recommended that they reevaluate these standards since this had not been done since 1996. Their reasoning is that “children, however, are not little adults and are disproportionately impacted by all environmental exposures, including cell phone radiation.”2 But, as of 2015, the FCC still says that there is no evidence between wireless device use and health problems and continues to uphold the regulations from 1996.8 Other countries have taken a different approach. As of 2014, Turkey, Belgium, Australia, and France have warned about the dangers of children’s cell phone usage.7

 

Conclusions

Scientists disagree on whether cell phone radiation can cause cancer or other health problems.  Since so many children and adults use cell phones so frequently, that makes it difficult to do a study comparing high and low cell phone usage.  And since brain tumors and other cancers usually do not develop until several decades after the initial exposure, it could be years before we know how risky cell phones are and under what circumstances.7

By the time we find out, many people will have been harmed if cell phones are found to be dangerous. Here are some precautionary tips on how to protect your children from the health issues that could be connected to cell phone radiation.9

  1. Turn airplane mode on when giving a child a technology device or when a cell phone is near a pregnant abdomen, to prevent exposure to radiation.
  2. Turn off wireless networks and devices to decrease your family’s radiation exposure whenever you aren’t actively using them. As an easy first step, turn your Wi-Fi router off at bedtime.
  3. Decrease use of phones or wifi where wireless coverage is difficult, in order to avoid an increase in radiation exposure.
    The warning about RF exposure found on an iPhone 5s.
    The warning about RF exposure found on an iPhone 5s.
  4. Use the speaker phone or a plug in earpiece when you use a cell phone. To protect children from radiation, they should not use cell phones except in emergency and should use the speaker phone.
  5. Increase the distance between you and your cell phone whenever it is on, to reduce your exposure to radiation emitted. For example, do not use a cell phone while a child is on your lap, and do not carry your cell phone in your baby carrier, crib, or pockets. When the phone is on, tell your kids to put it in a backpack as far from their body as possible (such as an outside pocket) or on the desk or other furniture at home, instead of holding it or carrying it in a pocket.
  6. Read the fine print: All device manufacturers advise that cell phones should be at least 5 millimeters, or about ¼ of an inch away from your body or brain. With the iPhone 6 and the iPhone 6s, the company advises users to keep the cell phone at least 10 millimeters, or about half an inch, away from your body or brain. See the safe distance for your phone. For iPhone 5 and iPhone 6, this is located under: Settings -> General -> About -> Legal -> RF Exposure.
  7. Share this info with your friends, family, and schools so that they can make these simple changes as well.

 

All articles on our website have been approved by Dr. Diana Zuckerman and other senior staff.

Can cell phones harm our health?

By Diana Zuckerman, PhD, Brandel France de Bravo, MPH, Dana Casciotti, PhD, Megan Cole, MPH, Krista Brooks, BS, Hannah Kalvin

You’ve probably heard about news stories claiming that “cell phones are dangerous” and others claiming that “cell phones have been proven safe.” It’s hard to know what to believe-especially when we’ve grown so dependent upon these convenient communication devices.

Should We Be Worried?

Have you ever read the fine print in your cell phone manual? All manuals say not to hold cellphonethe phone next to your ear, but how many of us actually talk on cell phones while holding them an inch away?

There have been concerns, from both scientists and the media, that cell phone usage is linked to tumor development. The extensive use of cell phones is a relatively recent phenomenon, and since cancers usually take at least 10-20 years to develop, it will be years before research is likely to conclude whether cell phones cause cancer or not.  In addition, the long-term risks of cell phone use may be much higher for children than adults.

International organizations have been researching this issue. The International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), brought together scientists, including those with financial ties to cell phone companies, to review all relevant data on radiation from wireless handheld devices such as cell phones. This type of radiation is known as Radio Frequency-Electromagnetic Radiation (RF-EMR), also referred to as microwave radiation.  The IARC concluded that the evidence suggests this radiation is “possibly carcinogenic to humans,” and that there wasn’t enough research evidence to conclude that cell phones are dangerous or that they are safe.10

This resulted in the IARC creating the Interphone Project, an international effort (that did not include the United States) to investigate the risk of tumors from cell phones. After the 10-year project was finished in February 2012, scientists found that due to biases present in the study, no strong conclusions could be made.11

The Centers for Disease Control and Prevention, or CDC, called for caution in cell phone use because of “the unresolved cancer question” in 2014. However, the CDC removed this statement from their website soon after.12 Critics assume it was removed because of political pressure from cell phone companies. Currently, the CDC says that more research is needed on this topic since “there is no scientific evidence that provides a definite answer.”13

What Does Research Tell Us About Cell Phones, Tumors And Other Health Issues?

