A paper delivered at the annual meeting of the American Society for Reproductive Medicine is being reported to say that there is an apparent dose response relationship between cell phone and sperm counts, i.e., the more hours spent on the phone each day the lower sperm count levels.
Scientists in Cleveland, Mumbai and New Orleans tracked 364 men who were being evaluated for infertility, and split them into three groups based on sperm count. In the group whose sperm counts were within the normal range, those who used a cell phone more than four hours a day produced on average 66 million sperm per milliliter, 23 percent less than those in the group who didn’t use the phones at all.
The proportion of the cell-phone users’ sperm that possessed “normal forms” was 21 percent, almost half the 40 percent of normal sperm produced by men who didn’t use the phones, said the researchers, who presented their conclusions this week in New Orleans at the annual convention of the American Society for Reproductive Medicine. (Bloomberg)
Since this is a news report it isn’t clear exactly what was found, for example, is this an estimate from a regression, is this the actual difference between the high and how groups, or what, and whether there was adequate adjustment for confounding and all the other qualifiers one worries about in such observational studies.
Over the years we have frequently been asked about the health effects of cell phone towers, especially those built in close proximity to schools or residences. In general it has been our view that the non-ionizing radiation from those tower transmitters falls off so rapidly there is not much exposure to the surroundings.
On the other hand, we have always been cautious about the other transmitter — the one you hold in your hand when talking. The antenna from that transmitter, though of much lower power, is right up against your skull, so exposures are much greater than from a tower. Whether that has anything to do with the results of this study remains to be seen.
There are three possible generic explanations for the reduced sperm parameters. One is that there was some kind of sytematic error in how the data was collected produced that the results. This is called “bias” by epidemiologists, although it is not meant to indicate lack of objectivity. Systematic error is in contrast to random error, the differences produced by the luck of the draw when sampling from a population where sperm parameters vary a great deal (which is usually the case). It could have happened that by chance more of the naturally low sperm count males also used cell phones. We usually evaluate this via statistical tests. The news story had no information on what tests, if any, were done on these data. Third, it could be that using cell phones in some ways impairs sperm growth and development. This is the most interesting but least desirable outcome.
Regarding the third possibility we need to have some mechanism that could produce this outcome. The radiofrequency radiation from the cell phone handset is non-ionizing, that is, it is not the kind of radiation we think of when we talk about nuclear events or radioactive materials. It has been demonstrated, however, that non-ionizing radiation can produce subtle biological effects, whose significance is not understood. The male gonads are too far away from the transmitter for us to think there is substantial exposure, but one might posit some effect on circadian rhythms (maybe Scibling Coturnix of A Blog Around the Clock has some thoughts on this; he’s the expert and I’m just making this up) or some interference in the hypothalamic – gonadal axis, wherein the brain affects the testes via hormones. If this effect is real — and that is a very big if at this point — it is not obvious what the mechanism would be. Local heating doesn’t seem plausible.
If this does turn out to be a real effect, the cell phone companies are in big trouble. Most males will take a cavalier attitude to the remote possibility they will develop cancer in thirty years, but if you suggest, however indirectly, that their balls are going to shrivel up and drop off . . .