Scientists in the field of cancer research, imaging, biophysics, biochemistry, and physics sent a second letter to White House science adviser John Holdren on April 28, 2011. The scientist’s concerns for the body scanners were more extensive than just the 21 listed here.
Last year, the U.S. House voted to cut off funding for the body scanners, but the White House and the Senate did not support the measure.
Please call your congressional reps and senators (especially your senators) and your state reps and senators. Let them know that if they don’t do something to stop the dangerous x-rays scanners and pat downs you will not vote for them again. It is time to start putting the pressure on them. Plan protests outside their offices.
Scientists List Reasons They Oppose Body Scanners:
1. There is still no rigorous, independent, verified hard data for the Safety of X-Ray Airport Passenger Scanners.
2. The recently released John Hopkins report on the scanners does not hold to critical principles of scientific reporting. The document is heavily redacted with red stamps over the words and figures. In every case the electric current used which correlates one to one with X-ray dose has been specifically redacted. Thus there is no way to repeat any of these measurements.
3. The JHU (John Hopkins University) APL personnel are unnamed anywhere in the document either as experimenters or as authors. Without signatories, there is no accountability for the document.
4. The JHU APL personnel were not provided with a machine by Rapiscan.
5. The JHU APL personnel were invited to the manufacturing site to observe a mock-up of components (spare parts) that were said to be similar to those that are parts of the Rapiscan system. The tests were performed by the manufacturer using the manufacturer’s questionable test procedures.
6. The wrong ion chamber was used:
These dose rates far exceed the limits specified for the ion chambers that were used in both the JHU measurements and the field measurements using the Fluke 451 reported by the TSA. There are also issues related to the incomplete coverage of the ion chamber by the flying spot of the backscatter machine. The data given in the Johns Hopkins report indicate that there must be something wrong.
7. Information has not been provided to the public regarding the beam intensity under operational conditions at airports; Values that would be especially useful in calculating the dose.
8. The issue of software has not been addressed , a careful analysis of the source code is essential.
How was the software qualified? How do we know if there is a ‘region of interest’ when intensity, for better resolution, is increased/changed? Can the intensity of the beam on different machines/airport scanners be changed, for example? Thus, how rigorously are the values of intensity or beam current maintained or dialed up or down to adapt to particularly suspicious subjects
9. The issue of the recently disclosed patent with new capabilities, implying significant X-ray transmission capability (in addition to the backscatter mode) as well as the ability to compare stored images, which was claimed previously but was not done.
What does the new capability mean for the configuration and modalities for those X-ray airport scanners already installed? Are the intensities of the beam now changed? How can one be confident that the scanners are in a known configuration, not continually changed (changing) with different X-ray doses?
10. Independent testing is needed
The independent testing of the safety of these specific scanners has not been rigorous nor has it been held to the standards usually associated with new devices before approval for utilization in the public sector.
11. Modern molecular and cell biological studies probing health issues of whole body x-ray scanners have not been undertaken. It is still unclear how much damage to cells occurs with low dose X-rays.
Being able to demonstrate that the x-irradiation does not induce the ‘damage response’ as compared to a control sample just exposed to background radiation would establish that the machines at least do not have a high (potentially damaging) X-ray intensity.
12. With low X-ray doses, the whole body is exposed to the X-ray scanning (this will include a vast number of skin and adjacent tissue cells) and therefore many cells could, summed up in toto, be damaged.
Keep in mind that the damaged cells might be relatively rare (or organ specific), possibly amplified by drug/pharmaceutical therapy, and there will be complications because of the different genetic backgrounds
13. The X-ray airport scanners can be characterized by a high dose rate (see Peter Rez calculation, a dose rate comparable to hospital CT X-ray machines), which adds additional unknowns for the potential damage by this radiation.
In the few documented studies (for example, see Witcofski et al., J. Nucl. Med. Vol. 15, pp. 241-245, 1972), it was shown that for the same overall dose, a 2-5 fold increase in damage can result from a high dose rate (for the short exposure) compared to a reduced dose rate (at a longer exposure time).
14. Human Biological Questions for X-ray Scanners Are Still Outstanding We are still greatly concerned that not all tissues are equally exposed to the X-ray doses. We all now agree (see HHS letter) that the skin and adjacent (critical) tissues are especially exposed.
There are several potential consequences: First, ocular (corneal) lens cells never regenerate in one’s lifetime, thus are at risk for cataract and other problems. Second, there is now data that, contrary to past medical belief, X-rays will induce skin localized melanomas.
The recent paper by Brenner (Brenner, D.J., Radiology, vol. 259, pp. 6-10, 2011) again emphasizes that a significant fraction of the population (~5%) is potentially at risk for increased sensitivity to X-rays. This fraction includes people undergoing chemotherapy, previous history of cancer, germ line mutations in DNA repair genes and people who are immuno-suppressed.
15. The issue of rescanning a subject after removing a belt, or an absorptive pad which would double, treble, or quadruple the dose received by the subject.
16. The effective dose is an average where the dose in different organs is weighted. For small children, these internal organs receive a much higher proportion of entrance skin dose, and the effective dose is much higher. Radiation effects are more serious for children.
17. Critical Maintenance Issues for X-Ray Scanners
A “Worst Case Failure” mode has not been evaluated. Because these machines are scanning mechanical/software integrated devices, with very intense pencil-like beams of X-rays, if they were to stop in the middle of a scan, there is the significant probability of a radiation burn.
What are the consequences, if there were a software glitch or power, even momentary, problems? This important issue, on a machine working 24 hours a day, year in and year out, has not been studied independently and merits major efforts and extensive analysis, not just tested for failure once or twice, given the extreme consequences of a failure. The casual nature for maintenance of these devices is alarming to us. These machines are built with components from clinical X-ray machines and are capable of delivering large X-ray doses. The actual doses are undefined by any objective tests disclosed to us or to the public. Have exhaustive tests of mean time between failures for these systems been done in realistic operational settings? How often will the machines be calibrated?
18. The damage from an accidental overdose may not be quantifiable for many years after the exposure. It will be difficult to determine delayed medical consequences of overexposure. The damage may not be apparent immediately, or recognized to be caused by the extra radiation exposure
19. Hospitals usually check for problems on X-ray machines daily, but we understand that TSA will only check once a year, at best, in spite of the fact that these machines are being used 24 hours a day, 7 days a week.
20. A major untested technology is being used on a large segment of our population, and where any damage may not be apparent immediately, or recognized to be caused by the extra radiation exposure.
21. There is no ideal device for measuring the radiation dose given by backscatter X-rays, said David Brenner, director of the Columbia University Center for Radiological Research.
The machines emit a pencil beam that rapidly moves across and up and down the body, he said.
“We are one of the oldest and biggest radiological research centers in the country, and we find this to be a very hard technical problem,” said Brenner, who was not involved with the letter.
**From Propublica article