In 2007, a published review of 18 studies of cell phones and brain tumors, concluded that studies of individuals using cell phones for more than 10 years “give a consistent pattern of an increased risk for acoustic neuroma and glioma,” with the risk being highest for a tumor on the same side of the head that the phone is used.14 Gliomas are the most common cancerous brain tumor, and most gliomas are malignant (and usually fatal). Acoustic neuromas are benign tumors of the acoustic nerve that can cause deafness.  In 2012, the same authors reviewed even more studies and also conducted a meta-analysis that combined the results of all the studies. These analyses confirmed the 2007 conclusions about the increase in acoustic neuromas and gliomas.15 However, a study conducted in 2013 found that while long-term cell phone use was associated with acoustic neuromas, it did not predict gliomas.16 In contrast, a study of 1,339 cell phone users, published in 2014, found that the heaviest cell phone users had an increased chance of developing gliomas.  These heaviest users, who had a total of over 900 hours of cell phone usage, were found to have spent an average of 54 minutes on the phone per day.17 Although the results of studies on the effects of cell phones are inconsistent, probably related to how the time spent on cell phones is increasing over time, there is a trend toward showing that cell phone usage is associated with brain tumors.

A 2015 study in Germany also identified a connection between cell phone radiation and tumor growth. Researchers found that in comparison to a known cancer-causing agent, weak cell phone signals were more likely to promote tumor growth. Although this study was carried out in mice, it implies that cell phone radiation may negatively affect human health more than previously thought and that limits for cell phone radiation need to be lower.18

Scientists in countries around the world have published their own results on other health problems that appear to be a result of increasing cell phone usage. the following health problems connected to cell phone radiation:

  • salivary gland tumors19,20
  • dizziness and migraines21
  • less sleep and poor sleep quality22
  • increases and decreases in production of specific proteins in human cells23
  • decreased sperm count and quality24,25,26
  • skin irritation, especially on the face (this is a condition known as electrohypersensitivity)27,28
  • behavioral problems and increased chance of cancer tumor development in children. You can read more about this here.

Meanwhile, cell phone companies continue to insist that the evidence shows that their cell phones are safe. Cell phone companies tend to draw conclusions based on the studies they funded themselves, and those studies have always found cell phones are safe.   In addition, many of those studies were conducted years ago, when cell phone usage was much lower for the average person than it is today.

Controversies On Cell Phone Research Results

Underlying the controversy about cell phone radiation is the belief by most physicists that cell phone radiation could not possibly cause cancer.  Although epidemiological research seems to suggest otherwise, that is undermined by other factors: cancer takes a very long time to develop, cell phone technology and frequency of usage has changed dramatically, and any link between cancer and cell phones could possibly be caused by unknown exposures or traits.  Additionally, there is potential for biases and errors in the collection of data in these studies, which could result in inaccurate conclusions. For example, many researchers questioned the Interphone study because they thought that risk was underestimated. Research is needed to determine the true effect of cell phones on different cancers.

Different Types Of Studies: How Can Researchers Get To The Bottom Of This?

There is a consensus among researchers that retrospective studies present problems and that prospective studies are needed. Retrospective studies are ones that look back in time to study or measure risk, such as whether past cell phone use makes a person more likely to develop cancer or other health problems. But people may not remember their past behaviors accurately and researchers have no way to verify the information.  Unless they use phone records, retrospective studies are also subject to “recall bias,” which means people with a disease might remember the past differently than people without a disease. In the case of cell phones, people with brain tumors may exaggerate their past cell phone use in an attempt to find an explanation for the inexplicable.  An analysis published in 2015 shows that information used for many retrospective studies may not be reliable because numerous brain tumor cases are not reported to the Swedish Cancer Register, the database that has commonly been used to try to disprove any connection between cell phones and tumors.29

Prospective studies are ones that follow people over time and monitor the health problems that arise in the different groups during the study period.  A prospective study of cell phone users would have to compare the health of infrequent users (controls) to heavy users (cases) but it is becoming increasingly difficult to find people who never use cell phones. In addition, any study started now would take at least 10 years to have useful information about the development of cancer; by that time, millions of people would have been harmed if cell phone radiation is dangerous.

Wireless technologies are proliferating daily, and different countries have different limits on radiation from wireless devices, which is why more and better designed research is urgently needed to determine safe levels of exposure.  And yet, as noted above, it is increasingly difficult to design and conduct studies that will answer key questions anytime soon.

