Watch: What you should know about male infertility
03:08 - Source: CNN
CNN  — 

Male sperm count has fallen by more than 50% globally in the last 50 years, leaving researchers scrambling to understand why. Could it be pollution, PFAS and other potential toxins in our food and water, an increase in obesity and chronic disease, or even the ever-present mobile phone?

A new study explored the role of cell phones and found men between the ages of 18 and 22 who said they used their phones more than 20 times a day had a 21% higher risk for a low overall sperm count. The men also had a 30% higher risk for a low sperm concentration, a less important measure of sperm count in a milliliter of semen. The study did not specify whether the men called or texted or used their phones to do both.

On the positive side, researchers found that as phone technology improved over the 13 years of the study, the impact on sperm count began to ease.

“I am intrigued by the observation that the biggest effect was apparently seen with older 2G and 3G phones compared to modern 4G and 5G versions. This is not something I am able to explain,” said Allan Pacey, deputy vice president and deputy dean of the faculty of biology, medicine and health at the University of Manchester in the United Kingdom, in a statement. He was not involved in the study.

Another plus: There was no decline in the shape and motility of the sperm, which refers to the way sperm swim to their destination, according to the study.

“Whilst sperm numbers matter, the ability of sperm to swim, have healthy intact DNA and be the right shape, is at least as important,” said Alison Campbell, chief scientific officer of Care Fertility, a network of fertility clinics, in a statement.

“This is a fascinating and novel study which should not cause alarm or drastic changes in habits,” said Campbell, who was not involved in the study. “Men looking to conceive, or wanting to improve their sperm health should exercise (but not overheat in their groin area), eat a balanced diet, maintain a healthy weight, avoid smoking and limit alcohol and seek help if they are having problems conceiving.”

An electronic field

Mobile phones have become indispensable parts of our lives. However, cell phones do emit low-level radiofrequency electromagnetic fields, or RF-EMF. If those cell phones are emitting at maximum power, the study said, surrounding tissue can be heated up to 0.5 degrees Celsius or about 33 degrees Fahrenheit.

“Cell phones are constantly sending and receiving signals and they are going to receive and send more intense signals when they’re in use,” said Dr. Alexander Pastuszak, an assistant professor of surgery and urology at The University of Utah School of Medicine in Salt Lake City.

“But especially with the modern cell phone, like that signal is going to vary depending on whether you’re talking or whether you’re sending data, said Pastuszak, who was not involved in the study.

Radiofrequency electromagnetic fields are greatly reduced when texting and highest when downloading large files, streaming audio or video, when only one or two bars are displayed, and when in a fast-moving bus, car or train, according to the California Department of Public Health.

The agency recommends keeping the phone away from the body and head — use the speakerphone or headphones instead — and carry the phone in a backpack in a backpack, briefcase or purse.

Whether those fields can actually damage male fertility, however, has been a source of controversy and debate for years in the scientific community.

Studies in mice have found RF-EMF fields at levels similar to cell phones do lower male fertility and contribute to sperm death and changes in the tissue of the testes. However, other animal studies have not replicated those effects, and there are huge differences between humans and mice in how sperm are created.

Observational studies in humans have also found that frequent use of mobile phones was connected to a decline in sperm viability as well as an impact on how the sperm swam. But those studies have been small and short. And they didn’t necessarily control for factors such as smoking and alcohol consumption, leaving many scientists unimpressed.