Chances are, you have a cellphone within inches of you. Maybe you're reading this story on one or you recently made a call or sent a text.

There are a whopping 6.9 billion mobile phones in the world, according to the World Health Organization. Obviously, we need and depend on our phones, but there's still the nagging question of safety.

A court in Italy awarded a 57-year-old man a state-funded pension of $500 a month in early 2017 after he said excessive cellphone use for his job caused a brain tumor. Roberto Romeo said he had to use his phone for four hours a day for 15 years.

While the court seemed to acknowledge at least a casual link between cellphones and health risks, scientific studies have been somewhat inconclusive.

Cellphones and cordless phones use radiofrequency radiation (RF) to send signals. Radiofrequency energy is a form of electromagnetic radiation, which can be either ionizing or non-ionizing, reports the National Cancer Institute. Ionizing radiation includes X-rays, which have been proven to be harmful; but the evidence is still iffy on non-ionizing rays.

CNN's Dr. Sanjay Gupta, a neurosurgeon, has long been outspoken about his use of a headset for his cellphone. "Non-ionizing radiation won’t strip electrons or bust up DNA. It's more like very low power microwaves," he says. "Short term, these microwaves are likely harmless, but long term could be a different story. Anyway, who likes the idea of a microwave, even a low-powered one, next to their head all day?"

In 2016, researchers at the U.S. National Toxicology Program exposed rats to RF radiation for about nine hours a day, seven days a week. The study found that the rats were more likely to develop brain and heart cancers. In contrast, the control rats were not exposed to RF, and none of them developed any tumors.

Although a study on rats doesn't directly translate to humans, it does give researchers more evidence when studying the effect of RF on people.

In the past, other studies have produced conflicting results:

  • Recent research and reviews have questioned whether non-ionizing radiation from cellphones may indeed damage DNA. A study on rats in May 2016 found that there was more DNA damage in those that received the highest radiation levels, reports Science magazine. A 2015 analysis of peer-reviewed scientific literature found that RF has damaging effects in living cells including oxidative damage of DNA.
  • A consortium of researchers from 13 countries looked at data from questionnaires filled out by cellphone users. Most analyses showed no increase in brain or central nervous system cancers in relation to higher cellphone use.
  • A cohort study out of Denmark compared records for 358,000 cellphone subscribers to brain tumor information from a national cancer registry. It found no association between cellphone use and various cancers.
  • Two studies in Sweden found an increase in brain cancer risk for people who started using cellphones before age 20.

The National Cancer Institute points out that research can be inconsistent due to various factors including inaccurate reporting, the changes in types of cellphones, and the fact that brain cancers are difficult to study because mortality rates are so high.

Because of conflicting studies, the WHO classifies RF as "possibly carcinogenic to humans."

California issues guidelines

woman's hand near cellphone and pillow The California Department of Public Health suggests keeping your cellphone out of your bed. (Photo: Niran Phonruang/Shutterstock)

With the caveat that the scientific community is undecided on the dangers, the California Department of Public Health released guidelines in December 2017 for people who want "to reduce exposure to radio frequency energy" from cellphones.

"Although the science is still evolving, there are concerns among some public health professionals and members of the public regarding long-term, high use exposure to the energy emitted by cell phones," said CDPH Director and State Public Health Officer Dr. Karen Smith in a statement. "We know that simple steps, such as not keeping your phone in your pocket and moving it away from your bed at night, can help reduce exposure for both children and adults."

The guidelines include:

  • Keep cellphones away from the body. Use headsets instead of holding the phone to your head to talk. Keep the phone in a backpack or purse, not in a pocket or belt holder.
  • Use your phone less when the signal is weak. Cellphones put out more RF energy to connect when you see only one or two bars.
  • Reduce the use of cellphones to stream audio or video, or to download or upload large files. Download them first, then switch to airplane mode when watching or listening to them.
  • Don't sleep with your phone in your bed or near your head.
  • Remove headsets when you're not on a call.
  • Avoid products that claim to block RF energy. They may force your phone to work harder to stay connected and actually increase your exposure.

A potential solution

Researchers at Drexel University and the Korea Institute of Science & Technology may be on to something. The team has manufactured a nanomaterial made out of a thin layer of MXene, which will protect a device from "electromagnetic pollution." That's the electric interference coming out of phones, televisions and other devices.

The material protects gadgets by effectively blocking electromagnetic waves emissions.

"To have all these electronic components working without interfering with each other, we need shields that are thin, light and easy to apply to devices of different shapes and sizes. We believe MXenes are going to be the next generation of shielding materials for portable, flexible and wearable electronics," said lead author Yury Gogotsi, Ph.D.

We wondered if the next step could be protecting humans in the same way, but that will require more research. In the meantime, if you're concerned about radiation, the Centers for Disease Control and Prevention recommends you use a speakerphone or wired headset as much as possible.

Editor's note: This story has been updated with new information since it was originally published in September 2016.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.