Precautions You Can Take

Scientists recognize that most people are not going to stop using cell phones. Since many studies suggest that there may be risks, experts recommend that cell phone users take some precautions:

  • Limit the number of calls you make.
  • Limit the length of your calls.
  • Use hands-free devices (wired cell phone headsets or wireless ones like Bluetooth).
  • If you are not using a hands-free device, put the cell on “speaker phone” or hold the phone away from your ear.
  • When speaking on your cell phone, alternate sides.
  • Avoid carrying your phone in your pocket, on your belt, or anywhere close to your body since cell phones emit radiation even when they are not in use
  • Limit your cell phone use in rural areas or in any place where reception is poor. More radiation is emitted when you are farther from a cell phone tower.
  • Text message instead of talking (never while driving!).
  • Check out how much radiation your phone emits by looking at its SAR (specific absorption rate), which is a measure of the amount of radiation absorbed by your body. When buying a new phone, try to select one with a lower SAR. A list of cell phones with the lowest SARs can be found here. But remember, these SARs are based on a six foot tall, 200 pound man with an 11 pound head, and the levels are higher for smaller people.

In summary, although not enough time has passed for research to agree on the exact impact of cell phones on brain tumors and other health risks, the evidence so far suggests that we should be cautious.  While hands-free driving laws are resulting in greater use of ear pieces in cars, more and more people are opting not to pay for land lines and are relying exclusively on their cell phone.  As a result, adults and children are holding cell phones to theirs ears for hours each day.

Should we be concerned?  Remember that most published studies evaluated relatively infrequent cell phone usage and that research is inadequate to draw conclusions regarding safety. The health impact of the long-term and frequent use of cell phones that is typical today could be substantially worse.  And, if there is a cancer risk, we won’t see the effects of cell phone use on cancer rates for another 10-20 years.  That is why it is important that researchers who do not have financial ties to cell phone companies continue long-term studies with more appropriate measures of high, medium, and low cell phone usage.  In the meantime, you can play it safe and limit your cell phone use.

 

Airport Security and Radiation

Laura Covarrubias, Cancer Prevention and Treatment Fund

Following the September 11th attacks in 2001, the Transportation Security Administration (TSA) was created and given responsibility for protecting the public from security threats in transportation systems, such as airports. Although metal detectors were once the main security devices used at American airports, the TSA introduced new technologies after terror attempts were made using hidden explosives (in shoes and underwear, for example). These backscatter and millimeter scanners have begun replacing metal detectors and are designed to scan a person to determine what weapons or explosives they may have beneath their clothing. Currently, there are about 250 backscatter and 264 millimeter wave scanners in the United States. The TSA hopes to have 1,800 scanners of either type installed by the end of 2014 – which would mean that nearly every airport in the country will have one.

Backscatter scanners look like two large blue boxes. People raise their arms and stand sideways between these two boxes when they are scanned.

In contrast, millimeter wave scanners look like circular glass phone booths, and the person being scanned stands with their arms raised while part of the scanner rotates around them:

If you are not sure which scanner is in use at your airport, ask a TSA official at the security checkpoint.

Privacy

When a millimeter scan is used, the machine determines if the person has any potentially harmful items on his or her body. If so, only the outline of a standard human body is shown with potentially dangerous objects highlighted in yellow. If no dangerous objects are detected, the security officer will only see an empty green screen. The security official does not see an image of the actual individual when the millimeter scan is used.

In contrast, when a backscatter scan is used, a blurred, colorless image of the individual (without clothing) is produced. A security officer views the image and determines if further screening is necessary. In an effort to increase passenger privacy, the TSA updated the software on backscatter machines to make it harder to see details in the images. Still, some people argue that both types of machines violate their privacy.

Radiation

While metal detectors and millimeter scans both use non-ionizing radiation, which until recently was assumed to be safe (see our article Can Cell Phones Harm our Health?), backscatter scans use ionizing radiation, which is used in x-rays and known to potentially increase the risk of cancer. Backscatter scans work a little differently from x-rays. X-rays work by sending high-energy radiation to the body and recording the radiation that passes through the body. Dense parts of the body (like bones) block some of the radiation, resulting in lighter areas on the recorded image.  Backscatter scanners also send radiation toward the body, but at much lower energy than an x-ray. Because it is not as strong as the radiation used in x-rays, the radiation does not pass through the body. Instead, the outer layers of the body “scatter” the radiation, which bounces off the body and back toward the machine. Most of the radiation that is absorbed by the body is deposited in the outer layers (like the skin and ribs), although a 2012 study showed that radiation from these scans may penetrate to other organs.[1] Because the radiation is concentrated in the skin, there are concerns that this could cause skin cancer.

All data on backscatter scans are provided by TSA, a government agency that does not allow independent researchers to examine the machines they use.[2] Researchers must therefore make educated guesses using data provided by the TSA, or they must make models of the scanners based on information that the agency releases.

Scientists differ in their opinions regarding whether small doses of radiation increases the risk of cancer.[3] Some scientists think that very small doses-like those received during backscatter scans-pose zero risk to the individual. Other scientists think that there isn’t enough research on the effects of such low doses of radiation to be able to say how it will affect a person’s cancer risk. However, radiation risk accumulates during a person’s lifetime. This means that even though a single exposure may be very small, it is “added” to every other exposure the person has ever encountered.

