Men who use their cell phones frequently have lower sperm counts than men who don’t, according to new research published in Fertility and Sterility on Tuesday, offering a fresh insight into a decades-long mystery of falling sperm counts and rising infertility that has baffled experts and sparked a global fertility crisis.
Between 2005 and 2018, Swiss scientists at the University of Geneva and the Swiss Tropical and Public Health Institute recruited 2,886 men aged between 18 and 22 from military conscription centers and asked them to keep track of their mobile phone use, as well as other information on their lifestyle and general health.
Scientists checked the quantity and quality of study participants’ sperm and analyzed data to see whether mobile phone use was linked to changes in sperm count, an important measure of fertility.
Men who used their phones more than 20 times a day had significantly lower sperm counts and sperm concentrations—a less important but still useful metric than total sperm count—than men who only used their phones once a week, the researchers found, a difference of around a fifth for both measurements.
Overall, the researchers said men who used their phones 20 or more times a day had a 21% higher risk of having a low overall sperm count that fell below the World Health Organization’s reference values for fertile men compared to those who rarely used their phones.
The regular phone users also had a 30% higher risk for low sperm concentrations below the WHO benchmark, the researchers said, adding that sperm count was higher for less frequent users and fell as usage climbed.
The research also suggests that where phones are kept when not in use—such as trouser pockets, belt carriers or jacket pockets—does not impact sperm concentration or sperm count, though Rita Rahban, one of the researchers leading the trial, said it was difficult to draw a “really robust conclusion on this specific point” as most participants carried phones close to their bodies.
What To Watch For
The study is observational in nature and the researchers stressed it cannot definitively point to cell phone usage as a cause for lower sperm counts, though they did try to account for other factors that could do so like lifestyle. In order to measure the impact of electromagnetic waves and the different types of phone use—such as calls, internet browsing and sending messages—the researchers have just launched a new trial that will record data more precisely using a smartphone app. They are actively recruiting for participants to get involved.
The link between phone use and sperm count became less pronounced over the course of the study, the researchers said. This decreasing association happened in stages that corresponded to the transition from 2G to 3G networks and from 3G to 4G networks, said Martin Roosli, an associate professor at Swiss Tropical and Public Health Institute involved in the research. The energy involved in sending and receiving phone signals, which could cause heating, is believed to be one possible reason why phones might impact sperm quality. As more modern networks use less power to transmit signals, the transitions to 3G and 4G “led to a reduction in the transmitting power of phones” and possibly reduced one of the potential factors influencing lower sperm count, Roosli explained. The impact of phones’ reduced transmission power will likely increase as newer networks spread and with the advent of new telecoms technology, the researchers said, calling for more research to better understand the impacts this may have on health and fertility.
Sperm counts have been falling for decades. Scientists are not clear why, and amid signs the decline is accelerating, have warned a fertility crisis is looming on the horizon. One study estimates total sperm counts, which affect the chances of conception, have fallen as much as 62% between 1973 and 2018. Various features of modern life have been posited as potential causes, for which there may not be one, including pollution, alcohol and drug use, increasing temperatures due to global warming, stress, poor diet, sedentary lifestyle and exposure to chemicals like pesticides. Not all scientists agree that sperm counts are falling, however, and the issue is not settled. Even in scientific settings, sperm counts can be notoriously hard to measure with precision and the many factors that can impact sperm count can vary greatly across cultures—such as underwear choices—and can be hard to account for in studies.
Are Sperm Counts Really Declining? (Scientific American)