Fiber Optics Goes to Our Heads
Now that quantities of research have been applied to the problem, it sometimes seems as if anything people eat, drink, breathe, or think about affects their chances of developing cancer. Recently, a scientist bumped into an odd finding that might add one improbable item to the list: Having gray hair may increase your cancer risk.
Wait, don't panic. First, nobody knows for sure. It's only a possible implication of an interesting development that turned up quite incidentally in the course of unrelated work. That's a far cry from an identified hazard. So take this odd little report as--at worst--a cautionary tale.
The apparently outrageous suggestion comes partly from the technology known as fiber optics, which has given us better communication using light, but it stems mostly from the curiosity of a British scientist who studies ways of measuring radiation doses received by animals.
The scientist, John Wells of Berkeley Nuclear Laboratories, has been investigating ways to use plucked hairs as a biological radiation dosimeter. According to the magazine Science News, Wells uses fluorescent dyes, various kinds of illumination, and microscopes in his studies. He even offers up his own hair to his work, and he's getting to an age when some of that hair is silvery.
Using one of those gray hairs plucked from his own crown, he snipped it into a quarter-inch specimen and mounted it through a chunk of cardboard for examination under his microscope. On a whim, he did not illuminate the sample from above, as he usually did. He turned on lights under the microscope stage--and discovered that the hair was a veritable light-pipe. "Light just shot out the end of the hair, he said.
Most of us have seen this phenomenon in a kind of novelty lamp sold more for decoration than illumination. The lamp has a light source hidden at the base of a solid fountain of string-sized transparent glass fibers. When the lamp is turned on, the fibers seem to stay dark, but their ends glow brightly. The array of gleaming dots looks eerie, but is perfectly reasonable given the nature of the glass fibers and the behavior of light. A working optical fiber only needs to be acceptably transparent with an index of refraction higher than that of the medium surrounding it--that is, when light travelling along a fiber hits its edge, it reflects inward rather than passing outward into the air. The light can escape only at the fiber's end.
What Wells found in his gray hair wasn't exactly like a glass-fiber lamp. No light comes through the core of the hair, but a great deal pours through the hair's middle section, between the core and the surface layer. The scaly surface seems to trap the contained light quite well, since little escapes out the sides. Under the microscope, the cross section of Wells' hair looked like a glowing oval doughnut.
At least his gray hairs did. Sacrificing some of his brown hairs for science, he found that the melanin pigment that gave them color absorbed light so well that little or none came through.
The possible connection with cancer enters the picture because visible light may not be the only kind that our head-covering optical fibers can carry. If silver hair sends solar ultraviolet radiation down below the protective surface of the scalp into what we call the roots, the dermal layer of the skin where the hair bulbs lie, then gray-haired people would have more danger of developing the type of skin cancer known as basal cell carcinoma. That's nasty stuff, and its association with ultraviolet exposure is well known.
The question awaits investigation, as Wells says (though not by him; perhaps to preserve his remaining hair of whatever color, he's returned to full-time consideration of biological dosimetry). If there really is any hazard, a hat should defuse it. The good news is that graying people who've yeamed to retum their hair to its youthful color now have a splendid reason to do so. It's not for vanity; it's preventive medicine.