The TSA states that backscatter scans use such low doses of radiation that estimating the potential effects of the scan is extremely difficult. [4] 2011 report using information from the TSA found that these backscatter scans expose people to the same amount of radiation that they receive from 3 to 9 minutes of normal daily life or from 1 to 3 minutes of flight. To put this into perspective, we would expect only 6 of the 100 million airline passengers each year to develop a cancer in their entire lives due to the backscatter scans.

Dr. David Brenner, a researcher at Columbia University, produced a different estimate based on the risk that the scanners are to the entire population, not just to an individual. Dr. Brenner multiplied the risk associated with one scan by the number of scans conducted each year to estimate the number of people who may develop cancer in one year because of the scanners. Because up to one billion scans may be performed each year, Brenner estimated that each year 100 people would develop cancer because of their exposure.

In April 2010, a group of scientists from the University of California, San Francisco wrote a letter of concern to Dr. John Holdren, the Assistant to President Obama for Science and Technology, about the backscatter scans. These researchers pointed out that because backscatter scans only penetrate outer layers of the body, it is possible that these layers receive a higher concentration of radiation than previously believed. Because of this, conventional estimates would be inaccurate.[5] This higher concentration of radiation could pose particular risk to certain groups such as:

  • The elderly (due to their susceptibility to skin cancer)
  • Women who have the BRCA gene mutation
  • People with weakened immune systems (such as those with HIV or cancer)
  • Children and adolescents (who have smaller bodies but receive the same amount of radiation as adults with larger bodies)5

The scientists also expressed concern that sperm may mutate because the testicles are close to the surface of the skin and are exposed to radiation during these backscatter scans. In addition, they noted that the effects of radiation on the cornea (the outer surface of the eye) and the thymus (a part of the immune system located in the chest) have not been studied. While this letter only outlined concerns of the scientists and did not present new data, it called for further testing of backscatter scans. The scientists called for more rigorous and independent studies to ensure that the scans are safe for the entire population, as well as for all parts of the body. When Dr. Holdren received the letter, he sent it along to the Food and Drug Administration (FDA). The Food and Drug Administration does not have authority to regulate backscatter scanners because the devices are classified as electronic devices, not medical devices. However, the FDA has experience in regulating radiation-emitting devices used in medicine, such as mammography devices. In a joint reply with the TSA, the FDA stated that the radiation exposures from the backscatter scans were within established legal limits, even for frequent fliers.[6] In reply to the scientists’ concerns that the radiation dose to the skin would be higher, the FDA wrote that their calculations showed that a person would have to pass through the scanner 1000 times in a year in order to begin to absorb the annual limit of what is considered safe.[7]

Not everyone agrees with the FDA, and some people have pointed out that TSA agents operating the scanners may improperly manage the devices or that mechanical errors may occur, either of which could cause the machines to emit more radiation than they are supposed to. From May 2010 to May 2011, there were 3,778 calls for mechanical problems on backscatter machines, but only 2% of those machines were evaluated for radiation safety. Anyone who is concerned about the radiation from the scanners has the legal right to refuse to undergo a scan, as long as they agree to a full-body pat-down by a security officer.

For more information on other types of radiation, see our article Everything You Wanted to Know About Radiation and Cancer, But Were Afraid to Ask.

References:

  1. Schmidt T, Hoppe M. Estimation of organ and effective dose due to Compton backscatter security scans. Medical Physics. 2012;39(3396).
  2. Mehta P, Smith-Bindman R. Airport full-body screening: what is the risk? Archives of internal medicine. 2011;171(12):1112-5. Available at: http://www.ncbi.nlm.nih.gov/pubmed/21444831. Accessed March 17, 2012.
  3. Brenner DJ. Are x-ray backscatter scanners safe for airport passenger screening? For most individuals, probably yes, but a billion scans per year raises long-term public health concerns. Radiology. 2011;259(1):6-10. Available at: http://www.ncbi.nlm.nih.gov/pubmed/21436091
  4. Cerra F. Assessment of the Rapiscan Secure 1000 Body Scanner for Conformance with Radiological Safety Standards. 2006. Available at: http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:Assessment+of+the+Rapiscan+Secure+1000+Body+Scanner+for+Conformance+with+Radiological+Safety+Standards#0. Accessed June 18, 2012.
  5. Sedat J, Agard D, Shuman M, Stroud R. Letter to Dr. John P. Holdren. 2010.
  6. Rabin R.C.. X-Ray Scans at Airports Leave Lingering Worries. The New York Times. August 6, 2012. Available at http://well.blogs.nytimes.com/2012/08/06/x-ray-scans-at-airports-leave-lingering-worries/. Accessed August 7, 2012.
  7. McCrohan J, Shelton Waters K. Letter to Dr. John P. Holdren. 2010.