While cellphones make communication easier and more convenient, the radiation from the devices can be dangerous, according to a new report.

» RELATED: Have a cell phone against your ear? Consider putting it down

Researchers from the National Toxicology Program recently conducted a study, which originated under the Clinton administration, to explore the link between cellphones and brain cancer.

To do so, they examined 30,000 rats and mice that were exposed to radiation nine hours a day for two years. The exposures began before birth and continued until they were about 2 years old.

After analyzing the results, they found that 2 to 3 percent of the male rats exposed to radiation developed malignant glioma, a deadly brain cancer. They also discovered that 5 to 7 percent of the male rats exposed to the highest level of radiation developed heart tumors. There was no apparent association between radiation and tumors among the female rats.

"We believe that the link between radio frequency radiation and tumors in male rats is real, and the external experts agreed," coauthor John Bucher said in a statement.

» RELATED: Sugar causes cancer cells to multiply, study says

However, the scientists explained the radiation levels and durations the animals were exposed to were far greater than what humans typically encounter. For their study, they assessed radio frequency radiation used in 2G and 3G devices made in the 1990s. Current cellphones use 4G technology, which doesn’t penetrate the body nearly as much.

“The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone,” Bucher said. “In our studies, rats and mice received radio frequency radiation across their whole bodies. By contrast, people are mostly exposed in specific local tissues close to where they hold the phone. In addition, the exposure levels and durations in our studies were greater than what people experience.”

The researchers now hope to continue their investigations, using newer technologies that will make it easier to evaluate data in weeks or months as opposed to years.

Want to learn more about the findings? Take a look at the full assessment here.

» RELATED: Junk food linked to higher risk of cancer, study says

About the Author