An under-the-radar Israeli study, published late last year, provides relatively strong evidence that some cell phone usage can and will affect men’s sperm counts. Specifically, the study found that it’s dangerous to use your phone in the following ways: For more than one hour per day, fewer than 50 centimeters from your groin, and while it’s charging.

People have wondered and scientists have debated about the effect of cell phone usage on general well-being for as long as the devices have existed. Is my phone giving me brain cancer? If I overuse a cell phone, will it harm my reproductive capacities? The definitive answers to these questions, taken literally, have long eluded scientists. (The figurative answer to both questions is a resounding yes.) Each year, it seems, a new group of scientists exclaims that they’ve settled the debate once and for all.

And so it goes with Ariel Zilberlicht et al.: They think they’ve got some proof that cell phones are at least in part responsible for the apparent, recent, “continuous decline in semen quality” in recent history.

But all this back and forth is not necessarily due to bad science, nor is it necessarily due to eager-to-publish scientists. The direct impacts of cell phone usage are, simply, hard to study, hard to isolate. There are too many other factors that could — or do — contribute to, in this case, the rise in male infertility. If you’re a smoker, your sperm are going to suffer. If you live in an overpolluted city, your sperm are going to suffer. If you consume too many soy products, your sperm are going to suffer. And if you wear tight underwear or pants, your sperm are going to suffer. Et-freaking-cetera.

In this study, though, the scientists argue that they were rigorous in eliminating variables. They trimmed the sample size down to about 100 men to ensure comparability between the subjects: heavy smokers, for example, were exempted from the study. (Since the study was so small, but the findings so dire, the scientists concluded that “large-scale studies” are now required.) Each participant responded to a survey that gave the scientists a comprehensive understanding of each’s cell phone usage habits, and then, after collecting samples, the scientists were able to draw some conclusions.

And the results? Men who talked on their phone for more than one hour per day and while it charged had almost “higher rates of abnormal sperm concentration.” The rate for less-avid phone diddlers was 35.7 percent, while the rate for the overly-talkative men was 60.9 percent. For men who tended to use their phone within 50 centimeters of their groins, the difference was more striking: 47.1 percent for those who did, and a mere 11.1 percent for those who did not.

This apparent cell phone-induced spermicide, if legitimate, must be a result of radio frequency electromagnetic radiation (RF-EMR). If RF-EMR is responsible for the rise in male infertility, the most logical explanation — even though it sounds unlikely — is that it’s an effect of temperature. Unlike ionizing radiation (from x-rays, nuclear fallout, and so on — the serious stuff), RF-EMR does not directly mess with molecules and DNA. RF-EMR does, however, raise temperatures. (Microwaves provide heat with a more intense version of a cell phone’s EMR.)

Testicles, needless to say, are sensitive. Get them a little too hot on a regular basis — in other words, use your cell phone within 50 centimeters of your groin for more than an hour a day and while it’s charging (which increases the radiation) — and your sperm will … suffer.

Photos via Getty Images

Joe is a writer from Vermont who lives in Brooklyn. He has written for PopSci and McSweeney’s Internet Tendency and spent a year playing with words and other writers’ dreams at Tin House in Portland, Oregon.