Q:Are there any harmful side effects from the routine use of x-ray by dentists to examine teeth for cavities or from the lamps used to harden non amalgam fillings? P.S., Bristol....
A:Run, don't walk, to your bookstore to pick up Stephen Fulder's How to be a Healthy Patient (reviewed on the opposite page). It's worth the price (£5.99) just to read the extensive section on x-ray treatments and their risks.According to Fulder, all x-rays are "very high frequency waves which have so much energy that they crash through living tissues like birdshot through a bush." Depending on how dense the tissues are, the body retains some of this radiation those absorbed rays are what gets recorded on the film as white or grey. The ones that "crash through" hit a plate of photographic film and show up as dark grey or black. Besides mammograms, bone x-rays and dental x-rays, the newest kind of x-rays include CAT scans, in which a moving beam of x-rays creates a three dimensional picture, usually of the brain, and fluoroscopy, which sends the x-ray shadow picture onto a television screen. Occasionally contrast mediums like dyes or barium are used to make a clearer picture.
Although the newest equipment uses lower and more precisely targeted doses, there is no such thing as a safe x-ray. That goes for dental x-rays too. Fulder reprints a highly valuable chart compiled by the Health Research Group listing the dosage of millirads for each type of x-ray, with the equivalent dosage the entire body gets zapped with and even the likely number of deaths from each million examinations.
Topping the list are x-rays of the upper intestines, which give an equivalent dose to the entire body of 400-800 millirads; besides the other organs, the next highest is the spine (100-500 millirads); stomach, breasts and pelvis (100-200 each); skull or shoulder rates (25-75), chest (20-60) with whole mouth dental x-rays taking up the rear at 10-30 millirads.
To put those numbers in context, a single shot of the intestines, says Fulder, quoting the US National Academy of Sciences, is the equivalent of smoking five to 20 cigarettes a year, in terms of cancer risk. And each million single examinations is likely to cause 30 to 100 deaths. In case you're feeling complacent about that low dosage from dental x-rays, one single photograph of your mouth is like smoking half a cigarette every day for a year. Each million shots is likely to cause between two and six deaths. Even the American Dental Association now maintains, says Fulder, that x-rays shouldn't be used unless there is "reasonable expectation of benefit" to the health of the patient.
Obviously there are times when x-rays are invaluable particularly when limbs are first broken (though many doctors insist on constant new shots to check progress of healing). The biggest problem is the cumulative effect of x-rays on the body. According to Sobel and Ferguson in The People's Book of Medical Tests (an excellent source book from Simon & Schuster, 1230 Avenue of the Americas, NY, NY 10020), an x-ray harms people in three ways. First, it can damage individual cells (although the harm caused by the lower doses is usually quickly repaired). Rarely (but depending on exposure), this damage can convert the cell to a cancer cell. Second, if a woman is pregnant, it can injure the developing foetus, causing death or malformations. Finally, x-rays can injure the sperm or ovaries of children or adults, causing abnormalities in future generations. So anyone planning to have children should keep x-ray exposure to an absolute minimum, for only those cases when there is a genuine problem to be investigated.
For people in this category those x-rays with the highest exposure of the reproductive organs include: abdominal x-rays, arteriograms, barium enemas, body CAT scans, x-rays of the urethra, hip and thigh x-rays, and x-rays of the uterus, lymphatic system, back and spine.
Fulder provides a wonderful checklist in his book about how to avoid unnecessary radiation. Basically it boils down to: if there isn't a problem, you don't need an x-ray. In sum he suggests you avoid:
Routine dental examinations if there aren't specific problems to be checked out.
Exams being done by your doctor as "just in case" measures to avoid a malpractice suit or to convince him or you that there's nothing there.
Routine examinations requested for jobs, insurance, or institutions or the army. This includes such things as a "routine" chest x-ray.
Then if you must have an x-ray, make sure, says Fulder, to:
Insist on a lead apron, even when your dentist shoots your teeth. That lead apron ought to be large enough to cover your reproductive organs and also the thyroid and thymus glands in the neck, which are also sensitive. I suffered the derision of my dentist for years in insisting on a lead apron in the States. If your dentist doesn't have one, you can buy one from a medical supply company and cart it with you to the dentist. Remember, he oftentimes goes out of the room when he switches the button or lets his dental hygienist get zapped by the radiation.
* Make sure to obey instructions (and have the operator do so as well) to avoid having to have a re-take.
* Keep a record of all your x-rays and those of your children.
* Never have an x-ray if you could be, or are, pregnant. Best times for women to have an x-ray are during or just after your period. Children who are smaller, and thus more vulnerable over a larger part of the body to x-rays, should especially be protected.
* Try to have a necessary x-ray done with one of the new lower dose machines (which has a rectangular opening, rather than the old plastic cone variety).
* Take vitamins C and E, selenium, and the amino acids cysteine and glutathione, which have been shown to protect against radiation.