Another look at those airport X-rays...

"Unsafe At Any Scan?"

According to a researcher at the University of California, Davis, there could be serious health questions surrounding the use of backscatter radiation scanners (aka: "porno-scanners") now being employed at U.S. airports.

Background: Jason Bell, a molecular biologist and biophysicist working in a research lab at UC Davis, notes that the lab "(as well as many others) has spent the better part of the last decade working on the molecular mechanism of how mutations in the breast cancer susceptibility gene, BRCA2, result in cancer. The result of that work is that we now better understand that people who have a deficient BRCA2 gene are hypersensitive to DNA damage, which can be caused by a number of factors including: UV exposure, oxidative stress, improper chromosomal replication and segregation, and radiation exposure."

At his blog, My Helical Tryst, Bell has posted a detailed critique of the research on the safety of airport backscatter radiation scanners. It's "a detailed, lay-friendly explanation of the scientific concerns expressed by the [research] team that believes that they are unsafe for use. His report is, to say the least, troubling:

"[How] the scanner works: Essentially, it appears that an X-ray beam is rastered across the body, which highlights the importance of one of the specific concerns raised by [the researchers]... what happens if the machine fails, or gets stuck, during a raster. How much radiation would a person's eye, hand, testicle, stomach, etc be exposed to during such a failure. What is the failure rate of these machines? What is the failure rate in an operational environment? Who services the machine? What is the decay rate of the filter? What is the decay rate of the shielding material? What is the variability in the power of the X-ray source during the manufacturing process? This last question may seem trivial; however, the Johns Hopkins Applied Physics Laboratory noted significant differences in their test models, which were supposed to be precisely up to spec. Its also interesting to note that the Johns Hopkins Applied Physics Laboratory criticized other reports from NIST (the National Institute of Standards and Technology) and a group called Medical and Health Physics Consulting for testing the machine while one of the two X-ray sources was disabled (citations at the bottom of the page).

These questions have not been answered to any satisfaction and the UCSF scientists, all esteemed in their fields and members of the National Academy of Sciences have been dismissed based on a couple of reports seemingly hastily put together by mid-level government lab technicians. The documents that I have reviewed thus far either have NO AUTHOR CREDITS or are NOT authored by anyone with either a Ph.D. or a M.D., raising serious concerns of the extent of the expertise of the individuals and organizations evaluating these machines. Yet, the FDA and TSA continue to dismiss some of the most talented scientists in the country...

Furthermore, when making this comparison, the TSA and FDA are calculating that the dose is absorbed throughout the body. According the simulations performed by NIST, the relative absorption of the radiation is ~20-35-fold higher in the skin, breast, testes and thymus than the brain, or 7-12-fold higher than bone marrow. So a total body dose is misleading, because there is differential absorption in some tissues. Of particular concern is radiation exposure to the testes, which could result in infertility or birth defects, and breasts for women who might carry a BRCA1 or BRCA2 mutation. Even more alarming is that because the radiation energy is the same for all adults, children or infants, the relative absorbed dose is twice as high for small children and infants because they have a smaller body mass (both total and tissue specific) to distribute the dose. Alarmingly, the radiation dose to an infant's testes and skeleton is 60-fold higher than the absorbed dose to an adult brain!

"What happens to a chromosome of a normal cell when it is exposed to radiation. It most cases, this damage is repaired; however, at high doses or when there is a genetic defect, the cells either die or become cancerous."

(Huge h/t: Boing Boing)