A few months after the Cleveland Clinic published its initial study on cell phone use and sperm, lead researcher Ashok Agarwal followed it up with a related experiment. He took 32 sperm samples -- 23 from healthy men and nine from men with existing infertility problems -- and divided them into a test group and a control group. Samples from both groups were stored in identical environmental conditions, except that the test group sat 0.98 inches (2.5 centimeters) away from a cell phone in talk mode. After just an hour of radiation exposure, the test group exhibited a 7 percent decrease in sperm motility and an 11 percent drop in the number of living sperm [source: Raymond]. Moreover, that same test group showed an 85 percent jump in the production of unstable atoms called free radicals.
Agarwal's sample size is too small to draw definitive conclusions, but he suspects that the thermal effect of cell phone radiation may have caused the negative sperm reaction. Muscle, tissue and fat help insulate the body from the thermal effect, but the eyes and the testes are more generally exposed and susceptible due to relatively low blood flow to those areas [source: Krewski et al]. And while the legal cell phone radiation limit (SAR) set by the Federal Communications Commission (FCC) is considered well below the thermal effect threshold, researchers at the Finnish Radiation and Nuclear Safety Authority found that the radiofrequency waves can nevertheless impact human cell behavior. In their study, researchers noted that exposure to the non-ionizing waves affected the expression of two types of proteins [source: New Scientist].
Over the past decade, cell phones have come under additional scrutiny, with researchers linking them to higher incidence rates of cancers, brain tumors, sleep disturbances and other disorders. But the U.S. Food and Drug Administration (FDA), which partners with the FCC to monitor cell phone radiation, maintains that mobile devices are safe. In addressing the issue of cell phones and health problems, the FDA contends that studies have merely established a correlation instead of a verifiable causation.
The $30 million Interphone study on the health effects of cell phones aptly illustrates how the correlation-causation debate has muddied the waters. Fifty scientists in 13 countries examined the frequency of cell phone use and the health conditions of 14,000 participants [source: The Economist]. After six years, the results were about as fuzzy as old-school analog reception.