On November 22, 2010, the New York Times published another one of those “protect the children” articles that quotes professional critics, plays on fears and perpetrates the journalistic assumption that the general public should be protected from math and numbers at all costs. The article, titled Radiation Worries for Children in Dentists’ Chairs describes how some dentists and some medical equipment vendors are encouraging the use of “cone beam scanning” technology that can produce detailed, three dimensional images of jaws, whole mouths or even whole heads.
According to the proponents, the tools are simple to use, dramatically reduce the time required in the chair and produce far more accurate results than other alternatives. According to the critics, the dentists who use the tools are at a comparable level of sophistication with shoe salesmen who used fluoroscopes to measure feet in the 1950s and they are guilty of exposing children to “dangerous” amounts of radiation. The authors of the article come down firmly on the side of the critics and paint the proponents of using the diagnostic tools as being firmly captured by profit-hungry corporations.
The more I read, the more angry I became at the lack of balance and the lack of real information that can help nervous mothers (and there are lots of them reading the New York Times) make good decisions for themselves and their children. Though I am sympathetic to the idea that some corporations will go to great lengths to sell tools that have questionable utility (like full body scanners at airports), I love human creativity and problem-solving.
There are many tools in modern society that I would hate to do without. I am writing this post on one of those tools – a fast computer with a 24″ flat panel display connected to the Internet at 3 Mbps. I would have loved it if the dental clinic where I received my exit physical from the Navy had a “cone-beam CT scanner” that required a single exposure lasting about a minute instead of the half dozen or so old fashioned x-rays that the technicians decided they needed for a full evaluation of my dental health.
Of course, I know that too much radiation can be hazardous; I am a trained radiation worker and once served as the Chemistry and Radiological Controls Assistant. I also know that the dose makes the poison – so I kept wanting to know how big the doses were. The article did not provide a single number or an actual unit of measure. Instead, it relied on weak comparisons and opinions on the level of “it’s safe” and “no it’s not.” It also mentioned that the devices emitted more concentrated radiation, but did not help readers to understand the overall effect on total dose from shorter periods of exposure.
The article itself was in a portion of the Times that does not accept comments, but there was an accompanying New York Times Well blog post titled Radiation in the Dentist Chair written by Tara Parker-Pope that invited a discussion about the article. Here is how that post started:
A new scanning device that emits significantly more radiation than conventional methods is gaining popularity among dentists despite the potential risks to young patients, an examination by The New York Times has found.
I read through some of the comments – which was a frustrating experience – and decided to add one of my own. Here is what I said:
I found myself hoping to see some numbers somewhere in the article so that I could better understand the scale of the potential risk. Sadly, there was not a number in the article nor any discussion about rem, sieverts, grays or any other unit of radiation exposure.
Though many radiation protection practitioners continue to assert – without evidence – the assumption that every dose of radiation poses a risk, study after study has provided real world evidence that there is a dose below which there appears to be either a tiny amount of risk, no risk or even beneficial effects known as hormesis.
The level below which there is no risk is several orders of magnitude higher than what people get from the proper use of medical tools like cone beam scanners that require only brief periods of exposure. A full head shot apparently gives a tissue weighted dose of about 210 micro Sv. (http://bjr.birjournals.org/cgi/content/full/82/973/35)
In units more familiar to US radiation workers, that is about 21 millirem. The radiation dose level at which there is some evidence that increased doses lead to increased harm is about 5,000 millirem per year. It would take about 230 full head shots from a modern cone beam scanner to reach that level. (Note: The numbers in the preceding paragraph were corrected on 11/24/2010 at 0826. The initial conversion of microsieverts to millirem was incorrect by a factor of 100.)
This result should surprise no one who understands that some sunlight is vital to life; too much can cause skin cancer. Some amount of most vitamins and minerals improve human health; overdoses can kill. Moderate exercise is healthy; overdoing it can cause early death or break down even the strongest physiques.
The link below leads to a book whose cost does not make it readily accessible to the general public, but it is a book that would make excellent reading for reporters of a major publication like the New York Times as they try to understand a bit more about how radiation affects humans. It is an incredibly important topic.
It is worth recognizing that consultants who are paid to perform studies by the European Commission, vendors of fast film that costs “pennies” more than slower film, and a doctor who runs a company that contracts with states to “keep dental radiation in check” are not exactly disinterested critics. They certainly have the right to criticize, but they are professionals who stand to make more money and obtain more work by hyping their criticism and inflating fears.
Finally, for those people who want dentists to simply work harder or longer and use tools that are “perfectly safe” but take 30 times as long, take a look around the world. There are billions of people who could use the services of well trained dentists. I like the idea of safe tools that allow them to see more patients every day and that have the potential for reducing costs.
Publisher, Atomic Insights
Host and producer, The Atomic Show Podcast