Despite fears among some people that using cellphones can lead to cancer from exposure to radiation, two recent government studies have found the ubiquitous devices are safe to use.

After exposing rats and mice to extremely high doses of cellphone radiation, scientists found only a weak link to a rare type of heart tumor in some male rats. Female rats were unaffected, as were mice in a separate study. Scientists with the National Institute of Environmental Health Sciences found no evidence linking cellphones to brain tumors. The male rat heart tumor issue does not translate to a concern for humans, they added.

While the animal studies do not fully represent cellphone use by humans, the researchers noted they did not find any indications that the devices could be linked to higher risks of cancer. Previous studies found no cause for concern, and the researchers did their latest work in order to test higher doses of cellphone radiation than could be experienced by humans.

During the research, mice and rats were exposed to nine hours of cellphone radiation. The constant radiation used on the animals was at a level that cellphone users would only experience briefly under transient conditions. The rats exposed to the radiation actually lived longer than those that were not exposed, something that scientists were unable to explain.

The research was funded by the U.S. Food and Drug Administration, which deemed the current safety limits for cellphones acceptable in light of the latest findings.

So, go ahead, make those calls. The biggest hazards of an unlimited calling plan might just be a stiff neck and a sore jaw.