Low-Dose Radiation Exposure Risk, Part II

Well, it’s been a while since I wrote the long, long post on WiFi Health and Safety, and there’s more to report. First, some good news:

I wrote the WiFi post because my local public school district was contemplating banning WiFi because of a small group of very concerned parents. And it was time for a technology refresh at the school (the WiFi access points were at end-of-life, and the new testing regime under the Common Core demanded more bandwidth school-wide, so the district needed to upgrade connectivity infrastructure). There were two proposals: One to do a basic upgrade of the access points and the like, the other to pull all WiFi from Ormondale Elementary (a K-3 school) and reduce it significantly for Corte Madera (a 4-8 school). The price points were very, very different. About $80k for the upgrade, and about $240k to remove WiFi and replace it with wired connections. Needless to say, sanity ruled the day and the district went with the $80k option. Some of the implementational details are, to me, a total waste of time, money and effort (like putting separate power switches for all classroom access points so that they could be “turned off” when the class wasn’t using WiFi), but the big $160k hit to our budget was avoided. (To put $160k into perspective, this would be about 1.5% of the total PVSD anual budget, or about 1.5 teacher-years of salary and benefits.) Victory for sanity!

But some very disturbing things came out of the process. One of our board members said in a meeting that he’d read many reports of harm and was convinced of danger, but when pressed, wouldn’t quote or provide a single reference (let’s just say we aren’t on each others Holiday Card list. Personally, I view this as an abdication of professional responsibility, but that’s another subject). One of the parents, a pediatric oncologist, stated that cells communicated with each other via radio waves, and that WiFi disrupts inter-cellular communication! (She’s lucky her cellular biology professors weren’t in the audience. I think they would have rescinded her degrees.) Also, the power switches for the room routers are actually bad for exposure, but no amount of explanation why would get that line item removed (for those that are curious, electronics are pretty smart now. If the access point is close, then the transceiver in the portable device runs at low gain and low power. If it can’t find a signal near by, it will just up it’s gain and broadcast power to find a more distant access point! This is why your cell phone battery drains so fast in areas with poor reception. So turning off the closest access point will INCREASE radiated intensity for the devices that are looking for connections.)

Anyway, this is now all water under the bridge. The district upgraded it’s infrastructure, most of the parents are happy, and the small part of the cost that was spent to appease those that fear WiFi was a small expense to enable progress.

ProtonTherapy
This is a gantry used to steer the proton beam for radiation therapy. This particular unit is in Switzerland, at the Proton Therapy Center of the Paul Scherrer Institute.

Even though the district had moved on, I kept my eyes open for relevant information. First off, in an article on treating radiation-resistant tumors with particle beams from Physics Today, I saw something that got me thinking…. The point of the article was that using carbon ions to target tumors resulted in better treatment due to more damage to the target DNA and less damage to surrounding, healthy cells. I found this particularly relevant because a friend of mine had recently been diagnosed with throat cancer, and was done with his surgery and was scheduled for radiation and chemo. But while the point of the article is that ion beams are much better at targeting the actual tumor, what really caught my eye was this paragraph:

Compared with protons, however, the heavier carbon ions deposit more energy in the tumor tissue, so they are considerably more destructive to the tumor. Moreover, “the lesions … you produce are predominantly double-strand breaks [to DNA] that can hardly be repaired,” says Thomas Haberer, scientific and technical director of Germany’s Heidelberg Ion-Beam Therapy Center (HIT), which began using carbon ions to treat patients in 2009. Since cells have mechanisms to repair single-strand DNA breaks, damage to both strands is required to ensure lethality. By one measure, known as the relative biological effect, carbon ions are up to three times as damaging to DNA as x rays, while protons are only modestly more lethal to the tumor than is radiation, notes James Deye, a physicist with the National Cancer Institute (NCI).

DNA is a double helix, and if there is a relatively simple break to one strand only, cells have the ability to repair the damage.  This video (from McGraw-Hill) is a bit dry, but it shows how a set of four proteins an edit out single strand damage. Repair starts to fail if there are double strand damage or the single strand damage events are too close together (what happens with high doses of things like UV light.)

The next item that caught my eye was a letter sent into Physics Today. Titled “Low-dose radiation exposure should not be feared,” the authors looked at the “Linear, No-Threshold” model of radiation-induced cancer, and found evidence going back to the original papers (from 1947) that show that the model is wrong, and there has always been a data-trail showing that evidence for low-level cellular repair exists. Even in the very same data-sets that was originally used to justify the LNT model! Their latest article is about this very issue (the data being wrongly interpreted in 1947) and will appear in the American Journal of Clinical Oncology. The full article is behind a pay wall, but the abstract can be read by anyone. But here is a quote from the abstract that really hits the nail on the head:

Yet, the persistent use of the linear no-threshold model for risk assessment by regulators and advisory bodies continues to drive an unfounded fear of any low-dose radiation exposure, as well as excessive expenditures on putative but unneeded and wasteful safety measures.

“Unneeded and wasteful” sounds like the extra $160k that my district was thinking of spending, and I’m sure it’s some of the $80k that we did actually spend. It definitely applies to the time and effort spend on even considering the perceived threat.

So, more nails in the coffin for the “non-ionizing radiation is bad” crowd. They have no model for how damage occurs. No model for how it overcomes the cellular repair mechanisms, and no good data sets showing population harms from low-level non-ionizing radiation. Yet more time, effort and expense will surely go down this rabbit hole. Time, effort and expense that could actually be spent on preventing real harms, or, in the case of our school district, be spent actually teaching our kids.

 

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